Modulating oxygen vacancies on bismuth-molybdate hierarchical hollow microspheres for photocatalytic selective alcohol oxidation with hydrogen peroxide production

Photocatalytic selective oxidation of alcohols into high value-added carbonyl compounds accompanied by producing hydrogen peroxide (H 2 O 2 ) is undoubtedly a more efficient solar energy conversion strategy with high atom economy. Herein, we have developed an efficient photocatalyst of bismuth-molybdate (Bi 2 MoO 6 ) hierarchical hollow microspheres with tunable surface oxygen vacancies (OVs) for promoting the photocatalytic selective alcohol oxidation with H 2 O 2 production. The effect of surface OVs on the photocatalytic efficiency is studied systematically by comparing the performance of different photocatalysts. The benzaldehyde and H 2 O 2 production rates over the OV-rich Bi 2 MoO 6 photocatalyst reach up to 1310 and 67.2 μmol g −1 h −1 , respectively, which are 2.3 and 4.0 times those generated from the OV-poor Bi 2 MoO 6 hollow microspheres. The roles of various active radicals in the photocatalytic reaction are probed by a series of controlled experiments and in situ ESR measurements, revealing that both superoxide radical (• O 2 - ) and carbon-centered radical are the key active intermediates. The introduction of surface OVs on Bi 2 MoO 6 hollow microspheres accelerates the separation and transfer of photo-generated charge carriers as well as enhances the adsorption and activation of reactant molecules, thereby greatly promoting the photocatalytic selective oxidation of alcohols along with H 2 O 2 production. This work not only demonstrates a facile strategy for the preparation of high-efficiency photocatalysts by simultaneous modulations of morphology and surface defects , but also offers insight into developing the dual-functional photocatalytic reactions for the full utilizations of photoinduced electrons and holes.