Optical and structural properties of nanocrystalline anatase powders doped by Zr, Si and Cu at high temperature

In this study, preparation of 20 mol% Si, 15 mol% Zr and 5 mol% Cu doped \(\hbox {TiO}_{2}\) nanopowders via sol–gel process have been investigated. The effects of Si, Zr and Cu doping and calcinations temperature (500–1,000 \(^{\circ }\hbox {C}\)) on the structural, and photocatalytic properties of titania nanopowders studied by X-ray diffraction (XRD), scanning electron microscope (SEM-EDX), transmission electron microscope and UV–Vis absorption spectroscope. XRD patterns showed peak of the cristobalite phase at temperature 900 and 1,000 \(^{\circ }\hbox {C}\). Also, XRD results suggest that adding dopants has a significant effect on anatase phase stability, crystallinity, and particle size of \(\hbox {TiO}_{2}\). Titania rutile phase formation in system (Ti–Si–Zr–Cu) was inhibited by \(\hbox {Zr}^{+4}\) and \(\hbox {Si}^{+4}\) at temperature 500–700 \(^{\circ }\hbox {C}\) and promoted by \(\hbox {Cu}^{+2}\) doped \(\hbox {TiO}_{2}\) in high temperatures (800–1,000 \(^{\circ }\hbox {C}\)), so that 41 and 15 % anatase composition is retained even after calcination at 800, 900 \(^{\circ }\hbox {C}\) respectively. The photocatalytic activity was evaluated by photocatalytic degradation kinetics of aqueous methyl orange (MO) under visible radiation. The degradation efficiency of MO reaches 85 % of the doped samples after 40 min of visible light irradiation at temperature \(700\,^{\circ }\hbox {C}\).