Enhanced biogas upgrading by photocatalytic conversion of carbon dioxide to methane by Methanosarcina barkeri–cadmium sulfide biohybrid

The semiconductive cadmium sulfide (CdS) nanoparticles were coated on the surface of Methanosarcina barkeri (M. barkeri) by self-assembly method to form the M. barkeri-CdS biohybrid in this work. It proved to be an effective and selective catalyst for the solar-driven conversion of CO₂ to CH₄, enabling the upgrading of biogas from anaerobic digestion. The physicochemical properties of the synthesized biohybrid were characterized, and the effect of various conditions on the CH₄ production of the biohybrid was also investigated. It was revealed that the CdS dosage, pH, cysteine, and concentration of sodium bicarbonate were key factors influencing the performance of the biohybrid. Additionally, it was observed that CH₄ was produced under both light and dark conditions. Finally, the mechanisms involved in the CH₄ production by the biohybrid under light and dark conditions were discussed.

Methanosarcina barkeri–cadmium sulfide biohybrid can effectively convert carbon dioxide to methane, achieving biogas upgrading.