Department of Chemistry, Massachusetts Institute of Technology , 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
J Am Chem Soc. 2018 Feb 14;140(6):2016-2019. doi: 10.1021/jacs.7b12784. Epub 2018 Feb 6.
The mechanism of proton conductivity in porous solids (i.e., Grotthuss or vehicular) is related to the structure and chemical environment of the pores. Direct observation of structure-function relationships is difficult because state-of-the-art solid proton conductors are often amorphous. Here, we present a systematic elucidation of two distinct proton transport pathways within MIT-25, a mesoporous metal-organic framework that exhibits parallel channels of ∼27 Å and ∼4.5 Å width. We characterize transport through these pores using temperature- and humidity-dependent proton conductivity measurements and density functional theory. Through control of vapor pressure we are able to sequentially fill the small and large pores, promoting proton conductivity with distinct activation energies at low and high relative humidity, respectively.
多孔固体（即 Grotthuss 或车载）中质子传导的机制与孔的结构和化学环境有关。由于最先进的固体质子导体通常是非晶态的，因此很难直接观察结构-功能关系。在这里，我们系统地阐明了 MIT-25 中两种不同的质子传输途径，MIT-25 是一种具有约 27Å 和 4.5Å 宽度的平行通道的中孔金属有机骨架。我们使用温度和湿度依赖的质子电导率测量和密度泛函理论来描述这些孔中的传输。通过控制蒸气压，我们能够依次填充小孔和大孔，分别在低和高相对湿度下促进具有不同激活能的质子传导。
