Irradiation

Selectivity

Physics

Packed bed

Organic chemistry

Photocatalysis

Porosity

Porous medium

Engineering

Catalysis

Reaction rate

Composite material

Aqueous solution

Nuclear physics

Chemistry

Materials science

Mass transfer

Chemical engineering

Chromatography

eScience

Solar-driven CO2 conversion to chemical fuels in an aqueous solution is restricted not only by photocatalysts but also by mass transfer. Here, a regulatable three-phase interface on a porous fixed-bed is constructed for efficient C–C coupling in photocatalytic CO2 reduction. The photocatalytic results show that ∼90% selectivity towards C2+ products is obtained by a Cu/Cd0.5Zn0.5S photocatalyst, with a yield of 6.54 ​μmol/h (an irradiation area of 0.785 cm2), while only 0.94 ​μmol/h (an irradiation area of 19.625 cm2) is achieved with a commonly used suspension photocatalytic reactor. We find that under the same CO2 feed rate, the local CO2 concentration in this porous fixed-bed photoreactor is obviously higher than in the suspension photoreactor. The larger local CO2 coverage derived from a higher CO2 supply and aggregation enhances the C–C coupling, thereby generating more C2+. Even an observable three-phase interface on the porous fixed-bed can be regulated by adjusting the CO2 supply, for which the optimal gas inlet rate is 5–10 sccm.

Porous fixed-bed photoreactor for boosting C–C coupling in photocatalytic CO2 reduction