Cysteine-Cystine Photoregeneration for Oxygenic Photosynthesis of Acetic Acid from CO2 by a Tandem Inorganic-Biological Hybrid System

Tandem Z-scheme approaches to solar-to-chemical production afford the ability to independently develop, and optimize reductive photocatalysts for CO2 reduction to multicarbon compounds and Oxidative photocatalysts for O-2 evolution. To connect the two redox processes, molecular redox shuttles, reminiscent of biological electron transfer, offer an additional level-of facile chemical tunability that eliminates the need for solid-state semiconductor junction engineering. In this work, we report a tandem inorganic-biological hybrid system capable of-oxygenic photosynthesis of acetic add from CO2. The photoreductive catalyst consists of the bacterium Moorella thermoacetica self-photosensitized with CdS nanoparticles at, the expense of the thiol amino acid cysteine (Cys) oxidation to the disulfide form cystine (CySS). To regenerate the CySS/Cys redox shuttle, the photooxidative catalyst, TiO2 loaded with cocatalyst phthalocyanine (MnPc), couples water oxidation to CySS reduction. The combined system M. thermoacetica-CdS + TiO2-MnPc demonstrates a potential biomimetic approach to complete oxygenic solar-to-chemical production.