Structure and Properties of Cs 7 (H 4 PO 4 )(H 2 PO 4 ) 8 : A New Superprotonic Solid Acid Featuring the Unusual Polycation (H 4 PO 4 ) +
Structure and Properties of Cs 7 (H 4 PO 4 )(H 2 PO 4 ) 8 : A New Superprotonic Solid Acid Featuring the Unusual Polycation (H 4 PO 4 ) +
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Cs 7 (H 4 PO 4 )(H 2 PO 4 ) 8 的结构和性能：一种具有特殊聚阳离子(H 4 PO 4 )的新型超质子固体酸
DOI：
10.1021/jacs.0c08870
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发表时间：
2020
影响因子：
15
通讯作者：
Haile, Sossina M.
中科院分区：
文献类型：
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作者：
Wang, Louis S.;Patel, Sawankumar V.;Sanghvi, Sheel S.;Hu, Yan-Yan;Haile, Sossina M.
我们报道了一种新的超质子化合物Cs 7（H4 PO 4）（H2 PO 4）8或CPP的发现，其在高温下由CsH 2 PO 4和CsH 5（PO 4）2反应形成。使用高温单晶X射线衍射解析并通过高温31 P NMR光谱确认的结构在空间群Pm 3中结晶，在130 °C下的晶格常数为20.1994（9）Ω。其晶胞类似于超质子CsH 2 PO 4的4 × 4 × 4超结构，但具有一个特殊的化学部分，旋转无序的H4 PO 4+阳离子，周期性地占据每八个阳离子位点中的一个。这种显着的阳离子的CPP相的结构，热力学和质子传输性能的影响进行了讨论。值得注意的是，CPP在90 °C的温度下形成，远低于CsH 2 PO 4的228 °C的超质子转变温度，并且该化合物似乎没有有序的低温形式。在名义上干燥的条件下，该材料在151 °C下对脱水是稳定的，并且这导致在不存在主动增湿的情况下超质子材料的特别宽的稳定区域。Cs 7（H4 PO 4）（H2 PO 4）8在140 °C时的电导率为5.8 × 10-4S cm-1，但似乎仍然受到聚阴离子（H2 PO 4-）基团重新取向的促进。
We report the discovery of a new superprotonic compound, Cs7(H4PO4)(H2PO4)8, or CPP, which forms at elevated temperatures from the reaction of CsH2PO4and CsH5(PO4)2. The structure, solved using high-temperature single-crystal X-ray diffraction and confirmed by high-temperature31P NMR spectroscopy, crystallizes in space groupPm3̅nand has a lattice constant of 20.1994(9) Å at 130 °C. The unit cell resembles a 4 × 4 × 4 superstructure of superprotonic CsH2PO4, but features an extraordinary chemical moiety, rotationally disordered H4PO4+cations, which periodically occupy one of every eight cation sites. The influence of this remarkable cation on the structure, thermodynamics, and proton transport properties of the CPP phase is discussed. Notably, CPP forms at a temperature of 90 °C, much lower than the superprotonic transition temperature of 228 °C of CsH2PO4, and the compound does not appear to have an ordered, low-temperature form. Under nominally dry conditions, the material is stable against dehydration to ∼151 °C, and this results in a particularly wide region of stability of a superprotonic material in the absence of active humidification. The conductivity of Cs7(H4PO4)(H2PO4)8is moderate, 5.8 × 10–4S cm–1at 140 °C, but appears nevertheless facilitated by polyanion (H2PO4–) group reorientation.