Monolithic nanoporous nickel fabricated via facile reduction for high-efficiency electrochemical water splitting

Monolithic nanoporous metals are regarded as advanced functional materials for diverse applications. Herein, a facile approach was used to fabricate monolithic nanoporous Ni (MNPN) via direct reduction of NiO under a H₂ atmosphere. This method avoided complex preparation processes, and the only byproduct was water vapor, so the process is facile and environmentally friendly. When the optimized MNPN was used as a self-supporting electrode for the hydrogen evolution reaction (HER), it demonstrated outstanding HER performance with a low overpotential of 41.3 mV at a current density of 10 mA cm⁻² in 1 M KOH solution. Using MNPN and electro-oxidized derivatives (NiOOH/MNPN) as the cathode and anode, an alkaline electrolyzer reached a current density of 10 mA cm⁻² at only 1.57 V and exhibited exceptional long-term durability for 200 h at 100 mA cm⁻², outperforming most reported electrolyzers assembled with Ni-based electrodes.