Photocatalytic cellulose reforming for H₂ and formate production by using graphene oxide-dot catalysts

The mechanism of photocatalytic biomass reforming for H₂ production is far from fully understood. This study uses functionalized graphene dots with Pt-cocatalyst to reform cellulose in an alkaline solution under 1 sun illumination. Reforming of cellulose is initiated with the peeling of its constituent D-glucose units, which subsequently transform into deprotonated isosaccharinic acid (C₆). Further degradation of C₆ into molecules C₅-C₁ proceeds through successive alternation of C-eliminating hydrolysis and photocatalytic oxidation of C₆ derivatives. The C₆-C₁ species are quantitatively identified using chromatography and mass spectroscopy. The end C-containing product is predominantly HCOO⁻ rather than HCO₃⁻ (or CO₂). The photocatalytic oxidation is accompanied by the photocatalytic reduction of water to produce H₂. This reforming steadily produced H₂ for 6 days with a negligible rate decay, accomplishing 35% of the theoretical ultimate value for the reforming of cellulose. This study elucidates the detailed mechanism in the photocatalytic reforming of cellulose.