Mn-doped CuNNi3 antiperovskite for high efficient urea assisted overall water splitting

Urea-assisted overall water splitting has emerged as a cost-efficient and promising technology for hydrogen production, which not only avoids the formation of an explosive H 2 /O 2 gas mixture but also significantly reduces the energy input required for water electrolysis. In this work, a bifunctional CuNNi 3-x Mn x catalyst self-supported on nickel foam (NF) was synthesized via a facile hydrothermal method followed by annealing, resulting in highly efficient and stable electrocatalysts for both the urea oxidation reaction (UOR) and the hydrogen evolution reaction (HER). Controlled Mn doping allows precise modulation of the electronic structure of CuNNi 2.4 Mn 0.6 at the Ni active sites, simultaneously enhancing the adsorption/desorption kinetics of hydrogen intermediates (H∗) and facilitating C–N bond cleavage in urea. The optimized CuNNi 2.4 Mn 0.6 catalyst requires only 1.336 V for UOR and 44 mV for HER to achieve a current density of 10 mA cm −2 , demonstrating remarkable bifunctional activity. Moreover, when employed as both anode and cathode in a urea-assisted overall water splitting system, the catalyst enables a cell voltage of merely 1.526 V at 10 mA cm −2 , significantly lower than that required for conventional water electrolysis (1.695 V vs. RHE). The system also exhibits excellent durability, maintaining stable performance for over 30 h at 10 mA cm −2 without significant activity loss. This work provides a foundation for the further exploration of transition metal-based bifunctional electrocatalysts, paving the way for energy-efficient hydrogen production and simultaneous treatment of urea-rich wastewater.