Co-catalyst design to control charge transfer and product composition for photocatalytic H2 production and biomass reforming

Abstract

The exploration of co-catalyst effects in photocatalytic H₂ production along with biomass reforming is still limited. This study employs S- and N-doped graphene oxide dots (SNGODs) along with Pt and Ag co-catalysts to investigate the photocatalytic reforming of xylose (C₅) into its derivatives and gaseous H₂. Our study shows that Pt-SNGODs effectively catalyze both the reduction and oxidation steps: water reduction for H₂ evolution and oxidative reforming of xylose into C₅–C₁ species through successive alternation of hydrolysis and photocatalytic oxidation. Ag-SNGODs are less effective in the H₂ evolution reaction and the accumulated photogenerated electrons facilitate cleavage of xylose, through the retro-aldol reaction, into C₃- and C₂-species, which are then reformed into C₃–C₁ species. In addition to xylose cleavage, Ag-SNGODs are effective in reducing xylose and formate into radicals, which would proceed with C–C coupling to produce a C₆ compound. The present study demonstrates how the co-catalyst of photocatalysts can influence the charge transfer dynamics and the product composition in photocatalytic biomass reforming.