Molecular-Linked Z-Scheme Heterojunction of Ti3+-Doped TiO2 and WO3 Nanoparticles for Photocatalytic Removal of Acetaldehyde

Photocatalytic removal of indoor organic air pollutants is effective, but there are practical limits to catalytic activation by indoor conditions. Here, we report a molecular-linked heterojunction of semiconducting metal oxide nanoparticles (e.g., Blue TiO2 and WO3) that can be activated by wide-range light including an indoor light-emitting diode (LED) under ambient conditions. Chemically reduced Blue TiO2 improves visible light absorption of white TiO2 by regulating the electronic structure with self-doping of Ti3+. The heterojunction between Blue TiO2 and WO3 is formed via a molecular linker, and a hybridized electronic structure of a molecular-linked Z-scheme alignment is generated without changes in chemical characteristics, increasing utilization of indoor light and effectively improving electron–hole separation. WO3 sufficiently adapts to the photooxidative degradation of air pollutants by •OH, while Blue TiO2 leads to the effective generation of •O2–, leading to the complete decomposition of gaseous acetaldehyde (CH3CHO) to CO2 and CO without remaining organic byproducts (e.g., formaldehyde). As a robust interfacial contact, molecular-linked heterojunctions provide efficient charge separation and highly stable performance and enhance solution-processable homogeneous coatings of metal oxide photocatalysts on real surfaces.