Titania polymorph and composition correlated photocatalytic formaldehyde degradation activity

Titanium dioxide (TiO₂) has garnered extensive research attention due to its broad applicability in the degradation of volatile organic compounds (VOCs). The polymorph and composition of TiO₂ significantly influence its photocatalytic activity. In this study, the crystal phase transition from TiO₂(B) to TiO₂(A) and TiO₂(R) was achieved by adjusting the annealing temperature, and the influence of these structures on its photocatalytic activity was systematically investigated. Interestingly, the photocatalytic activity order of single-phase catalysts followed the sequence of TiO₂(A)> TiO₂(R) > TiO₂(B), and a hump-shaped activity trend was observed, with two activity peaks corresponding to the diphase combinations of TiO₂(B)/TiO₂(A) and TiO₂(A)/TiO₂(R), respectively. Specifically, the TiO₂(A)/TiO₂(R) photocatalyst exhibited the highest formaldehyde degradation efficiency (100 %) within 45 min, with the mineralization ratio of 70.63 %. The enhanced activity predominantly was attributed to the existence of heterophase junctions, leading to the boosted the separation efficiency of charge carriers photoinduced. More interestingly, the crystal phase variations resulted in the selective generation of reactive oxygen species. This study provides insights for the development of photocatalysts with diverse polymorphs for improved activities and presents substantial potential to the improved efficiency in the decomposition of VOCs.