Challenges and performance optimization strategies of carbon-based transition metal single-atom catalysts derived from ZIF-8 for oxygen reduction reaction: Active site regulation, 3D structural engineering, and interfacial function design

The intensifying rising energy demands and environmental degradation have driven the advancement of sustainable energy solutions. Technologies such as fuel cells and metal-air batteries have garnered widespread interest for their superior efficiency and eco-friendliness. However, the inherently slow kinetics of the oxygen reduction reaction (ORR) at the cathode, along with dependence on noble metal catalysts, significantly impede their large-scale deployment, underscoring the urgent demand for cost-effective alternatives. Recently, transition metal-based single-atom catalysts (M-SACs), particularly those derived from metal-organic frameworks (MOFs), have emerged as promising candidates due to their maximal atom utilization, adjustable electronic structure, and economical synthesis. Among them, zeolitic imidazolate framework-8 (ZIF-8) derived SACs offer outstanding potential owing to their high surface area, ordered porous structure, and abundant nitrogen coordination sites. This review systematically summarizes recent advances in ZIF-8-derived M-SACs for ORR, with a focus on the key challenges and critical performance optimization strategies, including active site regulation, stabilization of high-density single atoms, construction of synergistic catalytic systems, and three-dimensional (3D) structural/functional design. In addition, this work discusses critical bottlenecks in structural characterization, performance benchmarking, and engineering scalability. It emphasizes the necessity of multi-technique cross-validation for accurate active site identification, standardized evaluation protocols for reliable data comparison, and robust synthesis strategies for scalable production. These insights provide theoretical guidance and practical strategies for the rational design and real-world application of high-performance ORR electrocatalysts based on ZIF-8 precursors.