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 CO 2 becomes a vital breakthrough to alleviate the greenhouse effect and achieve carbon neutrality. In this paper, ultrathin g-C 3 N 4 nanosheets of 1.74 nm were constructed, and K + was successfully doped between layers. The yields of CO and CH 4 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-C 3 N 4 , 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-C 3 N 4 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 CO 2 adsorption center of the K + intercalated g-C 3 N 4 is transferred from the coordinated carbon atom to the center of the triazine unit, and the binding energy is obviously increased, which strengthens the CO 2 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 CO 2 , resulting in the production of more intermediates, especially more hydrocarbon intermediates, which is more conducive to the photocatalytic reduction of CO 2 .