Control of ionomer thin films on metal surfaces is important for a range of electrodes used in electrochemical applications. In the case of enzymatic electrodes, ionic conduction is needed while enzymes also require shielding from regions of extreme pH that the ionomers help facilitate. In addition, increasing evidence suggests that control of ionomer-catalyst interactions is pivotal for efficient catalyst usage in electrochemical devices such as fuel cells and electrolyzers. Engineered proteins have emerged as powerful biomolecular tools in electrode assembly because binding sites and protein structures can be easily modulated by changing the amino acid sequence. However, no studies have been conducted showing proteins can be engineered to interact with ionomers, attach them to metal surfaces, and control their arrangement. Our lab has recently developed this technology, using an elastin-like protein to bind to metals, and bind to acidic and basic ionomer via a guest residue and ionic interactions. A quartz crystal microbalance with dissipation is utilized to provide detailed information on the thickness, packing density and binding behavior of the thin peptide and ionomer layers. Atomic force microscopy is used to understand the impact the peptide on ionomer phase separation. These thin layers are also analyzed using specular reflectance to reveal that the bound protein structures are maintained. Finally, our ionomer-organizing biomolecules are utilized to manufacture low-loaded, well dispersed electrolysis electrodes. Generally, our results demonstrate that engineered proteins are promising tools for ionomer control in electrode engineering.
Dr. Julie N. Renner started as an assistant professor at Case Western Reserve University in August 2016. Her group has multiple projects working at the interface of protein engineering and electrochemistry. She was recently awarded an Electrochemical Society Young Investigator Fellowship, sponsored by Toyota, for an innovative approach to electrode assembly. Prior to becoming a professor, Dr. Renner spent four years conducting industrial research at Proton OnSite, a world-leader in hydrogen generation via proton exchange membrane electrolysis. Her work was initially sponsored by a Small Business Postdoctoral Research Diversity Fellowship supported by the National Science Foundation under a grant to the American Society for Engineering Education. While there, she led projects in advanced electrode design and manufacturing, innovative membrane materials, and emerging electrochemical technologies such as microbial fuel cells and electrochemical ammonia generation. Prior to her work at Proton, she completed her thesis work as a NSF Graduate Research Fellow at the Purdue School of Chemical Engineering, where she specialized in designing, creating, and characterizing novel protein materials for cartilage tissue repair. As an undergraduate, she studied chemical engineering at the University of North Dakota, and obtained an Environmental Protection Agency (EPA) Greater Research Opportunities Fellowship to conduct research in microbial source tracking an EPA facility.