Hierarchical FeCo2S4@CoFe layered double hydroxide on Ni foam as bifunctional electrocatalyst for overall water splitting
Designing high efficiency and low cost bifunctional electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great significance to produce hydrogen by water electrolysis. Herein, hierarchical FeCo2S4@CoFe layered double hydroxide (LDH) core-shell structure catalyst was successfully fabricated via hydrothermal – sulfuration – electrodeposition three-step method. The unique structure can provide more abundant catalytic activity sites for electrochemical reaction. The resulting FeCo2S4@CoFe LDH electrode only requires overpotentials of 118 and 247 mV to reach the current density of 10 mA cm-2 for HER and OER in 1M KOH electrolyte, respectively. The electrode also delivers low tafel slope and excellent stability. Furthermore, the bifunctional catalyst for overall water splitting can exhibit a cell voltage of 1.6 V at 10 mA cm-2, along with outstanding durability for 24 h testing. This work provides a new strategy to design effective bifunctional catalysts for overall water splitting.