Visible light contributions transform CO2 into higher hydrocarbons during Fischer Tropsch synthesis over K-Fe catalysts

Current C 2+ hydrocarbon production from fossil fuel feedstocks will in-time be replaced by alternate synthesis methods involving cleaner energy strategies. One approach is to incorporate direct sunlight during catalytic C 2+ synthesis via the modified Fisher Tropsch synthesis (CO 2 -FTS) reaction. Light-driven studies targeting C 2+ products from CO 2 under high-pressure conditions are scarce. Herein, we demonstrate that direct visible light illumination can selectively boost hydrocarbon synthesis by a K-promoted Fe catalyst during the high pressure (23 bar), thermal catalytic CO 2 -FTS reaction. Visible light illumination imparts carrier-induced benefits to amplify CO activation and hydrocarbon synthesis. Visible light illumination modifies the surface charge of Fe. This promotes CO adsorption and C-O bond lengthening over the K-Fe catalysts, and dissociation to *C. The light-enhanced *C production boosted Fe carbide formation which facilitates FTS. Concurrently, *C hydrogenation leads to hydrocarbon synthesis. The findings offer new insight into the cascading impact of light within dynamic catalytic systems arising from the interdependence between catalyst activation and performance. Light assisted CO 2 – Fischer Tropsch synthesis has gained recent attention for making solar fuel, though the impact of light under pressurized conditions is unknown. Herein, under a K-Fe system at elevated pressure, light is shown to facilitate selective hydrocarbon synthesis, whilst aiding Fe carbide formation active for carbon coupling. • The influence of visible light illumination on CO 2 -FTS was explored under high pressure conditions (23 bars). • Visible light illumination was shown to enhance hydrocarbon synthesis. • Visible light illumination promotes CO activation over the K-Fe catalysts. This enhances CO dissociation to *C. • The resulting *C: (i) undergoes hydrogenation to facilitate hydrocarbon synthesis, and (ii) promotes Fe carburization. • The findings reveal how light influences activity, selectivity, and catalyst composition in dynamic catalytic systems.