Three-Phase Photocatalysis for the Enhanced Selectivity and Activity of CO₂ Reduction on a Hydrophobic Surface

The photocatalytic CO₂ reduction reaction (CRR) represents a promising route for the clean utilization of stranded renewable resources, but poor selectivity resulting from the competing hydrogen evolution reaction (HER) in aqueous solution limits its practical applicability. In the present contribution a photocatalyst with hydrophobic surfaces was fabricated. It facilitates an efficient three-phase contact of CO₂ (gas), H₂ O (liquid), and catalyst (solid). Thus, concentrated CO₂ molecules in the gas phase contact the catalyst surface directly, and can overcome the mass-transfer limitations of CO₂ , inhibit the HER because of lowering proton contacts, and overall enhance the CRR. Even when loaded with platinum nanoparticles, one of the most efficient HER promotion cocatalysts, the three-phase photocatalyst maintains a selectivity of 87.9 %. Overall, three-phase photocatalysis provides a general and reliable method to enhance the competitiveness of the CRR.