Abstract
Effective CO2 adsorption and fast electron injection are two crucial processes of photocatalysts for achieving high-efficiency CO2 photo-reduction. However, simultaneously enhancing these processes within a single photocatalyst remains a challenging task. Herein, we propose an intriguing edge effect based on the intrinsic atomic structure of g-C3N4 nanosheets (NSs) to enhance their CO2 adsorption and facilitate the transfer of photo-generated electrons to the adsorbed CO2. By cutting large pieces of g-C3N4 NSs into smaller fragments, the exposure of amino groups at the edges of its repeating tri-s-triazine units can be significantly increased. These edge-exposed amino groups serve as active sites for enhancing the CO2 capture capacity of g-C3N4 NSs. As we decrease the lateral size of g-C3N4 NSs from tens of micrometers to hundreds of nanometers, their CO2 adsorption capacity increases from 4.74 to 8.56 cm3 g−1. Reducing the size of g-C3N4 NSs also facilitates the transfer of photo-generated electrons to the edge-adsorbed CO2. Thus, our optimized g-C3N4 NSs with the edge effect exhibits a 37-fold enhancement in activity for CO2 photo-reduction compared to normal g-C3N4 NSs under simulated sunlight irradiation. Notably, by introducing Pt cocatalysts, we can control product selectivity from 85.9% CO to 97.9% CH4.
Published Version
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