In Situ Exsolution of Ba3(VO4)2 Nanoparticles on a V-Doped BaCoO3−δ Perovskite Oxide with Enhanced Activity for Electrocatalytic Hydrogen Evolution

The successful preparation of a perovskite-based heterostructure is important for broadening the applications of perovskites in the field of electrocatalysis, especially in a hydrogen evolution reaction (HER). Nevertheless, the limited active sites of perovskites severely hindered the HER properties. Herein, an in situ exsolution method was used to construct a nanocomposite based on V-doped BaCoO3-δ decorated with Ba3(VO4)2 (BVCO19) for alkaline HER. The exsolved Ba3(VO4)2 can induce more Co4+ ions on BaCoO3-δ, which serves as active sites for the release of H2. Meanwhile, by regulating the valency of V and Co species, the catalyst can reach a charge balance by generating more oxygen vacancies, which greatly facilitates the adsorption and dissociation of H2O molecules. The synergistic effect between the oxygen vacancies and high-valence Co4+ leads to an enhanced HER performance of BVCO19. The as-obtained catalyst delivers a low overpotential of 194 mV at 10 mA cm-2 as well as impressive stability for 100 h in alkaline media, which outperforms pristine BaCoO3-δ and most of the nonprecious-based perovskite oxides. This work provides new insights into the preparation of perovskite-based heterostructure for boosting HER.