Efficient photocatalytic C(sp3)-H oxidation of ethylbenzene enhanced by photochromic Mo-doped BiOCl ultrathin nanosheets

Abstract

The photocatalytic activation of C(sp³)-H bonds has exhibited great potential for producing high-value chemicals. However, the poor charge separation and transfer efficiency as well as limited active sites of semiconductor photocatalysts restrict photocatalytic performance. Herein, we report the photochromic Mo-doped BiOCl ultrathin nanosheets with abundant oxygen vacancies for efficient photocatalytic oxidation of C(sp³)-H of ethylbenzene. Mo-doping effectively extends the light absorption of BiOCl to visible range and empowers BiOCl visible-light-responsive photochromic properties. The photochromic effect induced Mo⁶⁺/Mo⁵⁺ species could act as electron trapping centers for capturing photogenerated electrons to improve the separation and transfer efficiency of photogenerated charges, and thus promoting the photogenerated holes to oxidize ethylbenzene to its benzyl radicals. The abundant oxygen vacancies in Mo-doped BiOCl ultrathin nanosheets act as active sites for enhancing adsorption and activation of the O₂ to O₂⁻ by photogenerated electrons stored at Mo⁶⁺/Mo⁵⁺ species and oxygen vacancies. The reduction of O₂ and oxidation of C(sp³)-H bonds can be effectively accomplished to produce acetophenone. The Mo-doped BiOCl ultrathin nanosheets display an excellent acetophenone production rate of 8033 μmol·g⁻¹·h⁻¹, which is 9 times higher than that of undoped BiOCl. This work shows that photochromic catalysts would provide a new way to design efficient photocatalysts for activation of C(sp³)-H bonds.