10 nm sized visible light TiO2 photocatalyst in the presence of MgO for degradation of methylene blue

Environmentally friendly, chemically inert, and cost-effective 10 nm-sized MgO/TiO2 nanocomposites were prepared by a chemical precipitation method at room temperature and followed by calcination. The structural and optical properties of photocatalyst were characterized by XRD, SEM, TEM, XPS, EIS, PL, and DRS. The MgO/TiO2 photocatalysts were tested for the degradation of methylene blue (MB) dye using visible light instead of UV irradiation. The highest photodegradation efficiency of 99.7% was achieved by MgO/TiO2-30 with a 30 wt% Mg precursor within 120 min. The effect of calcination temperature on the catalytic activity of the catalyst was also investigated. The degradation of MB was confirmed using HPLC. The rate constant of MgO/TiO2-30 was 2.4 x 10(-2) min(-1), which is 4 times greater than that of bare P25-TiO2 with a rate constant of 6.0 x 10(-3) min(-1). The excellent photocatalytic activity of MgO/TiO2 arises because of the incorporation of MgO to the 10 nm-sized TiO2 to form the MgO/TiO2 interface. A concept of the stoichiometric/nonstoichiometric oxide interface for better charge transport is proposed. The recyclability of the photocatalyst was evaluated. Finally, the suggestive reaction mechanism was also proposed.