Photocatalytic hydroxylation of benzene to phenol over organosilane-functionalized FeVO4 nanorods

Abstract

Photocatalytic benzene hydroxylation reaction using a clean oxidant such as H₂O₂ is a green synthetic approach for phenol synthesis. Here, our study shows that silylated iron vanadate (FeVO₄) nanorods can function as promising photocatalysts to direct hydroxylation of benzene to phenol, by taking advantage of the unique benefits of covalently bonded organosilane (OS) groups to realize kinetic control of heterogeneous photocatalytic reactions. The grafting of OS functional groups on FeVO₄ helps to tailor its surface affinity to fine-tune the benzene adsorption behavior and photo-Fenton process for H₂O₂ activation. In addition, the OS groups immobilized on the FeVO₄ surface via a rather strong Si–O bond also serve as an effective protective coating to suppress metal leaching, thus affording FeVO₄ with an excellent stability to undergo a heterogeneous photo-Fenton process. As a result, the silylated FeVO₄ exhibits robust photocatalytic benzene hydroxylation performance. The phenol yield and selectivity obtained on the optimized silylated FeVO₄ are determined to be 20% and 98%, much better than that obtained from pristine FeVO₄. Benefiting from its robust stability and tunable surface affinity, the silylated FeVO₄ will have broad applications in photocatalytic selective oxidation to produce fine chemicals.