Conduction Mechanism in Graphene Oxide Membranes with Varied Water Content: From Proton Hopping Dominant to Ion Diffusion Dominant
Conduction Mechanism in Graphene Oxide Membranes with Varied Water Content: From Proton Hopping Dominant to Ion Diffusion Dominant
复制标题
不同含水量氧化石墨烯膜的传导机制：从质子跳跃主导到离子扩散主导
DOI：
10.1021/acsnano.2c00686
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发表时间：
2022
期刊：
影响因子：
17.1
通讯作者：
Liang Hong
中科院分区：
文献类型：
--
作者：
Lei Zhang;Zhuo Liu;Chenxing Yang;Victoria García Sakai;Madhusudan Tyagi;Liang Hong
质子导体，特别是水合固体膜，在传感器、燃料电池和细胞生物系统中具有多种应用。揭示内在的质子转移机制对于建立质子传导的基础至关重要。实验和模拟已经报告了两种关于电传导的场景，即格罗特胡斯和车辆机制。但从实验中分离和量化这两种成分的贡献是很困难的。在这里，我们展示了二维层状质子导体氧化石墨烯膜（GOM）的导电行为，并发现质子跳跃在低含水量下占主导地位，而离子扩散随着含水量的增加而盛行。传导机制的这种变化归因于 GOM 纳米片中的水分子层。通过形成一层水分子，整体电导率大大提高。由于在 GOM 内创建了完整的氢键网络，它在两层水分子的情况下达到了最大值。当两层以上的水分子进入GOM纳米片时，导致有序层状结构的破坏，质子在GOM内部沿面内和面外方向扩散。我们的结果验证了两种传导机制的存在，并显示了它们对整体电导率的独特贡献。此外，这些发现为实现水参与材料中快速质子转移的设计提供了优化策略。
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.