Self-supporting electrodes from 2-methylimidazole coordination effect for water electrolysis

Electrolysis of water to produce hydrogen and oxygen is a crucial approach for achieving zero-carbon emissions and sustainable energy conversion. However, due to the slow kinetics of anode oxygen evolution reaction (OER), the hydrogen and oxygen evolution efficiency are reduced. Here, we synthesized a non-precious metal bifunctional catalyst (NF@CN), self-supporting nickel foam (NF) compounded with carbon-nitrogen (CN) for water electrolysis. Specifically, through the coordination effect between 2-methylimidazole N lone pair electrons and Ni 3d vacant orbitals, a ligand layer forms on NF surface. After high-temperature carbonization, 2-methylimidazole evolves into CN layer. From density functional theory (DFT), NF@CN exhibits good conductivity. Moreover, the introduced CN not only enhances the non-metallic active sites, but also promotes NF acid-base resistance. As a result, self-supporting electrode NF@CN-10 requires just 309 mV and 288 mV overpotential for OER and hydrogen evolution reaction (HER) respectively to achieve 50 mA cm −2 current density. Also, the NF@CN-10 electrolytic cell displays small battery voltage of 1.83 V at 50 mA cm −2 current density and 200 h long stability.