High-efficiency photoreduction of CO2 to solar fuel on alkali intercalated Ultra-thin g-C3N4 nanosheets and enhancement mechanism investigation

The visible-light photocatalytic reduction of CO2 becomes a vital breakthrough to alleviate the greenhouse effect and achieve carbon neutrality. In this paper, ultrathin g-C3N4 nanosheets of 1.74 nm were constructed, and K+ was successfully doped between layers. The yields of CO and CH4 are 1.65 μmol·g−1·h−1 and 0.15 μmol·g−1·h−1, which are 4.70 and 7.27 times higher than the original g-C3N4, respectively. The ultra-thin nano-lamellar structure shortens the carrier transmission distance, and the intercalation of K+ not only promotes the electron transport between g-C3N4 layers but also changes the original hybrid mode of the catalytic system, thus shortening the band gap and adjusting the energy band structure. In addition, the CO2 adsorption center of the K+ intercalated g-C3N4 is transferred from the coordinated carbon atom to the center of the triazine unit, and the binding energy is obviously increased, which strengthens the CO2 adsorption. Finally, through in-situ DRIFT characterization, it is speculated that the reaction enhancement mechanism is that the modified catalyst promotes the adsorption and activation of CO2, resulting in the production of more intermediates, especially more hydrocarbon intermediates, which is more conducive to the photocatalytic reduction of CO2.