Nanostructured TiO2 co-modified with silver and bismuth for formaldehyde degradation under visible light

This study investigated the effect of Ag-Bi co-modified nanostructured TiO2 on photodegradation of gaseous formaldehyde (HCHO). The Ag/Bi-TiO2 materials were synthesized using the hydrothermal method with various concentrations of Ag (0–2 %). The synthesized materials were characterized using XRD, SEM, TEM, EDS, PL, UV-Vis, XPS, and ESR. Their performance under visible-light irradiation was found to be significantly influenced by the amount of Ag doping, the calcination temperature and the air contact area. The results demonstrated higher Ag doping greatly enhanced the degradation of HCHO. The photocatalytic degradation efficiency of HCHO over 2%Ag/Bi-TiO2 reached 87.5 %, which was significantly higher compared to Bi-TiO2 (74.0 %) and TiO2 (65.6 %), and the concentration of HCHO decreased from 1.069 to 0.134 mg/m3 within 48 h. The heterostructure of Ag2O/Ag and Bi-TiO2 facilitated effective electron transfer and suppressed the recombination of electron-hole pairs. The enhanced adsorption of visible-light and the improved photocatalytic performance were attributed to the synergistic effect of surface hydroxyl and adsorbed oxygen.