Efficient photothermocatalytic hydrogen production performance over a graphene-titanium dioxide hybrid nanomaterial

Here, Graphene@TiO₂ nanomaterials were prepared for photothermocatalytic H₂ production to make full-use of solar spectrum. The H₂ evolution rate (HER) was 17.6 μmol/h and 89.8 μmol/h at room temperature and 90 °C, respectively. Interestingly, it could sharply increase to 436.5 μmol/h when the temperature reached 110 °C, which was about 24.8 times that of under room temperature. The introduction of graphene effectively promoted the specific surface area and pore volume of the composite, thus, contributing to the quick diffusion of reactants. Meanwhile, graphene absorbed and converted the energy of long wavelength photons into heat via photothermal effect, thus, enhancing the temperature of reaction system. The enhanced HER might be attributed to the existence of gas-liquid two-phase flow in micro-boiling state, the strengthened migration/diffusion rate of sacrificial reagent molecules, and as well as the excitation of adsorbed reactant molecules stemming from the elevated temperature. Our work should be valuable for the design of novel and efficient photothermocatalytic hydrogen production system driven by full-spectrum of sun light.