Improving Artificial Photosynthesis over Carbon Nitride by Gas–Liquid–Solid Interface Management for Full Light‐Induced CO₂ Reduction to C₁ and C₂ Fuels and O₂

The activity and selectivity of simple photocatalysts for CO 2 reduction remain limited by the insufficient photophysics of the catalysts, as well as the low solubility and slow mass transport of gas molecules in/through aqueous solution. In this study, these limitations are overcome by constructing a triphasic 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 (CO 2 –water–catalyst) triple interface. CN anchored onto the surface of a hydrophobic substrate exhibits an approximately 7.2‐fold enhancement in total CO 2 conversion, with a rate of 415.50 μmol m −2 h −1 under simulated solar light irradiation. This value corresponds to an overall photosynthetic efficiency for full water–CO 2 conversion of 0.33 %, which is very close to biological systems. A remarkable enhancement of direct C2 hydrocarbon production and a high CO 2 conversion selectivity of 97.7 % are observed. Going from water oxidation to phosphate oxidation, the quantum yield is increased to 1.28 %.