Interfacial Hydrophilicity Engineering in Photocatalysts: From Surface Reconstruction to Functional Applications

Abstract Photocatalytic materials have shown great promise for controlling environmental pollution, especially in air and water treatment, due to their ability to drive redox reactions under mild conditions. Surface wettability, a key physical-chemical property of photocatalytic interfaces, directly affects the adsorption, diffusion, and transformation of reactant molecules. Traditional photocatalytic materials are often highly hydrophilic, which facilitates proton transfer and interface reactions in processes such as photocatalytic water splitting. However, in complex liquid-phase or high-humidity gas-phase systems, this can lead to competitive adsorption, where water molecules occupy active sites and reduce the capture and transformation efficiency of target pollutants, significantly limiting the material's practical performance. This review systematically discusses the basic concepts and control principles of surface wettability in photocatalytic materials. It explains how hydrophilicity and hydrophobicity influence photocatalytic reaction kinetics and interfacial charge transfer. Furthermore, it highlights the relationship between surface structure, chemical composition, and wettability. Recent advances in strategies for tuning wettability, including atomic doping, defect control, surface modification, and multiscale interface design, are also systematically summarized. The review also covers typical applications of these materials in pollutant degradation, oil-water separation, and selective regulation of interface reactions. Finally, this review examines the key challenges and future development trends in surface engineering to improve the stability, selectivity, and environmental adaptability of photocatalytic materials, offering design ideas and theoretical foundations for creating efficient photocatalytic systems with programmable interface properties.