Enhanced Li-Ion Diffusion and Cycling Stability of Ni-Free High-Entropy Spinel Oxide Anodes with High-Concentration Oxygen Vacancies : Bin Xiao, Gang Wu, Tongde Wang, Zhengang Wei, Zelin Xie, Yanwei Sui, Jiqiu Qi, Fuxiang Wei, Xiahui Zhang, Lin-bo Tang, and Jun-chao Zheng;  ACS Appl. Mater. Interfaces 2023, 15, 2, 2792–2803 (https://doi.org/10.1021/acsami.2c12374)

Abstract

High-entropy oxide (HEO) is an emerging type of anode material for lithium-ion batteries with excellent properties, where high-concentration oxygen vacancies can effectively enhance the diffusion coefficient of lithium ions. In this study, Ni-free spinel-type HEOs ((FeCoCrMnZn)₃O₄ and (FeCoCrMnMg)₃O₄) were prepared via ball milling, and the effects of zinc and magnesium on the concentration of oxygen vacancy (O_V), lithium-ion diffusion coefficient (D_Li⁺), and electrochemical performance of HEOs were investigated. Ab initio calculations show that the addition of zinc narrows down the band gap and thus improves the electrical conductivity. X-ray photoelectron spectroscopy (XPS) results show that (FeCoCrMnZn)₃O₄ (42.7%) and (FeCoCrMnMg)₃O₄ (42.5%) have high O_V concentration. During charge/discharge, the O_V concentration of (FeCoCrMnZn)₃O₄ is higher than that of (FeCoCrMnMg)₃O₄. The galvanostatic intermittent titration technique (GITT) results show that the D_Li⁺ value of (FeCoCrMnZn)₃O₄ is higher than that of (FeCoCrMnMg)₃O₄ during charge and discharge. All of that can improve its specific discharge capacity and enhance its cycle stability. (FeCoCrMnZn)₃O₄ achieved a discharge capacity of 828.6 mAh g^–1 at 2.0 A g^–1 after 2000 cycles. This work provides a deep understanding of the structure and performance of HEO.

Selecting the Optimal Fluorinated Ether Co-Solvent for Lithium Metal Batteries: Chi-Cheung Su, Khalil Amine, Mei Cai, and Meinan He;  ACS Appl. Mater. Interfaces 2023, 15, 2, 2804–2811 (https://doi.org/10.1021/acsami.2c13034)

Abstract

To guide the selection of a suitable fluorinated ether (FE) co-solvent for lithium metal batteries, it is crucial to understand the relationship between the organic structures of the FEs and the electrochemical performance of an FE-containing electrolyte. In this work, 1,1,2,2-tetrafluoro-1-(2,2,2-trifluoroethoxy)ethane (FEE), 1,1,2,2-tetrafluoro-3-(1,1,2,2-tetrafluoroethoxy)propane (TTE), and 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane (OFDEE) were chosen as representative FE co-solvents because of their distinct structural properties. The structure–activity relationship between the FEs and the electrochemical performance of Li||LiNi_0.6Mn_0.2Co_0.2O₂ (Li||NMC622) cells was correlated and quantified by Fourier-transform infrared and multi-dimensional nuclear magnetic resonance techniques. Sand’s model was also employed to assess the extent of lithium dendrite formation in the cells using various FE electrolytes. The cycling performance of Li||NMC622 cells using different FE co-solvents follows the order FEE > TTE > OFDEE. Since the direct measurement of Sand’s time is difficult, we introduced relative Sand’s time to probe the diffusion behavior of each electrolyte, and the results showed that the best performance was obtained in the electrolyte with the longest relative Sand’s time. Moreover, the lithium metal cell using the electrolyte with FEE co-solvent showed similar capacity retention compared with the baseline electrolyte at room temperature, but it demonstrated significantly improved low-temperature performance. The results indicate that FEE is a promising co-solvent candidate for improving the low-temperature performance of lithium metal batteries because it possesses not only non-solvating behavior but also very low viscosity and non-flammability. The advanced electrolyte LiPF₆-FEC-DMC-FEE enables very stable cycling of lithium metal batteries at various temperatures.

Improving Separation Efficiency in End-of-Life Lithium-Ion Batteries Flotation Using Attrition Pre-Treatment. Anna Vanderbruggen , Aliza Salces , Alexandra Ferreira, Martin Rudolph  and Rodrigo Serna-Guerrero; Minerals 2022, 12(1), 72; https://doi.org/10.3390/min12010072

Abstract

The comminution of spent lithium-ion batteries (LIBs) produces a powder containing the active cell components, commonly referred to as “black mass.” Recently, froth flotation has been proposed to treat the fine fraction of black mass (<100 µm) as a method to separate anodic graphite particles from cathodic lithium metal oxides (LMOs). So far, pyrolysis has been considered as an effective treatment to remove organic binders in the black mass in preparation for flotation separation. In this work, the flotation performance of a pyrolyzed black mass obtained from an industrial recycling plant was improved by adding a pre-treatment step consisting of mechanical attrition with and without kerosene addition. The LMO recovery in the underflow product increased from 70% to 85% and the graphite recovery remained similar, around 86% recovery in the overflow product. To understand the flotation behavior, the spent black mass from pyrolyzed LIBs was compared to a model black mass, comprising fully liberated LMOs and graphite particles. In addition, ultrafine hydrophilic particles were added to the flotation feed as an entrainment tracer, showing that the LMO recovery in overflow products is a combination of entrainment and true flotation mechanisms. This study highlights that adding kerosene during attrition enhances the emulsification of kerosene, simultaneously increasing its (partial) spread on the LMOs, graphite, and residual binder, with a subsequent reduction in selectivity.

Confusion between Carbonate Apatite and Biological Apatite (Carbonated Hydroxyapatite) in Bone and Teeth; Tetsuro Kono, Toshiro Sakae, Hiroshi Nakada, Takashi Kaneda and Hiroyuki Okada:  Minerals 2022, 12(2), 170; https://doi.org/10.3390/min12020170

Abstract

Biological apatite in enamel, dentin, cementum, and bone is highly individualized hydroxyapatite with high tissue dependency. Often, standard and average textbook values for biological apatite do not apply to actual subjects, and the reported results of analyses differ among investigators. In particular, the term biological apatite is often confusingly and incorrectly used to describe carbonate apatite. The purpose of this review is to prevent further confusion. We believe that apatite should be well understood across disciplines and the terminology clearly defined. According to a definition by the International Mineralogical Association’s Commission on New Minerals Nomenclature and Classification, biological apatite formed by living organisms is a type of hydroxyapatite. More specifically, it is carbonated hydroxyapatite, which is quite different from frequently misnamed carbonate apatite. We hope that this definition will be widely adopted to remove confusion around the naming of apatite in many research and applied fields.

Anionic Redox Chemistry for Sodium-Ion Batteries: Mechanisms, Advances, and Challenges. Quan Wu, Tong Zhang, Jiarun Geng, Suning Gao, Hua Ma, and Fujun Li, Energy Fuels 2022, 36, 15, 8081–8095 https://doi.org/10.1021/acs.energyfuels.2c01601)

Abstract

The increasing reliance on energy demands has called for continual improvement of sodium-ion batteries (SIBs) due to the abundant Na resources and low cost. Na-based layered transition metal oxides (TMOs) are promising cathode materials due to their unique structural characteristics that provide two-dimensional (2D) ion diffusion channels and maintain structural integrity during the extraction and insertion of Na-ions. However, the energy density of conventional TMO cathodes is mainly limited by cationic redox reactions. Activating anionic redox (O^2–/O^n–) for additional capacity in TMO cathodes is promising to improve the energy density of SIBs, though the chemistry of anionic redox reaction (ARR) is still unclear. This overview focuses on the underlying science, development, and latest advances of ARR in SIBs. The challenges and possible approaches are discussed in light of ARR reversibility and voltage hysteresis. This review will provide insights on improving the energy density of advanced TMOs cathodes with ARR activity.

Utilization of Biomass for Iron Ore Sintering: Niesler, M., Kawaguchi, Takazo, J.Stecko; ISIJ International  2023, 53 (9), 1599-1606; DOI: 10.2355/isijinternational.53.1599

Abstract

Decrease of carbon dioxide emission is a serious subject in the steel works. Utilization of biomass as a carbon-neutral agent is an attractive one for iron ore sintering. Sinter pot tests were carried out with using raw biomass and biomass carbonized char. It is not good on yield and exhaust gas that raw biomass is used directly as carbon material for iron ore sintering. While, it is good on the productivity and the exhaust gas (NOx, SOx, dust, dioxins) that biomass carbonized char is used as carbon material. With using biomass char for the sintering, it is necessary to optimize operation (size control and moisture control of the biomass char), because combustion rate of the biomass char is too high. Biomass carbonized char is evaluated on sinter yield as similar as anthracite or coke. The biomass char is effective to decrease CO2, NOx, SOx, dust etc. emission in sinter exhaust gas.

Study of Dendromass Ashes Fusibility with the Addition of Magnesite, Limestone and Alumina: Pavol Vadász , Beatrice Plešingerová , Dávid Medved’ , Gabriel Sučik , Radka Bakajsová  and Vladimír Petrov: Minerals 2023, 13, 631 (https://doi.org/10.3390/min13050631)

Abstract

The fusibility of ash from woodchip combustion is characterised in the present work. The impact of the increase in MgO, CaO, and Al2O3 content in the bio-ash on the classification of ash into categories according to slagging and fouling indices was evaluated. The ash was characterized based on the chemical composition using slagging and fouling indices. However, these ash composition changes did not assign the ash into categories of the indices FU, SR, RS, and B/A (fouling, slagging, slag viscosity, basicity), with less ash inclination to slagging and fouling. The indices were primarily derived for ashes from coal combustion. The indices values characterizing the ash were compared with measured results of ash melting according to STN ISO 540. The measured ash fusibility values showed that the addition of magnesite, limestone, and alumina to dendro-ashes increases the DT (temperature of deformation), HT (temperature of hemisphere), and the AFI (ash fusibility index). There is no conformity between the values of the indices and the measurement of ash fusibility temperatures. In terms of temperatures in the combustion chamber, the measured sintering (Tsin) and DT are suitable for evaluating the tendency of ash to slagging and fouling as well as an accretion of ash particles sticking to the lining.

Can Weathering of Banded Iron Formations Generate Natural Hydrogen? Evidence from Australia, Brazil and South Africa: Ugo Geymond, Erick Ramanaidou, Dan Lévy, Abderrahim Ouaya and Isabelle Moretti; Minerals 2022, 12(2), 163; https://doi.org/10.3390/min12020163

Abstract

Oxidation of iron-rich rock is known to generate H₂ in oceanic as well as in continental domains. Here we tested the possibility of H₂ generation as the result of weathering of banded iron formations (BIF). The BIF constitute more than 60% of global iron ore reserves with low Fe³⁺/Fe_tot and total Fe ranging from 20 to 40 wt% and are therefore good candidates for H₂ production potential. In the vicinity of BIF-hosted iron mines in Australia, Brazil and South Africa, satellite imaging has revealed the presence of sub-circular depressions that usually are the proxy of H₂-emitting features. A morphological comparison of the sub-circular depressions with the ones observed in previous studies point to probable H₂ seeping in these areas. In parallel, a petrological study conducted on altered and fresh BIF samples from the Hamersley Province in Western Australia also suggests H₂ generation during BIF weathering. Indeed, mineral transitions from ferrous silicate (riebeckite and/or minnesotaite) to ferric iron oxi-hydroxides (goethite) or from ferrous and ferric oxides (magnetite) to exclusively ferric oxides (maghemite, hematite, goethite) were observed on the samples. The oxidation of ferrous iron by aqueous fluids circulating through and leaching the BIF is promising for H₂ generation. The BIF weathering profile suggests that the limiting factor is the presence of water, and that this reaction is happening at, or near, surface temperature. This challenges the idea that high temperatures are required to generate H₂ as it is the case during the serpentinization. The link between BIF and H₂ will have however to be further investigated to better constrain the reactions and their kinetics.

Crystal Engineering in Antisolvent Crystallization of Rare Earth Elements (REEs): Jonathan Sibanda, Jemitias Chivavava and Alison Emslie Lewis; Minerals 2022, 12(12), 1554; https://doi.org/10.3390/min12121554

Abstract

Antisolvent crystallization is a separation technology that separates the solute from the solvent by the addition of another solvent, in which the solute is sparingly soluble. High yields are achieved by using higher antisolvent-to-aqueous ratios, but this generates higher supersaturation, which causes excessive nucleation. This results in the production of smaller particles, which are difficult to handle in downstream processes. In this work, the effect of varying the organic (antisolvent)-to-aqueous (O/A) ratio and seed loading on the yield, particle size distribution, and morphology of neodymium sulphate product, during its recovery from an aqueous leach solution using antisolvent crystallization, was investigated. A batch crystallizer was used for the experiments, while ethanol was used as an antisolvent. Neodymium sulphate octahydrate [Nd₂(SO₄)₃.8H₂O] seeds were used to investigate the effect of seed loading. It was found that particle sizes increased as the O/A ratio increased. This was attributed to the agglomeration of smaller particles that formed at high supersaturation. An O/A ratio of 1.4 resulted in higher yields and particles with a plate-like morphology. The increase in yield was attributed to the increased interaction of ethanol molecules with the solvent, which reduced the solubility of neodymium sulphate. Increasing the seed loading resulted in smaller particle sizes with narrow particle size distribution and improved filtration performance. This was attributed to the promotion of crystal growth and suppression of agglomeration in the presence of seeds.

Global Trend for Waste Lithium-Ion Battery Recycling from 1984 to 2021: A Bibliometric Analysis : Yaoguang Guo, Yujing Liu, Jie Guan, Qianqian Chen, Xiaohu Sun, Nuo Liu, Li Zhang, Xiaojiao Zhang, Xiaoyi Lou and Yingshun Li;  Minerals 2022, 12(12), 1514; https://doi.org/10.3390/min12121514

Abstract

With the massive use of lithium-ion batteries in electric vehicles and energy storage, the environmental and resource problems faced by used lithium-ion batteries are becoming more and more prominent. In order to better resource utilization and environmental protection, this paper employs bibliometric and data analysis methods to explore publications related to waste lithium-ion battery recycling from 1984 to 2021. The Web of Science core set from the SCIE online database was used for this article. These findings demonstrate a considerable increase trend in the number of publications published in the subject of recycling used lithium-ion batteries, with a natural-sciences-centric focus. Argonne National Lab, Chinese Academy of Sciences, and China Academic and Scientific Research Center are the top three institutions in terms of quantity of papers published. The affiliated journals corresponding to these three institutions also have high impact factors, which are 106.47, 44.85, and 58.69, respectively. In comparison to comparable institutes in other nations, the American Argonne National Laboratory supports 223 research articles in this area. China and the US make up the majority of the research’s funding. The two key aspects of current lithium-ion battery recycling research are material structure research and environmentally friendly recycling. Nevertheless, high-capacity lithium-ion batteries, waste lithium-ion integrated structures, and gentle recycling of spent lithium-ion batteries will be the major aspects of study in the future. It is hoped that the above analysis can bring new ideas and methods to the field of waste lithium-ion battery recycling and provide a basis for the subsequent research and application of waste lithium-ion battery recycling.

Recovery of Rare Earth Elements from Mining Tailings: A Case Study for Generating Wealth from Waste: Luver Echeverry-Vargas a Luz Marina Ocampo-Carmona; Minerals 2022, 12(8), 948; https://doi.org/10.3390/min12080948

Abstract

The growing demand for rare earth elements (REE) driven by their applications in modern technologies has caused the need to search for alternative sources of these elements as their extraction from traditional deposits is limited. A potential source of light rare earth elements (LREE) may be the monazite present in the mining waste generated in the Bagre-Nechí mining district in Colombia due to the processing of sands containing alluvial gold. Consequently, in this research, a systematic evaluation has been carried out for the extraction of Ce, La and Nd from a leach liquor obtained from monazite present in alluvial gold mining tailings. The leaching process carried out with HCl indicated the recovery of approximately 90% of La and Nd and ∼60%∼60% of Ce; the solvent extraction tests of these elements showed that increasing the contact time and pH of the leaching liquor positively affects the extraction of lanthanum, cerium, and neodymium, achieving extractions close to 100% with D2EHPA2 and to a lesser extent with Cyanex572. McCabe–Thiele diagrams for extraction with D2EHPA2 indicated the requirement of three stages for the extraction of Ce, La and Nd.

Understanding Bubble-Induced Overpotential Losses in Multiphase Flow Electrochemical Reactors: Andrea E. Angulo, Daniel Frey, and Miguel A. Modestino; Energy Fuels 2022, 36, 14, 7908–7914 (https://doi.org/10.1021/acs.energyfuels.2c01543)

Abstract

Green hydrogen production via water electrolysis can play a significant role in decarbonizing energy and multiple industrial processes. In this electrolysis process, water molecules are oxidized to produce oxygen in the anode, while protons are reduced to hydrogen in the cathode. Both of these electrochemical products are gaseous species that lead to bubble nucleation at the surface of electrodes. This bubble evolution phenomena results in substantial energy losses due to the blockage of ion conduction pathways, reduction of the available electrocatalytic area, and disruption of concentration gradients at the electrode–electrolyte interface. In this study, we implement a microfluidic water electrolyzer to elucidate the impacts of electrochemical reaction conditions and convective flows on bubble-induced overpotential losses. We show that high Reynolds (Re) number flows (i.e., Re > 20) mitigate the formation of large bubbles, resulting in minimal bubble-induced overpotential losses. For flows with smaller Re, periodic evolution of large bubbles leads to overpotential fluctuations on the order of ∼100 mV. Furthermore, to understand the impact of bubbles on concentration overpotentials, we use fluorescence microscopy and pH sensitive dyes to capture the spatiotemporal dynamics of pH gradients and correlate the strength and shape of these gradients to the applied potential and convective forces. We find that the presence of large bubbles at low Re can result in more severe concentration gradients that are affected by the hydrodynamic flows around the bubbles. The findings presented in this work provide insights into the effects of convective flows in mitigating bubble-induced overpotential losses.

Sustainable Production of Rare Earth Elements from Mine Waste and Geoethics: Marouen Jouini, Alexandre Royer-Lavallée, Thomas Pabst, Eunhyea Chung, Rina Kim, Young-Wook Cheong  and Carmen Mihaela Neculita ;  Minerals 2022, 12(7), 809; https://doi.org/10.3390/min12070809

Abstract

The vulnerability of the rare earth element (REE) supply in a global context of increasing demands entails important economic and political issues, and has encouraged several countries to develop their own REE production projects. This study comparatively evaluated the production of REEs from primary and secondary resources in terms of their sustainability and contribution to the achievement of the Geoethics concept as responsibility towards oneself, colleagues, society, and the Earth system. Twelve categories of potential environmental and social impacts were selected: human health toxicity, global warming or climate change, terrestrial and aquatic eutrophication, acidification potential, particulate matter, resource depletion, water consumption, fresh water ecotoxicity, ionizing radiation, fossil fuel consumption, and ozone depletion. The results showed that the environmental impact of REE production from secondary sources is much lower relative to primary sources. A comparison of conventional and non-conventional REE resources showed that significant impact categories were related to particulate matter formation, abiotic resource depletion, and fossil fuel depletion, which could result from avoiding the tailings disposal before reuse. Based on these findings, governments and stakeholders should be encouraged to increase the recycling of secondary REE sources with Geoethics in mind, in order to balance the high demand of REEs while minimizing the overexploitation of non-renewable resources.

Extraction of Gold and Copper from Flotation Tailings Using Glycine-Ammonia Solutions in the Presence of Permanganate: Huan Li, Elsayed Oraby, Jacques Eksteen  and Tanmay Mali; Minerals 2022, 12(5), 612; https://doi.org/10.3390/min12050612

Abstract

This study presents the novel idea of a cyanide-free leaching method, i.e., glycine-ammonia leaching in the presence of permanganate, to treat a low-grade and copper-bearing gold tailing. Ammonia played a key role as a pH modifier, lixiviant and potential catalyst (as cupric ammine) in this study. Replacing ammonia with other pH modifiers (i.e., sodium hydroxide or lime) made the extractions infeasibly low (<30%). The increased additions of glycine (23–93 kg/t), ammonia (30–157 kg/t) and permanganate (5–20 kg/t) enhanced gold and copper extractions considerably. Increasing the solids content from 20 to 40% did not make any obvious changes to copper extraction. However, gold leaching kinetics was slightly better at lower solids content. It was indicated that the staged addition of permanganate was unnecessary under the leaching conditions. Recovery of gold by CIL was shown to be feasible, and it improved gold extraction by 15%, but no effect was observed for copper extraction. Percentages of 76.5% gold and 64.5% copper were extracted in 48 h at 20 g/L glycine, 10 kg/t permanganate, 20 g/L carbon, pH 10.5 and 30% solids. Higher extractions could be potentially achieved by further optimization, such as by increasing permanganate addition, extending leaching time and ultra-fine grinding.

Phosphonate-Functionalized Ionic Liquid Gel Polymer Electrolyte with High Safety for Dendrite-Free Lithium Metal Batteries: Jingbo Song, Kaisi Liao, Jia Si, Chuanli Zhao, Junping Wang, Mingjiong Zhou, Hongze Liang, Jing Gong, Ya-Jun Cheng, Jie Gao, and Yonggao Xia;  ACS Appl. Mater. Interfaces 2023, 15, 2, 2901–2910 (https://doi.org/10.1021/acsami.2c18298)

Abstract

The conventional lithium-ion battery technology relies on the liquid carbonate-based electrolyte solution, which causes excessive side reactions, serious risk of electrolyte leakage, high flammability, and significant safety hazards. In this work, phosphonate-functionalized imidazolium ionic liquid (PFIL) is synthesized and used as a gel polymer electrolyte (GPE) to replace the organic carbonate-based electrolyte solution. The as-prepared ionic liquid-based gel polymer electrolyte (IL-GPE) shows low crystallinity, flame retardance, and excellent electrochemical performance. Thanks to the fast double channel transport of lithium ions in the IL-GPE electrolyte, a high ionic conductivity of 0.48 mS cm^–1 and a lithium-ion transference number of 0.37 are exhibited. Symmetrical lithium cells with IL-GPE retain stable cycling even after 3000 h under 0.1 mA cm^–2. IL-GPE exhibits good compatibility toward lithium metal, yielding excellent long-term electrochemical kinetic stability. IL-GPE induces the formation of a uniform and robust SEI layer, inhibiting the growth of lithium dendrites and improving the rate performance and cycle stability. Furthermore, Li/LiFePO₄ cells exhibit a specific capacity of 63 mA h g^–1 after 150 cycles at 5.0 C, with a capacity retention of 90.2%. It is foreseen that this GPE is a promising candidate to enhance the safety of high-performance lithium metal batteries.

Revealing the Self-Doping Defects in Carbon Materials for the Compact Capacitive Energy Storage of Zn-Ion Capacitors: Renlu Yuan, Haohao Wang, Lei Shang, Ruoyang Hou, Yue Dong, Yutong Li, Su Zhang, Xiaohong Chen, and Huaihe Song; ACS Appl. Mater. Interfaces 2023, 15, 2, 3006–3016 (https://doi.org/10.1021/acsami.2c19798)

Abstract

Zn-ion capacitors are attracting great attention owing to the abundant and relatively stable Zn anodes but are impeded by the low capacitance of porous carbon cathodes with insufficient energy storage sites. Herein, using ball-milled graphene with different defect densities as the models, we reveal that the self-doping defects of carbon show a capacitive energy storage behavior with robust charge-transfer kinetics, providing a capacitance contribution of ca. 90 F g^–1 per unit of defect density (A_D/A_G value from Raman spectra) in both aqueous and organic electrolytes. Furthermore, a simple NaCl-assisted ball-milling method is developed to prepare novel graphene blocks (BSG) with abundant self-doping defect density, enriched pores, balanced electric conductivity, and high compact density (0.83 g cm^–3). The optimized ion and electron transfer paths promote efficient utilization of the self-doping defects in BSG, contributing to improved gravimetric and volumetric capacitance (224 F g^–1/186 F cm^–3 at 0.5 A g^–1) and remarkable rate performance (52.2% capacitance retention at 20 A g^–1). The defect engineering strategy may open up a new avenue to improve the capacitive performance of dense carbons for Zn-ion capacitors.

In Situ Neutron Reflectometry Study of a Tungsten Oxide/Li-Ion Battery Electrolyte Interface: Eric D. Rus and Joseph A. Dura; ACS Appl. Mater. Interfaces 2023, 15, 2, 2832–2842 (https://doi.org/10.1021/acsami.2c16737)

Abstract

The solid electrolyte interface/interphase (SEI) is of great importance to the viable operation of lithium-ion batteries. In the present work, the interface between a tungsten oxide electrode and an electrolyte solution consisting of LiPF₆ in a deuterated ethylene carbonate/diethyl carbonate solvent was characterized with in situ neutron reflectometry (NR) at a series of applied electrochemical potentials. NR data were fit to yield neutron scattering length density (SLD) depth profiles in the surface normal direction, from which composition depth profiles were inferred. The goals of this work were to characterize SEI formation on a model transition-metal oxide, an example of a conversion electrode, to characterize the lithiation of WO₃, and to help interpret the results of an earlier study of tungsten electrodes without an intentionally grown surface oxide. The WO₃ electrode was produced by thermal oxidation of a W thin film. Co-analysis of NR and X-ray reflectivity data indicated that the stoichiometry of the thermal oxide was WO₃. As the electrode was polarized to progressively more reducing potentials, starting from open circuit and down to +0.25 V versus Li/Li, the layer that was originally WO⁺₃ expanded and increased in lithium content. The reduced electrode consisted of two to three layers: an inner layer (the evolving conversion electrode) which may have been mixed W and Li₂O and unreacted WO₃ or Li_xWO₃, a layer rich in protons and/or lithium, possibly corresponding to LiOH or LiH (the inner SEI), and an outermost layer adjacent to the solution with an SLD close to that of the solution, possibly consisting of lower SLD species with solution-filled porosity or deuteron-rich species derived from the solvents (the outer SEI), though the presence of this layer was tenuous. For the steps in the direction of more oxidizing potentials, the evolution of the layer structure was qualitatively the reverse of that seen when stepping toward more negative potentials, though with hysteresis. The SLD gradient suggested that the reaction was not limited by diffusion within the film. No clear phase boundary was evident in the evolving conversion electrode.

Dual-Salt Localized High-Concentration Electrolyte for Long Cycle Life Silicon-Based Lithium-Ion Batteries: Gaopan Liu, Meng Xia, Jian Gao, Yong Cheng, Mingsheng Wang, Wenjing Hong, Yong Yang, and Jianming Zheng; ACS Appl. Mater. Interfaces 2023, 15, 2, 3586–3598 (https://doi.org/10.1021/acsami.2c17512)

Abstract

Silicon-based materials are considered the most promising anodes for next-generation lithium-ion batteries (LIBs) owing to their high specific capacity. However, poor interfacial stability due to enormous volume changes severely restricts their mass application in LIBs. Here, we design a fluoroethylene carbonate (FEC)-containing dual-salt (LiFSI-LiPF₆) ether-based localized high-concentration electrolyte (D-LHCE-F) for enhancing the interfacial stability of silicon-based electrodes. It is revealed that the dominating LiFSI salt of superior chemical and thermal stability prevents the formation of corrosive HF, while the addition of FEC improves the interface stability by promoting the formation of protective LiF-rich SEI and increasing the flexibility of the interface. This robust and flexible SEI layer can adapt to substantial variations in the volume of silicon electrodes while preserving the integrity of the interface. The SiO_x/C electrode using the unique D-LHCE-F retains up to 78.5% of its initial capacity after 500 cycles at 0.5C, well surpassing that of the control electrolyte (3.4% capacity retention). More notably, the cycle life of the SiO_x/C||NCM90 (LiNi_0.9Co_0.05Mn_0.05O₂) full batteries is effectively enhanced thanks to the stabilized electrode/electrolyte interfaces. The key findings of this work offer crucial knowledge for rationally designing electrolyte chemistry to enable the practical application of high-energy-density LIBs adopting silicon-based anodes.

Pt Nanoparticles Confined in a 3D Porous FeNC Matrix as Efficient Catalysts for Rechargeable Li-CO₂/O₂ Batteries: Peng-Fang Zhang, Hong-Ying Zhuo, Yun-Yun Dong, Yao Zhou, Yun-Wu Li, Hong-Guo Hao, Da-Cheng Li, Wen-Jing Shi, Su-Yuan Zeng, Shu-Ling Xu, Xiang-Jin Kong, Yi-Jin Wu, Jin-Sheng Zhao, Shu Zhao, and Jun-Tao Li;  ACS Appl. Mater. Interfaces 2023, 15, 2, 2940–2950 (https://doi.org/10.1021/acsami.2c18857)

Abstract

The cathodic product Li₂CO₃, due to its high decomposition potential, has hindered the practical application of rechargeable Li-CO₂/O₂ batteries. To overcome this bottleneck, a Pt/FeNC cathodic catalyst is fabricated by dispersing Pt nanoparticles (NPs) with a uniform size of 2.4 nm and 8.3 wt % loading amount into a porous microcube FeNC support for high-performance rechargeable Li-CO₂/O₂ batteries. The FeNC matrix is composed of numerous two-dimensional (2D) carbon nanosheets, which is derived from an Fe-doping zinc metal–organic framework (Zn-MOF). Importantly, using Pt/FeNC as the cathodic catalyst, the Li-CO₂/O₂ (V_CO2/V_O2 = 4:1) battery displays the lowest overpotential of 0.54 V and a long-term stability of 142 cycles, which is superior to batteries with FeNC (1.67 V, 47 cycles) and NC (1.87 V, 23 cycles) catalysts. The FeNC matrix and Pt NPs can exert a synergetic effect to decrease the decomposition potential of Li₂CO₃ and thus enhance the battery performance. In situ Fourier transform infrared (FTIR) spectroscopy further confirms that Li₂CO₃ can be completely decomposed under a low potential of 3.3 V using the Pt/FeNC catalyst. Impressively, Li₂CO₃ exhibits a film structure on the surface of the Pt/FeNC catalysts by scanning electron microscopy (SEM), and its size can be limited by the confined space between the carbon sheets in Pt/FeNC, which enlarges the better contacting interface. In addition, density functional theory (DFT) calculations reveal that the Pt and FeNC catalysts show a higher adsorption energy for Li₂CO₃ and Li₂CO₄ intermediates compared to the NC catalyst, and the possible discharge pathways are deeply investigated. The synergetic effect between the FeNC support and Pt active sites makes the Li-CO₂/O₂ battery achieve optimal performance.

Carbon Quantum Dots-Derived Carbon Nanosphere Coating on Ti₃C₂ MXene as a Superior Anode for High-Performance Potassium-Ion Batteries: Yefeng Feng, Kaidan Wu, Shanshan Wu, Yuanyuan Guo, Miao He, and Ming Xue; ACS Appl. Mater. Interfaces 2023, 15, 2, 3077–3088 (https://doi.org/10.1021/acsami.2c20559)

Abstract

Potassium-ion batteries (PIBs) are receiving increasing attention at present because of their cheap and lithium-like charge/discharge processes. Nevertheless, the large potassium-ion radius leads to poor potassium intercalation/depotassium kinetics and unstable structure, hindering their development. Here, we synthesized a novel carbon quantum dot-derived carbon nanosphere-encapsulated Ti₃C₂ MXene (CNS@Ti₃C₂) composite by polymer pyrolysis, while carbon nanospheres were derived from carbon quantum dots. The composites can suppress the layer stacking of Ti₃C₂ and prevent oxidation, thereby stabilizing the layered structure of Ti₃C₂ MXene and improving the cycle life. Besides, carbon nanospheres can increase the specific surface area and active sites, and then more potassium ions can enter the electrode material and boost the reversible capacity. Further, carbon nanospheres are embedded between the Ti₃C₂ layers, which can increase the interlayer spacing, and the potassium ions are more easily inserted and extracted, thereby improving the potassium storage power and rate performance. The CNS@Ti₃C₂ composite possesses an excellent synergy, resulting in a high reversible capacity of 229 mAh g^–1 at 100 mA g^–1 after 200 repeated cycles and a long cycle life of 205 mAh g^–1 at 500 mA g^–1 after 1000 repeated cycles with high coulombic efficiency (above 99%). This work offers a novel strategy to utilize carbon with MXene in energy storage.

Hybrid Nano-Phase Ion/Electron Dual Pathways of Nickel/Cobalt–Boride Cathodes Boosting Intercalation Kinetics for Alkaline Batteries: Junpeng Li, Xiping Liu, Hongyang Zhao, Qian Zhang, Baozhong Du, Leilei Lu, Nailiang Liu, Yihui Yang, Ningning Zhao, Xiufen Pang, Xiaojiao Yu,  Xiangyang Li, and Xifei Li; ACS Appl. Mater. Interfaces 2023, 15, 2, 2843–2851 (https://doi.org/10.1021/acsami.2c17217)

Abstract

Nickel-based hydroxides and their derivatives exhibit relatively low capacities and unsatisfactory durability as cathode materials for rechargeable alkaline batteries. In this work, a hybrid NiCo–B nanosheet cathode, integrating electrolyte ion-shuttling channels and electron-transferring networks into a metal–organic framework (MOF), was devised delicately. In the structure, the hybrid ion/electron dual pathways were constructed by NiCo-MOF frameworks and NiCo–B interpenetration networks. It revealed that nano-phase electron-transferring pathways in the MOF obviously boosted ion intercalation kinetics. The as-obtained hybrid NiCo–B nanosheets as cathode materials exhibited reversible capacity as high as 280 mA h g^–1 at a current density of 1 A g^–1 and excellent rate capability with a capacity retention of 78% from 1 to 10 A g^–1. After 2000 charge/discharge cycles at 4 A g^–1, the capacity still remained at 94% of the initial one. A full battery assembled with a hybrid NiCo–B cathode and a Fe₂O₃ anode showed a high capacity of 250 mA h g^–1 and a considerable stability of 89% after 1000 cycles. Ragone plots indicated the highest energy density of 409 W h kg^–1 and the lowest power density of 1.5 kW kg^–1, outperforming other aqueous batteries. It revealed that a syngenetic structure of ion/electron hybrid dual pathways integrated into an MOF could be a potential strategy to optimize ion intercalation electrode materials for alkaline batteries.

Surface Stabilization of Cobalt-Free LiNiO₂ with Niobium for Lithium-Ion Batteries: Seamus Ober, Alex Mesnier, and Arumugam Manthiram; ACS Appl. Mater. Interfaces 2023, 15, 1, 1442–1451 (https://doi.org/10.1021/acsami.2c20268)

Abstract

Lithium nickel oxide (LiNiO₂) is a promising next-generation cathode material for lithium-ion batteries (LIBs), offering exceptionally high specific capacity and reduced material cost. However, the poor structural, surface, and electrochemical stabilities of LiNiO₂ result in rapid loss of capacity during prolonged cycling, making it unsuitable for application in commercial LIBs. Herein, we demonstrate that incorporation of a small amount of niobium effectively suppresses the structural and surface degradation of LiNiO₂. The niobium-treated LiNiO₂ retains 82% of its initial capacity after 500 cycles in full cells with a graphite anode compared to 73% for untreated LiNiO₂. We utilize a facile method for incorporating niobium, which yields Li_xNbO_y phase formation as a surface coating on the primary particles. Through a combination of X-ray diffraction, electron microscopy, and electrochemical analyses, we show that the resulting niobium coating reduces active material loss over long-term cycling and enhances lithium-ion diffusion kinetics. The enhanced structural integrity and electrochemical performance of the niobium-treated LiNiO₂ are correlated to a reduction in the formation of nanopore defects during cycling compared to the untreated LiNiO₂.

Tuning Li Nucleation by a Hybrid Lithiophilic Protective Layer for High-Performance Lithium Metal Batteries: Kaixin Zhao, Lirong Zhang, Qi Jin, Junpeng Xiao, Lili Wu, and Xitian Zhang;  ACS Appl. Mater. Interfaces 2023, 15, 2, 3089–3098 (https://doi.org/10.1021/acsami.2c20616)

Abstract

Lithium (Li) metal has been recognized as the most promising anode material for next-generation rechargeable batteries. However, the practical application of Li anodes is hampered by the growth of Li dendrites. To address this issue, a robust and uniform Sb-based hybrid lithiophilic protective layer is designed and built by a facile in situ surface reaction approach. As evidenced theoretically and experimentally, the as-prepared hybrid protective layer provides outstanding wettability and fast charge-transfer kinetics. Moreover, the lithiophilic Sb embedded in the protective layer provides a rich site for Li nucleation, which effectively reduces the overpotential and induces uniform Li deposition. Consequently, the symmetric cell exhibits a long lifespan of over 1600 h at 1 mA cm^–2 and 1 mAh cm^–2 with a low voltage polarization. Furthermore, excellent cycling stability is also obtained in Li–S full cells (60% capacity retention in 800 cycles at 1 C) and Li||LFP full cells (74% capacity retention in 500 cycles at 5 C). This work proposed a facile but efficient strategy to stabilize the Li metal anode.

Review on the Development and Utilization of Ionic Rare Earth Ore: Xianping Luo, Yongbing Zhang, Hepeng Zhou, Kunzhong He, Caigui Luo, Zishuai Liu and Xuekun Tang; Minerals 2022, 12(5), 554; https://doi.org/10.3390/min12050554

Abstract

Rare earth, with the reputation of “industrial vitamins”, has become a strategic key metal for industrial powers with increasingly significant industrial application value. As a unique rare earth resource, ionic rare earth ore (IREO) has the outstanding advantages of complete composition, rich resource reserves, low radioactivity, and high comprehensive utilization value. IREO is the main source of medium and heavy rare earth raw materials, which are in great demand all over the world. Since the discovery of IREO, it has attracted extensive attention. Scientists in China and the around world have carried out a lot of research and practical work and achieved a series of important breakthroughs. This paper introduces the discovery process, metallogenic causes, deposit characteristics, and the prospecting research progress of IREO, so as to deepen the understanding of the global distribution of ionic rare earth resources and the prospecting direction of ionic rare earth deposits. The leaching principle of IREO, the innovation of leaching process, the influencing factors and technological development of in situ leaching process, and the technical adaptability of in situ leaching process are reviewed. The development of leachate purification and rare earth extraction technology is summarized. We aim to provide guidance for the industrial development of IREO through the above review analysis. Additionally, the problems existing in the development of IREO are pointed out from the aspects of technology, economy, and the environment. Ultimately, a series of suggestions are put forward, such as the development of ammonium free extraction technology in the whole exploitation process of in situ leaching and leachate purification and rare earth precipitation, research on enhancing of seepage and mass transfer process, and research on the development of new technologies for impurity removal of leachate and extraction of rare earth, so as to promote the development of green and efficient exploitation new technologies and sustainable development of ionic rare earth ore.

Accessing Metals from Low-Grade Ores and the Environmental Impact Considerations: A Review of the Perspectives of Conventional versus Bioleaching Strategies:Rosina Nkuna, Grace N. Ijoma, Tonderayi S. Matambo  and Ngonidzashe Chimwani;  Minerals 2022, 12(5), 506; https://doi.org/10.3390/min12050506

Abstract

Mining has advanced primarily through the use of two strategies: pyrometallurgy and hydrometallurgy. Both have been used successfully to extract valuable metals from ore deposits. These strategies, without a doubt, harm the environment. Furthermore, due to decades of excessive mining, there has been a global decline in high-grade ores. This has resulted in a decrease in valuable metal supply, which has prompted a reconsideration of these traditional strategies, as the industry faces the current challenge of accessing the highly sought-after valuable metals from low-grade ores. This review outlines these challenges in detail, provides insights into metal recovery issues, and describes technological advances being made to address the issues associated with dealing with low-grade metals. It also discusses the pragmatic paradigm shift that necessitates the use of biotechnological solutions provided by bioleaching, particularly its environmental friendliness. However, it goes on to criticize the shortcomings of bioleaching while highlighting the potential solutions provided by a bespoke approach that integrates research applications from omics technologies and their applications in the adaptation of bioleaching microorganisms and their interaction with the harsh environments associated with metal ore degradation.

Cost-Effective Smart Window: Transparency Modulation via Surface Contact Angle Controlled Mist Formation: Indrajit Mondal, Nilay Awasthi, Mukhesh K. Ganesha, Ashutosh K. Singh, and Giridhar U. Kulkarni; ACS Appl. Mater. Interfaces 2023, 15, 2, 3613–3620 (https://doi.org/10.1021/acsami.2c18052)

Abstract

Implementing simple and inexpensive energy-saving smart technologies in households is quite effective to accomplish on-demand privacy control and reduction in energy consumption. Conventional smart glasses face difficulty in making inroads into the consumer market due to utilizing expensive active layers, electrolytes, and transparent electrodes. Thus, the need of the hour is to develop an unconventional smart window, which should be cost-effective, power-efficient, and simple to fabricate. Against this backdrop, we report the fabrication of a new class of smart partition windows termed “mist-driven transparency switching glass”. The fabrication protocol includes surface energy modification of two glass panes, followed by assembling them into a square or rectangular-shaped narrow cell with appropriate inlets and outlets for mist. In its pristine state, the device is transparent, as expected of two plain glasses forming a cell. Insertion of cool mist into the device produces tiny droplets onto the inner walls due to condensation enabling scattering of light, thereby producing the translucent state. The optimized device shows a transmittance modulation of as much as ∼65% at 550 nm, allowing it to reduce the indoor temperature by more than 30% compared to a regular glass windowpane. To realize commercial viability, a large area device (30 × 30 cm²) was fabricated, which could be operated wirelessly through a cellphone application paving the way for incorporating the Internet of Things into the technology.

Systematic Design of a Graphene Ink Formulation for Aerosol Jet Printing: Livio Gamba, Zachary T. Johnson, Jackie Atterberg, Santiago Diaz-Arauzo, Julia R. Downing, Jonathan C. Claussen, Mark C. Hersam, and Ethan B. Secor ;  ACS Appl. Mater. Interfaces 2023, 15, 2, 3325–3335 (https://doi.org/10.1021/acsami.2c18838)

Abstract

Aerosol jet printing is a noncontact, digital, additive manufacturing technique compatible with a wide variety of functional materials. Although promising, development of new materials and devices using this technique remains hindered by limited rational ink formulation, with most recent studies focused on device demonstration rather than foundational process science. In the present work, a systematic approach to formulating a polymer-stabilized graphene ink is reported, which considers the effect of solvent composition on dispersion, rheology, wetting, drying, and phase separation characteristics that drive process outcomes. It was found that a four-component solvent mixture composed of isobutyl acetate, diglyme, dihydrolevoglucosenone, and glycerol supported efficient ink atomization and controlled in-line drying to reduce overspray and wetting instabilities while maintaining high resolution and electrical conductivity, thus overcoming a trade-off in deposition rate and resolution common to aerosol jet printing. Biochemical sensors were printed for amperometric detection of the pesticide parathion, exhibiting a detection limit of 732 nM and a sensitivity of 34 nA μM^–1, demonstrating the viability of this graphene ink for fabricating functional electronic devices.

Fully Screen-Printed PI/PEG Blends Enabled Patternable Electrodes for Scalable Manufacturing of Skin-Conformal, Stretchable, Wearable Electronics: Sehyun Park, Seunghyeb Ban, Nathan Zavanelli, Andrew E. Bunn, Shinjae Kwon, Hyo-ryoung Lim, Woon-Hong Yeo, and Jong-Hoon Kim; ACS Appl. Mater. Interfaces 2023, 15, 1, 2092–2103 (https://doi.org/10.1021/acsami.2c17653)

Abstract

Recent advances in soft materials and nano-microfabrication have enabled the development of flexible wearable electronics. At the same time, printing technologies have been demonstrated to be efficient and compatible with polymeric materials for manufacturing wearable electronics. However, wearable device manufacturing still counts on a costly, complex, multistep, and error-prone cleanroom process. Here, we present fully screen-printable, skin-conformal electrodes for low-cost and scalable manufacturing of wearable electronics. The screen printing of the polyimide (PI) layer enables facile, low-cost, scalable, high-throughput manufacturing. PI mixed with poly(ethylene glycol) exhibits a shear-thinning behavior, significantly improving the printability of PI. The premixed Ag/AgCl ink is then used for conductive layer printing. The serpentine pattern of the screen-printed electrode accommodates natural deformation under stretching (30%) and bending conditions (180°), which are verified by computational and experimental studies. Real-time wireless electrocardiogram monitoring is also successfully demonstrated using the printed electrodes with a flexible printed circuit. The algorithm developed in this study can calculate accurate heart rates, respiratory rates, and heart rate variability metrics for arrhythmia detection.

Influence of Pore Morphology on Permeability through Digital Rock Modeling: New Insights from the Euler Number and Shape Factor: Xiangjie Qin, Yuxuan Xia, Jinsui Wu, Chenhao Sun, Jianhui Zeng, Kai Xu, and Jianchao Cai; Energy Fuels 2022, 36, 14, 7519–7530 (https://doi.org/10.1021/acs.energyfuels.2c01359)

Abstract

The microscopic pore shape and topology significantly affect fluid transport and occurrence in porous permeable rock. A quantitive characterization of the impact of pore morphology on permeability is currently lacking, which limits the efficient development of underground hydrocarbon resources. This work introduces the Euler number and shape factor to characterize the pore topology and shape of heterogeneous sandstone based on CT imaging. The pore morphology under different pore sizes and the correlation of the Euler number, shape factor, fractal dimension, and surface area are analyzed. Furthermore, a modified Kozeny–Carman equation is established to explain the influence of the Euler number and shape factor on permeability. The results show that with the increase of pore diameter, the Euler number decreases while the shape factor increases. In a connected pore system, the smaller Euler number corresponds to the complex pore network, which leads to the increase in the surface area, shape factor, and fractal dimension. At constant porosity, the shape factor is negatively correlated with permeability, and with increasing Euler number, the heterogeneity of the pore structure increases, resulting in an increase of flow resistance and a decrease of permeability. The results provide a new pore morphology characterization method for digital rock and help to understand the flow mechanism of hydrocarbons in complex pore networks.

Staged Pyrolytic Conversion of Acid-Loaded Woody Biomass for Production of High-Strength Coke and Valorization of Volatiles : Fu Wei, Shinji Kudo*, Shusaku Asano, and Jun-ichiro Hayashi; Energy Fuels 2022, 36, 13, 6949–6958 (https://doi.org/10.1021/acs.energyfuels.2c01352)

Abstract

Lignocellulosic biomass is an attractive resource for metallurgical coke. The hot pelletization of powdered biomass followed by carbonization produces a high-strength biocoke. However, the fate of a major portion of biomass after carbonization is the production of low-value volatiles. Here, we enabled the valorization of woody biomass as valuable chemicals, such as anhydrosugars and phenols, and strong coke by loading mineral acid over wood and staged conversion consisting mainly of torrefaction, pelletization, and then carbonization. The loading of H₂SO₄ or H₃PO₄ at an amount equal to or slightly less than that of metals inherent in the wood, having catalysis for promoting the formation of valueless light oxygenates from carbohydrates, was effective for passivating those metals and drastically improving the anhydrosugar yield in torrefaction at 300–320 °C. The total yield of anhydrosugars from wood and the yield of levoglucosan, a dominant anhydrosugar, from cellulose in the wood reached 12.1 and 25.3 wt %, respectively. It was noteworthy that torrefaction altered the composition of components in wood and positively influenced the strength of coke prepared by pelletization and carbonization. In particular, torrefaction in the presence of H₂SO₄ led to a remarkable densification of pellets during carbonization. The resulting coke had a strength (tensile strength) of up to 24.2 MPa, which was much higher than that of coke directly pelletized and carbonized from wood (9.0 MPa). Moreover, the lignin-enriched torrefied wood selectively produced phenols and combustible gas with H₂ as the major component in the carbonization. Under the most optimal conditions examined in this work, 45.7 wt % of the wood was converted into the desired products with the remainder being water and heavy condensable volatiles, while the yield of light oxygenates was greatly reduced.

Catalytic Upgrading of Biomass-Gasification Mixtures Using Ni-Fe/MgAl₂O₄ as a Bifunctional Catalyst: Pilar Tarifa, Tomás Ramirez Reina, Miriam González-Castaño, and Harvey Arellano-García; Energy Fuels 2022, 36, 15, 8267–8273 (https://doi.org/10.1021/acs.energyfuels.2c01452)

Abstract

Biomass gasification streams typically contain a mixture of CO, H₂, CH₄, and CO₂ as the majority components and frequently require conditioning for downstream processes. Herein, we investigate the catalytic upgrading of surrogate biomass gasifiers through the generation of syngas. Seeking a bifunctional system capable of converting CO₂ and CH₄ to CO, a reverse water gas shift (RWGS) catalyst based on Fe/MgAl₂O₄ was decorated with an increasing content of Ni metal and evaluated for producing syngas using different feedstock compositions. This approach proved efficient for gas upgrading, and the incorporation of adequate Ni content increased the CO content by promoting the RWGS and dry reforming of methane (DRM) reactions. The larger CO productivity attained at high temperatures was intimately associated with the generation of FeNi₃ alloys. Among the catalysts’ series, Ni-rich catalysts favored the CO productivity in the presence of CH₄, but important carbon deposition processes were noticed. On the contrary, 2Ni-Fe/MgAl₂O₄ resulted in a competitive and cost-effective system delivering large amounts of CO with almost no coke deposits. Overall, the incorporation of a suitable realistic application for valorization of variable composition of biomass-gasification derived mixtures obtaining a syngas-rich stream thus opens new routes for biosyngas production and upgrading.

Identifying Key Design Criteria for Large-Scale Photocatalytic Hydrogen Generation from Engineering and Economic Perspectives: Cui Ying Toe, Jian Pan, Jason Scott, and Rose Amal; ACS EST Engg. 2022, 2, 6, 1130–1143 (https://doi.org/10.1021/acsestengg.2c00030)

Abstract

Photocatalytic hydrogen (H₂) generation has emerged as a promising approach for direct conversion of solar energy into green H₂ fuel. Prior works predominantly focused on photocatalyst material development and optimization with photoreactor and system design receiving considerably less attention. Further, significantly less focus has been devoted to the economic feasibility study of photoreactor systems. Therefore, this Perspective contemplates photoreactor design and scale up from an economic viewpoint. The economics of two popular large-scale photoreactor designs, (i) panel and (ii) slurry based, are evaluated. This Perspective suggests that the design of a photocatalytic slurry system is approximately 12% more cost effective than a panel photoreactor system under the base-case scenario in producing 10 kg H₂/day. The analysis also suggests that a cost reduction of up to 75% can be achieved if the photon conversion efficiency is increased from 1% to 5%, indicating that research and development should continue to be undertaken to increase process efficiency via photocatalyst and system engineering. In addition, other considerations, such as improving photocatalyst reusability (to give a photocatalyst lifespan of at least 1 year), reducing photocatalyst cost (using non-noble-metal-based photocatalysts) and increasing input photon density (installing a solar concentrator to harness more than 1 Sun intensity), will each impose an additional 20–30% of the cost.

Bioinspired Strategy for Efficient TiO₂/Au/CdS Photocatalysts Based On Mesocrystal Superstructures in Biominerals and Charge-Transfer Pathway in Natural Photosynthesis : Wenxuan Wang, Yanwei Zhang, Jingjing Xie, Yanze Wang, Shaowen Cao, Hang Ping, Zhaoyong Zou, Hui Zeng, Weimin Wang, and Zhengyi Fu;  ACS Appl. Mater. Interfaces 2023, 15, 2, 2996–3005 (https://doi.org/10.1021/acsami.2c19692)

Abstract

Natural photosynthesis involves an efficient charge-transfer pathway through exquisitely arranged photosystems and electron transport intermediates, which separate photogenerated carriers to realize high quantum efficiency. It inspires a rational design construction of artificial photosynthesis systems and the architectures of semiconductors are essential to achieve optimal performance. Of note, biomineralization processes could form various mesocrystals with well-ordered superstructures for unique optical applications. Inspired by both natural photosynthesis and biomineralization, we construct a ternary superstructure-based mesocrystal TiO₂ (meso-TiO₂)/Au/CdS artificial photosynthesis system by a green photo-assisted method. The well-ordered superstructure of meso-TiO₂ and efficient charge-transfer pathway among the three components are crucial for retarding charge recombination. As a result, the meso-TiO₂/Au/CdS photocatalyst displays enhanced visible light-driven photocatalytic hydrogen evolution (4.60 mmol h^–1 g^–1), which is 3.2 times higher than that of commercial TiO₂ (P25)/Au/CdS with disordered TiO₂ nanocrystal aggregates (1.41 mmol h^–1 g^–1). This work provides a promising bioinspired design strategy for photocatalysts with an improved solar conversion efficiency.

Atomic-Scale Surface Engineering for Giant Thermal Transport Enhancement Across 2D/3D van der Waals Interfaces: Quanjie Wang, Jie Zhang, Yucheng Xiong, Shouhang Li, Vladimir Chernysh, and Xiangjun Liu; ACS Appl. Mater. Interfaces 2023, 15, 2, 3377–3386 (https://doi.org/10.1021/acsami.2c20717)

Abstract

Heat dissipation in two-dimensional (2D) material-based electronic devices is a critical issue for their applications. The bottleneck for this thermal issue is inefficient for heat removal across the van der Waals (vdW) interface between the 2D material and its supporting three-dimensional (3D) substrate. In this work, we demonstrate that an atomic-scale thin amorphous layer atop the substrate surface can remarkably enhance the interfacial thermal conductance (ITC) of the 2D-MoS₂/3D-GaN vdW interface by a factor of 4 compared to that of the untreated crystalline substrate surface. Meanwhile, the ITC can be broadly manipulated through adjusting substrate surface roughness. Phonon dynamic and heat flux spectrum analyses show that this giant enhancement is attributed to the increased phonon densities and channels at the interfaces and enhanced phonon coupling. The slight surface fluctuation in MoS₂ and the increased diffuse interfacial scattering facilitate energy transfer from MoS₂’s in-plane phonons to its out-of-plane phonons and then to the substrate. In addition, it is further found that the substrate and its surface topology can dramatically influence the thermal conductivity of MoS₂ due to the reduction of phonon relaxation time, especially for low-frequency acoustic phonons. This study elucidates the effects of the amorphous surface of the substrate on thermal transport across 2D/3D vdW interfaces and provides a new dimension to aid in the heat dissipation of 2D-based electronic devices via atomic-scale surface engineering.

Enhancing Electrochemical Performance of CoF₂–Li Batteries via Honeycombed Nanocomposite Cathode: Yujie Wang, Mingyu Zhang, Yuxuan Zhang, Yafeng Wang, Wenxin Liu, Chujie Yang, Veniamin Kondratiev, and Feixiang Wu; Energy Fuels 2022, 36, 15, 8439–8448 (https://doi.org/10.1021/acs.energyfuels.2c01309)

Abstract

Metal fluoride–lithium batteries have been viewed as very promising candidates for next-generation rechargeable batteries with higher energy densities. However, the intrinsic insulating properties of metal fluoride cathode lead to the poor reaction kinetics and unsatisfactory electrochemical performance. Herein, a honeycombed CoF₂@C nanocomposite with a high specific surface area up to 180.4 m² g^–1, in which the nanosized CoF₂ particles with size of 5–25 nm are evenly embedded in the honeycombed carbon framework, is prepared by the low-temperature fluorination of honeycombed Co@C nanocomposite precursor. As expected, the as-produced CoF₂@C nanocomposite can deliver a high-capacity utilization of 365 mAh g^–1 and an average capacity retention of 81.9% over 300 cycles at a current density of 110 mA g^–1, as well as a reasonable capacity of 205 mAh g^–1 at 1100 mA g^–1. Such excellent electrochemical performance is due to the unique configuration that achieves the nanoconfinement of conversion reaction in the metal fluoride cathode. To be specific, on the one hand, the honeycombed structure provides uniformly isolated nanospace to inhibit the volume expansion and product agglomeration in the conversion reaction. On the other hand, the excellent reaction kinetics is attributed to the three-dimensional electron and ion conduction pathway, that is, the electrons are conducted through the honeycombed carbon walls, while Li are transferred via the interconnected honeycomb channels, facilitating the high-capacity utilization.

Polycrystalline Prussian White Aggregates as a High-Rate and Long-Life Cathode for High-Temperature Sodium-Ion Batteries: Xing Huang, Chao Yang, and Ya You; ACS Appl. Energy Mater. 2022, 5, 7, 8123–8131 (https://doi.org/10.1021/acsaem.2c00646)

Abstract

Cost and resource consideration requires the use of sodium-ion batteries (SIBs) instead of lithium-ion batteries for grid-scale stationary energy storage, which requires a battery to provide high energy density, high power density, and stable cycling over a wide temperature range. Prussian white (PW) is emerging as a potential cathode for SIBs, and the electrochemical properties of PW at room temperature and below have been intensively studied; however, the rapid capacity decay at elevated temperatures still remains a big challenge. In this work, we demonstrate a polycrystalline Prussian white aggregate cathode with fast and stable Na ion storage performance at high temperatures up to 70 °C. Thanks to the small surface-to-volume ratio and uneven surfaces, the thermodynamic stability of the surface and electric contact with conductive agents are evidently improved. In addition, the stability of the low-spin Fe redox pair at elevated temperatures is significantly improved, resulting in impressive cycling stability and high rate capability. The capacity retentions of Poly-PW cathodes cycled at 50 and 70 °C are, respectively, 82.8 and 77.8% over 300 cycles. At a high rate of 30C, Poly-PW shows a capacity of 99 mAh g^+–1, corresponding to 73% of that at 0.3C. In addition, we investigated the crystal nucleation and growth mechanism of the polycrystalline aggregated structure. These findings offer a direction to facilitate the practical viability of PW for hot climates.