Amorphous Ni(OH)₂ Coated Cu Dendrites with Superaerophobic Interface for Bipolar Hydrogen Production Assisted with...

Since formaldehyde oxidation reaction (FOR) can release H₂, it is attractive to construct a bipolar hydrogen production system consisting of FOR and hydrogen evolution reaction (HER). Although copper-based catalysts have attracted much attention due to their low cost and high FOR activity, the performance enhancement mechanism lacks in-depth investigation. Here, an amorphous-crystalline catalyst of amorphous nickel hydroxide-coated copper dendrites on copper foam (Cu@Ni(OH)₂/CF) is prepared. The modification of Ni(OH)₂ resulted in hydrophilic and aerophobic states on the Cu@Ni(OH)₂/CF surface, facilitating the transport of liquid-phase species on the electrode surface and accelerating the release of H₂. The Open circuit potential (OCP) and density functional theory (DFT) calculations indicate that this core-shell structure facilitates the adsorption of HCHO and OH^-. In addition, the catalytic mechanism and reaction pathway of FOR are investigated through in situ FTIR and DFT calculations, and the results showed that the modification of Ni(OH)₂ lowered the energy barrier for C─H bond breaking and H─H bond formation. In the HER//FOR system, Pt/C//Cu@Ni(OH)₂/CF can provide a current density of 0.5 A cm^-2 at 0.36 V and achieve efficient and stable H₂ production. This work offers new ideas for designing electrocatalysts for bipolar hydrogen production system assisted with formaldehyde oxidation.