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Free keywords:
photocatalysis, hydrophobic substrate, Polymeric carbon nitride, triphase interfaces, overall CO2 reduction
Abstract:
The activity and selectivity of simple photocatalysts for CO2 reduction were still limited by the insufficient photophysics of the catalysts, but also the low solubility and slow mass transport of gas molecules in/through aqueous solution. Herein, we present a way to overcome these limitation by constructing a triphase photocatalytic system, in which polymeric carbon nitride (CN) is immobilized onto a hydrophobic substrate, and the photocatalytic reduction reaction occurs at a gas-liquid-solid (CO2-water-catalyst) triple connection. It is found that the CN anchored onto the surface of a hydrophobic substrate exhibits an about 7.2-fold enhancement in the total CO2 conversion, with a rate of 415.50 ?mol m-2 h-1 under simulated solar light irradiation. This value corresponds to an overall photosynthetic efficiency for full water-CO2 conversion of 0.33%, i.e. very close to biological systems. Meanwhile, a remarkable enhancement of direct C2 hydrocarbon production, as well as a high CO2 conversion selectivity of 97.7% was observed. Going from water oxidation to phosphate oxidation, the quantum yield can be even increased to 1.28%.
