Stepwise photoassisted decomposition of carbohydrates to H2

Hydrogen (H2), as an indispensable clean energy vector, has been well demonstrated to be produced via biomass photoreforming powered by solar light. For future biomass refining, biomass photoreforming deserves a high decomposition extent of biomass to maximize H2 production, as the greenhouse gas emissions from biomass acquisition and pretreatment will minimize per mass of H2. The main obstacle to high H2 yield is the far insufficient C-C bond breaking to convert biomass carbons into CO2 with maximization of H2 production. Here, we emphasize C-C bond breaking instead of direct H2 production. Such a "C-C bond first" strategy realizes conversion of carbohydrates into C1 liquid hydrogen carriers (LHCs, consisting of HCOOH and HCHO) over Ta-CeO2 photocatalyst and is demonstrated in a flow apparatus powered solely by solar energy. The LHCs can release H2 on-site where needed by either photocatalysis or thermocatalysis. This work provides a new perspective for H2 production by photocatalysis.