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

Abstract

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 H₂ production over a hybrid Cd_0.7Zn_0.3S nanorod/NiSe₂ composite. Cd_0.7Zn_0.3S 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 H₂ reduction. Importantly, NiSe₂ with metal-like characteristics forms a Schottky contact with Cd_0.7Zn_0.3S, which captures the photoelectrons generated from the Cd_0.7Zn_0.3S nanorods, inhibits the back flow, and prolongs the lifetime of charge carriers. The optimal DFF and H₂ production rates of the Cd_0.7Zn_0.3S/NiSe₂ 4% sample are 1728 and 1690 μmol h⁻¹ g⁻¹, respectively, which are approximately 23 times greater than those of blank Cd_0.7Zn_0.3S. 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.