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 TiO 2 and WO 3 ) that can be activated by wide-range light including an indoor light-emitting diode (LED) under ambient conditions. Chemically reduced Blue TiO 2 improves visible light absorption of white TiO 2 by regulating the electronic structure with self-doping of Ti 3+ . The heterojunction between Blue TiO 2 and WO 3 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. WO 3 sufficiently adapts to the photooxidative degradation of air pollutants by • OH, while Blue TiO 2 leads to the effective generation of • O 2 –, leading to the complete decomposition of gaseous acetaldehyde (CH 3 CHO) to CO 2 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.