Preparation of Er3+:YAlO3/Fe- and Co-doped TiO2–ZnO coated composites and their visible-light photocatalytic activity in degradation of some organic dyes

Abstract

In this paper, an up-conversion luminescence agent (Er3+:YAlO3), which can effectively transform the visible light in solar light into ultraviolet light, was prepared. Then, for a visible-light photocatalytic degradation reaction, the prepared Er3+:YAlO3 was coated by Co- and Fe-doped TiO2–ZnO films thorough sol–gel process, respectively, and the Er3+:YAlO3/Fe- and Co-doped TiO2–ZnO coated composites were obtained. The crystal forms, particle sizes, chemical compositions, and weight change process of the Er3+:YAlO3/Fe- and Co-doped TiO2–ZnO coated composites were analyzed by using XRD, TEM, SEM, EDX, and TG–DTA instruments. The photocatalytic activities of the Er3+:YAlO3/Fe- and Co-doped TiO2–ZnO coated composites were evaluated through the degradation of azo fuchsine under visible light irradiation. It indicated that the visible light photocatalytic reduction ratio of Fe- and Co-doped TiO2–ZnO composites were 47.8 and 67.9 %, while after adding 15 wt% Er3+:YAlO3, the reduction ratio reached 93.5 and 95.5 %, respectively. In addition, the photocatalytic effect of Er3+:YAlO3/Co-doped TiO2–ZnO is better than that of Er3+:YAlO3/Fe-doped TiO2–ZnO.