Chitosan/graphene complex membrane for polymer electrolyte membrane fuel cell: A molecular dynamics simulation study. (30th September 2020)

• Record Type: Journal Article
• Authors: Zhang, Hong-Ping; Gandhi, Neha S.; Gu, Yuantong; Zhang, Yaping; Tang, Youhong
• Is Part Of: International journal of hydrogen energy. Volume 45:Number 48(2020)
• Page Start: 25960
• Page End: 25969
• Publication Date: 2020-09-30
• Subjects: Chitosan -- Graphene -- Molecular dynamics simulation -- PEMFC -- Proton conductivity; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2020.03.124
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Chitosan has been considered attractive in polymer electrolyte membrane fuel cells (PEMFCs) due to its excellent film forming and fuel barrier properties. Reflecting the limitation of its low proton conductivity, various materials were used to improve the proton conductivity of chitosan, through combination with inorganic materials like graphene oxide. We present an ideal molecular model for bio-nanocomposites and their mechanism of proton conductivity in PEMFCs. In this study, the diffusion behavior of hydronium ions in chitosan/graphene complex systems at various temperatures, concentrations and pH values were studied systematically using 3 ns long molecular dynamics (MD) simulations with an aim to provide the mechanisms of proton conductivity of chitosan/graphene composite at an atomistic scale. Various amounts of water content (10%, 20%, 30% and 40%), pH values (achieved by adjusting the protonation degree of amino groups of chitosan by 20%, 40%, 60%, 80% and 100%) and numbers of graphene sheets (1, 2, and 3) were considered during MD simulations at 4 temperatures (298 K, 320 K, 340 K and 360 K). Our results indicated that the chitosan system containing 40% water was the most suitable polymer electrolyte membrane and temperature was a key factor affecting diffusion proton. Adding graphene to the chitosan system and adjusting the pH values of chitosan were demonstrated to have a significant effect on improving the proton conductivity of the membrane. Highlights: Molecular model for bio-nanocomposites and their mechanism of proton conductivity in PEMFCs is presented in this work. Diffusion behavior of hydronium ions in chitosan/graphene complex systems was studied using 3 ns long MD simulations. Mechanisms of proton conductivity of chitosan/graphene composite were explored at an atomistic scale. Adding graphene and adjusting pH are efficient ways for improving the proton conductivity of membrane.