Optimized adsorption energy of intermediates on bimetallic NiCoSe nanoflowers for synergistic urea electrooxidation...

Integrating the urea oxidation reaction (UOR) with the hydrogen evolution reaction (HER) presents a promising strategy for environmental remediation and sustainable energy generation. However, the practical application of UOR is hampered by its sluggish kinetics and high overpotentials, orginating from a complex six-electron transfer pathway and the inefficient adsorption/desorption of multiple intermediates. Herein, we demonstrate that bimetallic NiCoSe exhibits optimized adsorption energy for urea and its intermediates compared to monometallic NiSe, resulting in a reduced energy barrier for the rate-determining-steps. The synthesized flower-shaped NiCoSe catalyst delivers significantly enhanced UOR activity, requiring a potential of only 1.17 ± 0.01 V vs. RHE to achieve a current density of 10 mA⋅cm^-2. Concurrently, it demonstrates a HER overpotential of 169.9 ± 34.7 mV at the same current density. The oxidation mechanism is elucidated through in situ Raman and electrochemical mass spectrometry, revealing urea oxidation pathway involving deprotonation, intramolecular NN coupling, and final conversion of the carbonyl group to CO₂. Density functional theory (DFT) calculations corroborate that NiCoSe provides more favorable adsorption energies and lower energy barriers for critical UOR intermediates than NiSe. These findings deepen the fundamental understanding of UOR mechanism on metal selenides and highlights their potential for efficient hydrogen production.