Enhanced photocatalytic performance of Cr doped MgO/Bi2O3 nanocomposite for efficient hydroxylation of benzene to phenol under visible-light irradiation

A series of Cr-doped MgO/Bi2O3 (Cr-MgO/Bi2O3) nanocomposites were prepared for the photocatalytic benzene hydroxylation to produce phenol by the visible-light exposure, and the catalyst dosage, solvents and volume ratio of benzene to H2O2 were thoroughly examined. The well-characterized photocatalyst (10% Cr-MgO/Bi2O3) by various physico-chemical and spectroscopic techniques was found to be highly efficient with an optimal phenol selectivity of 98.5% and yield of 13.8%, which were much higher than those obtained from bare Bi2O3, MgO and MgO/Bi2O3. The remarkably improved photocatalytic activity was resulted from the conduction of hetero-junction between Bi2O3 and MgO, as well as the generation of a new trapping level within Cr-MgO/Bi2O3 by Cr doping, which greatly accelerated the photogenerated charge carriers separation. This work combining heterojunction conduction and transition metal doping exhibits promising potential for future applications in organic transformation reactions.