Electronic structure regulation of nickel-iron layered double hydroxides by tuning ternary component for overall water splitting

NiFe layer double hydroxide (LDH) preserves high electrocatalytic activities for oxygen evolution reaction (OER); however, the catalytic performance on hydrogen evolution reaction (HER) is still suffering from poor catalytic activities. In this work, zinc (Zn)-doped NiFe LDH was synthesized as an excellent bifunctional electrocatalysts in alkaline electrolyte. For OER performance, the NiFeZn LDH achieves a Tafel slope of 35.2 mV/dec, which is much lower than that of commercial IrO2 catalysts (124.3 mV/dec). Expected, NiFeZn LDH also remains enhanced HER activity with an overpotential of 236 mV at 50 mA/cm2, superior to most of reported transition metal LDHs. The density functional theory results demonstrated that the Zn dopants could effectively manipulate the electronic structure of NiFeZn LDH, which is responsible to the enhanced active sites for HER.