Bifunctional surface-distributed RuO2 on NiFe double layer hydroxide for efficient alkaline water splitting

Designing highly active and stable electrocatalysts for the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is critical but remains challenging. In this study, we present a surface-distributed ruthenium oxide stabilized on nickel‑iron layered double hydroxide (A-RuNiFe/Ni foam), serving as an efficient bifunctional electrocatalyst for water splitting. X-ray absorption near edge structure analysis reveals that RuO 2 deposition alters the electronic structure of both Ni and Fe within the nickel‑iron layered double hydroxide, promoting electron transfer from Fe to Ni. The as-prepared A-RuNiFe/Ni foam electrode exhibits remarkable electrochemical activity in 1 M KOH, with overpotentials of 218 mV and 14 mV at a current density of 10 mA cm −2 for OER and HER, respectively. In overall water splitting evaluations, the A-RuNiFe/Ni foam requires only a low cell voltage of 1.88 V to achieve 1 A cm −2 . It can operate continuously for 360 h with negligible activity degradation at high current densities (0.5 A cm −2 for 100 h, 1 A cm −2 for 100 h, and 2 A cm −2 for 160 h), indicating a robust performance for alkaline water splitting.