Abstract:

Biophotovoltaics (BPV) is an environmentally friendly power generation technology that uses self-renewing photosynthetic microorganisms to absorb solar energy and convert it into electricity. BPV is an energy transduction process that involves photochemical reactions occurring in photosynthetic cells, extracellular electron transfer occurring at cell-electrode interfaces, and electrical current generation occurring in bioelectrochemical systems. However, the intrinsic light-dependent exoelectrogenic activity of photosynthetic microorganisms is extremely weak, which hampers the electrical outputs of BPV systems. In recent years, different electron transfer strategies have been developed to more efficiently extract photosynthetic electrons. These include the exogenous electron mediators-based strategy, conductive nanomaterials-based strategy, and synthetic microbial consortia-based strategy. Among them, the exogenous electron mediators-based strategy could improve the instantaneous efficiency; however, the improvement tends to be unstable. The conductive nanomaterials-based strategy can hardly achieve a targeted distribution of nanomaterials, and the cost of nanomaterials is also an issue. The synthetic microbial consortia-based strategy shows great potential in enhancing the power output and prolonging the lifetime of BPV systems. This review gives an overview of the development history of BPV technology, and summarizes the fundamental principles, advantages, and disadvantages of different strategies for electron extraction. Moreover, we also discuss different biotic/abiotic approaches that have been taken to improve the electrical outputs of BPV systems. These approaches mainly include broadening available photosynthetic materials, remolding intracellular metabolism and electron transfer, developing advanced electrodes with new materials and structures, and designing high-performance devices with novel configurations. Furthermore, we envision the real-world applications of BPV technology in the future, e.g., running small electronic sensors on environmental and agricultural internet of things, driving hydrogen production, and even being applied in space scientific research. To this end, the scale-up of BPV systems is required to amplify the output voltage and output power. Lastly, we propose that it is crucial to understand the molecular mechanisms behind the exoelectrogenesis of photosynthetic microorganisms in order to facilitate the advancement of BPV technology. One possible approach is to utilize synthetic biology to reconstruct transmembrane molecular wires using multi-heme cytochromes or nanowires.

Key words: biophotovoltaics, photosynthetic electron transfer, extracellular electron transfer, synthetic microbial consortia

摘要：

生物光伏利用可自我更新的光合细胞作为光电转化材料，是一种环境友好的新型太阳能利用技术。生物光伏包括光合细胞中的光化学反应、细胞与电极间的跨膜电子传递、生物电化学系统中的电流产生三个核心过程。光合细胞的天然跨膜电子传递效率较低，成为了生物光伏电能输出的主要限制因素。针对这一问题，近年来研究人员发展了一些新的跨膜电子传递策略，包括基于外源电子载体的间接电子传递、基于导电纳米材料的杂合电子传递以及基于合成微生物组的定向电子传递。本文简要回顾了生物光伏的发展历史，综述了不同电子传递策略的基本原理、优势和不足，总结了提高生物光伏电能输出的研究进展。最后，探讨了生物光伏在高功率电子器件领域的应用前景，及如何利用合成生物技术增强跨膜电子传递效率，以期加速生物光伏的发展。

关键词: 生物光伏, 光合电子传递, 跨膜电子传递, 合成微生物组