Construction and enhanced photocatalytic activities of a hydrogenated TiO2 nanobelt coated with CDs/MoS2 nanosheets

Abstract

A few-layered CDs (carbon dots)/MoS₂ nanosheet-coated hydrogenated TiO₂ (H-TiO₂) nanobelt heterostructures—referred to as CDs/MoS₂@H-TiO₂—with a flexible three-dimensional (3D) hierarchical configuration were prepared via a facial hydrothermal reaction. Note that the visible photocatalytic activity of H-TiO₂ was improved compared with that of pristine rutile TiO₂, which can be mainly attributed to the optical absorption and charge carrier trapping of oxygen vacancies and Ti³⁺ ions in TiO₂ nanobelts created by the hydrogenation. The CDs/MoS₂@H-TiO₂ ternary photocatalysts exhibit excellent UV and visible photocatalytic property. Via optimizing the proportion of each component, the CDs/MoS₂@H-TiO₂ composite showed the highest photocatalytic degradation activity when the content of the CDs/MoS₂ co-catalyst was 5.0 wt% and the content of CDs in this cocatalyst was 25%. Further study revealed that the considerable photodegradation rate under UV irradiation and a large promotion of the photocatalytic activity in both the visible and near-infrared (NIR) region originated from the synergistic effect of oxygen vacancies, interfacial modification, and the vectorial charge-transfer channel design. Our study provides a desired strategy to understand and realize a rationally designed electronic transition between a semiconductor and cocatalysts, which is of great importance for the enhancement of charge separation and obtaining improved photocatalytic performance.