Visible-light-driven anaerobic oxidative upgrading of biomass-derived HMF for co-production of DFF and H2 over a 1D Cd0.7Zn0.3S/NiSe2 Schottky junction

Visible-light-driven photocatalytic oxidation of renewable biomass into value-added chemicals is a prospective solar energy utilization strategy. However, the aerobic oxidation reactions commonly generate uncontrolled reactive oxygen species, which leads to the peroxidation of target products and results in low selectivity. Herein, we demonstrate a selective anaerobic oxidation of biomass-derived 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) coupled with H-2 production over a hybrid Cd0.7Zn0.3S nanorod/NiSe2 composite. Cd0.7Zn0.3S with a 1D structure serves as a light harvester that greatly promotes electron transportation over long distances, while NiSe2 acts as an advanced cocatalyst that provides abundant active sites to accelerate H-2 reduction. Importantly, NiSe2 with metal-like characteristics forms a Schottky contact with Cd0.7Zn0.3S, which captures the photoelectrons generated from the Cd0.7Zn0.3S nanorods, inhibits the back flow, and prolongs the lifetime of charge carriers. The optimal DFF and H-2 production rates of the Cd0.7Zn0.3S/NiSe2 4% sample are 1728 and 1690 mu mol h(-1) g(-1), respectively, which are approximately 23 times greater than those of blank Cd0.7Zn0.3S. The DFF selectivity is close to 98%. It represents one of the best photocatalytic performances for the selective oxidation of HMF reported thus far. This research shows the great potential of constructing a transition metal sulfide/selenide Schottky junction for photocatalytic biomass conversion and provides insights into the green value-added utilization of biomass-derived alcohols via selective anaerobic oxidation.