Yaoguang Guo , Yujing Liu, Jie Guan, Qianqian Chen, Xiaohu Sun, Nuo Liu, Li Zhang, Xiaojiao Zhang, Xiaoyi Lou, and Yingshun Li: Global Trend for Waste Lithium-Ion Battery Recycling from 1984 to 2021: A Bibliometric Analysis ; 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.

Ioanna Itskou, Anouk L’Hermitte, Sofia Marchesini, Tian Tian, and Camille Petit:  How to Tailor Porous Boron Nitride Properties for Applications in Interfacial Processes;  Acc. Mater. Res. 2023, 4, 2, 143–155 (https://doi.org/10.1021/accountsmr.2c00148)

Abstract

The research of new porous materials for applications in interfacial processes is key to addressing global energy and sustainability challenges. For example, porous materials can be used to store fuels such as hydrogen or methane or to separate chemical mixtures reducing the energy currently required by thermal separation processes. Their catalytic properties can be exploited to convert adsorbed molecules into valuable or less hazardous chemicals, thereby reducing energy consumption or pollutants emissions. Porous boron nitride (BN) has appeared as a promising material for applications in molecular separations, gas storage, and catalysis owing to its high surface area and thermal stability, as well as its tunable physical properties and chemistry.

However, the production of porous BN is still limited to the laboratory scale, and its formation mechanism, as well as ways to control porosity and chemistry, are yet to be fully understood. In addition, studies have pointed toward the instability of porous BN materials when exposed to humidity, which could significantly impact performance in industrial applications. Studies on porous BN performance and recyclability when employed in adsorption, gas storage, and catalysis remain limited, despite encouraging preliminary studies. Moreover, porous BN powder must be shaped into macrostructures (e.g., pellets) to be used commercially. However, common methods to shape porous materials into macrostructures often cause a reduction in the surface area and/or mechanical strength. In recent years, research groups, including ours, have started addressing the challenges discussed above. Herein, we summarize our collective findings through a selection of key studies. First, we discuss the chemistry and structure of BN, clarifying confusion around terminology and discussing the hydrolytic instability of the material in relation to its structure and chemistry. We demonstrate a way to reduce the instability in water while still maintaining high specific surface area. We propose a mechanism for the formation of porous BN and discuss the effects of different synthesis parameters on the structure and chemistry of porous BN, therefore providing a way to tune its properties for selected applications. While the syntheses covered often lead to a powder product, we also present ways to shape porous BN powders into macrostructures while still maintaining high accessible surface area for interfacial processes. Finally, we evaluate porous BN performance for chemical separations, gas storage, and catalysis.

While the above highlights key advances in the field, further work is needed to allow deployment of porous BN. Specifically, we suggest evaluating its hydrolytic stability, refining the ways to shape the material into stable and reproducible macrostructures, establishing clear design rules to produce BN with specific chemistry and porosity, and, finally, providing standardized test procedures to evaluate porous BN catalytic and sorptive properties to facilitate comparison.

Yanan Li, Yan Wang, Wei Wang, Xiao Yu, Li Zhang, Liu Deng, and You-Nian Liu: Covalent-Coupled Zn0.4Cd0.6S with g-C3N4 as a Sheet-on-Sheet Z-Scheme Photocatalyst for Water Splitting;  Ind. Eng. Chem. Res. 2023, 62, 8, 3538–3545 (https://doi.org/10.1021/acs.iecr.2c04265)

Abstract

Development of heterojunction to improve charge separation efficiency is one of the main strategies to enhance the hydrogen production performance of photocatalysts. Herein, we fabricate a 2D/2D Z-scheme heterojunction-coupled Zn0.4Cd0.6S with g-C3N4 by in situ hydrothermal approach. The sheet-on-sheet architecture provides full contact of heterojunction to accelerate interfacial charge transfer and increase surface-active sites. Additionally, the Zn–N coordination bond acts as a strong interfacial interaction between Zn0.4Cd0.6S and g-C3N4, and photogenerated charges are spatially separated along the Z-scheme mechanism. In particular, under visible-light (λ ≥ 420 nm) irradiation, the optimal photocatalyst exhibits a high hydrogen production (H2 production rates: 7.69 mmol g–1 h–1) without any cocatalysts, 4 times higher than that of the g-C3N4 photocatalyst using Pt as a cocatalyst. The catalyst has a long-term stability of up to 50 h. Therefore, a direct Z-scheme heterojunction with intimate contact and a well-definite bridging chemical bond could be a prospective photocatalyst for hydrogen generation.

Xinhua Wang, You Yuan, Donglin Chen, Bowen Sun, Jun Qian, Xiaoyun Liu, Peiyuan Zuo, Yi Chen, and Qixin Zhuang: BaTiO3 Nanoparticles Coated with Polyurethane and SiO2 for Enhanced Dielectric Properties;  ACS Appl. Nano Mater. 2023, 6, 4, 2615–2624 (https://doi.org/10.1021/acsanm.2c05042)

Abstract

Core–shell structures are commonly employed in dielectric nanocomposites to improve the energy storage capacity of polymers. However, few studies have focused on organic–inorganic double-layered shell structures. Thus, there is an urgent need to elucidate the detailed effects of the flexible segment of polymer shells and inorganic shells on the dielectric properties. Herein, we synthesized a hierarchical core–double shell BT/PU/SiO2 nanofiller with a thickness of 3–5 nm PU and 15 nm SiO2 layers. This unique shell structure possesses a gradient permittivity that regularly decreases from the inside to the outside of shells. Detailed electrical characterizations reveal that the intermediate PU shell with shorter flexible segments can limit the carrier migration and thus decrease the dielectric loss. The interfacial polarization in double-layered BT/PU/SiO2 is beneficial to improve the dielectric constant of the as-prepared nanocomposites. COMSOL Multiphysics simulation results also confirm that the delicate structure enables the internal electric field more homogeneous, which enhances the breakdown strength owing to its gradient dielectric constant. In addition, the dielectric loss of BT/PU/SiO2-PVDF is 0.032 when the filling is <4 wt %, which is only 45% compared with that of BT-PVDF. Meanwhile, the energy density of the nanocomposite reaches 7.41 J cm–3, which is 1.74 times higher than that of pure PVDF (2.7 J cm–3). Accordingly, our current work provides insight into the design of hierarchical core–double shell nanoparticles and their derived polymer nanocomposite capacitors for high-energy-density storage applications.

Mengen Hu, Zhulin Huang, Xinyang Li, Yuan Cheng, Zhen Wang, Kewei Li, Tianxu Wang, Xiaoye Hu, Yue Li, and Xinghong Zhang:  Ultrafine ZrB2 Ceramic Powders Prepared by a Sol–Gel Method Synergized with a Carbothermic Reaction and Their Improved Sintering Performance;  ACS Appl. Eng. Mater. 2023, 1, 2, 769–779 (https://doi.org/10.1021/acsaenm.2c00195)

Abstract

The sol–gel method synergized with a carbothermic reaction has been known to be one of the most promising strategies for preparing a high-quality boride and carbon-based ultrahigh-temperature ceramic, yet their growth mechanism remains underexplored. Herein, high-purity ZrB2 ceramic powders are prepared by a sol–gel method synergized with a subsequent carbothermic reaction. Specifically, sorbitol (C6H14O6) is adopted to build molecularly disperse networks of Zr–O–C–B. Structural characterizations reveal that the calcination temperature and duration have a great influence on the phase and morphological transformation of the precursor. The ZrB2 seeds start to be generated near ZrO2 particles around 1100 °C and grow from the surface to the core of ZrO2 particles with heat and mass transportation around ZrO2 driven by B2O3 at high temperature. Additionally, the ZrB2 powders could research a hardness of 22.5 GPa and a bending strength of 540 MPa after sintering, showing improved mechanical properties. This work reveals the growth mechanism of ultrafine and high-purity ZrB2 powders by a sol–gel method and a carbothermic reaction, which can be used as raw materials to obtain ZrB2 ultrahigh-temperature ceramics with improved mechanical properties.

10. Suresh Kumar Reddy, Anish Mathai Varghese, Adetola Elijah Ogungbenro, and Georgios N. Karanikolos : Aminosilane-Modified Ordered Hierarchical Nanostructured Silica for Highly-Selective Carbon Dioxide Capture at Low Pressure ; ACS Appl. Eng. Mater. 2023, 1, 2, 720–733 (https://doi.org/10.1021/acsaenm.2c00136)

Abstract

Ordered hierarchical nanostructured silica (OHNS) adsorbents were prepared, and their surface was controllably modified by aminosilanization using two different aminosilanes, one bearing one primary amine unit per molecule (4-aminobutyltriethoxysilane, ABTS) and the other bearing both a primary and a secondary amine (N-(2-aminoethyl)-3-aminopropylmethyldiethoxysilane, AAMS). Following physicochemical, structural, morphological, and porosity characterization, the CO2 adsorption performance was evaluated at low pressures (up to 100 mbar) and at different temperatures (25, 45, and 60 °C), including determination of CO2 adsorption–desorption, kinetics, CO2/N2 selectivity, regeneration/cycling, heat of adsorption, and CO2 adsorption under humid conditions. The unique hierarchical silica framework together with the aminosilanization scheme applied resulted in enhanced kinetics and CO2 uptake, the latter being increased with temperature, thus revealing a dominant chemisorption mechanism, which was further evidenced by the increase in the enthalpy of adsorption of the modified materials compared to the pristine OHNS. Among the tested adsorbents, at 100 mbar and 25 °C, the OHNS modified by AAMS yielded the highest CO2 uptake under dry (1.3 mmol/g) and wet (1.9 mmol/g) conditions. Notably, at very low pressure (1 mbar), the CO2 capacity of OHNS-AAMS reached >40% of the material’s total uptake at 1 bar. Compared to the unmodified OHNS, the CO2 capacity of the OHNS-AAMS and OHNS-ABTS increased by approximately 21- and 16-fold, respectively, at 1 mbar and 25 °C. At even lower pressure (0.4 mbar), a capacity of 0.55 mmol/g was evidenced for OHNS-AAMS in dry CO2. A very high CO2/N2 selectivity of the AAMS-modified analogue at low pressure was also obtained, i.e., 13,854 at 50 mbar, confirming the significant increase in CO2-philicity via aminosilanization with aminosilanes bearing combined primary and secondary amine groups. Furthermore, the water affinity of the aminosilane-modified OHNS adsorbents was found to decrease, which is beneficial for capture from humid mixtures. Cyclic stability was confirmed by performing 10 thermal pressure swing adsorption (TPSA) cycles up to 100 mbar. The hierarchical nanostructured silica-based framework and the functionalization scheme presented here render these robust systems promising for selective CO2 capture at low pressures in industrial applications and direct air capture.

Shile Chu, Tao Lu, Fanyan Zeng, Baoquan Liu, Yaohui Qu, and Yang Pan: In Situ Growth of Mo2C Crystals Stimulating Sodium-Ion Storage Properties of MoO2 Particles on N-Doped Carbon Nanobundles;  Ind. Eng. Chem. Res. 2023, 62, 8, 3602–3611 (https://doi.org/10.1021/acs.iecr.2c03712)

Abstract

Sodium-ion batteries (SIBs) are considered as the candidate for the upcoming large-scale energy storage systems. However, transition-metal oxides still have the problem of insufficient utilization of active sites, mainly signified by the low practical capacity in long cycles. Here, the composite (MoO2@Mo2C/C) of Mo2C crystals in situ grown in N-doped carbon nanobundles (N-CNBs) with MoO2 particles on their surface is designed by self-polymerization and two-step calcination. Through a series of characterizations and tests, it is found that the N-CNBs endow the composite with improved conductivity and reinforced structural stability and effectively alleviates the volume expansion and structural collapse of MoO2 particles. The high integration of Mo2C crystals with MoO2 particles/N-CNBs (Mo2C/C) further enhances the charge-transfer ability and structural stability for the composite. Importantly, the storage sites of MoO2 particles and Mo2C crystals are gradually activated during sodium-ion storage, significantly improving the effective capacity in the long cycles. After 8000 cycles at 5.0 A g–1, the reversible capacity of MoO2@Mo2C/C as a SIB anode gradually increases from 126.2 to 419.1 mAh g–1, with a capacity retention of up to 332.4%. This study fully demonstrates the potential advantages of metal carbides in energy storage and can provide a good reference for the development of metal ion batteries.

Xinglong Zhu, Yixuan Shi, Lijing Yang, Quanxin Chen, Xiaoping Luo, Qingke Zhang, Huinan Hannah Liu, Wensheng Sun, and Zhenlun Song:  Creation of Bioactive Ceramic Composite Coatings on Zn–Mn–Mg Alloy via Micro-arc Oxidation and Hydrothermal Treatment for Orthopedic Implant Applications;  ACS Appl. Eng. Mater. 2023, 1, 2, 734–743 (https://doi.org/10.1021/acsaenm.2c00156)

Abstract

Zinc alloys have emerged as promising biodegradable metals thanks to their critical physiological roles and encouraging degradation behavior. In this study, calcium phosphate (CaP) coatings were made on micro-arc oxidized Zn alloy using hydrothermal treatment (HT), which was motivated by the CaP-based minerals in natural bone tissue. The coating morphology was optimized by controlling the HT time, resulting in a homogeneous micro-CaP coating structure. The CaP coating significantly increased the cell viability and adhesion of MC3T3-E1 preosteoblasts and L-929 cells. Compared with the control group, the cell toxicity of the samples after MAO-HT was less, the number of cells was more, and the morphology was complete. Cell adhesion showed that the distribution of cells increased with the increase of HT time. In addition, the CaP coating significantly reduced the Zn ion release from the bulk material during the degradation process, resulting in a much lower Zn concentration and pH change in the surrounding environment. The micro-CaP coating structure and the regulated release of zinc ions are primarily responsible for the enhanced cytocompatibility and biomineralization of CaP-coated Zn biomaterials. In summary, the CaP coating on Zn-based biomaterial appears to be a viable approach to enhance its biocompatibility and to control its degradation rate. After that, the biocompatibility of the material can be improved by controlling the surface morphology of the material to adapt to the complex human environment.

Yu-cheng Zhang, Ya-qi Xue, Takayo Ogawa, Satoshi Wada, and Jin-Ye Wang: 3D Printed Alginate Hydrogels with Stiffness-Gradient Structure in a Carbomer Supporting Bath by Controlled Ca2+ Diffusion;  ACS Appl. Eng. Mater. 2023, 1, 2, 802–812 (https://doi.org/10.1021/acsaenm.2c00218)

Abstract

Manufacturing biocompatible materials with higher-order structure has great significance because they can mimic the extracellular medium of the human organism and are a novel strategy for tissue regeneration. In this study, a device with stiffness-gradient characteristics based on two biocompatible materials, alginate with presolidification and photocurable acrylamide-containing supporting bath, was designed and constructed by the 3D printing technique. The presolidification can avoid rapid diffusion of alginate in aqueous solutions, improve mechanical properties without the introduction of heterogeneous gel precursor, and endow gradient stiffness by the controlled diffusion of calcium ions. Besides, a photocurable supporting bath was combined to manufacture a device with a dual-gradient structure by a 4-step procedure, including 3D printing, removal of the inner hydrogel, solidification of alginate, and curing of the supporting bath. A cylinder-like container was manufactured as the template, and the wall of the resultant container with two types of gradient structures showed parabola-like stiffness changes (open upward), resulting from calcium ion diffusion-controlled gradient solidification and alginate diffusion-controlled gradient photocuring. Moreover, the resultant device exhibited lower cytotoxicity to both adherent and suspension cells than containers manufactured with alginate. Because of the high water uptake of the photocured supporting bath, the removal of toxic metabolic products together with cell culture medium from the container leads to better cell compatibility. This diffusion-controlled device is also applicable to other additive manufacturers with biomedical significance.

Dewen Zhang, Shilin Xu, Tianlin Li, Man Zhang, Jiqiu Qi, Fuxiang Wei, Qingkun Meng, Yaojian Ren, Peng Cao, and Yanwei Sui: High-Entropy Oxides Prepared by Dealloying Method for Supercapacitors;  ACS Appl. Eng. Mater. 2023, 1, 2, 780–789 (https://doi.org/10.1021/acsaenm.2c00198)

Abstract

High-entropy oxides (HEOs) are materials with a multielement mixture and a stable structure, which are widely used in energy storage due to their electrochemical properties. For application to supercapacitors, the method of preparation of HEOs needs to be improved, and the energy storage mechanism of the material needs to be investigated. In this experiment, 3 M NaOH was used to etch the FeCoNiCrMnAl95 alloy, and then (FeCoNiCrMn)3O4 was successfully produced by a facile oxidation treatment. HRTEM images show that the materials have a porous structure, and EDS mapping suggests that the individual elements are evenly distributed. The XRD and SAED patterns indicate that it has a stable crystal structure. The HEOs prepared by dealloying exhibited excellent supercapacitor characteristics, with a specific capacitance of 639 F/g at 1 A/g and retention of 80.77% at 10 A/g. Density functional theory (DFT) simulations back up this excellent energy storage capability. This work offers a novel method for manufacturing HEOs and a solid option for supercapacitor anode materials.

Sumnesh Gupta, J. Richard Elliott, Andrzej Anderko, Jacob Crosthwaite, Walter G. Chapman, and Carl T. Lira: Current Practices and Continuing Needs in Thermophysical Properties for the Chemical Industry; Ind. Eng. Chem. Res. 2023, 62, 8, 3394–3427 (https://doi.org/10.1021/acs.iecr.2c03153)

Abstract

The status of thermophysical property needs of the chemical industry is reviewed and updated relative to similar observations from 20 years ago. The paper is informed by a series of symposia held over several years in conjunction with the American Institute of Chemical Engineers (AIChE) national meetings. Experiences of the authors are also incorporated, including a discussion of the state of the art in this area, as well as references to several of the articles included in a recent special issue of Ind. Eng. Chem. Res. (2022, volume 61, issue 42) devoted to the subject. In general, the trend is toward more rigorous molecular methods but ingrained empirical methods tend to hold on for extended times by adding increasingly sophisticated multiparameter correlations. There is also a tendency for research in newer methods to end prematurely with anecdotal proofs of principle, undermining their ability to supersede tried and true methods. Significant gaps exist in experimental data, for the development of estimation methods and validation of models besides a general need for technical knowledge development. Although progress is clear, some of the goals articulated 20 years ago remain to be achieved, even as new needs are identified in estimation. modeling, and measurements. One possible solution, to close experimental data gaps and to provide a continuous stream of trained personnel, is to establish multidisciplinary research centers of excellence in this important methodology.

Fa He, Jiyang Kang, Tongli Liu, Hongjie Deng, Benhe Zhong, Yan Sun, Zhenguo Wu, and Xiaodong Guo: Research Progress on Electrochemical Properties of Na3V2(PO4)3 as Cathode Material for Sodium-Ion Batteries;  Ind. Eng. Chem. Res. 2023, 62, 8, 3444–3464 (https://doi.org/10.1021/acs.iecr.2c04054)

Abstract

The polyanion sodium vanadium phosphate Na3V2(PO4)3 (NVP) belongs to the sodium superionic conductors (NASICON) material. Its NASICON structural backbone forms a stable sodium accommodation site, and the open three-dimensional ion transport channel is conducive to the rapid intercalation/deintercalation of Na ions. As a cathode material for batteries, Na3V2(PO4)3 has an extremely high specific capacity, voltage plateau, and cycle stability, meeting the requirements of low cost and high safety. It is a large-scale energy storage material with ideal potential and has received extensive attention. However, the low electronic conductivity of Na3V2(PO4)3 material hinders its further application. Based on the current demand for large-scale application of sodium-ion batteries, this paper re-examines the effect of existing research progress on promoting practical applications and the problems that need to be solved in the future from the perspective of raw material cost system and process complexity. The paper first introduces the structural characteristics of Na3V2(PO4)3 material and the mechanism of sodium-ion intercalation/deintercalation. Then it introduces the synthesis methods, such as the sol–gel method, hydrothermal method, and solid-phase reaction method. In addition, it summarizes the modification studies of Na3V2(PO4)3, including carbon coating, ion doping and, morphology control, design of composite materials and structures based on Na3V2(PO4)3. Finally, it discusses the possible future development of Na3V2(PO4)3.

Keith Bateman, Shota Murayama, Yuji Hanamachi, James Wilson, Takamasa Seta, Yuki Amano, Mitsuru Kubota, Yuji Ohuchi and Yukio Tachi: Evolution of the Reaction and Alteration of Granite with Ordinary Portland Cement Leachates: Sequential Flow Experiments and Reactive Transport Modelling;  Minerals 2022, 12(7), 883; https://doi.org/10.3390/min12070883

Abstract

The construction of a repository for the geological disposal of radioactive waste will include the use of cement-based materials. Following closure, groundwater will saturate the repository, and the extensive use of cement will result in the development of a highly alkaline porewater, pH > 12.5; this fluid will migrate into and react with the host rock. The chemistry of the fluid will evolve over time, initially with high Na and K concentrations, evolving to a Ca-rich fluid, and finally returning to the natural background groundwater composition. This evolving chemistry will affect the long-term performance of the repository, altering the physical and chemical properties, including radionuclide behaviour. Understanding these changes forms the basis for predicting the long-term evolution of the repository. This study focused on the determination of the nature and extent of the chemical reaction, as well as the formation and persistence of secondary mineral phases within a granite, comparing data from sequential flow experiments with the results of reactive transport modelling. The reaction of the granite with the cement leachates resulted in small changes in pH and the precipitation of calcium aluminium silicate hydrate (C-(A-)S-H) phases of varying compositions, of greatest abundance with the Ca-rich fluid. As the system evolved, secondary C-(A-)S-H phases redissolved, partly replaced by zeolites. This general sequence was successfully simulated using reactive transport modelling.

Verity Fitch, Anita Parbhakar-Fox, Richard Crane and Laura Newsome:  Evolution of Sulfidic Legacy Mine Tailings: A Review of the Wheal Maid Site, UK;  Minerals 2022, 12(7), 848;

https://doi.org/10.3390/min12070848

Abstract

Historic tailings dams and their associated mine waste can pose a significant risk to human and environmental health. The Wheal Maid mine site, Cornwall, UK, serves as an example of the temporal evolution of a tailings storage facility after mining has ceased and the acid-generating waste subjected to surficial processes. This paper discusses its designation as a contaminated land site and reviews our current understanding of the geochemistry, mineralogy, and microbiology of the Wheal Maid tailings, from both peer-reviewed journal articles and unpublished literature. We also present new data on waste characterisation and detailed mineral chemistry and data from laboratory oxidation experiments. Particularly of interest at Wheal Maid is the presence of pyrite-bearing “Grey Tailings”, which, under typical environmental conditions at the Earth’s surface, would be expected to have undergone oxidation and subsequently formed acidic and metalliferous mine drainage (AMD). The results identified a number of mechanisms that could explain the lack of pyrite oxidation in the Grey Tailings, including a lack of nutrients inhibiting microbial Fe(II) oxidation, passivation of pyrite mineral surfaces with tailings processing chemicals, and an abundance of euhedral pyrite grains. Such research areas need further scrutiny in order to inform the design of future tailings facilities and associated AMD management protocols.

Marouen Jouini, Alexandre Royer-Lavallée, Thomas Pabst, Eunhyea Chung, Rina Kim, Young-Wook Cheong  and Carmen Mihaela Neculita:  Sustainable Production of Rare Earth Elements from Mine Waste and Geoethics ; 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.

Huan Li, Elsayed Oraby, Jacques Eksteen  and Tanmay Mali: Extraction of Gold and Copper from Flotation Tailings Using Glycine-Ammonia Solutions in the Presence of Permanganate; 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.

Jun Yang, Qin Yang, Hui Zhao, and Lirong He: Elastomeric Polyurethane Foam from Elemental Sulfur with Exceptional Mercury Capture Capability ;  Ind. Eng. Chem. Res. 2023, 62, 8, 3492–3502 (https://doi.org/10.1021/acs.iecr.3c00067)

Abstract

Elemental sulfur-derived polymers are good candidates for remediation materials of heavy metal pollutants especially mercury as sulfur provides an excellent active site for Hg2+. However, the hydrophobic nature and poor processibility of existing sulfur polymers endow the respective absorbents with inferior wetting ability and a limited surface area, which cannot bring Hg2+ into full contact with the active binding site, ultimately resulting in an unsatisfactory absorbing performance. In this work, for the first time, an elastomeric polyurethane foam derived from elemental sulfur is successfully fabricated by engineering sulfur oligomers featuring multi-hydroxyl functionalities into the soft segment while achieving reasonable sulfur utilization yields. The afforded foam exhibits good wetting behavior and an open cell structure with abundant micropores. As a result, the foam delivers a significantly enhanced relative mercury capture capability of 106 mg Hg2+/g sulfur, which stands out distinctively from that of state-of-the-art sulfur polymers. Moreover, the elastomeric foam nature enables the fast absorber separation after usage in a simple squeezing or pumping step, otherwise tedious post-treatments are mandatory for materials displayed in other forms, which greatly simplifies the water remediation process. This strategy not only demonstrates a novel roadmap for advancing the heavy metal uptake capability of elemental sulfur-derived functional materials but also enriches the application scenario of pollutant absorbents.

Hong Peng, Ngoc Quy Vu, James Vaughan, Sicheng Wang, and Shuai Gao: Revealing the Mechanisms of Metal Adsorption by Bauxite Residue; Ind. Eng. Chem. Res. 2023, 62, 8, 3515–3524 (https://doi.org/10.1021/acs.iecr.2c02928)

Abstract

Acid treatment of bauxite residue (BR) has been one of the main approaches to enhance its metal adsorption performance. However, the acid treatment mechanisms remain poorly understood and is complicated by the variable and complex mineralogy of bauxite residue and different test conditions in previous studies. In this study, bauxite residue samples were treated with aqueous HCl solutions, with concentrations ranging from 0 to 0.25 M. The dissolution kinetics of the major elements (Na, Al, Ca, Fe, and Si) and target metals (Pb2+ and Cu2+) for ion exchange and adsorption performance were measured. The solid samples were examined using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) cross-sectional elemental mapping to determine the reaction mechanisms. The results revealed that the adsorption performance decreased with increasing acid concentrations, which is related to the structural changes of the sodalite phase. Other mineral phases, such as hematite, boehmite, and quartz, play a minor role in the adsorption. Additionally, different adsorption mechanisms between Pb2+ and Cu2+ were revealed, which were related to surface disruption.

Ahmed Al-Mamoori, Mohammed Hameed, Ammar Saoud, Turki Al-ghamdi, Qasim Al-Naddaf, Abdo-Alslam ALwakwak, and Khaled Baamran:  Development of Sodium-Based Borate Adsorbents for CO2 Capture at High Temperatures;  Ind. Eng. Chem. Res. 2023, 62, 8, 3695–3704 (https://doi.org/10.1021/acs.iecr.2c04129)

Abstract

The excessive amounts of CO2 emissions to the atmosphere are a critical issue due to the global warming phenomenon. Development of CO2 adsorbents at high temperatures is of paramount importance because of their widespread application. In this investigation, sodium-based borate adsorbents have been developed for the CO2 capture process. Four different sodium precursors (NaOH, NaCl, Na2CO3, and NaNO3) have been employed as a sodium source, their effects on a boric acid material was investigated, and they were tested for CO2 capture application under different temperatures (500–700 °C). The proposed adsorbent materials showed promising results in terms of CO2 capture efficacy. The maximum CO2 uptake (5.45 mmol/g) and the fastest kinetic (90% of its capture uptake achieved within the first minute) have been obtained from the proposed NB4 (NaNO3@H3BO3) material at 600 °C and 1 bar. However, NB2 (NaCl@H3BO3) and the pristine materials (boric acid) showed no capacity toward CO2. Time on stream has also been tested for NB1, NB3, and NB4 after multiple cyclic adsorption–desorption. The materials showed high stability after eight consecutive adsorption–desorption cycles. For further investigation, XRD, FTIR, SEM, and TGA-DSC techniques have been performed for the proposed materials to study their crystalline composition structures, bonding interactions, material degradation, and melting points. The excellent performance of the newly synthesized materials is attributed to the chemical reaction of sodium borate with CO2 with the aid of the molten phase that facilitates CO2 diffusion over the proposed materials. The newly proposed materials could open a new avenue for CO2 capture technology.

Vaishnavi Kulkarni, Debashis Panda, and Sanjay Kumar Singh:  Direct Air Capture of CO2 over Amine-Modified Hierarchical Silica;  Ind. Eng. Chem. Res. 2023, 62, 8, 3800–3811 (https://doi.org/10.1021/acs.iecr.2c02268)

Abstract

The current study reports the utilization of tetraethylenepentamine (TEPA)-modified hierarchical silica particles having bimodal meso/macroporosity for CO2 capture under simulated direct air capture (DAC) conditions (400 ppm CO2 in He). Results infer a typical relation between TEPA loading and CO2 capture, where TEPA-impregnated HS (HS-TEPA-70) exhibits exceptionally high CO2 uptake (5.20 mmol/g), shorter adsorption half time (110 min), and excellent amine efficiency (0.32 mmol of CO2/mmol of N) with moderate CO2/N2 selectivity at 30 °C under DAC conditions. HS-TEPA-70 also showed appreciable CO2 adsorption performance (5.88 mmol/g) under humid conditions (50 ± 3% RH) with 400 ppm CO2 in He at 30 °C. TEPA-impregnated HS even displays better thermal stability up to 10 consecutive adsorption–desorption cycles with minimal amine leaching and moderate CO2 regeneration energy. Moreover, the pelletized form of HS-TEPA-70 also demonstrates better CO2 adsorption performance (3.34 mmol/g), which makes it a promising candidate for CO2 capture from ambient air by temperature swing adsorption.

Luver Echeverry-Vargas  and Luz Marina Ocampo-Carmona: Recovery of Rare Earth Elements from Mining Tailings: A Case Study for Generating Wealth from Waste; 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 D2EHPA indicated the requirement of three stages for the extraction of Ce, La and Nd.

Thulisile Nkomzwayo, Liberty L. Mguni, Xinying Liu, Ran Liu, and Yali Yao: Competitive Adsorption in a Multicomponent Diesel System Using Nickel Oxide/Activated Carbon;  Ind. Eng. Chem. Res. 2023, 62, 8, 3812–3827 (https://doi.org/10.1021/acs.iecr.2c03745)

Abstract

Nickel oxide, which acts as an intermediate Lewis acid, was loaded onto activated carbon (AC) to enhance the adsorption selectivity of AC in the desulfurization of model diesel. The total sulfur adsorption capacity increased from 2.46 to 4.42 mg-S·g adsorbent–1 and the total sulfur removal increased from 46.8 to 84.5% using the AC and Ni(10%)O/AC adsorbents, respectively. Multicomponent isothermal modeling showed that the incorporation of NiO onto AC significantly improved the synergistic interactions between the thiophenic compounds while mitigating competitive interactions between the more steric 4,6-dimethyl dibenzothiophene (4,6-DMDBT) and 4-methyl-dibenzothiophene (4-MDBT) compounds. The mitigation was attributed to new adsorbate-specific sites created by loading NiO on AC. Spent adsorbent characterization and pyridine adsorption-IR analysis suggested that higher desulfurization performance of the Ni(10%)O/AC adsorbent was attributed to an increase in the adsorbent’s Lewis acidity upon loading with NiO, leading to increased Ni–S acid–base interactions, in addition to π-complexation.

Ander Centeno-Pedrazo, Jonatan Perez-Arce, Zoraida Freixa, Pablo Ortiz, and Eduardo J. Garcia-Suarez : Catalytic Systems for the Effective Fixation of CO2 into Epoxidized Vegetable Oils and Derivates to Obtain Biobased Cyclic Carbonates as Precursors for Greener Polymers;  Ind. Eng. Chem. Res. 2023, 62, 8, 3428–3443 (https://doi.org/10.1021/acs.iecr.2c03747)

Abstract

The chemical fixation of carbon dioxide by cycloaddition to biobased epoxides, e.g., vegetable oils, fatty acids, etc., is an efficient, sustainable, and clean strategy to obtain biobased cyclic carbonates. These can be used as feedstocks for the synthesis of environmentally friendly biobased polymers as an alternative to polymers used in daily life such as polyurethanes (PUs) and/or polycarbonates (PCs). Nevertheless, this reaction is not trivial at all due to both the low reactivity of the CO2 molecule and the nature of the needed substrates (biobased epoxides) where the epoxide groups are internal and sterically hindered, hampering the CO2 cycloaddition reaction. Therefore, the design of efficient catalytic systems to overcome these hurdles is mandatory. Most of the catalytic systems developed for this transformation aim to facilitate the rate-determining step in the CO2 cycloaddition catalytic cycle. They comprise an ionic liquid or an ionic compound with a nucleophilic anion alone or in the presence of a cocatalyst to assist the epoxide ring-opening. The most commonly used catalyst is tetrabutylammonium bromide [TBA][Br] ionic liquid, but other ammonium-, phosphonium-, and sulfonium-based ionic liquids in combination or not with a cocatalyst have also been disclosed in the literature. This Review presents a structured overview of the reported catalytic systems, both homogeneous and heterogeneous catalysts, employed in the transformation of any epoxidized vegetable oil or derivates into biobased carbonated materials. The different catalytic systems have been discussed and compared in terms of catalytic performance, employed substrates, and reaction conditions.

Seyedeh Zahra Mousavi, Hamid Reza Shadman, Meysam Habibi, Mohsen Didandeh, Arash Nikzad, Mahsa Golmohammadi, Reza Maleki, Wafa Ali Suwaileh, Alireza Khataee, Masoumeh Zargar, and Amir Razmjou: Elucidating the Sorption Mechanisms of Environmental Pollutants Using Molecular Simulation;  Ind. Eng. Chem. Res. 2023, 62, 8, 3373–3393 (https://doi.org/10.1021/acs.iecr.2c02333)

Abstract

With the global expansion of industrial activities, the entry of various pollutants into the environment has remained a serious issue. One of the best ways to remove these pollutants is to use the adsorption method. Understanding adsorption mechanisms to improve and optimize adsorbents are pivotal for adsorbent development. In this study, the application of molecular simulation in developing various adsorbents has been reviewed. A variety of molecular simulation methods such as molecular dynamics (MD), density functional theory (DFT), hybrid quantum and classical molecular dynamics (QM/MM), ab initio molecular dynamics (AIMD), and coarse-grained molecular dynamics have been used to study these processes. Although hardware limitations prevented researchers from using this method for real systems, this problem has been solved thanks to the development of computing power units (CPUs) and graphic processing units (GPUs). Due to the increasing use of molecular simulations, an attempt has been made to review previous work in this field. Investigations were conducted on various capabilities of molecular simulations in studying the adsorption process and its limitations. In addition to lowering the cost and time of industrial research, this study advances molecular simulations in academic studies. These simulations can reveal the mechanisms underlying adsorption and the selection, development, and design of suitable adsorbents and adsorption processes. Although investigating the adsorption mechanisms for the selection and design of the process is a complicated problem, this work tends to shed light on almost all types of molecular simulations and their applications in studying the adsorption process of removing various environmental pollutants by various adsorbents.

Yigui Lao, Guangqiang Li, Yunming Gao, Cheng Yuan: Wetting and corrosion behavior of MgO substrates by CaO–Al2O3–SiO2–(MgO) molten slags;  Ceramics International, Volume 48, Issue 10, 15 May 2022, 14799-14812 (https://doi.org/10.1016/j.ceramint.2022.02.017)

Abstract

The corrosion of refractory is generally related to the wetting between slag and refractory. Investigating the wetting and corrosion characteristics of refractory by molten slag has a positive significance to elucidating the corrosion mechanism and understanding the slag resistance. In this work, the apparent contact angles of the CaO–Al2O3–SiO2–(MgO) molten slags on microporous magnesia aggregate (MM) and fused magnesia (FM) substrates were respectively measured by sessile drop method under Ar atmosphere at 1550 °C. The dissolution of the MM substrate and the slag penetration behavior were investigated by combining the theoretical calculation of the FactSage thermodynamic software with the examination of SEM-EDS. The results show that MM substrate had a better slag resistance than FM substrate. The final apparent contact angles (θf) of slags with the CaO/SiO2 values of 3, 5 and 11 on MM substrate were 15.8°, 21.4°, and 9.2°, respectively, and that with the MgO content of 3, 6 and 9 mass% were 11.1°, 14.2°, and 52.5°, respectively. The larger the CaO/SiO2 value of the slag, the more beneficial it was to slowing down the dissolution of MM and FM substrates; the original slag with MgO was also beneficial to lessening the dissolution of the MM substrate, which was better than that with a high CaO/SiO2 value. The formation of MA could inhibit the slag from penetrating. In addition, for slags with different CaO/SiO2 values, the effects of surface tension and viscosity on slag penetration were more significant than that of contact angle; for slags with different MgO contents, the effect of contact angle on slag penetration was more significant than those of surface tension and viscosity.

Arthur D. Pelton : Thermodynamic Calculations Support a Rain Cloud Model of Chondrule Formation, ACS Earth Space Chem. 2023, 7, 2, 404–415 (https://doi.org/10.1021/acsearthspacechem.2c00276)

Abstract

Thermodynamic calculations using the critically evaluated and optimized FactSage databases lead to the conclusion that chondrules of all types were formed from a “rain cloud” of undercooled liquid oxide droplets that were in equilibrium with the solar nebula. The droplets subsequently solidified rapidly and stochastically in the temperature and pressure gradients of the nebula to form solid chondrules that retained the compositions of the liquid droplets and thereafter were no longer in thermodynamic equilibrium with the nebular gas. This provides a simple unified model for the formation of chondrules in all chondrite meteorites including chondrule-like calcia alumina inclusions, anorthite-rich chondrules, and magnesio-silicate chondrules. Other models of chondrule formation, including the currently favored models of melting of pre-existing solids, are not consistent with thermodynamic calculations.

Kento Kosugi, Chiharu Akatsuka, Hikaru Iwami, Mio Kondo, and Shigeyuki Masaoka:  Iron-Complex-Based Supramolecular Framework Catalyst for Visible-Light-Driven CO2 Reduction ; J. Am. Chem. Soc. 2023, XXXX, XXX, XXX-XXX (https://doi.org/10.1021/jacs.3c00783)

Abstract

Molecule-based heterogeneous photocatalysts without noble metals are one of the most attractive systems for visible-light-driven CO2 reduction. However, reports on this class of photocatalysts are still limited, and their activities are quite low compared to those containing noble metals. Herein, we report an iron-complex-based heterogeneous photocatalyst for CO2 reduction with high activity. The key to our success is the use of a supramolecular framework composed of iron porphyrin complexes bearing pyrene moieties at meso positions. The catalyst exhibited high activity for CO2 reduction under visible-light irradiation (29100 μmol g–1 h–1 for CO production, selectivity 99.9%), which is the highest among relevant systems. The performance of this catalyst is also excellent in terms of apparent quantum yield for CO production (0.298% at 400 nm) and stability (up to 96 h). This study provides a facile strategy to create a highly active, selective, and stable photocatalyst for CO2 reduction without utilizing noble metals.

Jun Shen, Qin Li, Zhenyu Cai, Xiaolin Sun, and Jingquan Liu:  Metal–Organic Framework-Based Self-Supporting Nanoparticle Arrays for Catalytic Water Splitting;   ACS Appl. Nano Mater. 2023, 6, 3, 1965–1974 (https://doi.org/10.1021/acsanm.2c04942)

Abstract

One of the efficient methods for achieving the carbon peaking and carbon neutrality goals is the generation of hydrogen from water splitting. It has been proven that reasonable nanoengineering is an important strategy to increase the performance of non-noble-metal catalysts. A metal–organic framework (MOF) is a kind of porous and versatile nanomaterial that has great potential for industrial application in water electrolysis technology. However, MOF materials are mostly powders, which greatly limits their ability to be used directly as electrode materials in practical applications. Therefore, this paper innovatively designs a general strategy to prepare controlled MOF-based three-dimensional nanoparticle-array-structured catalysts with self-support and well-orientation on the surface of nickel foam. This strategy consists of simple hydrothermal, stable stirring, and high-temperature calcination methods. In this work, the self-supporting nanoparticle-array catalyst (ZIF-67/NiCo-S/NF) is successfully prepared using 2-methylimidazole cobalt salt (ZIF-67). The special structure and composition of ZIF-67/NiCo-S/NF provide several beneficial features such as a synergistic effect, high specific surface area, fast electron transport, more exposed active sites, and enhanced electrochemical stability. At room temperature and in a 1 M KOH solution, ZIF-67/NiCo-S/NF only needs 147 and 127 mV overpotentials to obtain a current density of 10 mA cm–2 for hydrogen and oxygen evolution reactions, respectively. The excellent performance of ZIF-67/NiCo-S/NF makes it a potential industrial water-splitting catalyst for hydrogen production. This study presents a general strategy for the synthesis of self-supporting nanoparticle arrays based on the MOF, which offers a new line for the preparation of more nanoscale electrocatalysts.

Erwei Huang, Ning Rui, Rina Rosales, Ping Liu, and José A. Rodriguez:  Activation and Conversion of Methane to Syngas over ZrO2/Cu(111) Catalysts near Room Temperature;  J. Am. Chem. Soc. 2023, XXXX, XXX, XXX-XXX (https://doi.org/10.1021/jacs.3c01980)

Abstract

Enzymatic systems achieve the catalytic conversion of methane at room temperature under mild conditions. In this study, varying thermodynamic and kinetic parameters, we show that the reforming of methane by water (MWR, CH4 + H2O → CO + 3H2) and the water–gas shift reaction (WGS, CO + H2O → H2 + CO2), two essential processes to integrate fossil fuels toward a H2 energy loop, can be achieved on ZrO2/Cu(111) catalysts near room temperature. Measurements of ambient-pressure X-ray photoelectron spectroscopy and mass spectrometry, combined with density functional calculations and kinetic Monte Carlo simulations, were used to study the behavior of the inverse oxide/metal catalysts. The superior performance is associated with a unique zirconia–copper interface, where multifunctional sites involving zirconium, oxygen, and copper work coordinatively to dissociate methane and water at 300 K and move forward the MWR and WGS processes.

Sukhyun Kang, Kangpyo Lee, Jeong Ho Ryu, Ghulam Ali, Muhammad Akbar, Kyung Yoon Chung, Chan-Yeup Chung, HyukSu Han, and Kang Min Kim: Transition Metal Compounds on Functionalized Multiwall Carbon Nanotubes for the Efficient Oxygen Evolution Reaction;   ACS Appl. Nano Mater. 2023, 6, 6, 4319–4327 (https://doi.org/10.1021/acsanm.2c05458)

Abstract

Numerous studies have attempted the oxygen evolution reaction (OER), a key half-reaction for water electrolysis, with low-cost catalysts exhibiting high activity and durability. This study reports a novel catalyst-design strategy for the heterogeneous growth of iron oxide (Fe2O3) nanoparticles on surface-functionalized multiwall carbon nanotubes (MWCNTs) through pulsed laser ablation (PLA). Strong physicochemical interactions at the functional Fe2O3 nanoparticles/conductive MWCNT support interface are confirmed by spectroscopic and computational investigations; the functional interface promotes charge transfer kinetics and reduces the energy barrier for the rate-determining step of OER. Furthermore, semi-circularly arranged Fe2O3 nanoparticles on the one-dimensional tubular MWCNT support, originating from heterogeneous nucleation and growth during the PLA process, facilitate mass and ion transfer during the OER. Thus, the optimized nanohybrid (0.5Fe@MWCNT) exhibits a low overpotential (310 mV) to generate a current density of 10 mA cm–2 and possesses excellent durability, maintaining a stable current output during 10 h of continuous OER in a 1.0 M KOH electrolyte. Moreover, this synthetic strategy is economically advantageous, as it requires a total processing time of less than 1 h.

Yawen Li, Naiyao Li, Guoping Li, Yi Qiao, Mingming Zhang, Lei Zhang, Qing-Hui Guo, and Gang He: The Green Box: Selenoviologen-Based Tetracationic Cyclophane for Electrochromism, Host–Guest Interactions, and Visible-Light Photocatalysis;  J. Am. Chem. Soc. 2023, XXXX, XXX, XXX-XXX (https://doi.org/10.1021/jacs.3c00800)

Abstract

The novel selenoviologen-based tetracationic cyclophanes (green boxes 3 and 5) with rigid electron-deficient cavities are synthesized via SN2 reactions in two steps. The green boxes exhibit good redox properties, narrow energy gaps, and strong absorption in the visible range (370–470 nm), especially for the green box 5 containing two selenoviologen (SeV2+) units. Meanwhile, the femtosecond transient absorption (fs-TA) reveals that the green boxes have a stabilized dicationic biradical, high efficiency of intramolecular charge transfer (ICT), and long-lived charge separation state due to the formation of cyclophane structure. Based on the excellent photophysical and redox properties, the green boxes are applied to electrochromic devices (ECDs) and visible-light-driven hydrogen production with a high H2 generation rate (34 μmol/h), turnover number (203), and apparent quantum yield (5.33 × 10–2). In addition, the host–guest recognitions are demonstrated between the green boxes and electron-rich guests (e.g., G1:1-naphthol and G2:platinum(II)-tethered naphthalene) in MeCN through C–H···π and π···π interactions. As a one-component system, the host–guest complexes of green box⊃G2 are successfully applied to visible-light photocatalytic hydrogen production due to the intramolecular electron transfer (IET) between platinum(II) of G2 and SeV2+ of the green box, which provides a simplified system for solar energy conversion.

Ning Wang, Pengfei Ou, Rui Kai Miao, Yuxin Chang, Ziyun Wang, Sung-Fu Hung, Jehad Abed, Adnan Ozden, Hsuan-Yu Chen, Heng-Liang Wu, Jianan Erick Huang, Daojin Zhou, Weiyan Ni, Lizhou Fan, Yu Yan, Tao Peng, David Sinton, Yongchang Liu, Hongyan Liang, and Edward H. Sargent: Doping Shortens the Metal/Metal Distance and Promotes OH Coverage in Non-Noble Acidic Oxygen Evolution Reaction Catalysts;  J. Am. Chem. Soc. 2023, 145, 14, 7829–7836 (https://doi.org/10.1021/jacs.2c12431)

Abstract

Acidic water electrolysis enables the production of hydrogen for use as a chemical and as a fuel. The acidic environment hinders water electrolysis on non-noble catalysts, a result of the sluggish kinetics associated with the adsorbate evolution mechanism, reliant as it is on four concerted proton-electron transfer steps. Enabling a faster mechanism with non-noble catalysts will help to further advance acidic water electrolysis. Here, we report evidence that doping Ba cations into a Co3O4 framework to form Co3–xBaxO4 promotes the oxide path mechanism and simultaneously improves activity in acidic electrolytes. Co3–xBaxO4 catalysts reported herein exhibit an overpotential of 278 mV at 10 mA/cm2 in 0.5 M H2SO4 electrolyte and are stable over 110 h of continuous water oxidation operation. We find that the incorporation of Ba cations shortens the Co–Co distance and promotes OH adsorption, findings we link to improved water oxidation in acidic electrolyte.

Aleena Tahir, Farhan Arshad, Tanveer ul Haq, Irshad Hussain, Syed Zajif Hussain, and Habib ur Rehman:  Roles of Metal Oxide Nanostructure-Based Substrates in Sustainable Electrochemical Water Splitting: Recent Development and Future Perspective;  ACS Appl. Nano Mater. 2023, 6, 3, 1631–1647 (https://doi.org/10.1021/acsanm.2c04580)

Abstract

Increasing energy demand to find everlasting and eco-friendly resources is now mainly dependent on green hydrogen production technology. Water electrolysis has been regarded as a clean route for green H2 production with zero carbon emission, but different bottlenecks in the development of electrodes impeded its realization. Recently, transition metal oxides (TMO) have gained tremendous attention as suitable cathodes and anodes due to their sustainability under harsh conditions, high redox features, maximum supportive capability, easy modulation in valence states, and enhanced electrical conductivity. In this review, we have highlighted the role of transition metal oxides as active and supported sites for electrochemical water splitting. We have proposed different perspectives for the rational design of TMO-based electrode materials, i.e., electronic state modulation, modification of the surface structure to control the aerophobicity and hydrophilicity, acceleration of the charge and mass transport, and stability of the electrocatalyst in harsh environments. We have systemically discussed the insights into the relationship among catalytic activity, certain specified challenges, research directions, and perspectives of electrocatalysis of the OER and HER.