Enhanced photocatalytic degradation of dye under visible light on mesoporous microspheres by defects in manganese- and nitrogen-co-doped TiO2

Abstract

Manganese- and nitrogen-co-doped mesoporous TiO2 microsphere photocatalysts are prepared by a simple sol–gel method with controllable sizes in the range of 400–500 nm and high surface area of 112 m2 g−1. Manganous acetate is the Mn source, and ammonia gas is the nitrogen source used. The dopants are found to be uniformly distributed in the TiO2 matrix. Interestingly, in (Mn,N)-co-doped TiO2, we observe an effective indirect band gap of ~2.58 eV. (Mn,N)-co-doped mesoporous TiO2 microspheres show higher photocatalytic activity than Mn–TiO2 microspheres under visible light irradiation. Among the samples reported in this work, 0.2 at.% Mn doping and 500 °C 2-h nitriding condition give the highest photocatalytic activity. The observed photocatalytic activity in the (Mn,N)-co-doped TiO2 is attributed to the contribution from improved absorption due to trap levels of Mn, oxygen vacancies and N doping. Manganese- and nitrogen-co-doped mesoporous TiO2 microspheres containing substitutional N, interstitial N and O vacancies show high visible light photocatalytic activity.