Enhanced photoinduced catalytic activity of transition metal ions incorporated TiO2 nanoparticles for degradation of organic dye: Absorption and photoluminescence spectroscopy

Abstract

Abstract Transition metal ions (Ag+, Cu2+, and Ni2+) doped and undoped TiO2 nanoparticles (NPs) were synthesized via cost effective sol-gel method with 1.0 wt% dopant concentration. The microstructure and chemical compositions of these NPs were examined using various techniques such as x-ray diffractometry, field emission scanning electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared and absorption and photoluminescence (PL) spectroscopy. The average size of the NPs is in the range of 10–20 nm and lattice spacing is 0.36 nm corresponding (101) plane. The absorption and photoluminescence (PL)-excitation spectra of metal-doped TiO2 NPs are shifted to the longer wavelength region, which indicates reduced bandgap than the bare TiO2 NPs. The absorption and PL spectra of methylene blue (MB) in the presence of undoped and metal ions doped TiO2 NPs show dramatic changes upon UV-irradiation. The absolute absorption intensity reduced entirely and the solution of MB became colorless in the presence of UV irradiation. The PL of the degraded dye exhibits a new band in the shorter wavelength region, which has a multi-exponential decay function and an increased average PL lifetime. Among all the samples, Cu2+ ions-doped TiO2 NPs shows the superior photocatalytic activity for the degradation of dye and followed pseudo-first-order kinetics.