Integrating ceria with cobalt sulfide as high-performance electrocatalysts for overall water splitting

The development of bifunctional electrocatalysts for overall water splitting is highly desired for converting elec-tricity into chemical energy. However, the synthesis of high-performance bifunctional electrocatalysts remains a pressing challenge. Here, we found that both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) performance of the Co3S4 electrode can be significantly improved by integration with CeO2. Specifically, as-prepared 5% Ce-Co3S4 and 1% Ce-Co3S4 delivered low overpotentials of 290 and 257 mV to achieve 10 mA cm-2 for the OER and HER in 1.0 M KOH, respectively. The crucial role of CeO2 originated from its unique surface with abundant oxygen vacancies, which were beneficial for the stabilization of Co2+ sites with high OER activity and both the adsorption and dissociation of water molecules in the HER process. This work is expected to provide a general approach to prepare a wide range of high-performance electrode materials for energy-related applications.