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 O-2 and hydrogen-stored Bi (Bi-H-x). The obtained Bi-H-x is subsequently used to generate electron-proton pairs under light irradiation to reduce CO2 to CO; meanwhile, Bi-H-x recovers to Bi, completing the catalytic cycle. This two-step strategy avoids O-2 separation and enables a CO production efficiency of 283.8 mu mol g(-1) h(-1) without sacrificial reagents and cocatalysts, which is 9 times that on pristine Bi in H-2 gas. Theoretical/experimental studies confirm that such excellent activity is attributed to the formed Bi-H-x intermediate that improves charge separation and reduces reaction barriers in CO2 reduction. Using a single catalyst to mimic the two-step photosynthesis for CO2 conversion remains a challenge. Here, the authors report a simple Bi catalyst that can act as an electron-proton-transfer mediator to spatially and temporally separate H2(O) splitting and CO2 reduction reactions in CO2-to-CO conversion process.

Automated summary

Mimicking natural photosynthesis using plasmonic Bi as an electron-proton-transfer mediator can effectively convert CO2 to CO. The two-step strategy avoids O-2 separation and enables a high CO production efficiency without sacrificial reagents. The use of a single catalyst to spatially and temporally separate hydrogen splitting and CO2 reduction reactions in the CO2-to-CO conversion process remains a challenge, but the authors have successfully demonstrated this using a Bi catalyst.