Phase Evolution on the Hydrogen Adsorption Kinetics of NiFe-Based Heterogeneous Catalysts for Efficient Water Electrolysis.

Transition metal layered double hydroxides, especially nickel-iron layered double hydroxide (NiFe-LDH) shows significant advancement as efficient oxygen evolution reaction (OER) electrocatalyst but also plays a momentous role as a precursor for NiFe-based hydrogen evolution reaction (HER) catalysts. Herein, a simple strategy for developing Ni-Fe-derivative electrocatalysts via phase evolution of NiFe-LDH under controllable annealing temperatures in an argon atmosphere is reported. The optimized catalyst annealed at 340 o C (denoted NiO/FeNi 3 ) exhibits superior HER properties with an ultralow overpotential of 16 mV@10 mA cm -2 . Density functional theory simulation and in situ Raman analyses reveal that the excellent HER properties of the NiO/FeNi 3 can be attributed to the strong electronic interaction at the interface of the metallic FeNi 3 and semiconducting NiO, which optimizes the H 2 O and H adsorption energies for efficient HER and OER catalytic processes. This work will provide rational insights into the subsequent development of related HER electrocatalysts and other corresponding compounds via LDH-based precursors.