Enhancing the surface polarization effect via Ni/NiMoOx heterojunction architecture for urea-assisted hydrogen generation

Electrocatalytic urea oxidation (UOR) has attracted significant interest as a promising anodic half-reaction to replace sluggish oxygen evolution reaction (OER) toward water splitting. However, the activation and decomposition of urea molecule maintains a challenge during electrocatalytic process because of its 6e- oxidation procedure. Herein, Ni nanoparticles decorated NiMoOx nanorod (Ni/NiMoOx) electrocatalyst with abundant heterojunction interfaces is fabricated and the density functional theory (DFT) calculation testifies that the interfaces are favorable for enhancing the conductivity and modulating the surface polarization of Ni/NiMoOx, thus improving its UOR's activity. The Ni/NiMoOx performs superb electrocatalytic capacities toward UOR with a potential of 1.355 V (vs RHE) at 20 mA cm-2, and HER with an overpotential of 98 mV at 10 mA cm-2. A hybrid two-electrode water splitting cell is further assembled via applying the Ni/NiMoOx as both anodic and cathodic electrodes with presence of 0.33 M urea, delivering 50 mA cm-2 at voltage of 1.589 V. The findings help to provide a reliable strategy for rational reconstruction of Ni based metal oxide with rich interfaces for diverse electrocatalytic reactions.