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Designing efficient and bifunctional electrocatalysts for water splitting conforms to the concept of energy conservation and emission reduction but remains challenging now. Herein, the fabrication of a heterostructure by anchoring cobalt‐polyoxometalates (Co‐POM) on NiFe layered double hydroxide (NiFe‐LDH) nanoplates in situ on nickel foam (NF) is first reported (Co‐POM@LDH/NF). The surface area, electron transfer ability, and stability of the heterostructure are increased due to the synergistic effect between Co‐POM and NiFe‐LDH. Particularly, Co‐POM@LDH/NF can deliver a current density of 100 mA cm−2 with an overpotential of only 220 mV for hydrogen evolution reaction (HER) and 226 mV for oxygen evolution reaction (OER) in 1.0 m KOH electrolytes. Impressively, the outstanding stability of Co‐POMs in heterostructures is verified by the experimental observations after electrolysis, indicating the successful construction of stable POMs‐based heterogeneous electrocatalysts. More attractively, the electrolyzer composed by Co‐POM@LDH/NF as anode and cathode shows a much lower operating voltage of 1.51 V at the current density of 10 mA cm−2 for overall water splitting. This study provides a feasible and extensible idea for the design of the POM‐based heterostructures. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDHs) are a family of layer materials that receive heightened attention. Herein a ternary NiFeMn-LDH is investigated with superior oxygen evolution activity, which is attributed to the Mn4+ doping in the intralayer, which modifies the electronic structure and improves the conductivity of the electrocatalyst. [ABSTRACT FROM AUTHOR]

A pine-shaped Pt nanostructured electrode with under-water superaerophobicity for ultrahigh and steady hydrogen evolution reaction (HER) performance is successfully fabricated by a facile and easily scalable electrodeposition technique. Due to the lower bubble adhesive force (11.5 ± 1.2 μN), the higher bubble contact angle (161.3° ± 3.4°) in aqueous solution, and the smaller size of bubbles release for pine-shaped Pt nanostructured electrode, the incomparable under-water superaerophobicity for final repellence of bubbles from submerged surface with ease, is successfully achieved, compared to that for nanosphere electrode and for Pt flat electrode. With the merits of superior under-water superaerophobicity and excellent nanoarray morphology, pine-shaped Pt nanostructured electrode with the ultrahigh electrocatalytic HER performance, excellent durability, no obvious current fluctuation, and dramatically fast current density increase at overpotential range (3.85 mA mV−1, 2.55 and 13.75 times higher than that for nanosphere electrode and for Pt flat electrode, respectively), is obtained, much superior to Pt nanosphere and flat electrodes. The successful introduction of under-water superaerophobicity to in-time repel as-formed H2 bubbles may open up a new pathway for designing more efficient electrocatalysts with potentially practical utilization in the near future. [ABSTRACT FROM AUTHOR]

Herein, a strategy for one-step fabrication of cobalt sulfide/graphene (Co1− xS/G) nanocomposite as bifunctional catalyst for oxygen catalysis is demonstrated. The one-step fabrication method involves annealing the mixture of cobalt salt, thioacetamide, and graphene oxide with the assistance of small amount of glycol without any further purification steps. The Co1− xS/G shows a morphology with small-sized Co1− xS nanocrystals strongly and uniformly anchored on the graphene surface. Systematically electrochemical studies demonstrate that the Co1− xS/G with optimized components shows superior catalytic activities toward oxygen reduction and oxygen evolution, which are comparable or even superior to commercial Pt/C and Ir/C catalysts. As a result, the potential hysteresis of Co1− xS/G is the lowest among all the samples. The facile operability of the fabrication method and the high bifunctional activity of Co1− xS/G may pave one practical way for broad applications including fuel cell, metal-O2 battery, and water electrolysis. [ABSTRACT FROM AUTHOR]