Enhanced CO2 reduction and valuable C2+ chemical production by a CdS-photosynthetic hybrid system

Semi-artificial photosynthesis is an emerging technique in recent years. Here, we presented an inorganic-biological hybrid system composed of photosynthetic Rhodopseudomonas palustris and CdS nanoparticles coated on the bacterial surface. Under visible light irradiation, the CO2 reduction and valuable C2+ chemical production of R. palustris could be promoted by the photo-induced electrons from the CdS NPs. The increased energy-rich NADPH cofactor promoted the generation of the Calvin cycle intermediate, glyceraldehyde-3-phosphate. As a result, the production of solid biomass, carotenoids and poly-β-hydroxybutyrate (PHB) was increased to 148%, 122% and 147%, respectively. The photosynthetic efficiency (PE) of CdS-R. palustris was elevated from the original 4.31% to 5.98%. The surface loaded NP amount and the material-cell interface both played important roles in the efficient electron generation and transduction. The CdS-R. palustris hybrid system also exhibited a survival advantage over its natural counterparts under the autotrophic conditions. Under a practical solar/dark cycle, the produced biomass, carotenoid and PHB from the hybrid system also reach 139%, 117% and 135%, respectively. The CdS-photosynthetic hybrid system represents a powerful and expandable platform for advanced CO2 reduction and solar-to-chemical (S2C) conversion.