Design of FeWO4@N-TiO2 nanocomposite and its enhanced photocatalytic activity in decomposing methylene blue and phenol under visible light

Abstract

Effluents from textile industries contain high levels of methylene blue (MB) and phenol from other industries, which are serious health hazard and a threat to biodiversity as well as the environment. Nitrogen (N) doped TiO2 modified by iron tungstate (FeWO4) composite photocatalyst (FeWO4 @N-TiO2) working under visible light (λ ≥ 420 nm) could be a suitable candidate to degrade this pollutant. X-ray diffractometry (XRD) and X-ray Photoelectron Spectroscopy (XPS) study suggested that the N was introduced as substitutional doping into TiO2 lattice which leads to narrowing band gap of TiO2 nanoparticles. The prepared FeWO4 @N-TiO2 was utilized to measure efficiency in decomposing the methylene blue (MB) and phenol in aqueous phase under visible light (λ ≥ 420 nm) irradiation. The FeWO4 @N-TiO2 showed better catalytic efficiency to degrade MB and phenol in several compositions of FeWO4. The composite demonstrated 77% and 85% removal of MB and phenol from aqueous medium after 2 h of visible light illumination, respectively. Interestingly, radical-hole hunting identifying tests indicated the presence of hydroxyl radical (°OH) in the photocatalytic decomposition reaction medium. The higher efficiency of FeWO4 @N-TiO2 was originated from absorption of visible energy as well as the relative energy band positions of the components FeWO4 and N-TiO2. Thus, photoexcited electron (e‾) and hole (h+) could take part by inter-particle transfer through the formation of °OH radical which was experimentally confirmed and a photocatalytic reaction mechanism has been proposed to mineralize organics.