Gao Jun, Meng Yuqing, Benton Allen, He Jian, Jacobsohn Luiz G, Tong Jianhua, Brinkman Kyle S
Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634, United States.
Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634, United States.
ACS Appl Mater Interfaces. 2020 Aug 26;12(34):38012-38018. doi: 10.1021/acsami.0c08120. Epub 2020 Aug 11.
Understanding the mechanisms of proton conduction at the interface of materials enables the development of a new generation of protonic ceramic conductors at low temperatures (<150 °C) through water absorption and proton transport on the surface and grain boundaries. Conductivity measurements under Ar-3% HO and Ar-3% DO revealed a σ(HO)/σ(DO) ratio of approximately 2, indicating a hopping-based mechanism for proton conduction at the interface. Raman spectroscopy was performed on water-saturated, porous, and nanostructured TiO membranes to directly observe the isotope exchange reactions over the temperature range of 25 to 175 °C. The behavior of the isotope exchange reactions suggested a Grotthuss-type proton transport and faster isotope exchange reactions at 175 °C than that at 25 °C with a corresponding activation energy of 9 kJ mol. The quantitative and mechanistic kinetic description of the isotope exchange process via Raman spectroscopy represents a significant advance toward understanding proton transport mechanisms and aids in the development of high-performance proton conductors with rapid surface exchange coefficients of importance to contemporary energy conversion and storage material development. In addition, new material systems are proposed, which combine interface and bulk effects at low temperatures (<150 °C), resulting in enhanced proton transport through interfacial engineering at the nanoscale.
了解材料界面处质子传导的机制，有助于通过表面和晶界的吸水及质子传输，开发新一代低温（<150°C）质子陶瓷导体。在Ar - 3% H₂O和Ar - 3% D₂O条件下的电导率测量显示，σ(H₂O)/σ(D₂O)比值约为2，表明界面处质子传导基于跳跃机制。对水饱和、多孔且纳米结构的TiO₂膜进行拉曼光谱分析，以直接观察25至175°C温度范围内的同位素交换反应。同位素交换反应的行为表明存在Grotthuss型质子传输，且在175°C时的同位素交换反应比25°C时更快，相应的活化能为9 kJ/mol。通过拉曼光谱对同位素交换过程进行定量和机理动力学描述，是理解质子传输机制的一项重大进展，有助于开发具有快速表面交换系数的高性能质子导体，这对当代能量转换和存储材料的发展至关重要。此外，还提出了新的材料体系，该体系在低温（<150°C）下结合了界面和体相效应，通过纳米尺度的界面工程增强了质子传输。
