Incorporation of Fe~(3+) ions into the W~(6+) and N~(3-) doped TiO_2: Exploration of crucial role of Fe~(3+) dopant ion and correlation of adsorption characteristics with reaction dynamics

摘要

The incorporation of W6+, N3- and Fe3+ ions into the anatase TiO2 lattice was attempted through simple sol-gel method. The optimum concentration of W6+ and N3- ions were detected and maintained constant. The concentration of Fe3+ ion was varied and the prepared photocatalysts were abbreviated as WNFexT, where x = 0.03, 0.06 and 0.09 atom. These catalysts were characterised by PXRD, BET, XPS, UV-DRS, SEM, FTIR and ICP-MS techniques. The transient photocurrent measurement of the prepared catalysts gives an insight to the time dependent extraction of charges generated by photovoltaic effect. XPS analysis revealed the elemental binding energy states of Ti, O, W, N and Fe ions in the sample. The presence of W6+ and Fe3+ dopant ions in the TiO2 lattice facilitates the incorporation of N3- ions at substitutional lattice sites. The band gap of WNFexT samples decrease with increase in the Fe content. WNFexT samples show good photocatalytic activity for the degradation of bisphenol-A (BPA) under the illumination of solar light. The photocatalytic efficiency of WNFe0.06T catalyst was found to be higher implying the importance of crucial dopant concentration. The adsorption characteristics of each catalyst were studied by fitting the obtained data to the Langmuir, Freundlich, Redlich-Peterson (R-P) and Koble-Corrigan (K-C) isotherms and the results were correlated to the dynamics of reaction kinetics.