Fukui Yoko, Yoshida Yukihiro, Kitagawa Hiroshi, Jikihara Yohei
NBC Meshtec Inc., 2-50-3 Toyoda, Hino, Tokyo 191-0053, Japan.
Division of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan.
Phys Chem Chem Phys. 2023 Sep 27;25(37):25594-25602. doi: 10.1039/d3cp03546h.
A systematic study of Ag-ion conducting behavior in Ag-loaded porous materials was conducted over the entire sub-10 nm region for the first time. The effects of the pore diameter of mesoporous aluminas (MPAs) and the amount of silver iodide (AgI) loaded into MPAs were investigated using N gas adsorption/desorption, powder X-ray diffraction, differential scanning calorimetry, and electrochemical impedance spectroscopy measurements. Confinement of AgI in the mesoporous space lowers the phase transition temperature between the β/γ- and α-phases relative to that of bulk AgI. The AgI-loading into the MPAs with smaller pores led to a more significant decrease in the transition temperature, possibly because the smaller AgI nanoparticles in the pores must have a higher surface energy to stabilize the high-temperature phase. The room-temperature ionic conductivity exhibits a volcano-type dependence on the pore diameter with the highest value when AgI was loaded into MPA with a pore diameter of 7.1 nm (7.2 × 10 S cm at room temperature). Concerning the 7.1 nm-MPA, the room-temperature ionic conductivity was the highest for the nearly fully occupied composite, which is more than three orders of magnitude higher than that of the bulk AgI. The present study reveals that the Ag-ion conductivity in AgI/MPA composites can be controlled by optimizing the pore diameter of MPA and the AgI-loading ratio.
首次在整个亚10纳米区域对负载银的多孔材料中的银离子传导行为进行了系统研究。使用氮气吸附/脱附、粉末X射线衍射、差示扫描量热法和电化学阻抗谱测量，研究了介孔氧化铝（MPA）的孔径和负载到MPA中的碘化银（AgI）量的影响。将AgI限制在介孔空间中会降低相对于块状AgI的β/γ相和α相之间的相变温度。将AgI负载到孔径较小的MPA中会导致转变温度更显著地降低，这可能是因为孔中较小的AgI纳米颗粒必须具有更高的表面能来稳定高温相。室温离子电导率对孔径呈现出火山型依赖性，当将AgI负载到孔径为7.1纳米的MPA中时（室温下为7.2×10 S cm）具有最高值。对于7.1纳米的MPA，室温离子电导率对于几乎完全占据的复合材料最高，比块状AgI高三个数量级以上。本研究表明，通过优化MPA的孔径和AgI负载率，可以控制AgI/MPA复合材料中的银离子电导率。
