In SituLocal Phase-Transitioned MoSe2in Perovskite Oxide Heterostructure and Excellent Overall Water Electrolysis

Abstract

Developing efficient bifunctional catalysts for overall water splitting that are earth-abundant, cost-effective, and durable is of considerable importance from the practical perspective to mitigate the issues associated with precious metal-based catalysts. In the present study, we introduce a heterostructure comprising perovskite oxides (La0.5Sr0.5CoO3–δ (LSC)) and transition metal dichalcogenides (TMDs, MoSe2) as an electrochemical catalyst for overall water electrolysis. Interestingly, formation of the heterostructure of LSC and MoSe2 (LSC&MoSe2) induces a local phase transition in MoSe2, 2H to 1T phase, owing to electron transfer from Co to Mo, and the semiconducting MoSe2 transforms to the metallic phase. In addition, LSC becomes more electrophilic, and Co-O and Co-OH bonds are favored owing to partial oxidation of the Co cation due to the electron transfer. Together with the electrochemically active nature of 1T MoSe2 and the increased amount of Co-O and Co-OH bonds in LSC, the electrochemical activities are significantly improved for both hydrogen evolution reaction and oxygen evolution reaction. In the overall water splitting operation, LSC&MoSe2 showed excellent stability at the high current density of 100 mA cm−2 over 1,000 h, which is exceptionally better than the stability of the state-of-the-art Pt/C || IrO2 couple.