Vacancy-interface coupling in nanomaterials for photocatalytic energy and environmental applications

Vacancy-interface coupling offers an attractive strategy for the rational design of nanomaterials for resolving global challenges in energy supply and environmental sustainability. Vacancies can tune local electronic states and redox positions, and interfaces can set up directional charge-transfer paths and stabilize reactive sites. This kind of interaction is conducive to various light-driven reactions, such as CO 2 reduction, biomass conversion, and pollutant degradation. The combination of synthetic methods, in situ characterization, and theoretical calculations is expected to enable the design of next-generation photocatalysts, further improve reaction systems, and promote their scalable application. Vacancy-interface coupling has emerged as a powerful strategy for boosting photocatalytic performance through the synergistic regulation of charge dynamics, interfacial structure, and surface pathways. Engineering vacancies at interfaces allow photogenerated carriers to be trapped, separated, and directed to reactive sites, enhancing activity and selectivity. This perspective highlights recent advances in vacancy-mediated interfacial engineering for solar-driven transformations through representative cases in plastics and biomass photoreforming, H 2 O 2 evolution, water splitting, and CO 2 reduction. Particular emphasis is placed on in situ spectroscopic evidence for the dynamic evolution of vacancies and their real-time interactions with reactive sites. By integrating experimental insights with theoretical modeling, we demonstrate how vacancy-interface coupling results in robust, tunable, and efficient photocatalysts. Finally, we outline key challenges and opportunities for developing robust and application-oriented systems that fully exploit defect-interface synergy for sustainable energy and environmental applications.