Improved Urea Oxidation Performance via Interface Electron Redistributions of the NiFe(OH)_x/MnO₂/NF p‐p Heterojunction

Abstract

The development of highly efficient urea oxidation reaction (UOR) electrocatalysts is the key to simultaneously achieving green hydrogen production and the treatment of urea‐containing wastewater. Ni‐based electrocatalysts are expected to replace precious metal catalysts for UOR because of their high activity and low cost. However, the construction of Ni‐based electrocatalysts that can synergistically enhance UOR still needs further in‐depth study. In this study, highly active electrocatalysts of NiFe(OH)x/MnO2 p‐p heterostructures are constructed on nickel foam (NF) by electrodeposition (NiFe(OH)x/MnO2/NF), illustrating the effect of electronic structure changes at heterogeneous interfaces on UOR and revealing the catalytic mechanism of UOR. The NiFe(OH)x/MnO2/NF only needs 1.364 V (vs Reversible Hydrogen Electrode, RHE) to reach 10 mA cm−2 for UOR. Structural characterizations and theoretical calculations indicate that energy gap leads to directed charge transfer and redistribution at the heterojunction interface, forming electron‐rich (MnO2) and electron‐poor (NiFe(OH)x) regions. This enhances the catalyst's adsorption of urea and reaction intermediates, reduces thermodynamic barriers during the UOR process, promotes the formation of Ni3+ phases at lower potentials, and thus improves UOR performance. This work provides a new idea for the development of Ni‐based high‐efficiency UOR electrocatalysts.