In-situ construction of cation vacancies in amphoteric-metallic element-doped NiFe-LDH as ultrastable and efficient alkaline hydrogen evolution electrocatalysts at 1000 mA cm-2

Developing efficient and stable electrocatalysts at affordable costs is very important for large-scale production of green hydrogen. In this study, unique amphoteric metallic element -doped NiFe-LDH nanosheet arrays (NiFeCdLDH, NiFeZn-LDH and NiFeAl-LDH) using as high-performance bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) were reported, by tuning electronic structure and vacancy engineering. It was found that NiFeCd-LDH possesses the lowest overpotentials of 85 mV and 240 mV (at 10 mA cm -2) for HER and OER, respectively. Density functional theory (DFT) calculations reveal the synergistic effect of Cd vacancies and Cd doping on improving alkaline HER performance, which promote the achievement of excellent catalytic activity and ultrastable hydrogen production at a large current density of 1000 mA cm -2 within 250 h. Besides, the overall water splitting performance of the as -prepared NiFeCd-LDH requires only 1.580 V to achieve a current density of 10 mA cm -2 in alkaline seawater media, underscoring the importance of modifying the electronic properties of LDH for efficient overall water splitting in both alkaline water/seawater environments.