Ni-Fe-Cu-layered double hydroxides as high-performance electrocatalysts for alkaline water oxidation

Alkaline oxygen evolution reaction (OER) electrocatalysts have been widely studied for improving the efficiency and green hydrogen production through electrochemical water splitting. Currently, iron-doped nickel-LDHs (NF-LDHs) are regarded as the benchmark electrocatalyst for alkaline OER, primarily owing to the physicochemical synergetic effects between Ni and Fe. Here, the third element addition into NF-LDHs is designed to further enhance the electrocatalytic performance through the modulation of electronic property. Cu-doped NF-LDHs (NFC-LDHs) are developed with the self-supported structure on porous supports. NFC-LDHs can be grown on carbon cloth (CC) in an intriguing 2D nanosheet structure, wherein the surface electronic configuration is suitably modulated by interactions among Ni-Fe-Cu. Importantly, activation energy for OER can be lowered by adding Cu into NF-LDHs. Thereby, the NFC-LDHs exhibited enhanced OER activity and improved stability than those of nickel-LDHs (Ni-LDHs) and NF-LDHs. For NFC-LDHs, small overpotentials of only 230 and 250 mV yield current densities of 50 and 100 mA cm⁻², respectively. In addition, excellent electrochemical stability is demonstrated during long-term OER tests without any degradation demonstrating no dissolution of active metals water electrolysis due to synergetic effects among Ni-Fe-Cu.