基于纯菌与氢化酶的产氢生物阴极电化学系统的构建与电子传递机理的研究

Electrochemically assisted bio-hydrogen production is becoming a promising bioprocess technology in the field of energy and environmental engineering. Platinum based catalysts limit its economical feasibilty in the application. Biocathode, by replacing the Pt with microorganisms as cathode catalyst, can greatly enhance the feasibility of bioelectrochemical systems (BESs) and thus, arouse much research attention in recent years. However, the key issues in biocathode BES, such as identification of functional microbes and genes, electron transfer mechanism and electrode/enzymatic reaction kinetics, etc, are still not fully understood. The aim of this project is to study the biocatalyzed hydrogen evolution and the electron transfer mechanisms in biocathode BES. The research will be started by the establishment of biocathode with hydrogenase-containing pure strains and the diversity and abundance of hydrogenases in biocathodic hydrogen-producing bacteria, the catalytic characterisitics and electro-transfer mechanisms of biocathode BES will be studied by using molecular and bioelectrochemical approaches, respectively. A hydrogenase-based biomimic thin-film biocathode would then be prepared by using molecular self-assembly method to testify the electron transfer mode of biocathode BES and to evaluate the influencing factors (such as electrode potential and solution chemistry) for hydrogen evolution. These factors will be finally fed back to modulate the hydrogen production in pure-culture based biocathode BES. This study will provide invaluable information for the enhancement of hydrogen production and widen the application of biocathode BES in diversified energy and environmental field.

生物电化学系统（BESs）产氢已成为可再生能源与环境领域极有潜力的生物过程技术。贵金属Pt阴极催化剂限制了其经济可行性。生物阴极，即微生物代替Pt作为阴极催化剂，已成为BES领域研究的重要方向之一。然而，生物阴极BES的功能微生物与基因、电子传递机理以及电极/酶促反应动力学等关键科学问题尚未揭示。本研究拟在构建基于纯菌的产氢生物阴极BES基础上，通过分子生物学解析产氢微生物所含氢化酶种类与丰度；借助生物电化学分析手段，研究产氢生物阴极的催化特性以及电子传递方式，揭示电子传递机理；利用分子自组装等方法构建基于氢化酶仿生薄膜生物阴极，验证生物阴极电子传递方式，通过研究电极电势、溶液化学对仿生酶基生物阴极产氢影响因素，最终达到反馈调控基于纯菌的生物阴极BES产氢过程。本研究为揭示生物阴极电子传递、提高生物阴极BES产氢效能，扩展生物阴极多功能化应用提供理论依据。

本项目成功建立基于混合菌群、纯菌生物阴极 BES 体系，实现生物阴极产氢，并解析产氢生物阴极电子传递过程中重要氧化还原介体与生物阴极 BES 电子传递的机理。通过电化学微分脉冲扫描（DPV）手段和荧光光谱分析研究阴极生物的胞外电子传递（EET）机制，提出基于不同产氢微生物的生物阴极电子传递方式。研究发现，Geobacter和Desulfovibrio主要以直接电子传递的方式传递胞外电子，而Shewanella则以间接电子传递方式从阴极获得电子。通过荧光光谱分析发现，生物阴极在特定电势下出现的特征吸收峰，其中包括黄素及蒽醌类电子中介体，而且适当降低阴极电势可促进中介体的分泌，加速EET速率，提高产氢性能。探索溶液化学、电极电势对纯菌、混菌生物阴极析氢的影响因素。目前已将产氢生物阴极扩展至反硝化生物阴极的过程，并通过将 BES 产生的电能与光敏材料转化的光能耦合，建立无外接能量输入的自驱动微生物光电化学（MPEC）产能系统，实现产电制氢与能源回收，并提出MPEC光电极稳定性与析氢策略调控。在生物阴极研究的基础上，首次提出基于生物光电蛋白与无机半导体复合的生物-无机杂化p-n结概念。从理论上阐述了生物-无机杂化体系之间存在电子耦合质子传输机制，并证实了该机制是光电流与光稳定性增加的主因。本项目的研究成果为揭示生物阴极的电子传递机制及生物阴极的应用提供了理论的支持。