Radical-Mediated Photocatalysis for Efficient Indoor Air Purification: A Case Study of Self-Wetting BaTiO₃ Co-Modified with Cu(II) Clusters and Periodate

Efficient generation of reactive oxygen radicals is key to improving the activity of photocatalytic degradation for indoor volatile organic compounds (VOCs). In this study, BaTiO3 (BTO) nanoparticles co-modified by Cu(II) and periodic acid (PA) were synthesized by a simple impregnation method to construct a visible-light-driven multiple-radicals photocatalytic system for indoor VOC elimination. The results show that PA interacts with BTO as well as the surface-grafted Cu(II) clusters to produce the BTO–Cu–O–I–(OH)n complex, improving visible light absorption efficiency and photogenerated charge lifetime. Furthermore, PA, with its hygroscopic properties, facilitates the formation of a water film on the surface, which contributes to the dissolution and accumulation of gaseous pollutants. Remarkably, hydroxyl radicals (•OH) and superoxide anion radicals (•O2–) are rapidly generated via Cu(II)/Cu(I) redox reactions with the help of hydrophilic PA. As expected, our optimized samples exhibit 26.3 times higher photocatalytic decomposition activity of gaseous isopropyl alcohol into CO2 compared to pristine barium titanate.