In-situ local phase-transitioned MoSe in LaSrCoO heterostructure and stable overall water electrolysis over 1000 hours.

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. Herein, we introduce a heterostructure comprising perovskite oxides (LaSrCoO) and molybdenum diselenide (MoSe) as an electrochemical catalyst for overall water electrolysis. Interestingly, formation of the heterostructure of LaSrCoO and MoSe induces a local phase transition in MoSe, 2 H to 1 T phase, and more electrophilic LaSrCoO with partial oxidation of the Co cation owing to electron transfer from Co to Mo. Together with these synergistic effects, the electrochemical activities are significantly improved for both hydrogen and oxygen evolution reactions. In the overall water splitting operation, the heterostructure showed excellent stability at the high current density of 100 mA cm over 1,000 h, which is exceptionally better than the stability of the state-of-the-art platinum and iridium oxide couple.