Progress on photocatalytic elimination of CO2 and gaseous pollutants over LDHs-based materials

The emission of nitrogen oxides (NO_x), volatile organic compounds (VOCs), and carbon dioxide (CO₂) is a significant contributor to air pollution and global warming, negatively affecting both the environment and human health. Photocatalysis has emerged as an effective technology for eliminating the aforementioned species from waste gases. Layered double hydroxides (LDHs) have attracted increasing attention for their potential as the photocatalysts in gaseous pollutant and CO₂ abatement reactions, relying on the advantages including earth abundance, easy fabrication, and low cost. This review provides a comprehensive summarization of recent progresses on the photocatalytic removal of NO_x, VOCs, and CO₂ using the LDHs-based materials. Simply put, the fundamentals of LDHs such as the crystal structures and the relevant synthesis methods were introduced at first. As activity and selectivity are recognized as the key properties for evaluating these catalysts, the advances in enhancing these properties were summarized and discussed in the subsequently sections. Furthermore, mechanisms of NO_x oxidation, VOCs degradation, and CO₂ reduction were also elucidated from a microscopic perspective. Finally, this review emphasizes the directions for improving the photocatalytic activity of the LDHs-based photocatalysts, along with the need to investigate the simultaneous removal of multi-pollutants and the catalysts’ gas component adaptability.