Facile Ion-Exchange Synthesis and Visible Light Photocatalytic Studies of Cu2+, Sn2+, and Ag+-Substituted LiMg0.5Ti0.5O2

A novel series of visible light-sensitive Cu2+, Sn2+, and Ag+-substituted LiMg0.5Ti0.5O2 photocatalysts were synthesized by a facile ion-exchange method and characterized by XRD, UV-Vis diffuse reflectance spectra, scanning electron microscopy equipped with an X-ray energy-dispersive spectroscopy, Brunauer-Emmett-Teller surface area, inductively coupled plasma mass spectrometry, and thermal gravimetric analysis. The characterization results showed that morphology, crystallite size, and surface areas of the ion-exchange products were almost similar to the parent compound. Absorption edges of Ag+-doped (AMT), Cu2+-doped (CMT), and Sn2+-doped (SMT) samples were red shifted remarkably into the visible light region while parent LiMg0.5Ti0.5O2 (LMT) was UV active. Photocatalytic activity of these samples was evaluated by studying the degradation of methylene blue and nitro benzene under visible light irradiation and the stability of all samples during photocatalytic experiment was also investigated. The activity of all photocatalysts was ranked accordingly as SMT AMT > CMT > LMT. The correlation between photocatalytic properties, band gap energy, rate of recombination of the charge carriers, and amount of .OH radicals generated during photocatalysis and the underlying reasons were discussed.