Molecular dynamics simulation on the effect of water uptake on hydrogen bond network for OH− conduction in imidazolium-g-PPO membrane. (5th February 2019)

• Record Type: Journal Article
• Authors: Huo, Jun; Qi, Wenxu; Zhu, Hongda; Yang, Boyun; He, Gaohong; Bao, Junjiang; Zhang, Xiaopeng; Yan, Xiaoming; Gao, Li; Zhang, Ning
• Is Part Of: International journal of hydrogen energy. Volume 44:Number 7(2019)
• Page Start: 3760
• Page End: 3770
• Publication Date: 2019-02-05
• Subjects: Imidazolium-g-PPO membrane -- OH− conduction -- Hydrogen bonding -- Water uptake -- Molecular dynamics simulation; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2018.12.090
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: OH − conduction involved in the hydrophilic channel of anion exchange membrane strongly depends on the water uptake. To investigate the effect of water uptake on the hydrogen bond network for OH − conduction, a series of molecular dynamics simulations based on all-atom force field were performed on the hydrated imidazolium-g-PPO membranes with different water uptakes. The systems were well verified by comparing the membrane density and OH − conductivity with previous experiments. By means of local structural properties and pair-potential energy, reasonable hydrogen bond criteria were determined to describe the hydrogen bond network confined in the membrane. Increasing water uptake enhances the hydration structures of water and OH −, and facilitates the reorganization of the hydrogen bond network. Water and OH − are nearly saturated with water when the water uptake reaches λ = 10, where well-connected hydrogen bond network is produced. Further increasing water uptake has much less contribution to improving the hydrogen bond network, but inevitably swells the membrane channel. This work provides a molecular-level insight into the effect of water uptake on the hydrogen bonding structures and dynamics of OH − and water confined in the imidazolium-g-PPO membrane. Highlights: We investigated Im-g-PPO membrane with various water uptakes. We explored the effect of water uptake on the hydrogen bond network in the membrane. Topology and connectivity of the hydrophilic membrane channel are closely related with water uptake. Hydrogen bond network in low-hydrated membrane could be much more regulated by water uptake than high-hydrated membrane. We find the Im-g-PPO membrane with the water uptake of λ = 10 has the superior performance.