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Hydrogen fuel is a non-toxic and source-abundant energetic system, but for its applications in the industry, several issues related to its storage must be resolved. Compounds like NaBH 4 appear as promising hydrogen sources, while can release the latter rapidly under controllable conditions with the use of heterogeneous catalyst systems. In this work, we synthesized a Ni–CoP catalyst by electrodeposition in a three-step process on carbon paper as support. The materials were characterized via SEM-EDS, XRD, and XPS techniques, while the hydrogen evolution reaction (HER) from alkaline NaBH 4 solutions was tested as a batch experiment. Ni–CoP catalyst showed a high amount of H 2 generated in a short time (∼550 mL in 1 min) and remained at 78 and 54% of its initial performance after respectively 100 and 300 h of a continuous hydrolysis process. Our catalyst revealed exceptional performance and stability at higher temperatures and a long process time, which have been a rare subject of investigation in other reports for NaBH 4 hydrolysis in the past. This work paves a new perspective in studying catalysts for hydrogen generation from borohydrides. [Display omitted] • Ni–CoP catalyst was electrodeposited on a carbon support. • Material characterization proved the formation of desired active layers. • High efficiency and stability of the catalyst for a long-term NaBH 4 hydrolysis was revealed. [ABSTRACT FROM AUTHOR]

High entropy materials (HEM) have been attracting much attention as emerging catalysts for electrochemical water splitting. HEM catalysts have unique properties such as an interesting cocktail effect, broad design space, customizable electronic structure, and excellent entropy stabilization effect compared with single-digit catalysts. This paper provides a comprehensive overview of the use of HEM as a catalyst for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and water splitting. HEM design strategies including phase structure modulation, defect engineering, electrode configuration engineering, and computational aids are discussed to develop HEM catalysts with high performance and stability. In particular, the importance of density functional theory, high-throughput screening techniques, and machine learning for the discovery and design of HEM catalysts is emphasized. Finally, the challenges and imminent difficulties are prospected, and the corresponding strategies to deal with these challenges are put forward to promote the development of HEM catalysts in the field of electrochemical water splitting. [ABSTRACT FROM AUTHOR]

Hydrogen, as a clean, safe, and efficient energy carrier, is one of the hot energy sources that have attracted much attention. Mo2C, due to the introduction of C atoms, makes the atomic spacing of the Mo lattice decrease and changes the width of the d-band, which makes the electronic properties of Mo2C similar to that of Pt noble metals, exhibiting excellent electrochemical hydrogen precipitation performance. MoS2, due to its special crystal structure and tunable electronic structure, has been widely studied. In this paper, Mo2C nanoparticles were prepared by high-temperature carbonization, and then two-dimensional layered MoS2 were be loaded on Mo2C nanoparticles by the hydrothermal method to synthesize Mo2C/MoS2 composite catalysts. Their electrochemical hydrogen precipitation (HER) performance under acidic conditions was tested. The above catalysts were also characterized by modern material testing methods such as XRD, SEM, TEM, and XPS. The results showed that the composite catalysts exhibited the most excellent electrochemical hydrogen precipitation performance at Mo2C/MoS2-3, with the lowest overpotential at a current density of 10 mA cm−2, Tafel slope, and electrochemical impedance. At the same time, the electrochemically active area was dramatically enhanced, with good stability under prolonged testing. The catalytic activity was significantly improved compared with that of Mo2C and MoS2. The characterization and experimental results indicate that the heterogeneous structure of Mo2C and MoS2 formed a built-in electric field between the two, which accelerated the electron transfer efficiency and provided more active sites. The Mo2C/MoS2 composite catalyst is a low-cost, easy-to-prepare, and high-efficiency electrochemical hydrogen precipitation catalyst, providing a new idea for developing green and clean energy. [ABSTRACT FROM AUTHOR]

Fe/N-doped carbon (Fe-NC) is an excellent base-metal catalyst for use in an electrocatalytic oxygen reduction reaction (ORR) with high activity. In this paper, graphite phase carbon nitride (g-C3N4) was first obtained from the pyrolyzing of melamine, and then different proportions of FeCl3 were separately doped into g-C3N4 to further prepare the Fe-NC catalyst. The Fe-NC catalyst was applied in an ORR reaction, and the results show that the Fe-NC catalyst doped with 0.5 mmol FeCl3 possesses exceptional electrocatalytic performance, with an onset potential of 0.96 V and a half-wave potential of 0.81 V, which approaches that of a Pt/C catalyst. Meanwhile, the Fe-NC catalyst displays high stability and methanol resistance. The results supply a new way to prepare efficient ORR electrocatalysts. [ABSTRACT FROM AUTHOR]

Molybdenum based phosphides have gradually become the investigation frontier of hydrogen evolution catalysts due to the platinum like electronic structure. In this paper, N, P double-doped graphite carbon layers wrapped with MoP nanoparticles (P–MoP@NPC), is directly compounded by one-step high-temperature carboning PMo 12 -APP@ZIF-8 precursor. P–MoP@NPC possesses splendid hydrogen production reactive, in two kinds of electrolytes, when the overpotentials of P–MoP@NPC are 132 mV and 161 mV, the slope of current density reaching 10 mA cm−2, Tafel slope are 67 and 79 mV dec−1, respectively. In the bargain, P–MoP@NPC displays satisfactory durability in acid and alkaline mediums and can continue to work for more than 24 h. The wonderful hydrogen production ability of P–MoP@NPC is ascribed to the synergistic effect of MoP nanoparticles, hierarchical porous structure as well as N, P double-doped carbon layers. The confinement effect of ZIF-8 makes most of the synthesized MoP nanoparticles evenly distributed. The hierarchical porous structure caused by the volatilization of Zn atoms with high temperature can expose more active centers. The N, P double-doped graphitic carbon layers not only protect the catalyst but also adjust the electronic structure of MoP, promoting the hydrogen production capacity. This work may provide a general way to study molybdenum phosphide catalysts synthesized by APP as a green phosphorus source for energy conversion. Molybdenum phosphide catalyst (P–MoP@NPC) was synthesized by simple solution mixing and high temperature calcination. The synthesized P–MoP@NPC has good catalytic activity and stability at 0.5 M H 2 SO 4 and 1 M KOH. [Display omitted] • APP is used as a green phosphorus source for phosphatization. • N, P dual-doped catalyst (P–MoP@NPC) was constructed with high efficiency hydrogen evolution activity; • Zn ions volatilization in ZIF-8 causes multistage pores to expose more active sites; • The confinement effect of ZIF-8 makes MoP nanoparticles evenly distributed. [ABSTRACT FROM AUTHOR]

It is highly attractive to develop a photoelectrochemical (PEC) sensing platform based on a non-noble-metal nano array architecture. In this paper, a PEC hydrogen peroxide (H2O2) biosensor based on Ni/WS2/WC heterostructures was synthesized by a facile hydrothermal synthesis method and melamine carbonization process. The morphology, structural and composition and light absorption properties of the Ni/WS2/WC catalyst were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV–visible spectrophotometer. The average size of the Ni/WS2/WC nanosheets was about 200 nm. Additionally, the electrochemical properties toward H2O2 were studied using an electrochemical workstation. Benefiting from the Ni and C atoms, the optimized Ni/WS2/WC catalyst showed superior H2O2 sensing performance and a large photocurrent response. It was found that the detection sensitivity of the Ni/WS2/WC catalyst was 25.7 μA/cm2/mM, and the detection limit was 0.3 mmol/L in the linear range of 1−10 mM. Simultaneously, the synthesized Ni/WS2/WC electrode displayed excellent electrocatalytic properties in hydrogen evolution reaction (HER), with a relatively small overpotential of 126 mV at 10 mA/cm2 in 0.5 M H2SO4. This novel Ni/WS2/WC electrode may provide new insights into preparing other efficient hybrid photoelectrodes for PEC applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Bifunctional catalyst Fe[ Pc (I) 4 ] + Ni[ Pc (I) 4 ]@NC PDI for ORR and OER is synthesized. • The NC PDI with 2D structure and superior stability was used as support. • Iodine groups in TM[ Pc (I) 4 ] creates a built-in electric field to enhance catalysis. • The synergistic effect of Fe[ Pc (I) 4 ]/Ni[ Pc (I) 4 ] enhances the catalytic performance. • The catalyst has superior performance for ORR/OER in rechargeable Zn-air batteries. In this paper, we report on the preparation and catalysis of a bifunctional molecular catalyst (Fe[ Pc (I) 4 ]+Ni[ Pc (I) 4 ]@NC PDI) for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in rechargeable Zn-air batteries. This catalyst is prepared by self-assembling tetraiodo metal phthalocyanines (Fe[ Pc (I) 4 ] and Ni[ Pc (I) 4 ]) on a 2D N -doped carbon material (NC PDI) through π-π interactions. The introduction of iodine groups in the edge of phthalocyanines controls the density of electron cloud and electrostatic potential around Fe-N/Ni-N sites and constructs a built-in electric field that facilitates directional transport of charges, enhancing the catalytic activity of the catalyst. Density functional theory (DFT) calculations support this mechanism by showing a reduced energy barrier for the ORR rate-determining step (RDS). The Fe[ Pc (I) 4 ]+Ni[ Pc (I) 4 ]@NC PDI exhibits excellent performance outperforming 20 wt% Pt/C and single-molecule self-assembled Fe[ Pc (I) 4 ]@NC PDI and Ni[ Pc (I) 4 ]@NC PDI , with a half-wave potential of E 1/2 = 0.940 V in the ORR process under alkaline condition. During the OER process, Fe[ Pc (I) 4 ]+Ni[ Pc (I) 4 ]@NC PDI exhibited a low overpotential of 298 mV at 10 mA cm−2 under the alkaline condition, which is much better than RuO 2 , Fe[ Pc (I) 4 ]@NC PDI and Ni[ Pc (I) 4 ]@NC PDI. The catalyst also demonstrates excellent catalysis and durability in rechargeable Zn-air batteries. This work provides a simple and specific method to develop efficient multifunctional molecular electrocatalysts. [ABSTRACT FROM AUTHOR]

At present, energy shortage and environmental pollution are becoming more and more serious. If environmental governance and energy supply can be combined, it will be more consistent with the long-term concept of sustainable development. Urea electrooxidation may achieve the degradation of pollutants and the conversion of energy supply, urea oxidation occurs at the anode and hydrogen evolution occurs at the cathode. However, the electrochemical oxidation process of urea requires the transfer of six electrons, and the reaction rate is slow. The electrocatalyst is a key factor in improving the reaction kinetics. In this context, catalysts used in urea electrocatalytic oxidation in recent years are reviewed in this paper. The application of the electrocatalyst in electrolytic hydrogen production, urea wastewater treatment, urea fuel cells and urea sensors are described in detail. In addition, the future research directions, research emphases and areas needing improvement of these catalysts are discussed. [Display omitted] • Urea electrooxidation has double benefits of environmental protection and energy supply. • Electrocatalysts for urea electrooxidation in alkaline electrolytes are reviewed. • The applications of electrocatalyst in the electrooxidation of urea are demonstrated. [ABSTRACT FROM AUTHOR]

In this paper, N-doped Ni 2 P (N-Ni 2 P) as a catalyst for hydrogen evolution was proposed. Firstly, the feasibility of N atom doping was calculated by density functional theory (DFT). Ni top site, Ni bridge site, Ni hollow site and P top site were calculated for Ni 2 P (001) and N-Ni 2 P (001). The results confirm that N atom doping can make the Gibbs free energy (ΔG H∗) closer to thermal neutrality (ΔG H∗ = 0) and move the d -band center away from Fermi level. Besides, charge density difference pattern and bader charge indicate N atom doping regulate the charge structure of the catalyst surface. Based on the guidance of DFT calculation results, Ni 2 P and N-Ni 2 P catalysts were also experimentally synthesized. It is revealed that the N-Ni 2 P can achieve cathodic current densities of 10 mA cm−2 and 100 mA cm−2 at overpotentials of 110 mV and 302 mV in 1.0 M KOH and 82 mV and 235 mV in 0.5 M H 2 SO 4 , respectively. This work shows that it is feasible to increase HER performance by modifying Ni 2 P catalyst with N doping. [Display omitted] • N-Ni 2 P exhibits an ideal hydrogen evolution performance in acidic and alkali media. • The introduction of N atoms modifies the electronic structure of Ni 2 P. • N-Ni 2 P has a Gibbs free energy closer to thermal neutrality than Ni 2 P. • N-Ni 2 P with unique scale structure is conducive to the increase of active site. [ABSTRACT FROM AUTHOR]

The electrochemical CO2 reduction reaction (CO2RR) presents a promising approach for producing valuable chemicals and fuels, offering a dual benefit in terms of environmental preservation and the efficient utilization of carbon resources. In this work, we proposed a stepwise electrodeposition method to prepare Cu−Pb bimetallic heterojunction catalyst on polyaniline‐modified carbon paper (PANI‐CuPb‐x), where x is the electrodeposition times(min). Among the studied catalysts, the electrode electrodeposited for 2 min (PANI‐CuPb‐2) exhibited a remarkable performance during the electrocatalysis CO2 to multicarbon (C2+) products process, achieving a Faraday efficiency (FE) of 81.46 % and a partial current density of 15.41 mA cm−2 at −1.2 V (vs. RHE) in an H‐type cell. The detailed study demonstrated that introducing Pb could effectively improve the formation of COOH*inhibit hydrogen evolution reaction (HER). Furthermore, the heterojunction structure in the catalysts facilitated C−C coupling of the generated C1 intermediate species, which enhanced the CO2 to C2+ reaction. [ABSTRACT FROM AUTHOR]

Electrocatalytic CO 2 RR is an ideal method. It is capable of converting CO 2 into usable fuels and valuable chemical products. Electrocatalytic CO 2 RR produces a wide range of chemicals. Of these, ethanol (EtOH) is favored for its wide industrial and commercial value. However, electrocatalytic CO 2 RR preparation of EtOH involves C-C coupling reactions and is a multi-electron transfer process. For this reason, the efficient electrochemical conversion of EtOH by CO 2 RR remains a great challenge. The preparation of EtOH by electrocatalytic CO 2 RR involves the interference of a competing hydrogen evolution reaction as well as some other reaction intermediates. This limits the improvement of Faraday efficiency of ethanol (FE EtOH) and the current density of ethanol (J EtOH). To improve ethanol selectivity, the researchers designed and modified the catalysts using engineering regulation effects such as reaction conditions engineering regulation, surface engineering regulation, interfacial engineering regulation, and single atom engineering regulation, and achieved excellent results. Therefore, it is important to understand the key factors affecting the catalyst activity by different engineering regulations and to apply a combination of engineering regulations to the catalyst development. Therefore, this paper firstly provides a comprehensive summary of the catalysts applied for the preparation of EtOH by electrocatalytic CO 2 RR, including two major categories of catalysts containing pure metal active components and catalysts without pure metal active components. Subsequently, the main effects of engineering modulation on catalyst activity are analyzed and summarized in detail, respectively. Finally, the future challenges and development prospects of electrocatalytic CO 2 RR for EtOH preparation were highlighted. [Display omitted] • A review of the main regulation methods of the relevant electrocatalysts is given. • The effect of reaction conditions regulation on the reaction process is reviewed. • A detailed review of the mechanisms by which selective catalytic reactions proceed with engineered regulated catalysts is presented. • A look at the future development of electrocatalytic CO 2 RR. [ABSTRACT FROM AUTHOR]

The development of highly efficient and low-cost bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is the key to the industrialization of large-scale hydrogen production, while the development of non-precious-metal catalysts that can be substituted for precious-metal materials is the current trend of research. In this paper, nickel foam (NF) self-supported CoFe layered bimetallic hydroxide (LDH)-CuCo 2 S 4 electrocatalysts were prepared using a simple hydrothermal and electrodeposition method. The prepared CuCo 2 S 4 @CoFe-LDH/NF catalysts showed good performance in alkaline water oxidation, proton reduction and overall water decomposition with an overpotential of 293 mV for the oxygen evolution reaction (OER) at a current density of 50 mA cm−2 and 63 mV for the hydrogen evolution reaction (HER) at a current density of 10 mA cm−2. When CuCo 2 S 4 @CoFe-LDH/NF was used as a bifunctional electrocatalyst for the decomposition of water, the voltage of the 10 mA cm−2 electrolyzer was only 1.54 V, and the stability of the electrolyzer reached 60 h, which was superior to other bifunctional catalysts. [Display omitted] • CoCu-LDH grows firmly on nickel foam by a hydrothermal method. • Vulcanization at room temperature makes the experimental conditions milder and simpler. • An electrodeposition method was used to grow nanosheets on nanowires. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) catalyzed by non-precious metals and their compounds in alkaline environments are regarded as a key research topic for the use of water for hydrogen production to alleviate the global energy crisis. Cobalt-iron layered double hydroxide (CoFe-LDH) has attracted much attention as a potential high-performance oxygen evolution reaction catalyst. In this paper, we report a strategy to introduce metal elements M (M = Cu, K, Al, Cr and Zn) into CoFe-LDH to further enhance the OER performance. The experimental results show that CoFeK-15 exhibits the lowest overpotential (203 mV to reach 10 mA cm−2) and Tafel slope (77.1 mV dec−1) and maintains excellent catalytic activity after 50 h i-t test. Through the introduction of potassium ions, the electronic structure inside the catalyst underwent lattice distortion, resulting in a larger active surface area and exposure of more oxygen vacancies, which in turn accelerated the OER reaction. This study reveals the important influence of potassium doping on the electronic structure modification strategy to enhance the performance of OER and provides new ideas for the development of more efficient catalysts in the future. [Display omitted] [ABSTRACT FROM AUTHOR]

• An efficient Co 9 S 8 /Ni 3 S 2 bifunctional electrocatalyst is synthesized by hydrothermal method. • Co 9 S 8 /Ni 3 S 2 possesses a large specific surface area because of the flocculated structure. • Overpotentials of 53.6 and 107.6 mV were obtained to achieve current density of 10 mA/cm2 for HER and OER. • A cell potential of 1.55 V was required to drive the overall water splitting at a current density of 10 mA/cm2. Modern industrial hydrogen production is a crucial solution to address the energy crisis. Therefore, the development of a cost-effective and highly efficient hydrolytic hydrogen production catalyst holds significant practical importance. In this study, we propose to synthesize an efficient bifunctional electrocatalyst of Co 9 S 8 /Ni 3 S 2 grown on nickel foam (NF) by a one-step hydrothermal method, which has a large specific surface area due to its flocculated structure. Through electrochemical testing, the Co 9 S 8 /Ni 3 S 2 /NF electrode exhibits remarkable performance in both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Specifically, low overpotentials of 53.6, 90.2, and 209.2 mV are required to achieve current densities of 10, 20, and 100 mA/cm2 during HER, respectively. Similarly, for OER, the overpotentials are only 107.6, 150.6, and 350.4 mV. Additionally, the Co 9 S 8 /Ni 3 S 2 /NF electrode demonstrates a small Tafel slope of 68.7 mV/dec for HER and 91.8 mV/dec for OER, indicating efficient reaction kinetics. Notably, the electrode exhibits exceptional long-term stability. Moreover, in a self-assembled monolithic water splitting device with Co 9 S 8 /Ni 3 S 2 /NF electrodes as cathode and anode, a cell potential of 1.55 V is required to drive the overall water splitting process at a current density of 10 mA/cm2, and the reaction shows excellent stability with a loss of voltage of only 16.5 mV over a 10-hour period. This paper presents a simple and innovative approach for constructing bimetallic sulfides electrocatalysts. [ABSTRACT FROM AUTHOR]

The development of renewable clean energy is imminent as global warming and environmental pollution become more serious issues today. Hydrogen energy has been widely studied as an ideal green energy source. Among several common hydrogen production methods, hydrogen production by electrolysis of water is considered an efficient, environmentally friendly, and sustainable hydrogen production strategy. Transition metal phosphates have outstanding electrocatalytic conductivity and high catalytic efficiency, thus exhibiting catalytic effects similar to noble metals. To further enhance the catalytic activity of the transition metal phosphates, in this paper, the cauliflower-like Co-W-P-O 4 /NF catalyst based on three-dimensional nickel foam was prepared by the method of element doping. The catalyst exhibited good bifunctional catalytic activity in alkaline solution. The prepared Co-W-P-O 4 /NF has a unique crystalline-amorphous phase structure with abundant active sites at the interface. In addition, W atoms can interact with Co atoms to co-optimise the electronic structure, enabling the Gibbs free energy of hydrogen adsorption (ΔG H*) to be close to 0, which is conducive to improving the performance of water electrolysis. To achieve a current density of 10 mA·cm−2, the Co-W-P-O 4 /NF required overpotentials of 42.1 mV for HER and 348.2 mV for OER in 1 M KOH solution, with the Tafel slopes being 48.0 and 83.6 mV·dec−1, respectively. When Co-W-P-O 4 /NF was used as both cathode and anode for water splitting, the two-electrode electrolyzer could achieve 10 mA·cm−2 with only 1.62 V, along with good stability. [Display omitted] • The cauliflower-like Co-W-P-O 4 /NF with crystalline-amorphous phase structure is prepared. • Co-W-P-O 4 /NF catalyst shows good bifunctional catalytic activity in alkaline solution. • The electron rearrangement and the rough surface structure can improve the performance of catalyst. [ABSTRACT FROM AUTHOR]

• Alkaline Water Electrolysis functions best between 65 and 100 °C at 2–10 bar pressure. • Solid Oxide Electrolysis Cells operate at higher temperatures of 600–1200 °C. • Proton exchange membrane electrolyzers work at current densities >2 A cm−2. • Transition metal-based catalysts demonstrate high performance for HER and OER. • Photocatalysts such as Zn 0.5 Cd 0.5 S/Ti 2 C/TiO 2 have excellent catalytic activity. Hydrogen energy is essential to building a sustainable society with net zero carbon emissions in the face of global climate change and the energy revolution. Hydrogen generation begins with most Power-to-X methods that shape the future energy market. Electrolysis systems that use water/steam to make hydrogen have their own benefits and downsides. Electrolysis and photocatalysis are the main water-splitting methods employed to produce hydrogen. This study outlines these technologies and their future problems and potential. The literature suggests that Alkaline Water Electrolysis (AWE) is a commercial technology that can produce hydrogen on a large scale, whereas Proton Exchange Membrane Electrolysis (PEME) and Solid Oxide Electrolysis Cells (SOEC) are very efficient. Energy-efficient and economically feasible water electrolysis face several challenges. It requires effective, long-lasting catalysts to boost Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) efficiency. This publication includes a table of electrocatalyst groups. Transition metal catalysts are cheaper and as efficient as noble metal catalysts such as IrO 2 , RuO 2 , Pt, and Pd. It also highlights the challenges of electrocatalyst industrialization and commercialization and suggests solutions. The latter half of the paper reviews photocatalysis as an efficient method to produce hydrogen. It also discusses photocatalysts developed to increase H 2 production efficiency. The photocatalytic water splitting activity of pure photocatalysts is enhanced by manipulating morphology, cationic/anionic doping, heterojunction/nanocomposite constructions, and defect formation. The report also covers other alternative renewable energy sources for hydrogen generation. [ABSTRACT FROM AUTHOR]

• Structure-activity relationship of high entropy oxides (HEOs) catalysts for oxygen evolution reaction (OER) were studied. • Band gap of TM 3d-O 2p is a decisive descriptor of the intrinsic OER activity of HEOs. • Band gap of TM 3d-O 2p exhibited a volcano relationship with the intrinsic OER activity of HEOs. High entropy oxides (HEOs) are promising catalysts of oxygen evolution reactions (OER) in water splitting. However, multi-components, complicated phases and numbers of defects make a lack of deep understanding to the structure–activity relationship of HEOs catalysts. In this paper, different transition metal elements of Fe, Cr, Mn, Mg and Al were doped into (CoNiCuZn)O to form five quinary HEOs. To explore the structure–activity relationship of OER catalysts of HEOs, the phase structure, element valence, oxygen vacancies and electronic structure were characterized and their OER performance was tested. The results show that among all the HEOs, (FeCoNiCuZn)O has the optimal OER catalytic performance: an overpotential of 323 mV at a current density of 10 mA cm−2 in 1 M KOH solution, a Tafel slope of 64.5 mV dec-1, maintaining a high stability for at least 50 h. Its superior OER performance can be attributed to a combination of three main factors: an appropriate band gap of transition metal (TM) 3d and oxygen (O) 2p, a high concentration of oxygen vacancies and a spinel phase precipitation. Among them, the band gap of TM 3d and O 2p showing a volcano relationship with the intrinsic OER activity can be the most decisive descriptor of the intrinsic OER activity of HEOs. A moderate band gap of TM 3d and O 2p being tuned by various cations will lead to more reasonable intermediate adsorption and desorption abilities of HEOs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Atomically dispersed Ru/Mg-CeO 2 catalyst was prepared and possessed excellent catalytic performance for photo-thermal catalytic CO 2 methanation reaction. • The photo-electron excitation/migration path and the surface structure changes induced by light were systematically characterized by operando experiments. • All potential micro-reaction steps and light intensification steps were determined by in situ DRIFTs experiments. • The reversible dynamic structural evolution between Ru-O-Ce structure and Ru-O v -Ce structure could be induced by light. It is a promising green technology to reduce CO 2 to CH 4 by using renewable solar energy driving photo-thermal catalysis route. However, the efficiency of photo-thermal catalytic CO2 methanation remained to be improved, and the mechanism of this reaction still required further investigation. In this paper, a Ru/Mg-CeO 2 catalyst was designed based on the concepts of single atom catalyst and photo-thermal catalysis concept. The catalyst achieved the CH 4 formation rate of 469 mmol·gcat−1·h−1 at 400 °C under photo-thermal conditions with good catalytic stability. Besides, the superiority of the single-atom of Ru, Ru-O-Ce structure and doping of alkaline metals in catalytic process was proved by a series of physicochemical and optical characterization, and electron migration direction from Ce and Mg elements to Ru sites through Ru-O-Ce and Ru-O-Mg path under photo-thermal catalysis was determined by ISI-XPS experiment. Finally, the comprehensive reaction mechanism and reversible dynamic structural evolution process between Ru-O-Ce and Ru-O v -Ce structures were investigated by in situ DRIFTs experiments, and the source of the excellent performance and structure-function relationship of the catalyst was explored, which provided the theoretical and practical basis for the development of catalyst and industrial application of the reaction. [ABSTRACT FROM AUTHOR]

As a dual-functional catalyst for the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), Ru clusters have great potential, but there are certain difficulties regarding their stability on the substrate and the tunability of their electronic environment. Here, the S doped graphited biochar aerogel electrocatalyst was designed and synthesized using terrestrial lignin and algal polysaccharide as a carbon substrate. The Ru clusters were anchored on the S-doped carbon aerogel (P-Ru/SC) by carefully designing the Ru-S bond via a novel plasma assisted high temperature carbonization treatment. The optimized P-Ru/SC-2 catalyst exhibits excellent electrocatalytic performance for the HER and OER, achieving ultra-small overpotentials of 119.6 mV and 193.4 mV at 10 mA cm-2. The dual-electrode requires only 1.47 V to reach 10 mA cm-2. It is worth noting that a large number of S sites on graphited carbon can strongly interact with the Ru clusters, significantly improving the catalytic activity and stability for the HER and OER. [ABSTRACT FROM AUTHOR]