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 electricity 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 Co 3 S 4 electrode can be significantly improved by integration with CeO 2 . Specifically, as-prepared 5% Ce-Co 3 S 4 and 1% Ce-Co 3 S 4 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 CeO 2 originated from its unique surface with abundant oxygen vacancies, which were beneficial for the stabilization of Co 2+ 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. Co 3 S 4 -CeO 2 hybrid quasi-nanosheets (Ce-Co 3 S 4 ) with outstanding water-splitting performance are fabricated. CeO 2 plays the crucial role by its unique surface with abundant oxygen vacancies, which are of great benefit to the stabilization of active Co 2+ sites in OER, as well as the adsorption and dissociation of water in HER .