Efficient Photoelectron Capture by Ni Decoration in Methanosarcina barkeri-CdS Biohybrids for Enhanced Photocatalytic CO2-to-CH4 Conversion

Semi-artificial photosynthesis (biohybrid) provides an intriguing opportunity for efficient CO2-to-CH4 conversion. However, creating a desirable semiconductor in biohybrids remains a great challenge. Here, by doping Ni into CdS nanoparticles, we have successfully developed the Methanosarcina barkeri-Ni:CdS biohybrids. The CH4 yield by the M. barkeri-Ni(0.75%):CdS biohybrids was approximately 250% higher than that by the M. barkeri-CdS biohybrids. The suitable Ni dopants serve as an effective electron sink, which accelerates the photoelectron transfer in biohybrids. In addition, Ni doping changes the metabolic status of M. barkeri and results in a higher expression of a series of proteins for electron transfer, energy conversion, and CO2 fixation. These increased proteins can promote the photoelectron capture by M. barkeri and injection into cells, which trigger a higher intracellular reduction potential to drive the reduction of CO2 to CH4. Our discovery will offer a promising strategy for the optimization of biohybrids in the solar-to-chemical conversion.