A review on photocatalytic materials: synthesis strategies, morphology, and mechanisms

Photocatalysis is a promising approach for solar energy conversion and environmental remediation. Despite extensive research, advances in photocatalytic materials remain limited. Many reported performance improvements rely on empirical optimization rather than a clear mechanistic understanding. Existing reviews mainly focus on material classification and performance. However, they rarely examine how synthesis strategies control structure, defects, and charge-transfer behavior in a reproducible manner. This concept-driven critical review addresses these limitations by examining how synthesis methods influence structural evolution and charge carrier dynamics in photocatalytic materials. Rather than summarizing material types and applications, the review focuses on the role of crystallinity, defect chemistry, morphology, and interfacial properties in determining photocatalytic performance. Advanced architectures, including hierarchical structures and Z- & S-scheme heterojunctions, are assessed to understand the actual origin of their enhanced photocatalytic performance. In addition, the review highlights important issues related to mechanistic validation and inconsistent performance reporting that are often overlooked in conventional reviews. This review integrates synthesis strategies, charge-transfer mechanisms, and performance evaluation approaches to provide practical strategies for designing efficient, stable, and scalable photocatalytic materials for environmental and energy-related applications.