Hydrogen Dynamics in Hydrated Chitosan by Quasi-Elastic Neutron Scattering

Area of Science:

• Materials Science
• Electrochemistry
• Biopolymers

Background:

• Chitosan is a sustainable, biocompatible polymer with potential as a proton-conducting electrolyte.
• Efficient proton transport is critical for fuel cell performance.

Purpose of the Study:

• To elucidate the microscopic mechanisms of proton transport in hydrated chitosan.
• To investigate the role of water and chitosan's hydrogen atoms in proton conduction.

Main Methods:

• Quasi-elastic neutron scattering (QENS) was employed to study proton dynamics.
• Temperature-dependent diffusion constants and activation energies were analyzed.

Main Results:

• Hydration water in chitosan exhibits slower, jump-diffusion motion compared to bulk water.
• Proton transport in chitosan involves jump-diffusion of hydrogen atoms, similar to water.
• Activation energy for hydrogen jump-diffusion in chitosan (0.30 eV) aligns with conductivity data (0.38 eV).

Conclusions:

• Proton conductivity in chitosan arises from dissociated hydrogen atoms protonating hydration water.
• QENS provides microscopic insights into proton transport mechanisms in chitosan-based electrolytes.