Hierarchical CuOx@Ni1–yCoyO Nanotube Arrays Grown on Cu Foam as a Binder-Free Electrode for Hydrazine-Assisted Unprecedented Efficient Hydrogen Generation

Electrolyzed water is a continual and clean method to produce hydrogen. However, the slow anodic oxygen evolution reaction (OER) is still a formidable conundrum for effective H2 generation. Substituting the OER with the thermodynamic beneficial hydrazine oxidation reaction (HzOR) can decrease the cell voltage of water electrolysis and enhance energy-efficient hydrogen generation. In the present work, interconnected nickel cobalt oxide nanosheets supported on hollow copper oxides were directly grown on the Cu foam electrode (CuOx@Ni1–yCoyO/CF), which was fabricated through an in situ etching, solvothermal deposition, and thermal treatment method. The 3D nanotube@nanosheet hierarchical structure affords rich active sites of a catalytic reaction, and the trimetal elements and heterostructure improve the electronic structure, thereby enhancing the catalytic activity. In addition, the active material can improve the conductivity by in situ growing on the current collector without a binder. Benefiting from the above merits, the as-prepared CuOx@Ni1–yCoyO/CF catalysts displayed good HER performance (46.9 mV at 10 mA cm–2) and superior HzOR property (4.7 mV at 10 mA cm–2). When serving as the cathode or anode in 1 M KOH with a 0.5 M hydrazine solution, the as-prepared CuOx@Ni1–yCoyO/CF catalysts obtained the lowest potential for hydrogen production (95 mV at 10 mA cm–2) in comparison with the formerly reported catalysts, demonstrating great potential in highly efficient hydrogen production.