Exploring the Role of Multi-Catalytic Sites in an Amorphous Co-W-B Electrocatalyst for Hydrogen and Oxygen Evolution Reactions

Abstract

Amorphous materials are used in multitude of catalytic applications, including electrocatalytic water-splitting. Identification and investigation of active sites in amorphous catalysts are rarely reported, mainly owing to the complexity of the systems. Herein, we report an amorphous bifunctional Co-W-B electrocatalyst for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). The optimized Co-W-B catalyst showed promising overpotential values of 97 mV (HER) and 292 mV (OER), respectively, to achieve 10 mA cm-2 in 1 M KOH, with good stability. The promoting effect of W in Co-B was investigated experimentally, while computational tools were used to identify all the possible catalytic sites in an amorphous Co-W-B model and classify the most preferred sites for HER and OER. The presence of multi-catalytic sites with specific selectivity toward HER and OER was observed, which explained the bifunctional activity of Co-W-B. This study will foster better understanding of the origin of catalytic activity in similar amorphous systems.