Photocatalytic strategies for combating harmful algal blooms: synergistic approaches to multifactorial challenges

Harmful algal blooms constitute a critical global environmental challenge for aquatic ecosystems, driven by complex synergistic interactions of eutrophication, climate change, and hydrodynamic conditions that severely threaten public health, ecological integrity, and fisheries economies. This review highlights photocatalysis as a sustainable alternative that overcomes the limitations of traditional methods in terms of energy consumption and secondary pollution. It provides an in-depth evaluation of the evolution of photocatalytic technology as a sustainable solution, tracing its development from recyclable floating catalysts to functionally designed materials. We emphasize how metal–organic frameworks and perovskite oxides enable electronic and structural control, thereby enhancing visible-light activity and charge separation efficiency. We also explore the transition from material design to system-level integration, exemplified by photoelectrocatalytic systems, where spatial separation of redox reactions significantly improves efficiency and stability. Finally, we analyze the key challenges in material durability, ecological safety, and engineering and economic barriers to system scaling for practical applications. We construct a “lab-to-field” governance framework to provide forward-looking strategies for the practical translation and scaling of photocatalytic technologies.