Direct design of cage-like bimetallic NiFe hydroxides with regulated electron structure to boost the kinetic activity of oxygen evolution reaction

Abstract

The key to inhibiting agglomeration of bimetallic nanocatalysts and increasing their efficiency of oxygen evolution reaction (OER) highlights the necessity to design hollow porous structures in water electrolysis. Herein, the well-regulated NiFe bimetallic nanocages have been directly synthesized through the coordinated etching and precipitation (CEP) route, and then employed as advanced electrode materials in OER. Density functional theory (DFT) calculations disclosed that the synergistic effect between Fe and Ni significantly regulated the electron density and enhanced the conductivity. Significantly, the high catalytic activity of NiFe nanocages arises from the strong interactions between Fe and Ni along with rapid electron transfer, and the favorable structure with abundant porosity and large surface area. When employed as OER electrocatalysts, the electrode based on Ni2Fe1 nanocages exhibited a low overpotential of 280 mV at 10 mA·cm−2 combined with a low Tafel slop of 55.3 mV·dec−1 and large Cdl (double layers capacitance) value of 2.33 mF·cm−2. In summary, it is promising to directly design hollow porous structures based on bimetallic hydroxide to boost the OER performance.