Upgrading biomass-derived platform chemicals into biofuel additives in synergism with H2O2via a ZnIn2S4 photocatalyst: towards solar fuels

Abstract

The upgrading of non-edible biomass and its platform chemicals to supply value-added products unveils the potential of the biorefinery to combat global energy and environmental challenges. The effective and selective conversion of biomass-derived substrates to fine chemicals can ease the burden on petroleum-derived chemical production. In this direction, ZnIn₂S₄-based photocatalytic acetalization of furfural (FFaL), 5-hydroxymethylfurfural (HMF) and 2,5-diformylfuran (DFF) was successfully achieved with 94%, 89% and 99% conversions, respectively, with ethylene glycol (EG) to generate clean and renewable biofuel additives. The ternary metal chalcogenide (TMC) semiconductor, i.e., ZnIn₂S₄, with the necessary acidic sites, facilitates the formation of acetal along with the H₂O₂ production (a carbon-free fuel) for the first time. Extensive mechanistic investigations of these synergistic redox catalytic conversions were performed through several controlled experiments along with XPS, in situ EPR, electrochemical studies, and DFT calculations. In addition, green metrics were calculated for the acetalization reaction to demonstrate the sustainability of the photocatalytic system. Thus, the present report highlights the potential of 2D ternary metal chalcogenide-based nanostructures for biomass valorization and solar fuel generation via sustainable routes to supply commodity chemicals.