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

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/In 2 O 3 /TiO 2 composites with wide spectral response was prepared by vacuum impregnation and microwave-assisted hydrothermal method. The results show that CQDs/In 2 O 3 /TiO 2 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/In 2 O 3 /TiO 2 composites show excellent photocatalytic activity for methyl orange, of which photocatalytic activity is much higher than that of pure TiO 2 , displaying a certain degree of degradation for the different kinds of dyes. In addition, the hydrogen evolution capacity of CQDs/In 2 O 3 /TiO 2 composites is 1149.3 μmol/g for 8 h, which is 7 times of that of monomer TiO 2. The results of the capture experiments show that the possible photocatalytic mechanism of CQDs/In 2 O 3 /TiO 2 composites is more likely to be the result of a synergy between the traditional band theory and the "Z-scheme". The unique up-conversion characteristic of CQDs broadened the spectrum absorption range of gully-like CQDs/In 2 O 3 /TiO 2 composites, and the heterostructure between In 2 O 3 and TiO 2 accelerated the electron transfer, which jointly promoted the degradation of organic pollutants and the efficiency of photo-splitting water for hydrogen production. [Display omitted] • The gully-like CQDs/In 2 O 3 /TiO 2 composites were successfully prepared using polystyrene microspheres as the template. • The unique up-conversion characteristic of CQDs is used as an electron collector to extend the carrier life. • The heterojunction between In 2 O 3 and TiO 2 accelerates the electron transfer. • The unique gully-like structure provides more active sites for the reaction. • Photocatalytic hydrogen production activity of gully-like CQDs/In 2 O 3 /TiO 2 composites is much higher than that of TiO 2. [ABSTRACT FROM AUTHOR]