Solar energy is a clean and sustainable resource that is considered an alternative to fossil fuels. In green plants, photosynthesis occurs through fast charge separation upon solar energy absorption by energy transduction complexes. Many researchers have attempted to design artificial photosynthetic systems for the conversion of solar energy to chemical fuels using CO2 as a carbon source and water as an electron donor. In the context of artificial solar-to-fuel conversion, the natural photosynthesis that converts solar energy into high energy chemicals remains a target model for scientists to set forth their goal. Biocatalysis is a promising route for environmentally friendly synthesis of chemicals because of a variety of enzymes capable of converting substrates with high specificity under mild conditions. In this work, we demonstrate the development of all silicon-based photoelectrochemical (PEC) cell for solar driven biocatalytic conversion of CO2 to formate using water as an electron source under visible light irradiation. A new platform integrates an all-silicon-based PEC cell with a biocatalyst (i.e., FDH from Thiobacillus sp., TsFDH) for sunlight-driven CO2 reduction to formate. Our results revealed that sequential transfer of electrons, extracted via water oxidation reaction at a 3-jn-Si/ITO/CoPi photoanode to H-SiNW photocathode, and further to TsFDH, lead to effective formate production with Faradaic efficiency of 16.18%, while no formate was synthesized directly at the H-SiNW photocathode alone. The formate yield increased significantly through the integrated PEC system, which continuously regenerated NADH for TsFDH-catalyzed CO2 reduction. Moreover, the silicon-based biocatalytic system could be operated under natural sunlight using solar tracking module, which is a highly desirable result for practical utility of the PEC as a sustainable solar energy harvesting system. The current study suggests that the deliberate integration of biocatalysis to a PEC platform can provide an opportunity to synthesize valuable chemicals with the use of earth-abundant materials and sustainable resources. With our biocatalysis-integrated PEC platform, further engineering of enzymes and photoelectrode materials would provide more opportunity to improve efficiency of the system.

Silicon-based photoelectrochemical cell for enzymatic CO2 conversion

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.