Polyaniline π-electron mediated electron-hole separation of TiO2/diatomite composite for enhancing visible light-induced indoor formaldehyde degradation

Abstract

A novel ternary polyaniline (PANI)-TiO2/diatomite (PANI-TDE) composite with 3D nanostructure was synthesized via a simple self-assembling process and an in-situ polymerization approach. The resulting composite exhibited efficient performance in gaseous formaldehyde removal and antibacterial process (Staphylococcus aureus) under visible light. By tracking the variation of CO2 concentration during the photocatalytic process, the apparent rate constant of mineralized gaseous formaldehyde of 5%PANI-TDE was up to about 84.26 times, 48.49 times and 3.51 times higher than those of TiO2, TiO2/diatomite composite and PANI-TiO2 composite, respectively. Under the simulated indoor actual environment, the HCHO removal rate of the prepared 5%PANI-TDE composite could reach 82.69 % in 12 h. The designed ternary heterogeneous structure with intimate interface contacts among PANI, TiO2 and diatomite successfully constructed a high-efficient adsorption-photocatalysis collaborative system, and a large delocalized π-electron conjugation system was established due to the construction of organic–inorganic system, which significantly enhanced migration/separation efficiency of the photo-generated carriers. Notably, the reaction pathways with the reaction intermediates were tracked via in-situ DRIFTs.