Photobiocatalytic Solar Fuel and Solar Chemical Conversion: Sufficient Activity and Better Selectivity

Converting renewable solar energy into fuel and valueadded chemicals is a long-term objective of researchers and a promising solution for the energy crisis, environmental pollution, and global warming. Photosynthetic biohybrid systems (PBS) are receiving more and more attention, because they take advantage of both artificial semiconductor materials (high solar conversion efficiency) and living cells (high product selectivity) and, hence, enable the efficient capture and storage of solar energy in chemical bonds. In this perspective, we summarize findings on whole cell-semiconductor nanomaterial hybrid systems regarding solar driven H-2 evolution, CO2 reduction, and N-2 fixation in the past years. First, hydrogen yield and duration of different H-2 evolution PBS are compared, and various assembly modes and electron transfer pathways are also introduced. Then, we evaluate the performance of CO2 reduction PBS based on the type of multicarbon products, as well as the challenges encountered by researchers and corresponding tentative solutions. Finally, we focus on photobiocatalytic N-2 fixation, while introducing diverse N-2 fixing microorganisms. Overall, obvious achievements have been made in photobiocatalytic solar fuel and solar chemical conversion in recent years, as innovative PBSs are constructed, molecular mechanisms are explored, and tentative solutions are proposed for scaleup, but huge challenges still exist. In the future, we should focus on revealing the interfacial electron transfer mechanisms and cellular energy allocation in order to significantly promote the solar-to-chemical conversion efficiency and meet the practical requirements.