Hierarchical Cu@CoFe layered double hydroxide core-shell nanoarchitectures as bifunctional electrocatalysts for efficient overall water splitting

Efficient and low-cost bifunctional catalysts toward both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) for overall water splitting are of great significance to energy and environmental sustainability. Here, we report on a novel hierarchical Cu@CoFe layered double hydroxide (LDH) core-shell nanostructure catalyst for efficient overall water splitting in the alkaline medium. Benefiting from the smart structure, the optimized composite affords small overpotentials of 171 mV for the HER and 240 mV for the OER at a current density of 10 mA cm(-2), along with Tafel slopes of 36.4 and 44.4 mV dec(-1) for the HER and OER, respectively. Strikingly, the overall water splitting performance is very good since it just requires a voltage of 1.681 V to gain a current density of 10 mA cm(-2), which is only 60 mV larger than the benchmark of IrO2 (+)/Pt (-) electrodes. Moreover, the optimized composite electrodes exhibit outstanding durability within 48 h testing, which is much better than that of the benchmark. Our rational design of the hierarchical core-shell nanoarchitectures presents a simple approach to fabricate advanced catalysts for water splitting.