Oxygen vacancies activate electrophilic-nucleophilic dual sites in Mo-doped NiOOH for hydrogen evolution via urea-assisted electrocatalysis approaching industrial-level current densities

Urea-assisted hydrogen production can effectively improve the overall reaction rate, but achieving industrial-scale current density and long life is still a huge challenge. Herein, Vo-NiMoOOH/NF was prepared by hydrothermal-selenization-electrochemical reconstruction, which can achieve the industrial-grade current density of ∼860 mA cm −2 in an H-type reaction cell at 1.5 V (vs. RHE). A series of characterizations and DFT calculations reveal that the presence of oxygen vacancies and electrophilic-nucleophilic sites improves the D-band center of Ni, reduces the oxidation potential of Ni, accelerates the reconstruction of the catalyst, and inhibits the oxygen evolution reaction. Electrocatalytic urea oxidation coupled with hydrogen production was achieved in a two-electrode flow cell utilizing Vo-NiMoOOH/NF as a bifunctional catalyst. The current density of 1 A cm −2 at a cell voltage of 2.71 V and stable operation for more than 150 h at a current density of 500 mA cm −2 were realized, exhibiting excellent catalytic activity and stability.