(A) study on Nickel/Tungsten carbide composite catalysts for oxygen evolution reaction in alkaline water electrolysis

Abstract

Hydrogen, produced by water electrolysis, is one of the most promising systems which is to store electricity coming from renewables and to solve its intermittency. Due to the increase of global electricity generation from renewable energy sources, large-scale storage systems are required. Alkaline electrolysis is suitable for the large-scale energy storage system. However, high overpotential and slow kinetics, particularly in the oxygen evolution reaction (OER), still limit the efficiency of the system. To enhance the efficiency of alkaline electrolysis cell, catalysts with high electrocatalytic activity for OER should be developed. One promising method to enhance the catalytic activity of a catalyst is to make bimetallic interface composed of a host material and metal layer. Here, we synthesized nickel/tungsten carbide (Ni/WC) composite with large bimetallic interface area to increase the OER catalytic activity. Tungsten carbide was used as a support, and nickel was chosen for a surface metal layer. The Ni/WC composite showed drastic increase of electrocatalytic activity relatively to Ni nanoparticles and WC. Its OER activity was recorded with overpotential of 330 mV in 1 M KOH at 10 mA/cm2, which is lower than that of Ir/C (η @ 10 mA/cm2: 341 mV). In addition, the Ni/WC composite also exhibited excellent stability in alkaline electrolyte compared with Ir/C. The outstanding performance of the Ni/WC composite as an OER catalyst could be attributed to the chemical nature change of the surface due to the formation of bimetallic interface, and various techniques were employed to probe the surface modifications. A surface modification by introducing bimetallic interface can be suggested to develop a high performance electrocatalyst for oxygen evolution.