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

[Display omitted] • Cr-MgO/Bi 2 O 3 nanocomposites were synthesized for the first time and evaluated for the photocatalytic hydroxylation of benzene to phenol. • The syntheized 10% Cr-MgO/Bi 2 O 3 composite exhibited remarkably enhanced photocatalytic performance compared with bare Bi 2 O 3 , MgO and MgO/Bi 2 O 3. • The conduction of heterojunction between Bi 2 O 3 and MgO, coupled with the generation of a new trapping level within Cr-MgO/Bi 2 O 3 by Cr doping contribute to the enhanced photocatalytic performance. A series of Cr-doped MgO/Bi 2 O 3 (Cr-MgO/Bi 2 O 3) 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 H 2 O 2 were thoroughly examined. The well-characterized photocatalyst (10% Cr- MgO/Bi 2 O 3) 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 Bi 2 O 3 , MgO and MgO/Bi 2 O 3. The remarkably improved photocatalytic activity was resulted from the conduction of heterojunction between Bi 2 O 3 and MgO, as well as the generation of a new trapping level within Cr-MgO/Bi 2 O 3 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. [ABSTRACT FROM AUTHOR]