Systematic study of H2 production from photothermal reforming of α-cellulose over atomically thin Bi2MoO6

Photothermal reforming of biomass for hydrogen production is not only a low-carbon and environmentally friendly way to obtain hydrogen energy, but also a new strategy to achieve the utilization of waste resources. Due to the stable chemical properties of α-cellulose, the easy recombination of photogenerated carriers in photocatalysts, and the slow kinetics of hydrogen evolution, the catalytic conversion of biomass to hydrogen driven by sunlight remains a huge challenge. Herein, we report a new method for the conversion of α-cellulose to H2 by synergistic photothermal reforming over Bi2MoO6. Due to the unique atomically thin structure and more abundant oxygen vacancies, A-Bi2MoO6 has a narrow band gap, more negative conduction band and abundant hydrogen evolution sites. The material characterization reveals that the band gaps of A-Bi2MoO6 and N-Bi2MoO6 are 2.37 eV and 2.41 eV, respectively, and the conduction band edges are −0.33 eV and −0.03 eV, respectively. The DFT calculations show that the H atom obtains the ideal ΔGH0 (-0.65 eV) in the oxygen vacancy site. All these are beneficial to the production of H2. Therefore, the H2 yield produced by α-cellulose photothermal reforming over A-Bi2MoO6 was 214.63 μmol·gcat-1 after 4 h of reaction, which was 1.85 times higher than that of N-Bi2MoO6. Photothermal synergistic catalysis significantly increased the catalytic activity of A-Bi2MoO6, which was mainly attributed to the fact that temperature promoted the activation of some reactants, while light irradiation decreased the activation energy barrier of the reaction. Therefore, the H2 yield obtained by photothermal catalysis is higher than the sum of the H2 yield obtained by photocatalysis and the H2 yield obtained by thermocatalysis during the α-cellulose reforming reaction.