Novel Gel method MXene-Supported Dual-Site PtNi-NiO for Electrocatalytic Water Reduction and Urea Oxidation

Compared to the traditional oxygen evolution reaction (OER), the urea oxidation reaction (UOR) generally exhibits a lower overpotential during the electrolytic process, which is conducive to the hydrogen evolution reaction (HER) at the cathode. The superior structure and abundant sites play a crucial role in promoting the adsorption and cleavage of urea molecules. Therefore, this paper introduces a simple metal cation-induced gelation method to prepare an electrocatalyst with PtNi alloy-NiO dual sites supported on Ti₃C₂T_x, which simultaneously exhibits excellent UOR and HER performance. PtNi-NiO_x/Ti₃C₂T_x demonstrates good catalytic activity for the urea oxidation reaction, requiring only 1.364 V (overpotential of 0.994 V) to achieve a current density of 100 mA cm^-2 in UOR, and also exhibits remarkable catalytic activity in the hydrogen evolution reaction, with PtNi-NiO_x/Ti₃C₂T_x achieving a current density of 10 mA cm^-2 in HER with only 24 mV of overpotential. In the UOR//HER two-electrode electrolysis cell, it requires only 1.361 and 1.538 V to reach current densities of 10 and 100 mA cm^-2, respectively. According to density functional theory (DFT) calculations, the dual active sites can intelligently adsorb the electron-donating/electron-withdrawing groups in urea molecules, activate chemical bonds, and thereby initiate urea decomposition.