Industrial-level electrocatalytic urea oxidation: The role of cerium doping in nickel phosphide (Ce-Ni5P4) for tuning electronic structure and promoting surface reconstruction

Surface reconstruction is the key to improving the intrinsic activity of non-precious metal-based catalysts for the urea oxidation reaction (UOR). In this work, Cerium doped Nickel phosphide (Ce-Ni 5 P 4 ) porous nanosheets were synthesized by conventional hydrothermal and phosphorylation methods. It is found that the introduction of Ce 4f induces the electron transfer from P and Ni to Ce, increasing the chemical state of Ni, boosting the reconstruction of Ni 5 P 4 toward active substances of NiOOH with higher UOR activity and improves the UOR intermediates adsorption behavior on the (210) crystal plane for efficient electrochemical reaction. The results show that Ce-doped Ni 5 P 4 improves the UOR performance of only 1.33 V at 500 mA cm −2 , and exhibits exceptional stability over 120 h. Meanwhile, the AEMWE assembly by Ce-doped Ni 5 P 4 || MoNi foam possess a lower voltage of 2.37 V than RuO 2 ||MoNi foam at 1 A cm −2 , demonstrating an excellent performance in industrial applications. The in-situ Raman confirms the enhanced electrochemical reconstruction process caused by the introduction of Ce, which promotes the large current density UOR process. The theoretical calculations show that the stable (210) crystal plane without reconstruction is activated by the Ce doping, and the modulated electron distribution around the Ni sites weakens the binding energy of the Ni N bond, reducing the energy barrier of the rate-determining step for more efficient reaction kinetics. This work provides a hierarchical reconstruction strategy to promote the coupling of activated structures and stable bulks, improving the catalytic UOR activity at large current density and providing new insights for the development of catalysts for industrial applications.