Transforming CdS into an efficient visible light photocatalyst for selective oxidation of saturated primary C–H bonds under ambient conditions

Abstract

Selective activation of saturated sp³ C–H bonds to high-value-added chemicals remains a significant but challenging task for the sustainable exploitation of available feedstocks. However, the selective oxidation of C–H bonds with environmentally benign oxygen is often very difficult to control. Research works available in thermal heterogeneous catalysis often involve the use of transition metal particles together with harsh reaction conditions, e.g., high temperature and high pressure, which results in the difficulty in controlling the selectivity. Here, we report a very simple room temperature method to prepare a cubic phase, sheet structured semiconductor CdS sample. The as-prepared CdS is able to be used as a visible-light-driven photocatalyst for the selective oxidation of saturated primary C–H bonds in alkyl aromatics with high activity and selectivity using molecular oxygen as a benign oxidant and benzotrifluoride as the solvent under ambient conditions, i.e., room temperature and atmospheric pressure. The superior photocatalytic performance of CdS can be attributed to its unique assembly of sheet structure with cubic phase, high surface area and efficient separation of photogenerated charge carriers. The possible reaction mechanism for the photocatalytic selective oxidation of such C–H bonds over the CdS semiconductor has also been proposed.