Lattice Oxygen Redox Dynamics in Zeolite-Encapsulated CsPbBr₃ Perovskite OER Electrocatalysts

Understanding the oxygen evolution reaction (OER) mechanism is pivotal for improving the overall efficiency of water electrolysis. Despite methylammonium lead halide perovskites (MAPbX₃) have shown promising OER performance due to their soft-lattice nature that allows lattice-oxygen oxidation of active α-PbO₂ layer surface, the role of A-site MA or X-site elements in the electrochemical reconstruction and OER mechanisms has yet to be explored. Here, it is demonstrated that the OER mechanism of perovskite@zeolite composites is intrinsically dominated by the A-site group of lead-halide perovskites, while the type of X-site halogen is crucial for the reconstruction kinetics of the composites. Using CsPbBr_xI_{3- x}@AlPO-5 (x = 0, 1, 2, 3) as a model OER catalyst, it is found that the CsPbBr₃@AlPO-5 behaves oxygen-intercalation pseudocapacitance during surface restructuring due to absence of halogen-ion migration and phase separation in the CsPbBr₃, achieving a larger diffusion rate of OH^- within the core-shell structure. Moreover, distinct from the single-metal-site mechanism of MAPbBr₃@AlPO-5, experimental and theoretical investigations reveal that the soft lattice nature of CsPbBr₃ triggers the oxygen-vacancy-site mechanism via the CsPbBr₃/α-PbO₂ interface, resulting in excellent OER performance. Owing to the variety and easy tailoring of lead-halide perovskite compositions, these findings pave a way for the development of novel perovskite@zeolite type catalysts for efficient oxygen electrocatalysis.