Exploring the Formation of CoO/ZnO Heterostructure to Enhance Electrocatalytic Oxygen Evolution Reaction

Abstract Revealing the electrocatalytic microstructure is the basis for finding more efficient and stable electrode materials for clean energy conversion devices. However, there is still a lack of direct understanding of the phase transition process of the sample during heating, which makes the synthesis conditions of the catalyst often rely on experienced guidance. Herein, ZIF‐8@α‐Co(OH)₂ core‐shell structure and uniformly coated α‐Co(OH)₂ nanosheets on the surface of ZIF‐8 are synthesized. The effect of temperature on microstructure evolution is studied by in situ heating technique with high‐resolution transmission electron microscopy. Based on understanding the relationship between temperature, microstructure, and OER properties, a simple annealing synthesis strategy is designed effectively. During the annealing process, ZnO@CoO heterogeneous structure is formed at 400 °C, and the material reached a stable hydroxyl oxide structure after electrochemical cycle voltammetry in an alkaline solution. The OER performance test shows that the commercial IrO₂ catalyst has comparable catalytic performance.