Cerium doping induces in-situ reconstruction of Ni5P4 to enhance urea-assisted water splitting

Replacing the anodic oxygen evolution reaction (OER) of overall water splitting with urea oxidation reaction (UOR) can significantly reduce the energy consumption of hydrogen production via electrolysis. Ni₅P₄ has high catalytic activity in UOR with its noble-metal-like properties, but it still has the problems of difficulty in combining activity and stability and insufficient bifunctional catalytic performance. Ce, with its unique electronic configuration and variable valence states (Ce³⁺/Ce⁴⁺), can modulate the electronic structure of Ni₅P₄ and optimize the adsorption energy of reaction intermediates, thereby enhancing both catalytic activity and stability simultaneously. In this paper, Ce-doped Ni₅P₄ (Ce-Ni₅P₄/NF) bifunctional electrocatalysts were prepared by a facile hydrothermal and phosphorization method. Testing results indicated that the potentials of urea oxidation reaction at 10 and 100 mA cm^-2 were 1.331 V and 1.412 V, respectively, and hydrogen evolution reaction (HER) up to 10 mA cm^-2 required a mere 83 mV overpotential, and the performance of the total hydrolysis was stable for 300 hours. In situ Raman further demonstrated that Ce could accelerate the reconstruction of Ni₅P₄ to highly active NiOOH, increase the active sites, optimize the intermediate adsorption, and enhance the efficiency. This research presents a novel approach for developing advanced bifunctional electrocatalysts.