An S-scheme heterojunction of single Ni sites decorated ultrathin carbon nitride and Bi2WO6 for highly efficient photothermal CO2 conversion to syngas

Abstract

Solar-driven conversion of CO2 and H2O to value-added chemicals or fuels is an ideal strategy to tackle the energy crisis and environmental issues. However, construction of highly efficient photosynthesis systems remains a challenge. This work reports a heterojunction catalyst consisting of ultrathin carbon nitride with single Ni sites and Bi2WO6 for photothermal conversion of CO2 and H2O to syngas. The catalyst exhibits exceptional activity at medium temperature of 250 °C, with CO and H2 production rates of 4493 and 9191 μmol g−1 h−1, respectively. Experimental results and DFT calculations reveal that the construction of S-scheme heterojunction and the introduction of single Ni sites greatly improve the separation of photogenerated carriers as well as the adsorption and activation of CO2. Meanwhile, it is proved that light drives the generation of H+ and activates the CO2 molecules, while heat accelerates the generation and diffusion of H+. The photothermal synergistic effect promotes the catalyst activity by two orders of magnitude.