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In this work, we report an unexplored heterostructured catalyst consisting of Ni–Co-phosphate/sulphide phases (NCPSP) on carbon fibre paper through a single-step gas–solid reaction route for hydrogen evolution reaction (HER) in an acidic medium. The heterostructured electrode film of NCPSP depicted considerably enhanced electrochemical HER performance compared to the heterostructured controlled catalyst films consisting of Ni–Co-phosphide phases (NCPP), Ni–Co-sulphide phases (NCSP), and Ni–Co-phosphate/phosphide phases (NCPPP). Electrochemical and structural characterization reveals that superior catalytic credentials of NCPSP can be attributed to kinetically favourable H binding on the sulphur sites of transition metal (TM) sulphides and their beneficial heterostructure with TM phosphate component. Specifically, the minimum overpotential of 53 mV and 97 mV is observed for cathodic HER current of 10 mA cm−2 and 100 mA cm−2, respectively. The low Tafel slope of 43 mV dec−1 reveals the favourable Volmer–Heyrovsky mechanism. Also, superior kinetics was revealed by the low charge transfer resistance of 28 Ω. The catalytic credentials of NCPSP are also well in alignment with the highest values reported for the best state of art catalysts. [ABSTRACT FROM AUTHOR]

Lithium-sulfur (Li-S) batteries appear to be one of the most promising energy-storage devices owing to the unparalleled theoretical specific energy, relatively inexpensive price and abundant resources. Despite these attractive features, the practical performances of sulfur cathode still remain a lot of challenges, such as the electrical insulating nature of S and Li 2 S, huge volume change during cycling, notorious shuttle effect of lithium polysulfide intermediates (LiPSs), sluggish redox kinetics and construction of thick electrodes with high sulfur loading. Here, CoFe 2 O 4 nanoparticles anchored on the carbon nanotube (CNT) paper is proposed as free-standing sulfur host to address the issues. The cross-linking CNT network can serve as conductive matrix and accommodate volume change upon cycling simultaneously. Meanwhile, the CoFe 2 O 4 nanoparticles are capable of effectively anchoring LiPSs to suppress the shuttle effect and accelerating LiPSs conversion to boost redox kinetics. Moreover, the free-standing paper electrode without any binder is conducive to constructing stable cathode with high sulfur loading. In consequence, the well-designed S/CoFe 2 O 4 /CNT paper cathodes deliver impressive electrochemical performance, demonstrating an initial discharge capacity of 755.3 mAh g−1 and remaining a high reversible capacity of 642.6 mAh g−1 after 400 cycles at 2 C with an inconspicuous decay of 0.04% per cycle. The bimetallic oxide CoFe 2 O 4 nanoparticles anchored on the carbon nanotube paper is proposed as free-standing sulfur host with enhanced polysulfide trapping and catalytic effects for advanced Li-S batteries. [Display omitted] • Binder-free host realizes high sulfur loading and energy density for Li-S battery. • CoFe 2 O 4 /CNT paper inhibits the polysulfide shuttling via strong chemical interaction. • CNT-anchored CoFe 2 O 4 catalytically promotes the polysulfide conversion kinetics. • The Li-S battery with S/CoFe 2 O 4 /CNT cathode exhibits enhanced capacity and stability. [ABSTRACT FROM AUTHOR]

Large-scale growth of low-cost, efficient, and durable non-noble metal-based electrocatalysts for water splitting is crucial for future renewable energy systems. Atomic layer deposition (ALD) provides a promising route for depositing uniform thin coatings of electrocatalysts, which are useful in many technologies, including the splitting of water. In this communication, we report the growth of a NiO/Ni catalyst directly on carbon fiber paper by atomic layer deposition and report subsequent reduction and oxidation annealing treatments. The 10-20 nm NiO/Ni nanoparticle catalysts can reach a current density of 10 mA·cm-2 at an overpotential of 189 mV for hydrogen evolution reactions and 257 mV for oxygen evolution reactions with high stability. We further successfully achieved a water splitting current density of 10 mA·cm-2 at 1.78 V using a typical NiO/Ni coated carbon fiber paper two-electrode setup. The results suggest that nanoparticulate NiO/Ni is an active, stable, and noble-metal-free electrocatalyst, which facilitates a method for future water splitting applications. [ABSTRACT FROM AUTHOR]

In this paper, macroporous high‐entropy spinel oxide (HESO) (Fe0.2Ni0.2Co0.2Mn0.2Zn0.2)3O4 monoliths were successfully fabricated via a sol–gel method followed by calcination. Appropriate polyacrylic acid and propylene oxide contents allow the formation of three‐dimensional co‐continuous xerogel monoliths, and the water/glycerol ratio controls the macropore size of monoliths. Subsequent calcination achieves the precipitation of HESO (Fe0.2Ni0.2Co0.2Mn0.2Zn0.2)3O4 with a singular phase and exceptional structural stability. The macroporous HESO (Fe0.2Ni0.2Co0.2Mn0.2Zn0.2)3O4 demonstrates remarkable performance in the oxygen evolution reaction (OER) with an overpotential of 333 mV at 100 mA cm−2 and a Tafel slope of 43.2 mV dec–1, surpassing that of RuO2 (391 mV) under identical conditions. Furthermore, the catalytic stability of the HESO catalyst remains superior even after 24 h of testing. This process offers a promising avenue for the development of macroporous high‐entropy oxide OER catalysts for overall water splitting. [ABSTRACT FROM AUTHOR]

Cobalt oxide (Co3O4) serves as a promising electrocatalyst for oxygen evolution reactions (OER) in water-electrolytic hydrogen production. For more practical applications, advances in dry-deposition processes for the high-throughput fabrication of such Co3O4 electrocatalysts are needed. In this work, a thermal metal–organic deposition (MOD) technique is developed to form Co3O4 deposits on microscale-diameter carbon fibers constituting a carbon fiber paper (CFP) substrate for high-efficiency OER electrocatalyst applications. The Co3O4 electrocatalysts are deposited while uniformly covering the surface of individual carbon fibers in the reaction temperature range from 400 to 800 °C under an ambient Ar atmosphere. It is found that the microstructure of deposits is dependent on the reaction temperature. The Co3O4 electrocatalysts prepared at 500 °C and over exhibit values of 355–384 mV in overpotential (η10) required to reach a current density of 10 mA cm−2 and 70–79 mV dec−1 in Tafel slope, measured in 1 M KOH aqueous solution. As a result, it is highlighted that the improved crystallinity of the Co3O4 electrocatalyst with the increased reaction temperature leads to an enhancement in electrode-level OER activity with the high electrochemically active surface area (ECSA), low charge transfer resistance (Rct), and low η10, due to the enhanced electrical conductivity. On the other hand, it is found that the inherent catalytic activity of the surface sites of the Co3O4, represented by the turnover frequency (TOF), decreases with reaction temperature due to the high-temperature sintering effect. This work provides the groundwork for the high-throughput fabrication and rational design of high-performance electrocatalysts. [ABSTRACT FROM AUTHOR]

Fig. 3 Overview of the application of BDC materials in VRFB. [Display omitted] Biomass-derived carbon (BDC) materials are suitable as electrode or catalyst materials for vanadium redox flow battery (VRFB), owing to the characteristics of vast material sources, environmental friendliness, and multifarious structures. A timely and comprehensive review of the structure and property significantly facilitates the development of BDC materials. Here, the paper starts with the preparation of biomass materials, including carbonization and activation. It is designed to summarize the lastest developments in BDC materials of VRFB in four different structural dimensions from zero dimension (0D) to three dimension (3D). Every dimension begins with meticulously selected examples to introduce the structural characteristics of materials and then illustrates the improved performance of the VRFB due to the structure. Simultaneously, challenges, solutions, and prospects are indicated for the further development of BDC materials. Overall, this review will help researchers select excellent strategies for the fabrication of BDC materials, thereby facilitating the use of BDC materials in VRFB design. [ABSTRACT FROM AUTHOR]

As an important part of water splitting, the oxygen evolution reaction (OER) requires efficient, low-cost, and stable catalysts to overcome its sluggish kinetic barrier. In this study, based on previously reported OER catalyst materials of boron monosulfide mixed with graphene (r-BS+G), nickel foam (NF) is introduced as a supporting material for an r-BS+G electrocatalyst. The resulting r-BS+G-NF exhibits a very low overpotential at 10 (245 mV), 100 (308 mV), and 500 (405 mV) mA cm−2, with a low Tafel slope (56 mV dec−1). In addition, r-BS+G-NF exhibits high durability and can maintain high activity for more than 100 h at 100 mA cm−2. This is in sharp contrast to the catalyst without graphene (r-BS+NF), which shows lower durability. The results suggest that the unique morphology of the NF provides a large electrochemically active area and exposes more active sites on the surface of the prepared electrocatalyst, while the flexible graphene sheets play an important role as a support for effectively combining r-BS and NF. Consequently, the self-supporting structure can improve the OER performance as well as stability. Therefore, this study provides a promising strategy for use as an efficient and stable OER catalyst at high current densities. In the realm of electrocatalysis and the quest for sustainable energy conversion and storage technologies, our research introduces a distinctive contribution in the form of a nickel-foam-based boron monosulfide – graphene electrocatalyst (r-BS+G-NF) for the Oxygen Evolution Reaction (OER). Thanks to the porous structure of nickel foam and the important role of graphene in combining r-BS and nickel foam, r-BS+G-NF exhibits high catalytic activity and long durability for up to 100 hours. The findings presented in this paper represent a significant advancement in the field of electrocatalysis, with the potential to impact the development of cleaner and more efficient energy conversion and storage technologies. [ABSTRACT FROM AUTHOR]

Designing efficient electrocatalytic systems through facile synthesis remains a formidable task. To address this issue, this paper presents the design of a combination material comprising two transition metal oxides (copper oxide and manganese oxide (CuO/MnO2)), synthesized using a conventional microwave technique to efficiently engage as an active oxygen evolution reaction (OER) catalyst. The structural and morphological properties of the composite were confirmed by the aid of X-ray diffraction (XRD) studies, field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive spectrometry (EDS). FESEM clearly indicated well-aligned interlacing of CuO with MnO2. The OER performance was carried out in 1 M KOH. The assembled CuO/MnO2 delivered a benchmark current density (j = 10 mA cm−2) at a minimal overpotential (η = 294 mV), while pristine CuO required a high η (316 mV). Additionally, the CuO/MnO2 electrocatalyst exhibited stability for more than 15 h. These enhanced electrochemical performances were attributed to the large volume and expanded diameter of the pores, which offer ample surface area for catalytic reactions to boost OER. Furthermore, the rate kinetics of the OER are favored in composite due to low Tafel slope (77 mV/dec) compared to CuO (80 mV/dec). [ABSTRACT FROM AUTHOR]

[Display omitted] • The Zn-In-O catalyst exhibits FE HCOO− (94.25 %) at −1.16 V RHE. • Rich interface effects improve the catalytic performance of Zn-In-O. • In 2 O 3 active center of Zn-In-O is protected from reducing by sacrificing ZnO phase. Electrochemical CO 2 reduction reaction (eCO 2 RR) is considered an efficient approach to produce value-added chemicals and fuels. In this paper, a series of MOF-derived composite catalysts with coexisting In 2 O 3 and ZnO are fabricated using a simple process for eCO 2 RR to produce formate. The Zn-In-O/800 catalyst achieves a formate Faradaic efficiency (FE HCOO−) of 94.25 % at −1.16 V vs. RHE, which can maintain over 89 % after 30 h in a stability test. The electrochemical evidence and density functional theory analysis show that the strong interface effect between In 2 O 3 and ZnO can enhance the CO 2 adsorption and activation, and promote the conversion of CO 2 to formate. In addition, the ZnO phase can protect In 2 O 3 , as the main active site, from being reduced to a certain extent for a long time under negative potential, which ensures the high stability of the composite catalyst. [ABSTRACT FROM AUTHOR]

Significant amount of effort has been devoted in the development of water electrolysis technology as the prime technology for green hydrogen production. In this paper, we investigate nickel–iron-based electrocatalytic coatings on stainless-steel substrates for commercial alkaline water electrolysers. Stainless steel electrodes for water electrolysis have received attention lately, showing that they can be a low-cost substrate for water electrolysis. Coating stainless steel with low-cost electrocatalysts can prove beneficial to lower overpotential for the oxygen evolution reaction (OER), thereby reducing the overall energy consumption of water electrolysis at an affordable cost. We show that NiFe-deposited substrates have an overpotential of 514 mV at 10 mA cm−2 current. The substrates also exhibited excellent stability in strong alkaline condition for 60 h under continuous 1.2 V working potential vs SCE. The results in full-cell electrolysers demonstrate that the electrolyser with the NiFe-coated anode could generate nearly six times as much current density compared with the bare stainless-steel substrate. [ABSTRACT FROM AUTHOR]

Nitrogen-doped graphene is currently recognized as one of the most promising catalysts for the oxygen reduction reaction (ORR). It has been demonstrated to act as a metal-free electrode with good electrocatalytic activity and long-term operation stability, excellent for the ORR in proton exchange membrane fuel cells (PEMFCs). As a consequence, intensive research has been dedicated to the investigation of this catalyst through varying the methodologies for the synthesis, characterization, and technologies improvement. A simple, scalable, single-step synthesis method for nitrogen-doped graphene oxide preparation was adopted in this paper. The physical and chemical properties of various materials obtained from different precursors have been evaluated and compared, leading to the conclusion that ammonia allows for a higher resulting nitrogen concentration, due to its high vapor pressure, which facilitates the functionalization reaction of graphene oxide. Electrochemical measurements indicated that the presence of nitrogen-doped oxide can effectively enhance the electrocatalytic activity and stability for ORR, making it a viable candidate for practical application as a PEMFC cathode electrode. [ABSTRACT FROM AUTHOR]

A stable life support system in the spacecraft can greatly promote long-duration, far-distance, and multicrew manned space flight. Therefore, controlling the concentration of CO2 in the spacecraft is the main task in the regeneration system. The electrocatalytic CO2 reduction can effectively treat the CO2 generated by human metabolism. This technology has potential application value and good development prospect in the utilization of CO2 in the space station. In this paper, recent research progress for the electrocatalytic reduction of CO2 was reviewed. Although numerous promising accomplishments have been achieved in this field, substantial advances in electrocatalyst, electrolyte, and reactor design are yet needed for CO2 utilization via an electrochemical conversion route. Here, we summarize the related works in the fields to address the challenge technology that can help to promote the electrocatalytic CO2 reduction. Finally, we present the prospective opinions in the areas of the electrocatalytic CO2 reduction, especially for the space station and spacecraft life support system. [ABSTRACT FROM AUTHOR]

Photo(electro)catalytic nitrogen fixation technology is a promising ammonia synthesis technology using clean solar and electric energy as the driving energy. Abundant nitrogen and water as raw materials uphold the principle of green and sustainable development. However, the generally low efficiency of the nitrogen reduction reaction has seriously restricted the application and development of this technology. The paper introduces the nitrogen reduction process and discusses the main challenges and differences in the current photo(electro)catalytic nitrogen fixation systems. It focuses on promoting the adsorption and activation of N2 and the resolution and diffusion of NH3 generated. In recent years, reviews of the modification strategies of semiconductor materials in light of the typical cases of nitrogen fixation have been reported in the literature. Finally, the future development trend of this field is analyzed and prospected. [ABSTRACT FROM AUTHOR]

Non-metallic carbon-based catalysts are one of the most promising catalysts for electrocatalytic oxygen reduction (ORR). However, the controlled synthesis of the pore structures of carbon-based catalysts and the determination of catalytic sites still remains to be further explored. Based on this, two nitrogen-doped carbon-based catalysts with microporous and mesoporous structures were prepared in this paper. The two catalysts had different pore structures and nitrogen-doped species. The experimental results showed that the carbon-based catalyst (PC-NH3) rich in microporous structure and pyridine nitrogen doping had better catalytic performance, the electrocatalytic oxygen reduction performance of the catalyst was comparable to that of the platinum catalyst, and it had excellent methanol resistance and stability. This study provided important guidance for the application of porous carbon materials in oxygen reduction. [ABSTRACT FROM AUTHOR]

Direct ethanol fuel cell (DEFC) has attracted wide attention due to its wide range of fuel sources, cleanliness, and high efficiency. However, the problems of low catalytic efficiency and poor catalyst stability still exist in DEFC catalysts, which restrict its rapid development. With chloroplatinic acid (H2PtCl6·6H2O) as the precursor, Polyvinylpyrrolidone (PVP) plays the role of surfactant, stabilizer, and reducing agent in the experiment. Glycine is the surface control agent and co-reducing agent. Pt high-index facets nanocatalyst was prepared with the one-pot hydrothermal method by adjusting the amount of PVP and glycine. X-Ray Diffraction (XRD), transmission electron microscope (TEM), and scanning electron microscope (SEM) were used to characterize the micro-structure of the nanocatalyst, and the influence of PVP and glycine on the synthesis of high-index facets catalyst was studied. The electrocatalytic performance of the catalyst was tested with an electrochemical workstation, and it was found that the performance of the prepared catalyst was better than that of the commercial catalyst. When the mass ratio of PVP and Pt was 50:1 and the molar ratio of glycine and Pt was 24:1, Pt nanocatalysts with {310}, {520} and {830} high exponential facets were prepared. The electrochemical test results showed that the peak current density of ethanol oxidation was 2.194 m2/g, and the steady-state current density was 0.241 mA/cm2, which was 5.7 times higher than that of commercial catalyst. The results of this paper show that due to the defects such as steps and kinks on the surface of the high-index facets, the active sites are increased, thus showing excellent electrocatalytic performance. This study provides a theoretical basis for the development and commercial application of high index facets nanocatalysts. [ABSTRACT FROM AUTHOR]

Among clean energy transformation devices, fuel cells have gained special attention over the past years; however, advancing appropriate non-valuable metal impetuses to halfway supplant the customary Pt/C impetus is still in progress. In this paper, we propose a specific electrocatalyst in the formula of highly-active Cu species, associated with coated carbon (Cu@C-800), for oxygen reduction reaction (ORR) through post-treatment of a self-assembled precursor. The optimized catalyst Cu@C-800 showed excellent ORR performance (i.e., the onset potential was 1.00 V vs. RHE, and half-wave potential of 0.81 V vs. RHE), high stability, resistance to methanol, and high four-electron selectivity. The enhancement is attributed to the synergy between the carbon matrix and a high explicit surface region and rich Cu nano-species. [ABSTRACT FROM AUTHOR]

Designing nonprecious metal-based heteroatom-doped electrocatalysts with low overpotential for efficient hydrogen production via oxygen evolution reactions presents significant challenges. We fabricated and carbonized an N-doped bimetallic phosphide (CeFeP) in this study. Scanning electron microscopy and transmission electron microscopy analyses revealed the formation of a uniform spherical nanoparticle morphology, while structural changes were evidenced in the carbonization step at temperatures of 300 and 700 ℃ by XRD analysis. The synthesized materials were then coated onto carbon paper electrodes in a basic medium, and their performance in the oxygen evolution reaction was evaluated. The results show that the N-doped bimetallic phosphide material carbonized at 700 ℃ has enhanced catalytic activity, as indicated by its low overpotential of 155 mV and Tafel slope of 57 mV/dec, respectively, for a standard current density of 10 mA/cm2. The catalytic performance of the N-doped CeFeP sample was significantly higher than that of undoped CeFeP and the single metal phosphide, thereby indicating it has significant potential for practical applications. [Display omitted] • SEM and TEM reveal uniform spherical morphology, indicating efficient design. • XRD shows spinel structure, critical for electrocatalysis. • N@CeFeP-1 shows low overpotential and Tafel slope of 155 mV and 57 mV/dec. • N@CeFeP-1 has batter activity compare to un-doped CeFeP and single metal phosphide catalysts. • N@CeFeP-1 is a promising catalyst for hydrogen production. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • MOF-NCNT demonstrates better OER and ORR performances than commercial Pt/C. • Highest round trip efficiency of 90% is obtained in hybrid sodium-air batteries. • N dopants and confined cobalt in CNTs, robust open porous framework structures. Abstract Metal-organic framework (MOF)-derived carbon nanomaterials are investigated as promising non-noble metal-based oxygen electrocatalysts for metal-air batteries. Herein, metal-organic framework-derived N-doped carbon nanotubes (MOF-NCNTs) were first employed as electrocatalysts for hybrid sodium-air batteries (SABs), which exhibited higher electrocatalytic activity and stability for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) compared to commercial Pt/C. The battery using MOF-NCNTs displayed the voltage gap of 0.30 V at a current density of 0.1 mA·cm―2, which is the lowest among all the tested catalysts including commercial Pt/C (0.50 V), RuO 2 (0.50 V), Co-CNTs (0.67 V), NCNTs (0.77 V), MWNTs (0.90 V), and carbon paper (1.18 V). In addition, the average discharge plateau and round trip efficiency of the battery was 2.81 V and 87% during 35 cycles at a current density of 0.1 mA·cm―2, respectively. The remarkable electrocatalytic activity is mainly ascribed to the synergistic effect between the N dopants and confined Co nanoparticles in the CNTs, the hollow structure of NCNTs, and the robust porous cage structure. The N dopants and confined Co nanoparticles in the CNTs induce more catalytic active sites and promote electron transfer for the ORR and OER. The hollow framework structure of NCNTs not only offer structural defect sites for O 2 adsorption, but also improves mass transport and electronic conductivity, resulting in enhanced catalytic activity. The robust porous cage structure contributes to the stability of the catalysts. The highly efficient and inexpensive metal-organic framework-derived NCNT is a promising bifunctional oxygen electrocatalyst for practical applications in hybrid SABs and other metal-air batteries. [ABSTRACT FROM AUTHOR]

Cobalt carbide as a new type of transition metal carbides (TMACs) has received extensive attention in the field of magnetism and electrocatalysis. As one of the cobalt carbide materials, Co 2 C shows good hard magnetism. In this paper, we have designed a simple and efficient method to successfully prepare single-phase Co 2 C nanospheres. Co 2 C is synthesized by using Co 3 O 4 as precursor and small molecule amino ethylenediamine as carbon source. The material exhibits excellent hard magnetic properties, with saturation magnetization up (Ms) to 32.19 emu/g and coercivity up to 1111 Oe at room temperature. Co 2 C also demonstrats excellent hydrogen evolution reaction performance in 1 M KOH solution. Using nickel foam as the working electrode, the overpotential of only 92 mV can reach the current density of 10 mA cm−2, and the Tafel slope is 104 mV dec−1. This provides a new idea for the further development of synthetic cobalt carbide and its composite materials. • A new and simple method for synthesizing Co 2 C nanospheres was designed. • At room temperature, the saturation magnetization of the material can reach 32.19 emu/g and coercivity up to 1111 Oe. • Co 2 C can be used as catalyst for hydrogen evolution reaction. • In 1 M KOH solution, Co 2 C showed excellent HER activity (92 mV@10 mA cm -2 and 104 mV dec -1). [ABSTRACT FROM AUTHOR]

Hydrogen production technology by electrolyzing water plays an increasingly important role in the production of renewable hydrogen energy and is a powerful means to effectively alleviate the dependence on fossil fuels. It is an urgent task to develop electrocatalysts with high activity, high stability and low cost. Cathodic hydrogen evolution reaction (HER) of water electrolysis has attracted much attention due to its unique reaction mechanism. In recent years, the developed hydrogen spillover binary catalyst has been widely concerned and studied because of its advantages of achieving efficient hydrogen transfer, which has opened up a new way to promote the development of hydrogen production from electrolytic water. This paper comprehensively summarizes the latest research progress of hydrogen spillover binary electrocatalysts for HER. Firstly, the mechanism of HER is introduced. Then, the mechanism of hydrogen spillover and its role in HER are discussed. More importantly, the latest regulation methods to improve HER performance through hydrogen spillover effect and main experiments to prove the existence of hydrogen spillover are emphatically introduced. Finally, we systematically discuss some problems and challenges faced by hydrogen spillover electrocatalysts in the current development and look forward to their future application prospects. [Display omitted] • Hydrogen spillover effect is helpful to accelerate the kinetics of hydrogen evolution. • The research progress of metal-supported electrocatalysts based on hydrogen spillover effect is summarized. • The mechanism and recent regulations of hydrogen spillover in HER are highlighted. • Challenges and improvement directions in this field are also discussed and summarized. [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]

An electrocatalyst with high oxygen reduction reaction (ORR) activity and high stability during start–stop operation is necessary. In this paper, hollow-structure Pt-Ni electrocatalysts are investigated as ORR catalysts. After synthesis via sacrificial SiO2 template method, the electrocatalyst exhibits much higher specific activity (1.88 mA/cm2) than a commercial Pt/C catalyst. The mass activity (0.49 A/mg) is 7 times higher than the commercial Pt/C catalyst. The kinetics of the ORR is evaluated using Tafel and K-L plots. It also exhibits a higher durability than commercial Pt/C catalyst during accelerated durability test (ADT). Moreover, the electrocatalyst shows good resistance against accelerated durability test for start–stop, the specific activity and mass activity drops 34.6% and 40.8%, respectively, far better than the commercial catalyst. [ABSTRACT FROM AUTHOR]

Oxygen evolution reaction (OER) is a key reaction in electrochemical systems such as metal-air batteries and hydrogen production by electrolysis of water. Research on high-efficiency and stable nonprecious metal electrocatalysts is very important. In this paper, nickel-cobalt bimetallic phosphides (NiCo-P) with multi-shell hollow structures were prepared by high-temperature calcination with metal-organic framework (MOF) as precursors. The unique structure is conducive to the penetration of the electrolyte and mass transfer, and can provide a wealth of exposed active sites. At the same time, the nickel-cobalt bimetal has a synergistic effect to promote electrochemical performance. The results show that the NiCo-P-0. 1 catalyst prepared with a molar ratio of nickel to cobalt of 0. 1 exhibits good catalytic activity and stability in 1. 0 mol/L KOH electrolyte, which has good application prospects. This work provides a brand new approach for the development of electrocatalytic oxygen evolution catalysts with highly activity and stability. [ABSTRACT FROM AUTHOR]

Neutral chloride-based electrolyte and directly grown manganese oxide on carbon paper are used as the electrolyte and air cathode respectively for rechargeable Zn-air batteries. Oxygen reduction and oxygen evolution reactions on manganese oxide show dependence of activities on the pH of the electrolyte. Zn-air batteries with chloride-based electrolyte and manganese oxide catalyst exhibit satisfactory voltage profile (discharge and charge voltage of 1 and 2 V at 1 mA cm −2 ) and excellent cycling stability (≈90 days of continuous cycle test), which is attributed to the reduced carbon corrosion on the air cathode and decreased carbonation in neutral electrolyte. This work describes a robust electrolyte system that improves the cycle life of rechargeable Zn-air batteries. [ABSTRACT FROM AUTHOR]

In this paper, a novel three-dimensional (3D) MoS 2 /CoS 2 micro-nano heterostructured electrocatalyst has been successfully derived from ZIF-67 on carbon cloth (CC) by a simple method of low temperature vulcanization. The metal-organic framework (MOFs) of ZIF-67 on CC was obtained at room temperature and used as both the precursor of Co and structure template to construct the 3D self-supporting spindle CoS 2 nanodiscs on CC. Large amounts of 2D MoS 2 nanosheets were subsequently grown on the surface of spindle-shaped CoS 2 nanodiscs to form 3D self-supporting MoS 2 /CoS 2 /CC heterostructural electrocatalyst. This 3D self-supporting heterostructural electrocatalyst showed good hydrogen evolution reaction (HER) performance in both acid and alkali electrolytes. At 10 mA/cm2, the HER overpotentials of the MoS 2 /CoS 2 /CC heterostructural electrocatalyst in the alkali and acid electrolyte were 147 mV and 119 mV, and their corresponding Tafel slopes were 90.5 mV dec−1 and 111.4 mV dec−1, respectively, indicating that this MoS 2 /CoS 2 /CC heterostructural electrocatalyst had a good application prospect in the electrolysis of water to produce hydrogen. Moreover, this work provides a new idea for low-cost, scale fabrication of 3D self-supporting heterostructured transition metal sulfide catalysts. [Display omitted] • A 3D MoS 2 /CoS 2 nanomaterial used ZIF-67 as sacrificing template grown on carbon cloth, exposes more catalytic active area. • The unique spindle shape structure increases the specific surface area of 2D MoS 2 , facilitate the transfer of electrons. • The addition of Co greatly increases the electron transfer rate of MoS 2 ,and reduce the adsorption energy of hydrogen. [ABSTRACT FROM AUTHOR]

• A self-supporting electrode modify by mott schottky heterostructure is designed. • The heterostructure induces ordered deposition of Li 2 Se n via built-in electric field. • DFT reveals mott schottky heterostructure improves catalytic activity for Li 2 Se n. Selenium cathodes have attracted particular interest due to their high volumetric capacity and electronic conductivity compared to sulfur cathodes. However, slow conversion reaction kinetics and shuttle effect of polyselenides lead to poor cycling performance of lithium selenium batteries. To overcome these limitations, this paper designs a cobalt selenide-sulfide mott schottkyl heterostructure catalyst on carbon fibers (CoSe 2 -CoS 2 @CNF). Through the built-in electric field and high catalytic activity of heterostructure, the CoSe 2 -CoS 2 @CNF effectively decreases the nucleation barrier for polyselenides, enhances the liquid–solid conversion process and ultimately realizes ordered radial deposition of polyselenides on carbon fibres. Density functional theory calculations also prove that CoSe 2 -CoS 2 mott schottkyl heterostructure has the highest catalytic activity and accelerates the rapid conversion of polyselenides. As a result, Se/CoSe 2 -CoS 2 @CNF free-standing electrodes exhibit a high initial specific capacity of 401.6 mAh g−1 at 5C and maintained a capacity of 410.2 mAh g−1 after 1000 cycles at 0.5C, with a capacity decay rate of only 0.04% per cycle. This work opens up a new field for achieving high stability lithium selenium batteries by forming mott schottkyl heterostructure structures to promote rapid conversion and ordered deposition of polyselenides. [ABSTRACT FROM AUTHOR]

Non-noble metal electrocatalysts with hierarchically structural design and heteroatom-doped is highly urgent for high-efficiency, low-cost electrochemical water splitting systems. Herein, this paper uses a simple and low-cost method to synthesize amorphous carbon-based Ni-Fe-Co-B-P composite material as efficient OER catalyst. Specifically, the catalytic performance can be enhanced through processes such as etching-recombination-reduction. First, we use ZIF-67 as the precursor to provide Co source and carbon source. Fe and Ni are creatively incorporated into the Co 3 O 4 lattice as auxiliary metal atoms. Then, the above three metal oxides were simultaneously reduction with NaH 2 PO 2 and NaBH 4. Although this is the first time that MOF-based materials have been treated with P and B, the resulting samples are chemically stable. The obtained amorphous carbon-based material Ni-Fe-Co-B-P benefits from the advantages of its structure and composition, showing that the electron density is rearranged around the center of the catalytic metal atom and the energy barrier formed by the intermediate is reduced by weakening the metal-metal bond, thereby exhibiting excellent electrochemical performance. The overpotential to afford the current density of 10 mA cm-2 (268 mV) and the small Tafel slope (51.83 mV dec-1) show a predatorily competitive advantage compared with commercially available RuO 2 (284 mV and 69.34 mV dec-1 respectively). [Display omitted] [ABSTRACT FROM AUTHOR]

Carbon-metal composites are promising multifunctional electrocatalysts, but it is still challenging to prepare carbon-metal composites with tunable structure and strong metal-carbon interactions. Here, we present a unique gas-foaming assembly strategy to prepare cytosine-Co chelate derived Co and N codoped carbon nanotube (Co-NCNT). The structure for Co-NCNTs could be easily controlled by regulating cytosine-Co coordination or the carbonization temperature. The optimal Co-NCNT possesses homogeneous distributed NCNTs (10 nm), CoO x (5 nm) and CoN x moieties to synergistically boost electrochemical processes, and offer mesoporous nanosheet architecture to guarantee fast mass migrate and electron transfer. As a result, Co-NCNT shows remarkable ORR performance (onset potential of 0.93 V in 0.1 M KOH electrolyte) along with significant OER and HER activity. More important, it was found that CoN x moieties are responsible for the remarkable electrocatalytic activity in Co-NCNTs, because CoN x could alter active center, enhance metal-carbon synergy, decrease interfacial resistance and reinforce the strength of composites. Therefore, this paper not just demonstrates an advanced multi-functional electrocatalyst, but could also give deep understanding on the designing of multifunctional electrocatalysts. [ABSTRACT FROM AUTHOR]

In the development of fuel cells, it is the key to large-scale commercialization of fuel cells to rationally design and synthesize efficient and non-noble metals-based bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this paper, spinel CoFe 2 O 4 /carbon nanotube composites (CoFe 2 O 4 /CNTs/FA) were synthesized by solvothermal and calcination method. XRD, TEM, XPS and BET characterizations indicate that the addition of complexing agent fumaric acid can improve the crystal growth kinetics and morphology of CoFe 2 O 4 /CNTs nanohybirds. The as-synthesized CoFe 2 O 4 /CNTs/FA pyrolyzed at 500 °C have an outstanding bifunctional catalytic activity for ORR and OER with the potential of 1.62V (vs. RHE) at a current density of 10 mA/cm2 and half-wave potential E 1/2 = 0.808V (vs. RHE) in alkaline electrolyte, respectively. It is obviously better than unloaded CoFe 2 O 4 nanoparticles and commercial CNTs. CoFe 2 O 4 /CNTs/FA also exhibit better methanol tolerance ability and durability than commercial Pt/C and RuO 2 catalyst. This investigation broadens an idea of simple compounding of spinel with carbon-based materials to improve electrochemical properties. [ABSTRACT FROM AUTHOR]

The reduction of CO 2 to a tunable syngas by electrochemical catalysis for the industrial synthesis of hydrocarbons, alcohols, aldehydes, and other compounds can effectively realize carbon recycling. Herein, in this paper, non-precious metal FeNi precursors were synthesized by solution method, and then a series of FeNi-NC catalysts were obtained by one-step pyrolysis. The results show that on the prepared catalysts, the products of CO 2 electroreduction are CO and H 2 , and the total Faraday efficiency is close to 100 %. Comparison of the prepared catalysts showed that the Fe 3 Ni 7 -NC 800 °C had the best selectivity for CO, with a maximum Faraday efficiency of 81.3 % for CO(FE CO) generation at a potential of − 0.9 V (vs. RHE), and a current density of − 22.5 mA cm−2 at − 1.2 V. The catalysts had better durability. Moreover, the syngas ratio from 1:1 to 6:1 (CO/H 2) can be easily adjusted by controlling the potential applied during the process over a wide potential range, and the resulting syngas in different ratios can be used for the production of chemical raw materials and fuels. A series of Fe-Ni bimetallic composite N-doped carbon catalysts were successfully prepared for CO 2 RR using a simple and reliable strategy, and the results show that different metal ratios and different pyrolysis temperatures have an effect on the CO 2 RR performance. The best performance of Fe 3 Ni 7 -NC 800 °C CO 2 RR was achieved at a potential of − 0.9 V (vs. RHE), with a maximum FE CO of 81.3 % and FE H2 of 16.3 %; current density of − 22.5 mA cm−2 at − 1.2 V; and good stability. The synthesis gas (CO:H 2) ratio can be adjusted from 1 to 3 at lower potentials, which can be used for industrial synthesis of olefins, alcohols, aldehydes and other compounds. The excellent catalytic performance of Fe 3 Ni 7 -NC 800 °C may be attributed to the synergistic interaction between Fe and Ni, which allows more defects to become catalytic sites and facilitates the rapid electron transfer in the N-doped carbon substrate. This study provides a prospective strategy for designing more efficient bimetallic catalysts for CO 2 reduction reactions. [Display omitted] • Bimetallic composite nitrogen-doped carbon catalysts. • Effects of different metal ratios and different pyrolysis temperatures on the carbon dioxide reduction properties of catalysts. • Fe 3 Ni 7 -NC 800 °C exhibits high activity and stability for carbon dioxide reduction reaction. [ABSTRACT FROM AUTHOR]

Developing enhanced electrocatalysts for the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is essential for commercializing green energy technologies, such as Zn–air batteries. In this study, a uniquely designed metal catalyst–support material composite was synthesized using a Prussian blue analogue (PBA) and Y2Ru2O7 (YRO) pyrochlore for Zn-air battery. P–S-doped Ru nanoparticles and PBA-derived NiFe alloys anchored on the YRO pyrochlore (YRO@NiFe/Ru-PS) were synthesized in one pyrolysis process via in situ exsolution. The electronic structure of the Ru and NiFe particles was tailored by the pyrochlore support and P–S dual doping, which decreased the energy barrier for the catalytic reaction. YRO@NiFe/Ru-PS exhibited outstanding OER (overpotential = 241 mA/cm2; Tafel slope = 36 mV/dec) and ORR (half-wave potential = 0.83 V; Tafel slope = 65 mV/dec) performances. Furthermore, it also exhibited high performance in Zn–air battery applications (power density = 112 mW/cm2). This paper proposes an efficient and unique design strategy for developing OER/ORR bifunctional electrocatalysts. [Display omitted] • Pyrochlore@PBA derived bifunctional catalyst was synthesized by co-precipitation and in situ exsolution. • OER/ORR bifunctional catalyst contains Ru nanoparticles and NiFe alloy derived from PBA. • Metal-support structure and P–S dual doping enhances OER/ORR catalytic activity. • Zn-air battery application was conducted and revealed that synthesized YRO@NiFe/Ru-PS is an efficient electrocatalyst. [ABSTRACT FROM AUTHOR]

• A Co/CoSe 2 Mott Schottky heterojunction electrocatalytic electrode was designed. • The Mott Schottky heterojunction achieves rapid conversion of polysulfides. • The Mott Schottky heterojunction achieves rapid Li 2 S deposition dissolution. • DFT calculation proves built-in electric field interface effect of the heterojunction. Rechargeable lithium-sulfur (Li-S) batteries are considered ideal candidates for the next generation of energy storage devices. However, the insulation properties of S and Li 2 S, as well as the notorious "shuttle effect" of lithium polysulfide, result in severe loss of active sulfur, poor redox kinetics, and rapid capacity decline. To overcome these limitations, this paper designs a self-supporting electrocatalytic electrode based on Co/CoSe 2 Mott Schottky heterojunction coated carbon nanofibers (Co/CoSe 2 @NCNFs), and engineers it for capturing and converting polysulfides. Density functional theory calculations show that the introduction of Co/CoSe 2 heterojunction effectively reduces the redox barrier of Li 2 S. The electron current and electron interaction at the Co/CoSe 2 interface induce the redistribution of charge density in the depletion region, thus increasing the chemical reactivity of the metal semiconductor heterojunction interface, which is conducive to the ion/electron transport, polysulfide conversion and Li 2 S oxidation process. Therefore, the Li-S battery assembled by Co/CoSe 2 @NCNFs/S electrode exhibited a high initial specific capacity of 1043.3 mAh/g at 1C, and maintained a capacity of 709.9 mAh/g after 1000 cycles, with a capacity decay rate of only 0.032% per cycle. The proposed Mott Schottky heterojunction as an electrocatalyst deepens the promotion of polysulfides and Li 2 S in long-life Li-S batteries. [ABSTRACT FROM AUTHOR]

In this paper, nickel-iron (Ni-Fe) on a graphite substrate was electrodeposited as an effective electrocatalyst for hydrogen and oxygen evolution reactions using the cyclic voltammetry method for the first time. Some important factors such as the range of applied potential, scan rate, and the number of cycles were optimized. In addition, the used substrate is a graphite rod, which is cheap, stable, and has good electrical conductivity. The main results show that the improved Ni-Fe coating on graphite rod has promising hydrogen evolution reaction (HER) activity, which exhibits small over voltages of − 191.2, − 394.0, and − 687.3 mV at the current densities of − 10, − 100, and − 400 mA. cm−2, respectively. Furthermore, the synthesized Ni-Fe electrocatalyst only needs 284 mV overpotentials to operate at a current density of 10 mA. cm−2, indicating its great performance for the oxygen evolution reaction (OER). This paper offers a method for generating a bifunctional, binder-free, affordable, and fast water splitting electrocatalyst that has excellent performance. • For the first time, Ni-Fe was electrodeposited by cyclic voltammetry. • The Ni-Fe is an effective electrocatalyst for hydrogen and oxygen evolution reactions. • The catalyst layer formation was done in a short time. • The proposed bifunctional catalyst on cheap graphite sheet substrate is binder free. [ABSTRACT FROM AUTHOR]

Stainless steel (ST) is widely used in many different fields due to its low cost and excellent stability. However, the electrocatalytic property of ST film for water oxidation, especially combined with TiO 2 photoanode, is seldom investigated. In this paper, we report a one-step sputtering strategy to synthesize ST film electrocatalysts on TiO 2 film in order to boost the oxygen evolution reaction (OER) in water splitting. Compared to pristine TiO 2 electrode, the ST modified electrode achieved a largely enhanced PEC performance. Such enhancement could be manipulated in an optimal manner when the ST film thickness was further varied, where the 80 nm ST modified TiO 2 (ST-80-TiO 2) showed the lowest overpotential of 132 mV, with the highest photocurrent density enhancements of nearly 18-fold and 11-fold under dark and simulated sunlight illumination, respectively. This facile and effective decoration approach makes it possible to design ST electrocatalyst-semiconductor structures for other general photoanode improvements. • ST electrocatalysts modified on TiO 2 film was synthesized to boost the reaction rate of OER. • The ST-8-TiO 2 showed as low as 132 mV overpotential. • Current density of ST-8-TiO 2 under AM 1.5G was more than 11 times higher than that of TiO 2 film. • ST electrocatalyst modified TiO 2 films offers a promising application potential for PEC devices. [ABSTRACT FROM AUTHOR]

Highlights • Preparation of Pd@CuNWs/MWCNTs-CH using galvanic displacement and ultrasonic. • Application of the catalyst for EOR and durability in alkaline media. • Pd@CuNWs/CNTs-CH displays high catalytic activity toward EOR. Abstract In this paper, a fast and effective method for the palladium (Pd) wire nanostructures synthesis with the great surface area through galvanic replacement reaction utilizing copper nanowires (CuNWS) as a template by the assistance of ultrasound under room temperature condition is proposed. A multifunctional catalyst with the mentioned nanostructure, Pd@CuNWs, and multi walled carbon nanotubes (MWCNTs) and chitosan (CH) as a binder was fabricated. To investigate the morphology and bulk composition of the prepared catalyst, Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray Spectroscopy (EDS), X-ray Powder Diffraction (XRD), and Inductively Coupled Plasma atomic Emission Spectroscopy (ICP-AES) were utilized. Various electrochemical techniques including chronoamperometry and cyclic voltammetry were employed for the electrocatalytic activity of ethanol electrooxidation and durability in basic solution. Electrochemical catalytic activity and durability evaluation results proved that the as-synthesized Pd@CuNWs/MWCNTs-CH has a super electrocatalytic activity compared to Pd/MWCNTs and Pd/C electrocatalysts for ethanol electrooxidation. Pd@CuNWs/MWCNTs-CH catalyst demonstrated substantially enhanced performance and long-term stability for ethanol electrooxidation in the basic solution in comparison to Pd/MWCNTs and commercial Pd/C demonstrated the potential in utilizing Pd@CuNWs/MWCNTs-CH as an efficient catalyst for ethanol oxidation. Additionally, thermodynamic and kinetic evaluations revealed that the Pd@CuNWs/MWCNTs-CH catalyst has lower activation energy compared to Pd/MWCNTs and Pd/C which leads to a lower energy barrier and an excellent charge transfer rate towards ethanol oxidation. Noticeably, the Pd@CuNWs/MWCNTs-CH presented excellent catalytic activities with high peak current density which was 9.5 times more than Pd/C, and more negative onset potential in comparison to Pd/C is acquired for ethanol electrooxidation denoting synergistic effect between CuNWs/MWCNs-CH and Pd. The Pd@CuNWs/MWCNTs-CH can be considered as a valid candidate among available electrocatalysts in direct ethanol fuel cells (DEFCs). [ABSTRACT FROM AUTHOR]

Water electrolysis to produce high-purity hydrogen has been regarded as the most promising and attractive method for renewable energy production. The intrinsic high kinetic barrier of the involved electrode reactions, especially that of the anodic oxygen evolution reaction (OER), however severely hinders the application of the water electrolysis technology for large scale hydrogen production. In this paper, a nano-composite Fe- and Co-based material containing crystalline metal sulfide ((NiFeCo)S) and amorphous metal phosphide ((FeCo)P) was in-situ grown on the surface of foam nickel (NF). The (FC)P-(NFC)S/NF catalyst exhibits ultra-high activities for OER at high current densities in 1.0 M KOH, delivering 500 and 1000 mA cm−2 at ultralow overpotentials of 274 and 280 mV, respectively with a small Tafel slope of 37.8 mV dec−1. The excellent catalytic activities of (FC)P-(NFC)S/NF far exceed those of the reference single-component (FC)P/NF and (NFC)S/NF catalysts, and also exceed those of most non-noble metal catalysts reported in literature. Besides, the (FC)P-(NFC)S/NF catalyst exhibits high stability with almost no significant activity attenuation after the chronopotentiometric test at both 100 and 500 mA cm−2 for 40 h. The synergistic effects between the metal sulfide and metal phosphide have positive impacts on the OER activity through increasing the surface area, enhancing the reactivity of each active site, improving the electrical conductivity as well as the interface between the crystalline and amorphous phases. The present work provides a new strategy to develop cost-effective and efficient electrocatalysts toward OER and water electrolysis. ● (FeCo)P-(NiFeCo)S/NF shows ultrahigh activity for OER at large current densities. ● Ultralow overpotential (η 1000 =280 mV) is needed with Tafel slope of 37.8 mV dec−1. ● The catalyst shows high stability with no activity decay after 40 h of CP test. ● The interface between crystalline and amorphous phases contributes to the catalysis. [ABSTRACT FROM AUTHOR]

[Display omitted] • The restructuring and degradation of OD-Cu during CO 2 reduction were revealed. • The C 2 + FE of OD-Cu decreased from 39.4% at 1 h to 26.0% at 5 h at −1.5 V vs. RHE. • Cu defect sites are easily dissolved during electrochemical CO 2 reduction. • Low-coordinated Cu defect sites are responsible for CO 2 reduction to C 2+ products. • The degradation can be circumvented and the FE of C 2+ products maintained at ca. 47.2% with the Cu redeposition process. Renewable energy produced through electrochemical CO 2 reduction is promising for mitigating the energy crisis and environmental issues. Notably, oxide-derived copper (OD-Cu) has attracted considerable attention owing to its unique ability to catalyze CO 2 electroreduction to >2e− products, especially C 2+ products, which are the key feedstocks for the chemical process. However, Cu under operating conditions usually leads to structure reconstruction and degradation, which hinders understanding the origin of its activity. Understanding the restructuring and degradation of OD-Cu catalyst to form C 2+ products is critical for understanding the active sites and, thus for designing effective and durable catalysts for CO 2 reduction. This paper describes that Cu defect sites are easily dissolved during electrochemical CO 2 reduction, and the presence of defect sites is strongly related to the catalytic performance of C 2+ products. Here, the C 2+ products Faradaic efficiency (FE) of OD-Cu decreased from 39.4% at 1 h to 26.0% at 5 h at −1.5 V vs. RHE, along with a decrease in low-coordinated defect sites. The low-coordinated defect sites facilitate CO adsorption and help to increase the CO coverage, thus promoting CO–CO coupling. The decrease in the number of defect sites and activity degradation is circumvented by promoting the Cu redeposition process. The C 2+ products FE of OD-Cu can be maintained at ca. 47.2% without an obvious decrease in CO 2 -saturated 0.1 M KHCO 3 with 1 mM Cu2+. The results of this study help in understanding the activity of OD-Cu and reveal its deactivation mechanism. This knowledge will aid in designing highly active and stable catalysts for CO 2 reduction. [ABSTRACT FROM AUTHOR]

Rechargeable Li-O 2 batteries have great potential on achieving large-capacity electrochemical energy storage. However, the poor cyclic stability seriously limits its commercial application. In this paper, peanut shaped MnCo 2 O 4 which winding by multi-walled carbon nanotubes (MCO/MWCNTs) were synthesized through a facile solvothermal method. As-prepared MCO/MWCNTs have a unique hierarchical mesoporous of three-level pore sizes and show good ORR and OER electrocatalytic activity. When MCO/MWCNTs served as cathode catalysts in Li-O 2 batteries, the batteries exhibited long cycle life of 120 times at 100 mA g −1 with a limited capacity of 500 mAh g −1 and high discharge capacity up to 8849 mAh g −1 with a restrict voltage of 2 V at 100 mA g −1 . [ABSTRACT FROM AUTHOR]

Inexpensive graphite substrate is applied to grow WSe 2 nanofilms for catalytic application in the hydrogen evolution reaction. W nanofilms with a thickness of about 10 nm were deposited onto the graphite substrate by direct-current magnetron sputtering. The graphite with 10 nm W nanofilms was rapidly selenized at 600 °C in horizontal tube furnace to form WSe 2 nanofilms. Scanning electron microscopy, Raman spectroscopy, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy indicated that graphite surface was covered by nano-sized vertically aligned WSe 2 platelets. The effects of the N 2 pressure in the selenization process on the HER performance have been studied in details. Turning of the selenization parameters can optimize the HER performance of the WSe 2 nanofilms, which has been evaluated via linear sweep voltammetry and Tafel slope. WSe 2 nanofilms prepared at the highest N 2 pressure of 0.08 MPa behave optimal performance. The current density reaches 10 mA cm −2 at an over potential around −189 mV vs reversible hydrogen electrode and corresponding Tafel slopes is ∼72 mV dec −1 . WSe 2 nanofilms electrodes exhibit high stability in acidic solution which shows no degradation after 10000 continuous cycles. Thus, WSe 2 nanofilms exhibit superior electrocatalytic performance which is much better than those recently reported grown on carbon paper substrate and W foil. [ABSTRACT FROM AUTHOR]

High entropy alloys (HEAs) have been the focus of research as a new class of multi-metal alloys due to their outstanding corrosion resistance, radiation stability, and superior mechanical properties. Unfortunately, there are still limitations in the current research on the characteristics of HEA, which can't satisfy the wide application of HEAs. Therefore, it is critical to focus the research on the functional aspects of HEAs to achieve their maximum potential. It is exciting that the complex surface chemistry and flexibility of HEAs in shaping unique functions, have been proven to be excellent materials for catalysts in recent years. The superior functionality of HEAs has led to a rapidly growing demand for them. In particular, HEAs as electrocatalysts for oxygen evolution reactions (OER) have become a hot spot for research. However, the applicability of the HEA as catalysts is affected by various factors such as elemental composition, preparation method, surface morphology. The limited research work and unclear catalytic mechanism of HEA electrocatalysts result in the widespread high overpotential, which hinders the application of high entropy electrocatalysts. This paper summarizes the morphological engineering, derived compositional engineering, synthetic methods, electrical properties of the HEA and their derivatives, and applicability as catalysts. Moreover, the paper highlights the challenges and perspectives for the development of high entropy electrocatalysts in order to provide valuable guidance for future research on HEA and its derivatives in the field of OER. [Display omitted] • The main preparation method and control strategy of high-entropy catalysts were summarized. • The advantages and disadvantages of high-entropy electrocatalysts and other types of electrocatalysts were introduced. • The opportunities and challenges of high-entropy materials as electrocatalysts in the future were discussed. [ABSTRACT FROM AUTHOR]

Although iridium diphosphide (IrP 2) has emerged as a promising electrocatalyst, the harsh synthetic conditions requiring high temperature (≥ 850 ℃) limits its wide application. This paper demonstrates a facile synthetic approach of single-phase IrP 2 nanoparticles under a mild condition. Instead of commonly used iridium chloride precursors (e.g., IrCl x), Ir(OH) 3 formed via acid/base precipitation reaction was employed as the iridium source. The following phosphorization step at 650 °C under argon atmosphere successfully produced IrP 2 nanoparticles. Moreover, the electroactivity of as-prepared IrP 2 nanoparticles for electrochemical oxidation of hydrogen sulfide (H 2 S) was investigated for the first time. IrP 2 nanoparticles showed an excellent amperometric response to H 2 S with ca. 2.5-fold greater sensitivity than iridium phosphide (Ir 2 P), presenting the feasibility of IrP 2 as an efficient electrode material for electrochemical H 2 S sensing. [Display omitted] • Single phase P-rich IrP 2 nanoparticles (IrP 2 NPs) were synthesized. • A facile synthetic methodology of IrP 2 at moderate temperature (650 ℃). • IrP 2 NPs shows an excellent amperometric response for H 2 S oxidation. [ABSTRACT FROM AUTHOR]

In recent years, increasing attention has been focused on the utilization of ammonia as a fuel for anion exchange membrane fuel cells (AEMFCs) due to the significant development of anion exchange membranes (AEMs). Although the improvement in catalytic activity for ammonia oxidation reaction was achieved for some Pt-based electrocatalysts, no effective methods were established to enhance the tolerance toward the catalyst poisoning, which is known as the major issue for the utilization of ammonia as a fuel. In this paper, first, the additive effect of Y 2 O 3 was intensely investigated by in situ ATR-IR spectroscopy. For the Y 2 O 3 -modified Pt surface, the IR band area of N 2 H 4,ad species, which is the intermediate species of ammonia oxidation reaction, was distinctively increased, suggesting the promotion of NH 2,ad dimerization process. This effect of Y 2 O 3 was then accurately clarified by applying the Y 2 O 3 modification for Pd surface. Despite that Pd was inactive for the NH 2,ad dimerization reaction, the IR band of N 2 H 4,ad species was clearly detected only in the case of Y 2 O 3 -modified Pd surface. This is the strong evidence that the Y 2 O 3 additive itself promotes the NH 2,ad dimerization reaction. Furthermore, the electrocatalytic performance of Y 2 O 3 -modified Pt/C electrocatalyst was evaluated using the commercial AEMFC system. A twofold increase in both maximum power density and tolerance toward the catalyst poisoning was confirmed as compared to the cell with the conventional Pt/C electrocatalyst. These results clearly show the applicability of our catalyst design strategy to improve the performance of the real-world electrocatalyst for the ammonia oxidation reaction. [ABSTRACT FROM AUTHOR]

Oxygen reduction reaction (ORR) electrocatalysts with high activity, low cost and good durability are crucial to promote the large-scale practical application of fuel cells. Particularly, iron carbide (Fe 3 C) supported on nitrogen-doped carbon has recently demonstrated compelling promise for ORR electrocatalysis. In this paper, we report the facile synthesis of mesoporous Fe/N-doped graphene with encapsulated Fe 3 C nanoparticles (Fe 3 C@Fe/N-graphene) and its superior ORR catalytic activity. This hybrid material was synthesized by the spontaneous oxidative polymerization of dopamine on graphene oxide (GO) sheets in the presence of iron ion, followed by thermal annealing in Argon (Ar) atmosphere. As-prepared material shows high ORR catalytic activity with overwhelming four-electron reduction pathway, long-term durability and high methanol tolerance in alkaline media. This work reports a facile method to synthesize promising ORR electrocatalysis with multiple components and hierarchical architecture, and may offer valuable insight into the underlying mechanism of Fe 3 C-boosted ORR activity of Fe/N doped carbon. [ABSTRACT FROM AUTHOR]

In this paper, well decorated Pd Ce bimetallic on carbon nanofibers were synthesized by the cost effective electrospinning process and effectively applied as electro-catalyst for the detection of methanol fuel cells (MFCs). The synthesized Pd Ce bimetallic decorated carbon nanofibers were characterized in details using morphological, crystalline, structural, surface and electrochemical techniques. The crystalline and structural properties expressed the formation of Pd Ce alloys on the surface of carbon nanofibers during the electrospinning process. The Pd Ce bimetallic decorated carbon nanofibers were used to construct the effective anode for the high performance DMFCs and the cell performance evaluated by electrochemical measurements such as cyclovoltametry and electrochemical impedance. The Pd Ce bimetallic decorated carbon nanofibers based electrode presented the reasonable performance toward the methanol oxidation as increasing the current density with the increase of methanol concentration in alkaline medium. The addition of methanol in alkaline medium significantly increased the current density, which suggests that Pd Ce bimetallic decorated carbon nanofibers based electrode have excellent electrocatalytic activity towards the methanol. [ABSTRACT FROM AUTHOR]

Searching for non-noble-metal hydrogen evolution reaction (HER) electrocatalysts with high efficiency and excellent durability is a great challenge for the hydrogen-based energy industry. In this paper, a three-dimensional self-supported hydrogen evolution cathode is present, where the MoP nanosheet array was grown on flexible carbon cloth (MoP NA/CC) via a two-step strategy: hydrothermally growing MoS 2 nanosheet array on CC (MoS 2 NA/CC) in advance, and then phosphidation to chemically convert the MoS 2 NA/CC precusor into MoP NA/CC. When used as an integrated three-dimensional electrode for HER, MoP NA/CC shows a quiet low onset overpotential (50 mV vs reversible hydrogen electrode), high current density (j > 10 mA cm −2 at η = 124 mV), and a small Tafel slope (58 mV dec −1 ), as well as remarkable stability (<9% decay after 46 h electrolysis) in acidic conditions. Interestingly, the flexible MoP NA/CC electrode also offers superior electrocatalytic performance and remarkable durability for HER in both neutral and basic conditions. [ABSTRACT FROM AUTHOR]

Abstract: The present paper reviews the best anode electrocatalysts, mainly the alloys, which have been tested in direct liquid-feed fuel cells fed with methanol, ethanol or formic acid. It attempts to interpret the alloys catalytic behaviours by using the Nørskov and co-workers’ theoretical work [A. Ruban, B. Hammer, P. Stoltze, H.L. Skriver, J.K. Nørskov, J. Mol. Catal. A 115 (1997) 421; B. Hammer, J.K. Nørskov, Adv. Catal. 45 (2000) 71; J. Greeley, J.K. Nørskov, M. Maurikakis, Annu. Rev. Phys. Chem. 53 (2002) 319], who proposed surface theories and databases about the metals d-band centre shift and the segregation. It also attempts to suggest new alloys combinations. For example, for the methanol oxidation, the best catalyst is Pt-Ru and the following features make this catalyst stand out: the d-band centre of Pt shifts down what supposes weaker molecules adsorption and Pt strongly segregates. From this analysis, it is suggested that the Pd-Ni alloy may be a potentially good catalyst. Similar interpretations are given for the three fuel cell systems regarded in the present paper. [Copyright &y& Elsevier]

Electrocatalytic water splitting is a vastly reliable method for hydrogen production. Nonetheless, its wide practical application urgently requires the development of highly active and stable bifunctional electrocatalysts with self-supported structures. This paper reports on a novel, simple way to fabricate an efficient cobalt/cobalt selenide (CS) catalytic electrode with a unique 3-D finger-like structure. More specifically, porous Co substrate was fabricated by a phase-inversion tape-casting and sintering method, followed by one-step selenization in Ar atmosphere. The resultant CS electrode manifested superior catalytic performance in both HER and OER (hydrogen and oxygen evolution reaction, respectively) that took place in an alkaline medium, with low overpotential and high long-term stability. Furthermore, the electrolysis test for overall water splitting was successfully performed by assembling the CS electrodes as both anode and cathode. The excellent electrocatalytic performance is ascribed to the high conductivity of the Co substrate, the distinctive finger-like structure, and the numerous in-situ developed heterojunctions, which suitably adjust the electronic structure and decrease the energy barrier of water splitting. Moreover, the density function theory (DFT) calculations revealed that the heterojunction enhances the density of the state near the Fermi level and optimize the kinetics of HER and OER processes. As a result, the hydrogen adsorption free energy (ΔG H*) is close to zero, and the energy barrier of the rate-determining step of OER is low due to the heterojunction formed. [Display omitted] • Bifunctional electrocatalyst qualified for overall water splitting. • In-situ grown cobalt selenide on cobalt substrate with Self-supported 3-D structure. • Heterojunction can adjust the electronic structure between the interface. • Prepared via a simple and scalable method. [ABSTRACT FROM AUTHOR]

The electrochemical oxygen reduction reaction has received increasing attention as a relatively green, safe and sustainable method for in situ hydrogen peroxide (H 2 O 2) production. Recently, significant achievements have been made to explore carbon-based (noble metal-free) low-cost and efficient electrocatalysts for H 2 O 2 electroproduction, which could potentially replace the traditional anthraquinone process. However, to realize industrial-scale implementation, a highly active and selective catalytic material is needed. In this review paper, we first expound on the oxygen reduction reaction (ORR) mechanism, which is the origin of in situ H 2 O 2 production. Then, the recent progress in the development of modified carbon-based catalysts is reviewed and classified, corresponding to their physical or chemical modulation. Furthermore, an overview is provided of the available examples from pilot/large-scale applications. Finally, an outlook on the current challenges and future research prospects to transfer the lab-developed catalysts into pilot or industrial-scale reactors is briefly discussed. [Display omitted] • Electrochemical hydrogen peroxide production process is described. • Recent progress in modification of carbon-based cathode is reviewed. • Pilot-scale examples of in situ hydrogen peroxide production are summarized. • Challenges in exploitation are discussed and future perspectives are suggested. [ABSTRACT FROM AUTHOR]

Hydrogen production from electrochemical water dissociation has been considered as a facile and promising approach to address energy related crisis in the world. In this regard, development of high performance, stable, and cost-effective catalysts for full water splitting is highly demanded. In this work a high performance electrocatalyst based on commercially available Tin oxide nanoparticles mixed with carbon nanotubes (CNT) is presented for electrocatalytic water splitting. The catalyst prepared through facile dropped casting method and obtained a high electrocatalytic activity for full water splitting. One of the key important parameters in water splitting is producing hydrogen/oxygen at high rate under long term stability. This is problematic because it would result in catalyst degradation and performance fallen. However, herein, the prepared electrocatalyst demonstrated a high stability of more than 10 h operation under a high applied current density of 100 mA.cm−2 for hydrogen evolution reaction. For the both hydrogen and oxygen, the prepared catalyst (SnO 2 /CNT coated on carbon paper) delivered the current density of 10 mA.cm−2 at a low overpotentials of 150 mV and 250 mV, respectively. Our observations validate the excellent capability in significantly modifying the catalytic activity of transition metal compound catalysts with carbon nanostructures. [Display omitted] • A synergetic effect of CNT and SnO 2 combination on the electrocatalytic performance was observed. • A lower overpotentials required to reach high current densities, along with high stability at high current. • CNT hybridization with SnO 2 influenced the Volmer step of HER. Also, the adsorption of oxygen and hydrogen affected. • The open structure accelerated the gas detachments during OER or HER, influencing the performance of the system. [ABSTRACT FROM AUTHOR]

This paper presents a facile approach for the synthesis of a novel Pt/graphene-nickel foam (Pt/GNF) electrode composed of flower-like Pt nanoparticles (NPs) and 3D graphene. The fabrication process involved the chemical vapor deposition of graphene onto Ni foam as a substrate and the subsequent growth of Pt NPs via a galvanic replacement reaction without using any seed and organic solvent. The surface morphology and composition of the prepared materials were characterized. Meanwhile, cyclic voltammetry and electrochemical impedance spectroscopy were employed to confirm their typical electrochemical characteristics. The as-prepared nanocomposites displayed enhanced catalytic activity and kinetics toward methanol electro-oxidation. Such an excellent performance can be ascribed to the high dispersion of flower-like Pt NPs and to the exposure of more sites provided by the flower-like structure. The improved stability, decreased charge transfer resistance, and enhanced reaction rate of the nanocomposites promise new opportunities for the development of direct methanol fuel cells. [ABSTRACT FROM AUTHOR]