关键词: 铜掺杂, 镍铜合金, 异质结, 尿素氧化反应, 析氢反应, 协同效应

Abstract: Urea-assisted electrolytic hydrogen production saves energy and reduces emissions, where developing high-activity electrode materials is critical. A self-encapsulated Cu-doped Ni catalyst (Ni(Cu)/NF) with a NiO phase was constructed on Ni foam (NF) via pulse voltammetric deposition and constant-potential dissolution. The material features a three-tier porous architecture (100 nm floral nanopores, 300-500 nm nanoclusters, and NF micropores), delivering an electrochemical active area (ECSA) 12.17 times that of bare NF and providing abundant active interfaces and mass-transfer channels for the hydrogen evolution reaction (HER) and urea oxidation reaction (UOR). Cu doping induces lattice distortion in the Ni-rich phase, which, together with strong electronic interactions from the surface NiO/Ni heterojunction, synergistically boosts intrinsic catalytic activity. In 1 mol·L^-1 KOH, Ni(Cu)/NF achieves 10 mA^-2 with an HER overpotential of only 53 mV and a UOR potential of only 1.364 V. The assembled urea-assisted electrolyzer requires only 1.732 V to deliver 500 mA·cm^-2, outperforming commercial noble-metal catalysts, and shows excellent stability with a voltage rise rate of only 0.38 mV·h^-1 after 120 h. This “structure-electronics” synergistic strategy offers a new route to efficient and stable bifunctional catalysts for urea-assisted hydrogen production.

Key words: copper doping, nickel-copper alloy, heterojunction, urea oxidation reaction, hydrogen evolution reaction, synergistic effect