Developing highly active electrocatalysts with low cost and high efficiency for hydrogen evolution reactions (HERs) is of great significance for industrial water electrolysis. Herein, a 3D hierarchically structured nanotubular copper-doped nickel catalyst on nickel foam (NF) for HER is reported, denoted as Ni(Cu), via facile electrodeposition and selective electrochemical dealloying. The as-prepared Ni(Cu)/NF electrode holds superlarge electrochemical active surface area and exhibits Pt-like electrocatalytic activity for HER, displaying an overpotential of merely 27 mV to achieve a current density of 10 mA cm and an extremely small Tafel slope of 33.3 mV dec in 1 m KOH solution. The Ni(Cu)/NF electrode also shows excellent durability and robustness in both continuous and intermittent bulk water electrolysis. Density functional theory calculations suggest that Cu substitution and the formation of NiO on the surface leads to more optimal free energy for hydrogen adsorption. The lattice distortion of Ni caused by Cu substitution, the increased interfacial activity induced by surface oxidation of nanoporous Ni, and numerous active sites at Ni atom offered by the 3D hierarchical porous structure, all contribute to the dramatically enhanced catalytic performance. Benefiting from the facile, scalable preparation method, this highly efficient and robust Ni(Cu)/NF electrocatalyst holds great promise for industrial water-alkali electrolysis.

Hindered by sluggish kinetics and large overvoltages of direct hydrazine oxidation, energy-efficient electrolytic hydrogen generation from whole cell hydrazine electrolysis still remains a great challenge. Herein, we present a 3D hierarchically nanotubular Ni–Cu alloy on nickel foam (Ni­(Cu)/NF) and demonstrate its high efficiency and strong durability for the hydrazine oxidation reaction (HzOR) with a required potential of merely 86 mV to afford a current density of 100 mA cm–2 in alkaline hydrazine aqueous solution. The normalization of HzOR polarization curves for Ni­(Cu)/NF manifests that the superlarge electrochemical active surface area (ECSA) with an 18-fold increase is the main contributor to the excellent HzOR performance. The superior cell performance makes Ni­(Cu)/NF a good alternative transition-metal-based electrocatalyst for utilization in the HzOR electrolyzer. The remarkable performance toward the hydrogen evolution reaction (HER) of Ni­(Cu)/NF allows the use of a superior bifunctional electrocatalyst for electrolytic hydrogen production via HzOR and HER. In a two-electrode electrolyzer cell employing Ni­(Cu)/NF to function as the cathode and anode, an extremely low cell voltage of 0.41 V is required to afford 100 mA cm–2 with remarkable long-term stability.

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Herein, a double-hierarchy copper-doped nickel cubic nanopores (Ni(Cu) CNPs) catalyst is fabricated by a normal-pulse-voltammetry electrodeposition and a subsequent facile in-situ electrochemical etching process. As a bifunctional catalysts, the Ni(Cu)...