Deep eutectic solvothermal NiS2/CdS synthesis for the visible-light-driven valorization of the biomass intermediate 5-hydroxymethylfurfural (HMF) integrated with H2 production

Abstract

Visible-light-driven transformation of biomass to high-valued chemicals is attractive for achieving a low-carbon environment. The solar-catalyzed oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) has great industrial potential because DFF is a pivotal precursor in industries. Here, we present a one-step deep eutectic solvothermal technique for the production of NiS₂/CdS nanospheres. Because NiS₂ can act as a cocatalyst enhancing the transfer and separation of photogenerated carriers, the prepared NiS₂/CdS exhibits efficient visible-light-driven dehydrogenation of HMF to H₂ and DFF. DFF and H₂ can be produced at rates of up to 519.64 and 476.60 μmol g⁻¹ h⁻¹, respectively, which are about 10.03 and 9.81 times higher than those of bare CdS under visible light irradiation. Moreover, the photocatalytic process was carried out at ambient temperature and pressure in water without using a sacrificial agent. Both h⁺ and e⁻ are involved in the process of photocatalytic reaction, and the valence band position of the NiS₂/CdS photocatalyst is essential for the high DFF selectivity (95.2%). This work paves a sustainable way to realize the photocatalytic valorization of biomass.