Zinc cadmium sulphide-based photoreforming of biomass-based monosaccharides to lactic acid and efficient hydrogen production

[Display omitted] Approaches that add value to biomass through the use of photoreforming reactions offer great opportunities for the efficient use of renewable resources. Here, we constructed a novel zinc cadmium sulphide/molybdenum dioxide-molybdenum carbide–carbon (ZnxCd1-xS-y/MoO2-Mo2C-C) heterojunction which was applied to photoreforming of biomass-based monosaccharides for hydrogen and lactic acid production. Bandgap engineering effectively modulated the redox capacity of ZnxCd1-xS-y and exposed more (101) crystalline surfaces, which improved the lactic acid selectivity. The MoO2-Mo2C-C (MC) co-catalysts had unique microstructures that increased the light absorption range and the number of active sites of ZnxCd1-xS-y. These features effectively promoted the separation and migration of photogenerated carriers, which in turn enhanced the photoreforming activity. The optimised Zn0.4Cd0.6S-0/MC composites exhibited superior photocatalytic activity with a hydrogen yield of 12.2 mmol/g/h. Conversion of biomass-based monosaccharides was approximately 100 %, where arabinose had the greatest lactic acid selectivity (64.1 %). Active species, including h+, ⋅O2−, ⋅OH, and 1O2, all favoured lactic acid production, where ⋅O2− played a major role in the conversion. This study demonstrates that rational design of photocatalysts can achieve the selective conversion of biomass into high value-added chemicals as well as the generation of clean energy.