Radical-Mediated\nPhotocatalysis for Efficient Indoor\nAir Purification: A Case Study of Self-Wetting BaTiO<sub>3</sub> Co-Modified\nwith Cu(II) Clusters and Periodate

Efficient generation of reactive oxygen radicals is key\nto improving\nthe activity of photocatalytic degradation for indoor volatile organic\ncompounds (VOCs). In this study, BaTiO<sub>3</sub> (BTO) nanoparticles\nco-modified by Cu(II) and periodic acid (PA) were synthesized by a\nsimple impregnation method to construct a visible-light-driven multiple-radicals\nphotocatalytic system for indoor VOC elimination. The results show\nthat PA interacts with BTO as well as the surface-grafted Cu(II) clusters\nto produce the BTO–Cu–O–I–(OH)<sub><i>n</i></sub> complex, improving visible light absorption efficiency\nand photogenerated charge lifetime. Furthermore, PA, with its hygroscopic\nproperties, facilitates the formation of a water film on the surface,\nwhich contributes to the dissolution and accumulation of gaseous pollutants.\nRemarkably, hydroxyl radicals (•OH) and superoxide anion radicals\n(•O<sub>2</sub><sup>–</sup>) are rapidly generated via\nCu(II)/Cu(I) redox reactions with the help of hydrophilic PA. As expected,\nour optimized samples exhibit 26.3 times higher photocatalytic decomposition\nactivity of gaseous isopropyl alcohol into CO<sub>2</sub> compared\nto pristine barium titanate.