Transforming bad electrocatalysts into good ones: Dual functional hot H2S treatment

Abstract

Nanostructuring is an essential step in synthesizing highly active electrocatalysts. Unfortunately, it has not been widely adopted in the electrodes of commercial electrolyzers because of difficulties associated with scalability and process complexity. As a remedy to this long-standing problem, we demonstrate a facile thermal route to transform poor oxide electrocatalysts into highly active ones by utilizing hot H2S gas as a dual functional agent. Using bulk cobalt oxide as a model system, we reveal that H2S that would otherwise be stable up to 1000 ◦C can be catalytically decomposed on the surface of Co3O4 into H2 and sulfur species at a moderately high temperature. The produced H2 and sulfur react with Co3O4 and transform it into nanostructured Co3O4/CoO@CoSx particles that are highly active towards the oxygen evolution reaction. The optimum sample can be produced after only 10 min of H2S treatment, highlighting the simplicity and scalability of our process.