Edge activation of an inert polymeric carbon nitride matrix with boosted absorption kinetics and near-infrared response for efficient photocatalytic CO2 reduction†
The reduction of CO2 into C1 feedstocks (e.g., CO) by utilizing solar energy has attracted increasing attention for the efficient production of renewable energy. However, a significant challenge in the reduction of CO2 is achieving high conversion efficiency due to the high CO dissociation energy of CO2 and difficultly in accessing the surface of photocatalysts. Herein, we fabricated a polymeric carbon nitride (PCN) catalyst with hydroxyethyl groups grafted on its edge via a facile bottom-up strategy, facilitating the efficient surface absorption of CO2 and lowering the CO2 transformation energy barrier; this was accompanied with exceptional extended optical absorption ability to the near-infrared region and increase in the density of states at the Fermi level. Thus, concentrated CO2 molecules could contact the surface of PCN and be easily activated; this resulted in an excellent CO production rate of up to 209.24 μmol h−1 g−1 in the modified PCN (i.e., 39.5-fold increase compared to that of pristine PCN) and a selectivity of 98.5% under white LED illumination, exceeding that of most PCN-based energy conversion systems reported to date. Notably, this PCN matrix also exhibited photocatalytic activity for the production of CO in the near-infrared region from 780 to 850 nm. These results pave the way for the development of structured photocatalysts with easy accessibility for CO2 and broadband spectral response for the efficient photocatalytic reduction of CO2.