Efficient perovskite oxide@CdS composite catalysts for hydrogen production from oilfield wastewater electrolysis

Perovskite oxides are considered promising efficient and cost-effective water splitting electrocatalysts under alkaline conditions because of their excellent hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) activity. However, due to their poor electron transfer and lack of exposed active sites, their HER activity is still much lower than that of precious metal catalysts. Besides, to date, few studies have been reported on the HER in complex water systems. In this study, a new composite electrocatalyst, SrCo0.7Fe0.3O3−δ@CdS, with a core–shell structure (denoted as SCF@CdS) was successfully prepared using an in situ coprecipitation method, which exhibited efficient HER activity in an alkaline environment and oilfield wastewater. The better electrocatalytic performance of SCF@CdS than pure SCF can be attributed to the larger specific surface area and more exposed active sites in this core–shell structure, and the lone pair electrons from S in CdS can also form coordination bonds with the vacant orbital of Co in the perovskite by sharing electron pairs, thus increasing the concentration of oxygen vacancies. This study provides a strategy to improve the HER performance of perovskite catalysts in complex water systems via the construction of a core–shell structure.