Single atom Cu anchored graphitic-C3N5 for photocatalytic selective oxidation of biomass-derived furfurals to maleic anhydride

Abstract

It is undoubtedly more in line with the requirements of a future sustainable society to replace fossil resources with biomass. A main challenge lies in converting biomass into useful chemicals through an efficient and low-cost approach. Herein, we have developed a copper single-atom-anchored nitrogen-rich graphitic carbon nitride (Cu₁@C₃N₅-1) for photooxidation of biomass-derived furfurals. This catalyst can selectively afford good to excellent yields of maleic anhydride (up to 98%) from furfural and 5-hydroxymethylfurfural (HMF) under visible light irradiation and 1 atm O₂ at 40 °C. The mechanistic studies demonstrate that (1) O₂ activation should be included in the rate-determining step; (2) ¹O₂ and ·O₂⁻ play a synergetic oxidation role during the reaction. The benefits of Cu doping include the activation of oxygen species, and the promotion of exciton effects and electron transfer. This catalyst also displays outstanding recyclability and stability, which can be recycled at least 8 times without significant loss of activity.