Phosphonated Hexaphenylbenzene: A Crystalline Proton Conductor
Phosphonated Hexaphenylbenzene: A Crystalline Proton Conductor
复制标题
DOI：
10.1002/anie.200902116
复制
发表时间：
2009-01-01
影响因子：
16.6
通讯作者：
Muellen, Klaus
中科院分区：
文献类型：
--
作者：
Jimenez-Garcia, Lucia;Kaltbeitzel, Anke;Muellen, Klaus
质子电导率因其在生物和化学过程中的重要性而受到广泛的研究燃料电池（FC）是一种极具发展前景的高效、低环境影响的电能提供装置。严重阻碍FC性能的一个关键问题是质子交换膜（PEMs）的合成，该膜同时提供高温下恒定的高质子导电性。在汽车应用的情况下，美国能源部为1208℃和50%相对湿度（RH）下膜的质子电导率制定了接近1 10À1 S cmÀ1的指导方针作为目标操作条件最先进的聚合物电解质是以磺酸为基础的全氟聚合物，如Nafion。这些电解质呈现出高但依赖于温度的质子电导率，因为质子的传输是由基于含质子基团扩散的载体机制控制的另外，由于膦酸的两性特性，它被认为是本导电隔膜材料的原生基团已经证明，这些能够聚集的高浓度酸性基团是高内在质子电导率所必需的。[4b]无机晶体（固体酸性质子导体）已被提出作为聚合物电解质的替代材料然而，尽管这些晶体具有较高的固有电导率（10À2-10À3 S cmÀ1； grotthuss型机制），但它们也有一定的缺点，如机械性能差、水溶性差、高温操作条件（CsH2PO4在大气压下高于2308C）。虽然迄今为止的研究主要集中在增加原生基团的灵活性上，例如，通过引入间隔物或添加小分子，但我们采用了一种不同的方法，我们提出通过使用自组装和预组织概念来提高质子的迁移率。
Proton conductivity has been widely studied because of its importance in biological and chemical processes.[1] A fuel cell (FC) is a promising device that can provide electrical energy with high efficiency and low environmental impact. A critical issue that severely hampers FC performance is the synthesis of proton-exchange membranes (PEMs) that simultaneously provide high proton conductivity that is constant over temperature. In the case of automotive applications, a guideline of close to 1 10À1 S cmÀ1 for the proton conductivity of the membrane at 1208C and 50% relative humidity (RH) was established by the US Department of Energy as target operating conditions.[2] State-of-the-art polymeric electrolytes are sulfonic acid based perfluorinated polymers such as Nafion. These electrolytes present high but temperaturedependent proton conductivity, since proton transport is governed by the vehicle mechanism that is based on the diffusion of proton-containing groups.[3] Alternatively, phosphonic acid has been suggested as a protogenic group for intrinsically conducting separator materials because of its amphoteric properties.[4] It has been demonstrated that a high concentration of these acidic groups, which are able to aggregate, is required for a high intrinsic proton conductivity.[4b] Inorganic crystals (solid acid proton conductors) have been proposed as alternative materials to polymer electrolytes.[5] However, despite their high intrinsic conductivities (10À2–10À3 S cmÀ1; Grotthuss-type mechanism), these crystals have certain disadvantages, such as poor mechanical properties, water solubility, and high-temperature operating conditions (above 2308C under atmospheric pressure for CsH2PO4).[6]Although research has focused to date on increasing the flexibility of the protogenic groups, for example, by introducing spacers or by adding small molecules,[7] we have followed a different approach, in which we proposed to increase proton mobility by using a self-assembly and preorganization concept.