Next Generation Superprotonic Solid Acids

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。技术概述这项研究的目标是推进固体酸质子导体的科学，其中固体酸化合物可以被描述为MnHm（XO 4）p，M =碱金属，碱土金属，甚至稀土，X = S，P，Si，Se，As或Ge。这项工作的主要部分将集中在探索性合成上，以开发具有所需特性的新化合物，这些特性包括不溶于水、对化学还原的稳定性以及即使在室温下也具有高（或超）质子导电性。一个超质子导体表现出快速重新取向的XO 4阴离子基团的质子传输机制。水热和相关的合成路线将用于制备假设的磷酸盐和硅酸盐类似物已知的硫酸盐（和硒酸盐）固体酸具有高导电性。新的和已知的超质子固体酸的分解/脱水行为将进一步通过在高（高达0.6atm）水分压至300 °C的温度下的热重分析来确定。从这些研究中，不仅可以建立燃料电池的操作条件，而且还可以建立基本的热力学量（生成熵和熵）。这些术语可以反过来用于系统地评估氢键形成对化合物稳定化的作用。同时，一种新的电化学测试配置将用于探测与固体酸燃料电池使用的金属电极上的电化学反应路径，以消除Pt的最终目标。本研究的目标是（1）开发用于燃料电池应用的新型质子传导材料，（2）了解燃料电池反应途径，以便最终从燃料电池设计中消除贵金属。电解质材料的成功发现与能源技术的这项工作中的目标特性的意义不能被夸大。固体酸燃料电池（SAFC）在未开发的温度范围（150-300°C）下操作，因此为燃料电池操作的新模式创造了机会。最终，没有固体氧化物燃料电池的极端温度的无Pt燃料电池系统是可能的。SAFC的商业开发正在迅速发展（在分拆的Superprotonic公司的主持下），然而，为了充分实现固体酸电解质的潜在益处，需要下一代真正坚固的材料。除了新材料的开发，这些全面的研究将有助于澄清超质子跃迁的化学和结构基础以及氢键在稳定化合物中的整体作用。要利用的工具的广度，材料合成的相对容易，以及公众对能源技术的高度兴趣，使其成为培养材料化学及其应用于社会相关问题的未来领导者的理想系统。这种培训将具体通过本科生、研究生和博士后研究人员参与这项研究以及通过针对K-12学生的外联活动来实现。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).TECHNICAL SUMMARYThe goal of this research is to advance the science of solid acid proton conductors, where solid acid compounds can be described generically as MnHm(XO4)p with M = alkali metal, alkaline earth, or even rare earth, and X = S, P, Si, Se, As or Ge. A major part of the effort will focus on exploratory synthesis to develop new compounds with the desired characteristics of insolubility in water, stability against chemical reduction, and high (or super-) protonic conductivity even at room temperature. A superprotonic conductor exhibits rapid reorientation of XO4 anion groups as the mechanism of proton transport. Hydrothermal and related synthesis routes will be utilized to prepare hypothesized phosphate and silicate analogs to known sulfate (and selenate) solid acids with high conductivity. The decomposition/dehydration behavior of new and known superprotonic solid acids will further be determined via thermal gravimetric analysis under high (up to 0.6 atm) water partial pressures to temperatures of 300 °C. From these studies not only can fuel cell operation conditions be established, but also fundamental thermodynamic quantities (formation enthalpies and entropies). These terms can, in turn, be used to systematically evaluate the role of hydrogen bond formation on compound stabilization. Simultaneously, a novel electrochemical test configuration will be employed to probe electrochemical reaction pathways on metal electrodes used with solid acid fuel cells, with the ultimate goal of eliminating Pt. NON-TECHNICAL SUMMARYThe goals of this research are to (1) develop new proton conducting materials for fuel cell applications and (2) understand fuel cell reaction pathways so as to ultimately eliminate precious metals from fuel cell designs. The significance of successful disovery of electrolyte materials with the characteristics targetted in this work on energy technologies cannot be overstated. Solid acid fuel cells (SAFCs) operate in a temperature regime (150-300°C) that is unexplored and as such create opportunities for new modes of fuel cell operation. Ultimately, Pt-free fuel cell systems without the extreme temperatures of solid oxide fuel cells may be possible. Commercial development of SAFCs is moving rapidly (under the auspices of the spin-off Superprotonic, Inc.), however, next-generation, truly robust materials are required in order to fully realize the potential benefits of solid acid electrolytes. In addition to new materials development, these comprehensive studies will help to clarify the chemical and structural bases for superprotonic transitions and the overall role of hydrogen bonds in stabilizing compounds. The breadth of tools to be utilized, the relative ease with which the materials can be synthesized, and the high level of public interest in energy technologies, renders this an ideal system for training future leaders in materials chemistry and its application to societally relevant problems. Such training will be specifically achieved through participation in this research by undegraduate, graduate and post-doctoral researchers, as well as through outreach activities for K-12 students.