Reactive template‐derived interfacial engineering of CoP/CoO heterostructured porous nanotubes towards superior electrocatalytic hydrogen evolution

Abstract The development of economical, efficient, and robust electrocatalysts toward the hydrogen evolution reaction (HER) is highly imperative for the rapid advancement of renewable H₂ energy‐associated technologies. Extensive utilization of the heterointerface effect can endow the catalysts with remarkably boosted electrocatalytic performance due to the modified electronic state of active sites. Herein, we demonstrate deliberate crafting of CoP/CoO heterojunction porous nanotubes (abbreviated as CoP/CoO PNTs hereafter) using a self‐sacrificial template‐engaged strategy. Precise control over the Kirkendall diffusion process of the presynthesized cobalt–aspartic acid complex nanowires is indispensable for the formation of CoP/CoO heterostructures. The topochemical transformation strategy of the reactive templates enables uniform and maximized construction of CoP/CoO heterojunctions throughout all the porous nanotubes. The establishment of CoP/CoO heterojunctions could considerably modify the electronic configuration of the active sites and also improve the electric conductivity, which endows the resultant CoP/CoO PNTs with enhanced intrinsic activity. Simultaneously, the hollow and porous nanotube architectures allow sufficient accessibility of exterior/interior surfaces and molecular permeability, drastically promoting the reaction kinetics. Consequently, when used as HER electrocatalysts, the well‐designed CoP/CoO PNTs show Pt‐like activity, with an overpotential of only 61 mV at 10 mA cm⁻² and excellent stability in 1.0 M KOH medium, exceeding those of the vast majority of the previously reported nonprecious candidates. Density functional theory calculations further substantiate that the construction of CoP/CoO heterojunctions enables optimization of the Gibbs free energies for water adsorption and H adsorption, resulting in boosted HER intrinsic activity. The present study may provide in‐depth insights into the fundamental mechanisms of heterojunction‐induced electronic regulation, which may pave the way for the rational design of advanced Earth‐abundant electrocatalysts in the future.