In-situ electrochemical activation of Cu/Co(OH)2/Ti3C2(OH)X-MXene for improved hydrazine electrooxidation-assisted hydrogen generation
The sluggish kinetics of the oxygen evolution reaction (OER) in conventional water electrolysis imposes a substantial energy penalty, necessitating the development of thermodynamically favorable anodic alternatives. This study reports a Cu/Co(OH)2/Ti3C2(OH)X-MXene (MX) catalyst synthesized via electrodeposition followed by in-situ electrochemical reduction, which induces surface reconstruction to form the activated Cu/Co/Co(OH)2/MX phase. The reconstructed catalyst achieves an ultra-low overpotential of −78 mV at 10 mA cm−2 for hydrazine oxidation (HzOR), with a Tafel slope of 28.7 mV dec−1. Density functional theory calculations reveal that MXene incorporation enhances conductivity and wettability, promotes electron transfer to Co(OH)2, and lowers the Co d-band center from −0.867 to −0.883 eV upon Cu addition, thereby facilitating N2 desorption. This synergy reduces the free energy barrier of the rate-determining step from 0.33 to 0.24 eV. A two-electrode electrolyzer employing this bifunctional catalyst requires only 0.252 V to reach 100 mA cm−2, representing a 1.519 V reduction compared to conventional water electrolysis. These findings demonstrate a viable pathway for energy-efficient hydrogen production via hydrazine-assisted water splitting.