CAREER: Transport and Stability in Biocatalytic Fuel Cells

这个职业项目的使命是(1)创造电极结构，提高酶生物电催化剂的反应性和稳定性，用于高功率密度生物燃料电池；(2)将这些和其他燃料电池设备整合到广泛的教育和推广中，以促进社区、学校和大学的工程产品设计和新能源系统的概念。生物催化燃料电池技术具有在传统燃料电池和电池技术失效的情况下提供电力的潜力。虽然氧化还原酶的关键特性，包括选择性和室温活性可以在生理可植入燃料电池中利用，但目前生物燃料电池的实施受到低催化活性和生物催化电极低稳定性的阻碍。这个程序解决了这两个问题。所研究的模型系统是一个氧还原电极，由涂有漆酶、氧还原酶的交联静电加合物的多孔碳和导电氧化还原聚合物水凝胶组成。设计多孔支架及其与介质/酶水凝胶的界面以最大化凝胶分布将提高酶的利用率并增加电流密度。孔隙率接近95%、纤维直径小于等于1微米的支撑结构（由碳纳米管或静电纺碳纳米纤维组成）对酶-水凝胶加合物催化活性的影响将被评估。利用气相中高速率的氧传质，进一步提高电极催化活性的气体扩散电极将得到发展。稳定性问题将通过溶胶-凝胶、气凝胶和湿凝胶处理将生物催化剂封装在多孔二氧化硅或其他金属氧化物中来解决。使用碳纳米管和氧化还原聚合物介质可以实现透膜电子介质。燃料电池能否成功推向市场，取决于是否有合格的科学家和工程师，以及能源消费者是否接受燃料电池。此外，整个化学工程学科目前正经历着从过程导向设计到化学产品设计的转变，燃料电池就是一个很好的例子。这个职业计划通过强调新能源系统和工程产品设计的教育活动来满足这些需求。教育方案将包括(a)为处境不利的高中学生提供以社区为基础的课后能源系统实践方案；(b)为一年级工程学生开设强化的化学工程入门课程，通过逆向工程和小组设计项目介绍产品设计的概念；(c)为毕业生和高年级本科生开设的高级电化学能源系统课程；(d)对中学生、本科生和研究生进行沉浸式研究训练。该计划提高了对生物燃料电池设计的认识和理解，同时促进了能源系统背景下化学产品工程的培训和学习。

The mission of this CAREER program is (1) the creation of electrode structures that enhance the reactivity and stability of enzyme bioelectrocatalysts as implemented in high power-density biofuel cells, and (2) the integration of these and other fuel-cell devices into a broad spectrum of education and outreach to promote concepts of engineering product design and new energy systems in communities, schools, and universities. Biocatalytic fuel cell technology has the potential to provide electrical power in conditions where conventional fuel cell and battery technologies fail. While key characteristics of redox enzymes, including selectivity and room temperature activity can be exploited in, for example, physiologically implantable fuel cells, implementation of current biofuel cells is hindered by low catalytic activity and low stability of biocatalytic electrodes. This program addresses both of these issues. The model system to be studied is an oxygen-reducing electrode comprised of porous carbon coated with a crosslinked electrostatic adduct of laccase, an oxygen-reducing enzyme, and an electron-conducting redox polymer hydrogel. Engineering the porous support and its interface with the mediator/enzyme hydrogel to maximize gel distribution will improve enzyme utilization and increase current density. Support structures with porosities near 95% and fiber diameter of order 1 micron or less, consisting of carbon nanotubes or electrospun carbon nanofibers, will be evaluated for impact on catalytic activity of the enzyme-hydrogel adduct. Gas-diffusion electrodes will be developed which take advantage of high-rate oxygen mass transfer in the gas phase to further increase electrode catalytic activity. The issue of stability will be addressed by encapsulation of the biocatalysts in porous silica or other metal oxide by means of sol-gel, aerogel, and wet gel processing. Through-film electron mediation will be enabled using carbon nanotubes and redox polymer mediators. Successful introduction of fuel cells to the marketplace depends on an available workforce of qualified scientists and engineers, and the acceptance of fuel cells by energy consumers. Moreover, the chemical engineering discipline as a whole is currently undergoing a transition from process-oriented design to design of chemical products, of which fuel cells are an excellent example. This CAREER program addresses these needs through educational activities emphasizing new energy systems and engineering product design. Educational programs will include (a) A community-based, hands-on after school program in Energy Systems for disadvantaged high-school students; (b) An enhanced introductory Chemical Engineering course for first-year engineering students presenting the concepts of product design through reverse-engineering and team-based design projects; (c) An advanced Electrochemical Energy Systems course for graduates and senior undergraduates; (d) Immersive research training for secondary, undergraduate, and graduate students. This program advances the knowledge and understanding of biofuel cell design while promoting training and learning of chemical product engineering in the context of energy systems.