Ni₃Fe/NiFe₂O₄ heterojunction engineering and vanadium promoter synergetically accelerating urea degradation

Urea oxidation reaction (UOR) is significant in reducing hydrogen production energy consumption and treating urea wastewater, necessitating the development of efficient UOR electrocatalysts. Herein, we develop a vanadium (V)-doped Ni₃Fe/NiFe₂O₄ heterojunction (V-Ni₃Fe/NiFe₂O₄), wherein the combined effect of V doping and the heterojunction architecture improve the material's conductivity, facilitate electron transfer, and optimize the electronic structure of active sites. Consequently, the V-Ni₃Fe/NiFe₂O₄ electrocatalyst requires a potential of only 1.48 V to achieve a current density of 100 mA·cm^-2 and achieves ∼78 % urea degradation within 3 h. Density functional theory calculations reveal that V doping increases the density of states near the Fermi level of Ni₃Fe/NiFe₂O₄, thereby enhancing the electron transfer capability. Moreover, the formation of the heterojunction structure improves urea adsorption and lowers the energy barrier for the UOR. This study offers valuable insights for the rational design of heterojunction-based UOR electrocatalysts.