4.8 Article

Conduction Mechanism in Graphene Oxide Membranes with Varied Water Content: From Proton Hopping Dominant to Ion Diffusion Dominant

期刊

ACS NANO
卷 16, 期 9, 页码 13771-13782

出版社

AMER CHEMICAL SOC
DOI: 10.1021/acsnano.2c00686

关键词

graphene oxide membrane; neutron scattering; proton hopping; ion diffusion; hydrogen-bond network

资金

  1. Natural Science Foundation of China [31630002, 11974239, 11904224]
  2. National Science Foundation [DMR-2010792]

向作者/读者索取更多资源

This study reveals the conductive behavior of a two-dimensional layered proton conductor and finds that the conduction mechanism changes with different water content. The presence of water molecules has a significant impact on the overall conductivity. The study validates the existence of different conduction mechanisms and provides an optimization strategy.
Proton conductors, particularly hydrated solid membranes, have various applications in sensors, fuel cells, and cellular biological systems. Unraveling the intrinsic proton transfer mechanism is critical for establishing the foundation of proton conduction. Two scenarios on electrical conduction, the Grotthuss and the vehicle mechanisms, have been reported by experiments and simulations. But separating and quantifying the contributions of these two components from experiments is difficult. Here, we present the conductive behavior of a two-dimensional layered proton conductor, graphene oxide membrane (GOM), and find that proton hopping is dominant at low water content, while ion diffusion prevails with increasing water content. This change in the conduction mechanism is attributable to the layers of water molecules in GOM nanosheets. The overall conductivity is greatly improved by forming one layer of water molecules. It reaches the maximum with two layers of water molecules, resulting from creating a complete hydrogen-bond network within GOM. When more than two layers of water molecules enter the GOM nanosheets, inducing the breakage of the ordered lamellar structure, protons spread in both in-plane and out-of-plane directions inside the GOM. Our results validate the existence of two conduction mechanisms and show their distinct contributions to the overall conductivity. Furthermore, these findings provide an optimization strategy for the design of realizing the fast proton transfer in materials with water participation.

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