Ru induced oxygen vacancies activate lattice oxygen mechanism in CoFe-LDH for overall water splitting

Developing bifunctional electrocatalysts with high activity and long term durability remains challenging for overall water splitting, mainly due to sluggish reaction kinetics and structural instability under high current densities. Herein, an oxygen vacancy rich RuCoFe-LDH electrocatalyst with low Ru content was successfully fabricated on nickel foam through a one step hydrothermal method. TMAOH inhibition, pH dependent analyses, and isotope labeling DEMS measurements collectively reveal that the synergistic coupling between Ru doping and oxygen vacancies promotes lattice oxygen participation and activates the LOM pathway during OER. Benefiting from the optimized electronic structure, RuCoFe-LDH/NF requires overpotentials of only 212 and 131 mV to reach 10 mA cm −2 for OER and HER, respectively, with corresponding Tafel slopes of 30.7 and 61.7 mV dec −1 . Moreover, the RuCoFe-LDH based electrolyzer achieves 100 mA cm −2 at a cell voltage of only 1.75 V and maintains stable operation for 1000 h during both OER and HER, and the corresponding full electrolyzer also operates stably for 1000 h at 100 mA cm −2 . This work provides an effective strategy for designing high performance LDH based bifunctional electrocatalysts through low content Ru incorporation and oxygen vacancy engineering.