Continuous CO ₂ Capture with Photochemical Release in a Slug Flow Reactor

CO2 capture and release via a light-driven pH swing offers a promising route to carbon management by harnessing sunlight and reducing reliance on external energy inputs. Recent studies have explored diverse photoactive compounds, yet the engineering of light-driven CO2 separation systems remains underexplored. We introduce a microfluidic slug flow reactor that couples efficient light delivery with molecular pKa alignment to drive separation. A synthesized polymeric photoacid with a high ground-state pKa (∼10) remains protonated in the dark during CO2 absorption and deprotonates under illumination to drive CO2 release. Since higher loadings attenuate light and confine activation near the surface, we tuned illumination depth and reactor geometry to maintain uniform activation and sustained operation, with stable performance over 125 h, releasing 34 mmol of CO2 captured from a 5% CO2/3% O2 feed while minimizing photothermal effects. Overall, this architecture provides a versatile platform for coupling with future advanced photoactive chemistries.