Electrochemical Characterization of Chitosan Films As Proton-Conducting Layers for Bioprotonic Devices

Monday, 2 October 2017: 11:00
National Harbor 5 (Gaylord National Resort and Convention Center)
J. Pietron (U.S. Naval Research Laboratory), J. T. Robinson (Naval Research Laboratory), B. Blue (University of Central Florida), E. Josberger, Y. Deng (University of Washington), and M. Rolandi (University of California at Santa Cruz)
We describe the lithographic fabrication, electrochemical characterization, and modeling of bioprotonic conduction channels, using a proof-of-concept material, chitosan, as a proton-conducting film deposited onto palladium electrodes. Linear sweep voltammetry (LSV) has been used to probe both the electrochemical generation of protons from H2 feed gas and the conduction of those protons through channels fabricated with different molecular weights of chitosan. Higher MW chitosan produces channels with significantly higher proton conductivity. Additionally, rigorous evaluation of the LSV data by both standard electroanalytical expressions and by digital simulation reveal that proton generation at the PdHx electrodes varies substantially between devices of different geometries. Multiple hydrogen oxidation reaction (HOR) pathways are operational at some devices, while at others a single pathway dominates. The analyses reveal the sensitivity of proton-generation kinetics on the chitosan/PdHxinterface, and furthermore, to the geometry of the device itself. Simulations of the proton conductivity in the chitosan membrane, however, yields excellent agreement between devices. Direct measurement of proton conductivity using electrochemical impedance spectroscopy further corroborates this agreement, yielding proton conductivity values nearly identical to those determined by analysis of the LSV results.

This work is supported by the Office of Naval Research.