Regulating Ni2P electronic structure and morphology with cobalt: a one-step route to enhanced electrocatalytic urea oxidation and water splitting†

Abstract

The effectiveness of electrochemical hydrogen production is predominantly impeded by the slow kinetics associated with the anodic oxygen evolution reaction (OER). Nevertheless, the method of urea-assisted energy-efficient alkaline hydrogen production has surfaced as a viable alternative strategy. In this study, a highly efficient Ni₂P/NiCoP/NF electrocatalyst, featuring a unique combination of nanosheet and nanoneedle structures, is fabricated by fine-tuning the synthesis process. When employed as a catalyst, Ni₂P/NiCoP/NF demonstrated exceptional catalytic efficiency, achieving a current density of 100 mA cm⁻² at a notably low potential of 1.31 V (vs. RHE) in the urea oxidation reaction (UOR). Notably, this potential was 210 mV lower than that required for the OER. Moreover, the system demonstrated excellent stability, maintaining a stable performance for over 36 hours. Theoretical calculations suggested that cobalt incorporation could facilitate the relocation of the d band center of Ni₂P/NiCoP/NF towards the Fermi level, thereby enhancing electron transport efficiency. This adjustment enhanced the electron transport and increased urea adsorption, thereby accelerating the urea oxidation reaction (UOR). Scanning electron microscopy (SEM) analysis revealed a highly uniform and well-distributed nanostructure, whereas electrochemical measurements indicated significant enhancement in performance. Both of these outcomes directly resulted from the precise control of the synthesis parameters. This study showcases the successful integration of hybrid structure formation and morphology control strategies to design cost-effective catalysts for electrochemical conversion processes, thereby offering a sustainable and environmentally friendly approach towards energy-efficient hydrogen production.