Glycerol-Assisted Sol-Gel Synthesis of Nitrogen-Doped Titanium Dioxide for Visible Light-Driven Photodegradation of Indoor Gaseous Formaldehyde

Abstract

In the present paper, the synthesis of nitrogen-doped titanium dioxide (N-doped TiO2) photocatalyst and its application for photodegradation of gaseous formaldehyde are reported. The N-doped TiO2 was synthesized via the glycerol-assisted sol-gel technique. The efect of various synthesis parameters such as nitrogen to titanium (N:Ti) molar ratio, calcination temperature, calcination duration and TiO2 loading was investigated on the photocatalytic properties of TiO2 and photodegradation of HCHO vapor. The characterization results obtained through diferent analytical techniques such as XRD, XPS, FESEM, DRUV-Vis, and BET revealed that all the N-doped TiO2 photocatalysts were anatase phase with enhanced visible light absorption, narrow bandgap (2.64–2.50 eV), and small particle sizes ranging from 23.12–25.17 nm. The surface area decreased from 252.7 m2 /g to 72.3 m2 /g with an increased N:Ti molar ratio. The N:Ti molar ratio plays an important role in the formation of crystalline structure and surface area and performance. The photodegradation of HCHO vapor was the highest (70.59%) when the N:Ti molar ratio was 20:1. The best photodegradation efciency was achieved using the N-doped TiO2 calcined at 300°C for 1 h. This study signifes the importance of optimizing N:Ti molar ratio and calcination temperature for tuning the properties of the TiO2 and the enhancing photodegradation of indoor HCHO vapor under visible light irradiation.