title: Stereochemistry-Dependent Proton Conduction in Proton Exchange Membrane Fuel Cells.
abstract: Graphene oxide (GO) is impermeable to H2 and O2 fuels while permitting H(+) shuttling, making it a potential candidate for proton exchange membrane fuel cells (PEMFC), albeit with a large anisotropy in their proton transport having a dominant in plane (σIP) contribution over the through plane (σTP). If GO-based membranes are ever to succeed in PEMFC, it inevitably should have a dominant through-plane proton shuttling capability (σTP), as it is the direction in which proton gets transported in a real fuel-cell configuration. Here we show that anisotropy in proton conduction in GO-based fuel cell membranes can be brought down by selectively tuning the geometric arrangement of functional groups around the dopant molecules. The results show that cis isomer causes a selective amplification of through-plane proton transport, σTP, pointing to a very strong geometry angle in ionic conduction. Intercalation of cis isomer causes significant expansion of GO (001) planes involved in σTP transport due to their mutual H-bonding interaction and efficient bridging of individual GO planes, bringing down the activation energy required for σTP, suggesting the dominance of a Grotthuss-type mechanism. This isomer-governed amplification of through-plane proton shuttling resulted in the overall boosting of fuel-cell performance, and it underlines that geometrical factors should be given prime consideration while selecting dopant molecules for bringing down the anisotropy in proton conduction and enhancing the fuel-cell performance in GO-based PEMFC.
authors.affiliation: Department of Chemistry and Centre for Energy Science, Indian Institute of Science Education and Research (IISER) Pune , Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
authors.forename: Ravikumar
authors.initials: R
authors.lastname: Thimmappa
authors.affiliation: Department of Chemistry and Centre for Energy Science, Indian Institute of Science Education and Research (IISER) Pune , Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
authors.forename: Mruthyunjayachari Chattanahalli
authors.initials: MC
authors.lastname: Devendrachari
authors.affiliation: Department of Chemistry and Centre for Energy Science, Indian Institute of Science Education and Research (IISER) Pune , Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
authors.forename: Alagar Raja
authors.initials: AR
authors.lastname: Kottaichamy
authors.affiliation: Department of Chemistry and Centre for Energy Science, Indian Institute of Science Education and Research (IISER) Pune , Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
authors.forename: Omshanker
authors.initials: O
authors.lastname: Tiwari
authors.affiliation: Department of Chemistry and Centre for Energy Science, Indian Institute of Science Education and Research (IISER) Pune , Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
authors.forename: Pramod
authors.initials: P
authors.lastname: Gaikwad
authors.affiliation: Department of Chemistry and Centre for Energy Science, Indian Institute of Science Education and Research (IISER) Pune , Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
authors.forename: Bhuneshwar
authors.initials: B
authors.lastname: Paswan
authors.affiliation: Department of Chemistry and Centre for Energy Science, Indian Institute of Science Education and Research (IISER) Pune , Dr. Homi Bhabha Road, Pashan, Pune 411008, India.
authors.forename: Musthafa Ottakam
authors.initials: MO
authors.lastname: Thotiyl