Photothermal Effect Promoting Photocatalytic Process in Hydrogen Evolution over Graphene-Based Nanocomposite

Photocatalysts capable of utilizing full-spectrum solar energy for solar hydrogen evolution are highly appealing. Although graphene-based nanocomposites show certain photocatalytic characteristics due to its excellent conductivity, as a photothermal material, studies on its photothermal conversion effect have not been valued enough so far. Herein, reduced graphene oxide/TiO2 (rGO/TiO2) was synthesized for enhanced hydrogen evolution and photothermal conversion in the photocatalytic process. In our study, it was found that the 1.0 wt% reduced graphene oxide/TiO2 shows optimal hydrogen evolution rate of 7.82 mmol g−1 h−1 under the full spectrum irradiation of the solar light. Especially, through the infrared imaging camera, the synergistic photothermal effect for the graphene-based nanocomposite was directly revealed in a non-contact way. The temperature index Tk, indicating the temperature ratio between the gas phase inside and the outside surface of the reactor, was found to be increased by 13.92% corresponding to a 38.11% enhancement of the hydrogen evolution rates. Overall, this study could propose a new access to the photothermal of a graphene-based nanocomposites for its high performance of photocatalysis and promoting their applications in the solar energy conversion.