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.