Efficiently selective oxidation of glycerol by BiQDs/BiOBr–Ov: promotion of molecular oxygen activation by Bi quantum dots and oxygen vacancies

Abstract

Selective oxidation of biomass resource glycerol to produce high value-added formic acid, dihydroxyacetone and other fine chemicals is in line with the current development concept of green and sustainable chemistry. A Bi quantum dot and oxygen vacancy modified BiOBr photocatalyst was applied to the selective aerobic oxidation of glycerol. A series of characterization results showed that the introduction of Bi quantum dots and oxygen vacancies can promote the effective transfer of photo-generated electrons and the adsorption of molecular oxygen on the catalyst surface to promote the activation of molecular oxygen, thereby significantly improving the photocatalytic efficiency of BiOBr. Bi_QDs/BiOBr–O_v can efficiently catalyze the oxidation of glycerol to yield FA and DHA (FA selectivity 46.2%, DHA selectivity 26.9% at 98.4% glycerol conversion) under mild conditions, which is around 2.9 times that of normal BiOBr. In addition, the relevant reaction mechanism and path were systematically studied: two reaction paths to yield FA and DHA independently were found, where photo-generated holes and superoxide radicals played important roles. This work provided an efficient catalyst modification scheme by promoting the activation of molecular oxygen to improve the photocatalytic oxidation efficiency of biomass resources.