Gully-like CQDs/In2O3/TiO2 composite with broad spectral response and its enhanced photocatalytic performance

Abstract

The morphology and structure of photocatalytic materials often have a great influence on their photocatalytic performance. The photocatalytic degradation and hydrogen production capacity can be enhanced by optimizing the morphology and properties of the catalysts. In this paper, on the basis of carbon quantum dots (CQDs) with up-conversion photoluminescence (UCPL) properties and polystyrene colloid microspheres (PS) as templates, a kind of gully-like CQDs/In2O3/TiO2 composites with wide spectral response was prepared by vacuum impregnation and microwave-assisted hydrothermal method. The results show that CQDs/In2O3/TiO2 composites with PS colloid microsphere as templates have a gully structure, which provides more active sites for photocatalytic reaction. The heterostructure formed among components optimizes the charge transfer path, significantly improving the separation and transfer efficiency of photogenerated electrons and holes. In the multi-mode photocatalytic experiments, CQDs/In2O3/TiO2 composites show excellent photocatalytic activity for methyl orange, of which photocatalytic activity is much higher than that of pure TiO2, displaying a certain degree of degradation for the different kinds of dyes. In addition, the hydrogen evolution capacity of CQDs/In2O3/TiO2 composites is 1149.3 μmol/g for 8 hours, which is 7 times of that of monomer TiO2. The results of the capture experiments show that the possible photocatalytic mechanism of CQDs/In2O3/TiO2 composites is more likely to be the result of a synergy between the traditional band theory and the "Z-scheme".