Sulfur Vacancy Engineering in Photocatalysts for CO2 Reduction: Mechanistic Insights and Material Design

Against the backdrop of increasing global warming, exploring sustainable pathways to mitigate the greenhouse effect has become a central issue for the ecological and energy future. Photocatalytic reduction of CO2 technology shows a broad application prospect due to its ability to directly convert CO2 into high-value-added hydrocarbon fuels and to use solar energy, a clean energy source, to drive the reaction. However, traditional semiconductor catalysts generally suffer from insufficient activity and poor product selectivity in the actual reaction, which cannot meet the requirements of practical applications. In recent years, sulfur vacancy, as an effective material modulation strategy, has demonstrated a remarkable role in enhancing photocatalytic performance. This paper reviews a series of research reports on sulfur vacancies in recent years, introduces the methods of preparing sulfur vacancies, and summarizes the commonly used characterization methods of sulfur vacancies. Finally, the mechanism of introducing sulfur vacancies to promote CO2 reduction is discussed, which improves the photocatalytic activity and selectivity by enhancing light absorption, facilitating carrier separation, improving CO2 adsorption and activation, and promoting the stability of reaction intermediates. This review aims to provide theoretical support for an in-depth understanding of the role of sulfur vacancies in photocatalytic systems and to provide a view on the future direction and potential challenges of sulfur vacancies.