CAREER: Transport and Stability in Biocatalytic Fuel Cells

这一职业计划的任务是(1)创造电极结构，以提高高功率密度生物燃料电池中实施的酶生物电催化剂的反应性和稳定性，以及(2)将这些装置和其他燃料电池装置整合到广泛的教育和宣传中，以在社区、学校和大学推广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有可能在传统燃料电池和电池技术失败的情况下提供电力。虽然氧化还原酶的关键特性，包括选择性和室温活性，可以在生理植入型燃料电池中得到利用，但生物催化电极的低催化活性和低稳定性阻碍了当前生物燃料电池的实施。该计划解决了这两个问题。被研究的模型体系是由涂有漆酶的交联型静电加合物的多孔炭、氧还原酶和电子导电氧化还原聚合物水凝胶组成的氧还原电极。设计多孔载体及其与介体/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。由碳纳米管或电纺碳纳米纤维组成的孔隙率接近95%且纤维直径在1微米或更小的支撑结构将评估对酶-水凝胶加合物催化活性的影响。气体扩散电极将被开发，它利用气相中的高速氧气传质来进一步提高电极的催化活性。稳定性的问题将通过溶胶-凝胶、气凝胶和湿凝胶工艺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。将使用碳纳米管和氧化还原聚合物介体实现透过薄膜的电子调节。燃料电池能否成功推向市场取决于合格的科学家和工程师的可用劳动力，以及能源消费者对燃料电池的接受程度。此外，整个化学工程学科目前正在从面向过程的设计过渡到化学产品的设计，燃料电池就是一个很好的例子。这一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。教育计划将包括：(A)针对贫困高中生的能源系统课后社区实践课程；(B)为一年级工程学学生提供的增强的化学工程入门课程，通过逆向工程和基于团队的设计项目介绍产品设计的概念；(C)为毕业生和大四本科生提供高级电化学能源系统课程；(D)为中学生、本科生和研究生提供身临其境的研究培训。这一计划提高了对生物燃料电池设计的知识和理解，同时促进了能源系统背景下的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.