Electrochemical promotion of nanostructured catalysts and electrocatalysts for environmentally important processes

用于环境重要过程的纳米结构催化剂和电催化剂的电化学促进

• 批准号: RGPIN-2014-05494
• 负责人: Baranova, Elena
• 金额: $ 1.46万
• 依托单位: University of Ottawa
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567206
• 关键词: Electrochemical; promotion; nanostructured; catalysts; electrocatalysts

In recent decades, the world has witnessed an exponential increase in energy demand and consumer product materials production based on fossil fuels, mainly oil, gas and coal. Because it is not possible to decrease the human activity and therefore the growing global energy demand it is evident that the game-changing strategies are required to implement the alternative energy sources based on renewable feedstocks as well as the alternative approaches for sequestration and recycling of greenhouse gas emissions. Modern heterogeneous catalysts, powerful nanostructured systems used to enhance chemical reactions and significantly reducing energy demand, offer outstanding opportunities. A typical heterogeneous catalyst consists of a nanosized metal or metal oxide particle deposited on the high surface area supports. Catalysts often suffer from deactivation or low catalytic activity. Therefore, various promoting routes are used: (i) Chemical promotion: addition of chemical species to the catalyst during preparation, e.g., K, Na, Ce, Sn, etc., to improve its catalytic behavior and often its stability and a life-span. The addition of such species changes the electronic or crystal structure of the catalyst, thus improving catalytic performance and selectivity for the desired chemical reaction. (ii) Metal-support interaction (MSI) defined as the effect where the support plays a key role in changing the properties of the catalyst as a result of the interaction between the two materials, usually resulting in higher catalytic activity; (iii) Electrochemical promotion of catalysis (EPOC) or also referred to as non-Faradaic electrochemical modification of catalytic activity (NEMCA) was discovered 30 years ago and is an alternative approach to enhance catalytic activity. EPOC introduced a new class of promoters previously unknown in heterogeneous catalysis, e.g., O2-, H+, K+, Na+, OH-, etc. By applying electrical current or potential between the catalyst-working electrode and a counter electrode deposited on a solid electrolyte, catalytic activity and selectivity can be significantly altered due to modifications of electronic properties of the catalyst. It is well established that an operational and not a functional difference between the above three phenomena exists. Whereas chemical promotion and MSI are difficult to control under operating conditions, the EPOC phenomenon offers in-situ control of the amount of promoters on surfaces and offers a unique opportunity to modify catalyst properties via application of small electrical current or potential. Despite that EPOC has been investigated for more than 30 years and applied for over 100 catalytic systems with various electrolytes, catalysts and reactions, several important issues and applications remain and need to be addressed: (i) What are the reaction conditions and the electrochemical cell design to observe electrochemical promotion with highly dispersed nanoparticle catalysts? (ii) What is the mechanism of the “self-induced” or “wireless” promotion with NPs supported on ionically conductive supports and its relationship to MSI? (iii) What are new approaches for application of EPOC phenomenon in electocatalysis for oxidation of complex organic fuels using proton or anion conductors? The long-term objectives of the proposed research program are to establish a comprehensive understanding of the EPOC with nanostructured catalysts supported on ionically conductive ceramics and proton (anion) exchange polymer electrolytes. To develop a fundamental understanding and a relationship between EPOC and MSE at the nanoparticle scale for the rational design of the efficient catalytic systems for fuel cells and abatement of greenhouse gas from the stationary and automobile sources.

近几十年来，世界能源需求和基于化石燃料（主要是石油、天然气和煤炭）的消费品材料生产呈指数级增长，因为人类活动不可能减少，因此全球能源需求不断增长。显然，需要采取改变游戏规则的战略来实施基于可再生原料的替代能源，以及封存和回收温室气体排放的替代方法，现代多相催化剂、用于增强化学反应和显着减少能源的强大纳米结构系统。需求，提供出色的机会。典型的非均相催化剂由沉积在高表面积载体上的纳米级金属或金属氧化物颗粒组成，催化剂通常会失活或催化活性较低，因此，使用各种促进途径：（i）化学促进：向催化剂中添加化学物质。在制备过程中添加例如 K、Na、Ce、Sn 等，以改善其催化行为以及稳定性和寿命。此类物质的添加会改变催化剂的电子或晶体结构， (ii) 金属-载体相互作用 (MSI) 定义为载体由于两种材料之间的相互作用而在改变催化剂性能方面发挥关键作用的效应，通常会导致更高的催化活性；促进催化 (EPOC) 或也称为非法拉第电化学修饰催化活性 (NEMCA) 于 30 年前发现，是增强催化活性的另一种方法EPOC引入了多相催化中以前未知的一类新的促进剂，例如O2-、H+、K+、Na+、OH-等。通过在催化剂工作电极和沉积在其上的对电极之间施加电流或电势。众所周知，在固体电解质中，由于催化剂电子特性的改变，催化活性和选择性可能会发生显着改变，上述三种现象之间存在操作上的差异，而不是功能上的差异。和 MSI 在操作条件下难以控制，EPOC 现象提供了表面助催化剂数量的原位控制，并提供了通过施加小电流或电位来改变催化剂性能的独特机会。 30多年来，并应用于100多种具有各种电解质、催化剂和反应的催化系统，仍然存在一些重要问题和应用需要解决：（i）什么是反应条件和电化学电池设计来观察高度电化学促进？ (ii) 离子导电载体上的纳米粒子的“自诱导”或“无线”促进机制是什么及其与 MSI 的关系 (iii) EPOC 现象在电催化中的应用有哪些新方法？使用质子或阴离子导体氧化复杂有机燃料？拟议研究计划的长期目标是建立对离子导电纳米结构催化剂的 EPOC 的全面了解陶瓷和质子（阴离子）交换聚合物电解质在纳米粒子尺度上建立 EPOC 和 MSE 之间的基本理解和关系，以便合理设计高效燃料电池的催化系统以及减少固定和汽车来源的温室气体。