Boosting thermo-photocatalytic CO2 conversion activity by using photosynthesis-inspired electron-proton-transfer mediators

Natural photosynthesis proceeded by sequential water splitting and CO₂ reduction reactions is an efficient strategy for CO₂ conversion. Here, mimicking photosynthesis to boost CO₂-to-CO conversion is achieved by using plasmonic Bi as an electron-proton-transfer mediator. Electroreduction of H₂O with a Bi electrode simultaneously produces O₂ and hydrogen-stored Bi (Bi-Hx). The obtained Bi-Hx is subsequently used to generate electron-proton pairs under light irradiation to reduce CO₂ to CO; meanwhile, Bi-Hx recovers to Bi, completing the catalytic cycle. This two-step strategy avoids O₂ separation and enables a CO production efficiency of 283.8 μmol g⁻¹ h⁻¹ without sacrificial reagents and cocatalysts, which is 9 times that on pristine Bi in H₂ gas. Theoretical/experimental studies confirm that such excellent activity is attributed to the formed Bi-Hx intermediate that improves charge separation and reduces reaction barriers in CO₂ reduction.