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Water electrolysis for H2 production is restricted by the sluggish oxygen evolution reaction (OER). Using the thermodynamically more favorable hydrazine oxidation reaction (HzOR) to replace OER has attracted ever‐growing attention. Herein, we report a twisted NiCoP nanowire array immobilized with Ru single atoms (Ru1−NiCoP) as superior bifunctional electrocatalyst toward both HzOR and hydrogen evolution reaction (HER), realizing an ultralow working potential of −60 mV and overpotential of 32 mV for a current density of 10 mA cm−2, respectively. Inspiringly, two‐electrode electrolyzer based on overall hydrazine splitting (OHzS) demonstrates outstanding activity with a record‐high current density of 522 mA cm−2 at cell voltage of 0.3 V. DFT calculations elucidate the cooperative Ni(Co)−Ru−P sites in Ru1−NiCoP optimize H* adsorption, and enhance adsorption of *N2H2 to significantly lower the energy barrier for hydrazine dehydrogenation. Moreover, a self‐powered H2 production system utilizing OHzS device driven by direct hydrazine fuel cell (DHzFC) achieve a satisfactory rate of 24.0 mol h−1 m−2. [ABSTRACT FROM AUTHOR]

Synergistic catalysis opens up a new venue to improve the comprehensive application of the catalyst. Herein, a composite catalyst (Mo-Pd@N-C) consisting of the N-doped carbon derived from pyrolysis of spherical polypyrrole and MoPd nanoparticles (NPs) was constructed to emphasize the strong metal—support interaction for robust oxygen reduction reaction (ORR). The enhanced anchoring between the MoPd NPs and the substrate, and the N-species formed on the carbon matrix make the Mo-Pd@N-C deliver excellent performance with a half-wave potential of 0.945 V (vs. reversible hydrogen electrode (RHE)) for ORR, superior than that of commercial Pt/C (0.86 V). More importantly, it shows a negligible half-wave potential decline (< 5 mV) and only ∼ 20% of mass activity (MA) attenuation after 30,000 cycles stability test, obviously better than those of Pt/C (∼ 70% of MA attenuation and ∼ 30 mV of half-wave potential decline after only 15,000 cycles). This work highlights a novel synergistic method to prolong the life and improve the commercial prospects of the catalysts. [ABSTRACT FROM AUTHOR]

Single‐atom‐alloys (SAAs), as an emerging kind of materials, combine the advantages of alloy and single‐atom catalysts. The full atomic utilization of active sites and well‐defined bonding environments in SAAs lead to superior electrocatalytic performance and give a deep insight into the structural–activity relationship. In this review, the recent advances of SAAs in various electrochemical reactions are highlighted for further designing of highly effective electrocatalysts. This review starts with an introduction to the fundamental concepts of several effects, which influence the electrocatalytic activities. Then the preparation and characterization methods on SAAs are listed and compared. Next, the recent advances of SAAs in hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, alcohol/hydrogen/formic acid oxidation reaction, carbon dioxide reduction reaction, etc. are illustrated and discussed in detail. Finally, the challenges and suggestions for the future development of SAAs in energy‐conversion electrocatalysis are presented. [ABSTRACT FROM AUTHOR]

Developing facile methods to construct hierarchical-structured transition metal phosphides is beneficial for achieving high-efficiency hydrogen evolution catalysts. Herein, a self-template strategy of hydrothermal treatment of solid Ni-Co glycerate nanospheres followed by phosphorization is delivered to synthesize hierarchical NiCoP hollow nanoflowers with ultrathin nanosheet assembly. The microstructure of NiCoP can be availably tailored by adjusting the hydrothermal treatment temperature through affecting the hydrolysis process of Ni-Co glycerate nanospheres and the occurred Kirkendall effect. Benefitting from the promoted exposure of active sites and affluent mass diffusion routes, the HER performance of the NiCoP hollow nanoflowers has been obviously enhanced in contrast with the solid NiCoP nanospheres. The fabricated NiCoP hollow nanoflowers yield the current density of 10 mA cm−2 at small overpotentials of 95 and 127 mV in 0.5 mol L−1 H 2 SO 4 and 1.0 mol L−1 KOH solution, respectively. Moreover, the two-electrode alkaline cell assembled with the NiCoP and Ir/C catalysts exhibits sustainable stability for overall water splitting. The work provides a simple but efficient method to regulate the microstructure of transition metal phosphides, which is helpful for achieving high-performance hydrogen evolution catalysts based on solid-state metal alkoxides. [ABSTRACT FROM AUTHOR]

Sulphur(S) modulated Ni 3 FeN supported on N/S co-doped graphene (S-Ni 3 FeN/NSG) is synthesized via controlling the nitriding process of NiFe disulfides, and delivers excellent bifunctional oxygen electrode reaction electrocatalyic performance, particularly exhibits practical application potential in rechargeable/flexible Zn-air battery. This work provides new insights into highly efficient and low-cost electrocatalyst designing strategies. • The S-Ni 3 FeN/NSG-700 is synthesized by controlling the nitriding process of the NiFe disulfides. • The N/S co-doped graphene with porous structure provides a large number of ORR reactive sites. • The S residues in Ni 3 FeN nanoparticles expedite the rate-determination step of OER. Exploring feasible strategy for preparation of sulfur (S) modulated NiFe compounds and meanwhile clarifying the performance promoting mechanism of such catalysts has triggered numerous interest in rechargeable Zinc-air battery research field. Herein, S modulated Ni 3 FeN supported on N/S co-doped graphene (S-Ni 3 FeN/NSG) is synthesized via controlling the nitriding process of NiFe disulfides. The beneficial effect of the design strategy and S decoration on electrocatalytic activity are determined and analysed systematacially. The S-Ni 3 FeN/NSG-700 delivers excellent bifunctional oxygen electrocatalysis performance with half-wave potential of 0.878 V for ORR and low OER overpotential of 260 mV at 10 mA cm−2. Density Functional Theory (DFT) calculations demonstrate that S decoration effectively promotes the formation of OOH* intermediates and observably decreases the maximum of change of the Gibbs free energies for four primitive OER steps. Notably, when S-Ni 3 FeN/NSG-700 as air electrode applied in Zn-air battery test, the device shows superb durability for 1200 discharge/charge cycles at 10 mA cm-2. The corresponding all-solid Zinc-air battery exhibits excellent mechanical flexibility and a high power density of 140.1 mW cm-2. Two Zinc-air batteries in series can long-term stably power a self-made water-splitting device. This work provides new insights into highly efficient and low-cost bifunctional oxygen electrocatalyst designing. [ABSTRACT FROM AUTHOR]

Exploring high-efficient non-noble metal hydrogen evolution reaction (HER) electrocatalysts is still a challenge for high purity hydrogen producing. The sluggish water dissociation kinetics (Volmer step) in alkaline electrolyte results in poorer HER activities than that in acid media. In this work, an efficient strategy to accelerate the Volmer step in alkaline media is proposed through the synergistic effect between metal and metal oxide. A hybrid catalyst composed of Ni/MoO 2 was prepared by using a facile hydrothermal-reduction method. The metal nickel acts as the adsorption site for hydrogen, while MoO 2 promotes the dissociation of water molecules and optimizes the Ni–H bond energy. In addition, the nanosheet structure is beneficial for exposing more active sites. Electrochemical test reveals that the Ni/MoO 2 catalyst exhibits outstanding HER performance with a small overpotential of 40 mV to deliver the current density of 10 mA cm−2 as well as excellent stability. Hydrogen oxidation reaction (HOR) experiment was performed to study the mechanistic insights into the activity enhancement. Ni/MoO 2 hybrid catalyst with excellent HER performance in alkaline media was prepared by using a facile hydrothermal-reduction method. HOR test demonstrated that the MoO 2 accelerated the OH adsorption thus the Volmer step, which corresponding to the main reason for performance improvement. Image 1 • High efficient catalyst for hydrogen evolution reaction (HER) composed of Ni/MoO 2 was prepared by using a facile hydrothermal-reduction method. • The MoO 2 favors the adsorption and dissociation of water molecules. • Hydrogen oxidation reaction (HOR) test was performed to study the mechanistic insights into the activity enhancement. [ABSTRACT FROM AUTHOR]