High-performance NiMo@Co@NSC electrocatalyst for efficient overall water splitting

The widespread application of water electrolysis is hindered by the sluggish kinetics of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) due to the high overpotentials of conventional electrodes. Developing efficient electrocatalysts is essential to overcome these limitations. In this study, bifunctional MOFderived electrocatalysts containing non-precious metal compounds were developed and evaluated for water electrolysis. Electrochemical tests revealed that incorporating Mo and Ni into the Co@NSC structure significantly enhanced both HER and OER performances. The CC/NiMo@Co-NSC electrode demonstrated a low overpotential of 66 mV at -10 mA cm- 2 with a Tafel slope of 65 mV/dec for HER, comparable to the commercial CC/Pt electrode. For OER, an overpotential of 335 mV at 50 mA cm- 2 was achieved, with a stable current density of 19.49 mA cm- 2 after 12 h. These improvements are attributed to the synergistic effects of Mo, Ni, and Co-NSC, which optimize the electronic structure, enhance charge transfer efficiency, and reduce charge transfer resistance (Rct), leading to improved ion and gas diffusion. This study highlights the potential of NiMo@Co-NSC as a highefficiency, bifunctional catalyst for sustainable hydrogen and oxygen production through water splitting.