Technologies for industrial pollutant purification and hydrogen (H2) production via water reduction are effective for environmental management but are often energy-intensive, costly, and result in direct/indirect carbon emissions. Here, we report a formaldehyde-water fuel cell that uses formaldehyde as fuel and the hydrogen evolution reaction (HER) as the cathode reaction, converting pollutant at the anode into valuable chemicals while simultaneously producing H2 at the cathode through water reduction, and generating electricity without any carbon emissions. The anodic formaldehyde 1-electron oxidation reaction (FOR-1) produces formate and H2, enabling fuel cell to simultaneously and equimolarly generate H2 fuel at both cathode and anode. For each 1 Nm3 H2 generated, 38.5 mol of formate and 0.062 kWh of electricity are produced. Experiments and simulations indicate that the weak intrinsic reactivity of hydrogen on Cu among various catalysts prevents excessive oxidation of formaldehyde, ensuring the selectivity of FOR-1. The innovative fuel cell, coupling HER with a low oxidation potential half-reaction, offers an energy-free alternative for water reduction and pollutant treatment.

Perovskites are promising electrocatalysts for solid oxide cells (SOCs) due to their tunable structures. The reactivity/stability can be effectively enhanced by tuning the spin, whereas few studies have been able to elucidate the correlation between spin and reactivity/stability. Herein, the double-exchange effect coupling spin modulation is studied for Sr2Fe1.3Ni0.2Mo0.5O6, which exhibits a current density of 2.48 A cm-2 with high stability at 800 °C and 1.5 V as the cathode in CO2 reduction. Based on Mössbauer spectroscopy, X-ray absorption spectroscopy, and density functional theory calculations, it is revealed that the doped Ni induces an additional double-exchange effect with enhanced conductivity coupling spin modulation. It produces high-spin Fe4+ (t2g3eg1) with vacant eg orbitals which can accommodate additional electrons from the lone pairs of oxygen, thus facilitating CO2 reduction by enhancing CO2 adsorption and weakening CO adsorption. This work provides a general strategy for the design of SOC electrocatalysts.

The BaCo0.4Fe0.4Zr0.1Y0.1O3-delta (BCFZY) perovskite oxide is a highly promising cathode material for solid oxide fuel cells (SOFCs), mainly due to its exceptional three-phase conductivity at the elevated temperatures and remarkable oxygen reduction reaction (ORR) activity. Nevertheless, its limited electronic and ionic conductivities at relatively lower temperatures poses a significant challenge for its low-temperature applications. To address this issue, the Cu doping in the B-site of BCFZY is proposed. It is observed that Cu doping significantly enhances both the electronic conductivity and oxygen exchange kinetics, leading to a notable reduction in polarization resistance and a substantial improvement in ORR catalytic activity. Specifically, the Ni-YSZ anodesupported single cell equipped with BCFZYCu(4) as the cathode exhibits a remarkable power density of 1.30 W cm(-2) at 700 degrees C, which surpasses that of the single cell with BCFZY cathode by 51.16 %. An in-depth mechanism study has revealed that the enhanced performance is closely linked to the increased orbitals hybridization induced by Cu doping. This not only enlarges the covalency of the Co-O/Cu-O bonds but also shifts the metal 3d and O2p band center closer to the Fermi level, which significantly facilitates the oxygen adsorption, dissociation, and oxygen ion exchange processes of the BCFZYCu(4) cathode.

Water decomposition is the most promising system for developing renewable energy, but the sluggish kinetics of the oxygen evolution reaction (OER) is the key limiting factor. Recently, inorganic nanomaterials have been widely used as an effective catalyst for the stimulation of OER kinetics, for which the subsequent dispersion and the current collector are essential. We present a three-dimensional NiFe-layered double hydroxide (NiFe-LDH) synthesized by electrochemical corrosion, with increased electrochemical performance for electrocatalytic water splitting. Electrochemical measurements reveal that the NiFe-LDH has a lower Tafel slope of 46 mV center dot dec(-1) compared with the NiFe foam. The resulting elec-trode had a current density of 50 mA center dot cm(-2) and a remarkably low overpotential of 150 mV. Theoretical calculations and experimental observations showed and explained NiFe-LDH-90 electrode has high alkaline medium endurance, implying excellent OER electrocatalytic activity. The produced composite is expected to bring new insights into the design of foam electrocatalyst materials for OER. (c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Single-atom catalysts (SACs) have gained substantial attention because of their exceptional catalytic properties. However, the high surface energy limits their synthesis, thus creating significant challenges for further development. In the last few years, metal-organic frameworks (MOFs) have received significant consideration as ideal candidates for synthesizing SACs due to their tailorable chemistry, tunable morphologies, high porosity, and chemical/thermal stability. From this perspective, this review thoroughly summarizes the previously reported methods and possible future approaches for constructing MOF-based (MOF-derived-supported and MOF-supported) SACs. Then, MOF-based SAC's identification techniques are briefly assessed to understand their coordination environments, local electronic structures, spatial distributions, and catalytic/electrochemical reaction mechanisms. This review systematically highlights several photocatalytic and electrocatalytic applications of MOF-based SACs for energy conversion and storage, including hydrogen evolution reactions, oxygen evolution reactions, O-2/CO2/N-2 reduction reactions, fuel cells, and rechargeable batteries. Some light is also shed on the future development of this highly exciting field by highlighting the advantages and limitations of MOF-based SACs.

Solid oxide cells (SOCs) are regarded as a promising energy technology due to their large current density, diverse range of fuels, and high energy conversion efficiency. The double perovskite Sr2FeMoO6 (SFM) has attracted considerable attention for SOCs due to its tunable structure with superior performance of high conductivity, excellent thermal stability, and remarkable carbon deposition resistance in a reducing atmosphere. However, the electrocatalytic activity of SFM is considerably lower than that of commercial Ni-based SOC electrodes. A timely summary of the synthesis, modulation, and application of SFM perovskites is of great significance for its further development for SOCs. In this review, the methods employed in the preparation of SFM electrocatalysts are introduced first. Then, the advancements in the application of different SFM-based electrocatalysts in the field of SOCs are reviewed, and the research progress in the in situ exsolution of SFM-based electrocatalysts through ion regulation is assessed. Finally, the future issues associated with SFM-based electrocatalysts are addressed in the realm of electrocatalysis, to advance their application.

Sr2Fe1.5Mo0.5O6-delta (SFM) perovskite oxide is one of the most promising materials for solid oxide fuel cells (SOFCs) anode. However, the low catalytic activity is a major roadblock that obstructs its practical applications. Although in situ exsolution of B-site metals is demonstrated as a promising approach to enhancing its performance, it can easily induce the co-segregation of A-site Sr, which seriously deteriorates the performance stability. In this work, the A-site Sr element in SFM is partially replaced by Pr, while B-site Mo is partially replaced by Ni. The in situ co-exsolution of both FeNi alloy and PrOx nanoparticles on the reduced Pr0.8Sr1.2Fe1.5Mo0.3Ni0.2O6-delta (R-PSFMN) perovskite is successfully achieved. It is found that the peak power densities (P-max) of the single cell using R-PSFMN as the anode reaches as high as 2.29, 1.60, 1.07, and 0.67 W cm(-)(2) in H-2 atmosphere at the operating temperatures of 850, 800, 750 and 700 degrees C, respectively. Furthermore, it also exhibits excellent performance stability and anticoke properties when using ethane as fuel. The impregnation experiment further corroborates that the improved performance and stability are partly attributable to the contribution of PrOx nanoparticles, presenting a promising approach to enhance the electrochemical performance of SOFC perovskite anodes.

The electrochemical conversion of small organic molecules to value-added chemicals and hydrogen/electricity without CO2 emissions integrates efficient energy conversions (hydrogen energy or electricity) and value-added chemical productions in one reaction system, which is essentially competitive in the carbon-neutral era. However, the activity, stability, and cost-effectiveness of electrocatalysts, as well as the safety, durability, and scalability of devices, are still challenging for their industrial applications. In addition, a lack of knowledge about relevant and detailed mechanisms restricts the further development of electrocatalysts and devices. A timely review of the electrocatalysts, devices, and mechanisms is essential to shed lights on the correct direction towards further development. In this review, the advances in the design of electrocatalysts, fabrication of devices, and understanding of reaction mechanisms are comprehensively summarized and analyzed. The major challenges are also discussed as well as the potential approaches to overcoming them. The insights for further development are provided to offer a sustainable and environmentally friendly approach to cogeneration of energy and chemicals production.

Solid oxide fuel cells (SOFCs) are one of the most efficient energy conversion devices. However, the sluggish oxygen reduction reaction (ORR) kinetics at low temperatures significantly challenge the performance and commercialization of SOFCs. Introducing negative expansion coefficient materials has been recognized as an effective approach to enhancing the ORR catalytic properties, but a clear understanding of this enhanced electrochemical performance is still lacking. In this work, the composite cathode of PrBa0.5Sr0.5Co1.5Fe0.5O5+delta(PBSCF) with different amounts of negative-thermal-expansion material Sm0.85Zn0.15MnO3 (SZM) is prepared, and in-depth analysis the effect of SZM on the catalytic activity of cathodic ORR is systematically investigated. Simultaneously, the mechanistic studies verify that the enhanced ORR activity might be attributed to the constructed compression strain during sintering, which significantly improves the adsorption, dissociation, and oxygen ion exchange process of the PBSCF cathode.

Water/Methanol Coelectrolysis NiCo2S4 is developed through electrochemical deposition on carbon cloth, with the surface magnetism fine-tuned. The surface spin enhanced NiCo2S4 electrodes possess high stable bifunctional performance even in high current density in water/methanol coelectrolysis system. Hydrogen and value-added formate are harvested on both sides of the electrodes in the membrane-less cell, simultaneously, with energy saved. More details can be found in article number 2205257 by Xian-Zhu Fu, Jing-Li Luo, and co-workers.

Co-N-C is a promising oxygen electrochemical catalyst due to its high stability and good durability.However,due to the limited adsorption ability improvement for oxygen-containing intermediates,it usually exhibits inadequate catalytic activity with 2-electron pathway and high selectivity of hydrogen peroxide.Herein,the adsorption of Co-N-C to these intermediates is modulated by constructing heterostructures using transition metals and their derivatives based on d-band theory.The heterostructured nanobelts with MoC core and pomegranate-like carbon shell consisting of Co nanoparticles and N dopant（MoC/Co-N-C） are engineered to successfully modulate the d band center of active Co-N-C sites,resulting in a remarkably enhanced electrocatalysis performance.The optimally performing MoC/Co-N-C exhibits outstanding bi-catalytic activity and stability for the oxygen electrochemistry,featuring a high wave-half potential of 0.865 V for the oxygen reduction reaction（ORR）and low overpotential of 370 mV for the oxygen evolution reaction（OER） at 10 mA cm -2 .The zinc air batteries with the MoC/Co-N-C catalyst demonstrate a large power density of 180 mW cm -2 and a long cycling lifespan（2000 cycles）.The density functional theory calculations with Hubbard correction（DFT+U） reveal the electron transferring from Co to Mo atoms that effectively modulate the d band center of the active Co sites and achieve optimum adsorption ability with "single site double adsorption" mode.

Abstract The non-classical anodic H2 production from 5-hydroxymethylfurfural (HMF) is very appealing for energy-saving H2 production with value-added chemical conversion due to the low working potential (~0.1 V vs RHE). However, the reaction mechanism is still not clear due to the lack of direct evidence for the critical intermediates. Herein, the detailed mechanisms are explored in-depth using in situ Raman and Infrared spectroscopy, isotope tracking, and density functional theory calculations. The HMF is observed to form two unique inter-convertible gem-diol intermediates in an alkaline medium: 5-(Dihydroxymethyl)furan-2-methanol anion (DHMFM−) and dianion (DHMFM2−). The DHMFM2− is easily oxidized to produce H2 via H− transfer, whereas the DHMFM− is readily oxidized to produce H2O via H+ transfer. The increases in potential considerably facilitate the DHMFM− oxidation rate, shifting the DHMFM− ↔ DHMFM2− equilibrium towards DHMFM− and therefore diminishing anodic H2 production until it terminates. This work captures the critical intermediate DHMFM2− leading to hydrogen production from aldehyde, unraveling a key point for designing higher performing systems.

Electrocatalytic water splitting is a viable technique for generating hydrogen but is precluded from the sluggish kinetics of oxygen evolution reactions（OER）.Small molecule oxidation reactions with lower working potentials,such as methanol oxidation reactions,are good alternatives to OER with faster kinetics.However,the typically employed Ni-based electrocatalysts have poor activity and stability.Herein,a novel three-dimensional（3 D）-networking Modoped Ni（OH） 2 with ultralow Ni-Ni coordination is synthesized,which exhibits a high MOR activity of 100 mA cm -2 at 1.39 V,delivering 28 mV dec -1 for the Tafel slope.Meanwhile,hydrogen evolution with value-added formate cogeneration is boosted with a current density of more than 500 mA cm -2 at a cell voltage of 2.00 V for 50 h,showing excellent stability in an industrial alkaline concentration（6 M KOH）.Mechanistic studies based on density functional theory and X-ray absorption spectroscopy showed that the improved performance is mainly attributed to the ultralow Ni-Ni coordination,3 D-networking structures and Mo dopants,which improve the catalytic activity,increase the active site density and strengthen the Ni（OH） 2 3 D-networking structures,respectively.This study paves a new way for designing electrocatalysts with enhanced activity and durability for industrial energy-saving hydrogen production.

Pt-Co electrocatalysts have attracted significant attention because of their excellent performance in many electrochemical reactions. This review focuses on Pt-Co electrocatalysts designed and prepared for electrocatalytic applications. First, the various synthetic methods and synthesis mechanisms are systematically summarized; typical examples and core synthesis parameters are discussed for regulating the morphology and structure. Then, starting with the design and structure-activity relationship of catalysts, the research progress of the morphologies and structures of Pt-Co electrocatalysts obtained based on various strategies, the structure-activity relationship between them, and their properties are summarized. In addition, the important electrocatalytic applications and mechanisms of Pt-Co catalysts, including electrocatalytic oxidation/reduction and bifunctional catalytic reactions, are described and summarized, and their high catalytic activities are discussed on the basis of their mechanism and active sites. Moreover, the advanced electrochemical in situ characterization techniques are summarized, and the challenges and direction concerning the development of high-performance Pt-Co catalysts in electrocatalysis are discussed.

The development of efficient and robust non-precious electrocatalysts for water oxidation at a mild condition is extremely desirable for industrial water splitting. Herein we developed a facile solvothermal strategy to synthesize cobalt metal organic frameworks (Co-MOFs) with sheet-like structure, which showed highly promising performance for electrocatalytic oxygen evolution. The best Co-MOF sample afforded an ultra-high oxygen evolution current density of 63.4 mA cm(-2) at 1.75 V in 1 M KOH with a catalyst loading of only 0.21 mg cm(-2). Notably, its electrochemical performance remained unchanged after 10,000 cyclic voltammograms indicating very promising long-term stability. Detailed study of the mechanism of the oxygen evolution by density functional theory (DFT) indicated that the strong pi-conjugation formed between the central cobalt ion and adjacent aromatic rings favored the high electrocatalytic performance. The solvothermally synthesized MOFs proposed in this paper are expected to inspire the rational design of high-performance electrocatalysts for water oxidation with atomic and molecular level structural control and the exploration of structure-performance relationships to understand the electrocatalytic origin. (C) 2021 Elsevier Inc. All rights reserved.

Small MethodsVolume 6, Issue 3 2270021 Back CoverFree Access Less-Energy Consumed Hydrogen Evolution Coupled with Electrocatalytic Removal of Ethanolamine Pollutant in Saline Water over Ni@Ni3S2/CNT Nano-Heterostructured Electrocatalysts (Small Methods 3/2022) Bin Zhao, Bin Zhao Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060 ChinaSearch for more papers by this authorJianwen Liu, Jianwen Liu Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060 ChinaSearch for more papers by this authorRenfei Feng, Renfei Feng Canadian Light Source Inc., Saskatoon, Saskatchewan, S7N 0X4 CanadaSearch for more papers by this authorLei Wang, Lei Wang Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060 ChinaSearch for more papers by this authorJiujun Zhang, Jiujun Zhang Institute for Sustainable Energy, College of Sciences, Shanghai University, Shanghai, 200444 ChinaSearch for more papers by this authorJing-Li Luo, Jing-Li Luo Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060 ChinaSearch for more papers by this authorXian-Zhu Fu, Xian-Zhu Fu Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060 ChinaSearch for more papers by this author Bin Zhao, Bin Zhao Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060 ChinaSearch for more papers by this authorJianwen Liu, Jianwen Liu Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060 ChinaSearch for more papers by this authorRenfei Feng, Renfei Feng Canadian Light Source Inc., Saskatoon, Saskatchewan, S7N 0X4 CanadaSearch for more papers by this authorLei Wang, Lei Wang Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060 ChinaSearch for more papers by this authorJiujun Zhang, Jiujun Zhang Institute for Sustainable Energy, College of Sciences, Shanghai University, Shanghai, 200444 ChinaSearch for more papers by this authorJing-Li Luo, Jing-Li Luo Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060 ChinaSearch for more papers by this authorXian-Zhu Fu, Xian-Zhu Fu Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, College of Materials Science and Engineering, Shenzhen University, Shenzhen, 518060 ChinaSearch for more papers by this author First published: 21 March 2022 https://doi.org/10.1002/smtd.202270021AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Abstract Back Cover In article number 2101195, Fu and co-workers developed an effective countermeasure for both energy and environmental challenges by integrating electro-oxidation removal of organic pollutants with energy-efficient hydrogen production in saline water. The as-synthesized core/shell Ni@Ni3S2/carbon nanotubes nano-heterostructures are competent for stably electro-oxidizing ethanolamine pollutant in saline water at the anode with long-term working stability at high current densities, which not only suppresses oxygen/chlorine evolution reactions but also decreases the energy cost to boost hydrogen production. Volume6, Issue3March 18, 20222270021 RelatedInformation

Machine learning (ML) is emerging as a powerful tool for identifying quantitative structure–activity relationships to accelerate electrocatalyst design by learning from historic data without explicit programming. The algorithms, data/database, and descriptors are usually the decisive factors for ML and the descriptors play a pivotal role for electrocatalysis as they contain the essence of catalysis from the physicochemical nature. Despite the considerable research efforts regarding electrocatalyst design with ML, the lack of universal selection tactics for descriptors bridging the gap between structures and activity impedes its wider application. A timely summary of the application of ML in electrocatalyst design helps to deepen the understanding of the nature of descriptors and improve the application scope and design efficiency. This review summarizes the geometrical, electronic, and activity descriptors used as input for ML training and predicting to reveal the general rules for their application in the design of electrocatalysts. In response to the challenges of hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, CO2 reduction reaction, and nitrogen reduction reaction, the ML application in these areas is tracked for the progress and prospective changes. Additionally, the potential application of the automated design and discovery are discussed for the other well‐known electrocatalytic processes.

Electrocatalytic water splitting is an appealing method for generating renewable hydrogen. In acidic media, noble metals are commonly used as electrocatalysts, whereas in alkaline media, non-noble metals are used. However, due to the high cost and rarity of noble metals, as well as the low activity and stability of non-noble metals, industrial uses are severely constrained. Heterostructures are a possible alternative to costly electrocatalysts because of their tunable properties. The origin of activity and stability of heterostructures lies in the coupling between their constituent components. Thus, the establishment of interfacial component coupling effects such as the Mott-Schottky effect, the Strong-Metal-Support-Interaction effect, the support-stabilizing effect, and the synergistic effect is a promising technique for enhancing activity and stability. However, a lack of the generation rules for the interfacial coupling effects impedes their widespread application for the rational design. This review summarizes the progress made towards heterostructure design from the interfacial component coupling effects with respect to the various components. The challenges and future prospective have also been presented for the heterostructure electrocatalyst design. The findings reported in this review pave a way for the heterostructure electrocatalyst design for water splitting as well as other electrocatalytic processes such as oxygen reduction, CO2 reduction, nitrogen reduction reactions, etc.

Cesium (Cs+) and strontium (Sr2+) ions are the main fission byproducts in the reprocessing of spent nuclear fuels for nuclear power plants. Their long half-live period (30.17 years for 137Cs and 28.80 years for 90Sr) makes them very dangerous radionuclides. Hence the solidification of Cs+ and Sr2+ is of paramount importance for preventing them from entering the human food chain through water. Despite tremendous efforts for solidification, the long-term stability remains a great challenge due to the experimental limitation and lack of good evaluation indicators for such long half-life radionuclides. Using density functional theory (DFT), we investigate the origin of long-term stability for the solidification of Cs+ and Sr2+ inside sodalite and establish that the exchange energy and the diffusion barrier play an important role in gaining the long-term stability both thermodynamically and kinetically. The acidity/basicity, solvation, temperature, and diffusion effect are comprehensively studied. It is found that solidification of Cs+ and Sr2+ is mainly attributed to the solvation effect, zeolitic adsorption ability, and diffusion barriers. The present study provides theoretical evidence to use geopolymers to adsorb Cs+ and Sr2+ and convert the adsorbed geopolymers to zeolites to achieve solidification of Cs+ and Sr2+ with long-term stability.

Nickel based materials are promising electrocatalysts to produce hydrogen from water in alkaline media. However, the stability is of great challenge, limiting its practical material functions. Herein, a new technique for electro-deposition flower-like NiCo2 S4 nanosheets on carbon-cloth (CC@NiCo2 S4 ) is proposed for energy-saving production of H2 from water/methanol coelectrolysis at high current density by constructing array architectures and regulating surface magnetism. The optimized and fine-tuned magnetism on the surface of the electrochemical in situ grown CC@NiCo2 S4 nanosheet array result in (0 1 -1) surface universally exposed, high catalytic activity for methanol electrooxidation, and long-term stability at high current density. X-ray photoelectron spectroscopy in combination of density functional theory calculations confirm the valence electron states and spin of d electrons for the surface of NiCo2 S4 , which enhance the surface stability of catalysts. This technology may be utilized to alter the surface magnetism and increase the stability of Ni-based electrocatalytic materials in general.