Multi-electron collaborative photo-Fenton-like system for indoor air purification: A case study of Cu(II) grafted BaTiO3 with oxygen vacancies

Indoor air purification belongs to one of the most important and traditional applications of photocatalysis, which brings forward an impending need for more efficient photocatalytic systems. Herein, we initiated a multi-electron collaborative photo Fenton-like system for mineralization of indoor volatile organic compounds by jointly modified with oxygen vacancies and Cu(II) clusters on barium titanate. Oxygen vacancies effectively increase the visible light absorption and photoinduced charge separation efficiency. Benefiting from the energy level match with oxygen vacancies and Cu(II) species, the trapped electrons in the oxygen vacancies can effectively migrate towards Cu(II) clusters. More importantly, the Cu species that have received electrons can trigger the multi-electron reduction of oxygen to in-situ form H2O2 through the redox of Cu(II)/Cu(I). In parallel, the reactive center dot OH radicals can be effectively produced by the photo-like Fenton reaction. Thus, the newly developed barium titanate based photocatalysts exhibit over 38-fold improvement in the removal efficiency of volatile organic compounds (in terms of CO2 evolution rate) by virtue of the strong oxidizing power of holes in the valance band and multi-electron photoFenton-like reaction to generate center dot OH radicals. Notably, the absorbed H2O molecules play an indispensable role in the formation process of in-situ H2O2. Thus, even under high-humidity condition, our photocatalysts present stable and high photocatalytic activity, which provides great potential for practical applications in indoor air purification.