Collaborative Research: Development of Self-biased Solar Microbial Electrolysis Cells

103422Li智能价值该提案的目标是开发一种太阳能驱动的微生物电解电池(太阳能MEC)，该电池由半导体纳米线阵列光电阴极和细菌定植阳极组成，可将溶解的有机物转化为氢气。溶解的有机物可以来自废流或可再生的生物资源。微生物电生氢可能比细菌发酵产氢具有更高的产氢量、更高的效率和底物多样性。然而，传统MEC设备中的微生物电加氢过程需要额外的能量输入，即外部偏置，通常在0.2-1.0V的范围内，以克服制氢的吸热障碍，这增加了操作成本并限制了设备的效率。太阳能驱动的MEC设计采用了半导体纳米线阵列光电阴极，以帮助电子从细菌定植的阳极转移，并为制氢提供光伏。具体地说，在照明时，半导体导带上的光生电子将质子还原为氢，而价带上的光生空穴与阳极上产电细菌细胞的电子重新结合。半导体纳米线阵列光电阴极结构具有比表面积大、光吸收强、电子扩散长度短等优点，旨在提高阴极的光吸收和质子还原能力。将系统地研究基本问题，如生物阳极和光电阴极的材料和结构，以及细菌/阳极界面上的电子传递。研究将提出优化装置配置的方法，最终目标是展示一种高效和自我维持的太阳能MEC。这项建议中开发的新设备概念可以应用于其他用于能量转换的生物-无机混合设备，如微生物燃料电池。广泛影响拟议的教育计划将整合加州大学圣克鲁斯分校(UCSC)和威斯康星大学密尔沃基分校(UWM)的多学科研究和教育活动。将开发利用微生物电解槽(MEC)研究技术的实验室课程的新讲义和实验。例如，UCSC将开发一项新的MEC实验并将其用于本科物理化学实验室课程，基于微生物燃料电池的课程材料将被纳入UWM大学的一门本科环境工程课程。研究经验将提供给来自代表性不足群体的本科生，他们分别通过NSF赞助的夏季本科生研究奖学金(SURF)和NIH赞助的Access计划招募。SURF计划针对的是大学生，而Access计划针对的是圣克鲁斯和圣何塞地区社区学院水平的学生。通过加州大学洛杉矶分校现有项目的协调，将为通过当地高中招收的学生提供高中生的研究经验。教育推广活动的重点是为微生物燃料电池开发一个网站，其内容是为普通公众和高中观众设计的，包括图形、卡通和视频。

1034222LiIntellectual MeritThe objective of the proposal is to develop a solar-driven microbial electrolysis cell (solar MEC) that consists of a semiconductor nanowire-arrayed photocathode and a bacteria-colonizing anode to convert dissolved organic matter to hydrogen gas. The dissolved organic matter could be from waste streams or renewable bio-based resources. Microbial electrohydrogenesis may have several advantages over bacterial fermentation for hydrogen production, such as higher hydrogen yield, higher efficiency, and substrate diversity. However, the microbial electrohydrogenesis process in conventional MEC devices requires additional energy input in terms of an external bias, typically in a range of 0.2-1.0 V, to overcome the endothermic barrier for hydrogen generation, which adds operation cost and limits the device efficiency. The solar-driven MEC design adopts a semiconductor nanowire-arrayed photocathode to assist electron transfer from a bacteria-colonizing anode and provide photovoltage for hydrogen generation. Specifically, upon illumination, the photogenerated electrons at the semiconductor conduction band reduce protons to hydrogen, while the photogenerated holes at valence band recombine with the electrons from electrogenic bacteria cells at the anode. The semiconductor nanowire-arrayed photocathode structure offers large surface area, strong light absorption and short electron diffusion length, and is designed to enhance the light absorption and proton reduction at the cathode. Fundamental issues, such as the bioanode and photocathode materials and structure, as well as electron transfer at the bacteria/anode interface, will be systematically studied.The research will suggest approaches to optimize device configuration with the ultimate goal of demonstrating an efficient and self-sustained solar-MEC. The new device concept developed in this proposal can be applied to other bio-inorganic hybrid devices for energy conversion applications, such as microbial fuel cells.Broader ImpactsThe proposed education plan will integrate multidisciplinary research and educational activities at University of California Santa Cruz (UCSC) and University of Wisconsin at Milwaukee (UWM). New lecture material and experiments for laboratory courses will be developed that will make use of the microbial electrolysis cell (MEC) research techniques. For example, a new MEC experiment will be developed and used in an undergraduate physical chemistry laboratory class at UCSC, and course materials based on microbial fuel cells will be incorporated into an undergraduate environmental engineering course at UWM. Research experiences will be provided to undergraduate students from under-represented groups, recruited through NSF-sponsored Summer Undergraduate Research Fellowship (SURF) and NIH-sponsored ACCESS programs respectively. The SURF program targets college/university students, while the ACCESS program targets students at the community college level in the Santa Cruz and San Jose regions. Research experiences for high school students, coordinated through existing programs at UCSC, will be provided for students recruited through local high schools. Educational outreach activities focus on development of a website for microbial fuel cells, with content designed for the general public and high school audiences that includes graphics, cartoons, and videos.