Investigation of Practical Electro-catalysis using the Floating Electrode

使用浮动电极研究​​实际电催化

• 批准号: 2135758
• 金额: --
• 依托单位: Imperial College London
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2017
• 资助国家: 英国
• 起止时间: 2017 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2135758
• 关键词: Investigation; Practical; Electro; catalysis; using; Investigation; Practical; Electro; catalysis; using

The purpose of this project is to investigate the behaviour of electro-catalysts at the high current densities they need to operate at for industrial electro-catalysis applications. The main context of the project will be the cathode catalyst layer responsible for the oxygen reduction reaction (ORR) in PEM fuel cells. The ORR is the most difficult reaction in a PEM fuel cell and improvements to this reaction rate are the main route to lower cost membrane electrode assemblies (MEAs), because the currently required PGM loading on the MEA cathode is considered too high. Lower cost MEAs will enable wider penetration of fuel cells into existing and developing markets, such as automotive.At present, only one electrochemical method is available that can probe electro-catalysis behaviour of gas diffusion electrodes outside of an MEA at high current density; this is the Floating Electrode (FE) method developed at Imperial College in Prof. Kucernak's group . The principle of the FE is shown in Figure 1: the electro-catalyst is simultaneously in contact with gaseous reactant, aqueous electrolyte and a good electronic conductor (sputtered gold). A key feature of the technique is its ability to bridge the gap between studying discrete electro-catalyst agglomerates and continuous catalyst layers of different PGM loading, whilst avoiding the complicating issues encountered using full-blown in-cell MEA testing. Whilst the feasibility and utility of this method has been shown by Chris Zalitis and bought in-house to JMTC, application of the FE has thrown up many new questions, for example:1. Why does the mass activity of the ORR catalyst (Pt/C) apparently decrease significantly with increased electrode loading?2. How limiting to the ORR is the proton conduction within the catalyst layer and within the electrolyte that the catalyst layer contacts (solid membrane or aqueous acid)?3. Can it be definitively shown that Pt alloy catalysts are actually less active at high current densities than Pt-only catalysts, despite the converse being true at low current densities?Resolution of these questions will feed in to the FCR group understanding of the behaviour of MEAs and complimentary work will focus on applying the understanding to improved catalyst and catalyst layer design.Once the fundamental questions above have been resolved, the project in its later stages can examine other gas-phase electro-catalyst systems. These will include the hydrogen evolution reaction, ubiquitous at the cathodes of industrial electrochemical processes such as electro-chlorination and central to the generation of hydrogen from renewable energy using PEM electrolysers. Further, the flexibility of electrochemical systems enables the use of intermittent renewable energy to synthesise valuable chemicals other than hydrogen, including ammonia and small chain hydrocarbons. The FE allows such high rate gas-consuming or gas evolving electrochemical reactions to be studied in a fundamental way under much more realistic conditions.

该项目的目的是调查电流催化剂的行为，以用于工业电催化应用所需的高电流密度。该项目的主要环境将是负责PEM燃料电池中氧还原反应（ORR）的阴极催化剂层。 ORR是PEM燃料电池中最困难的反应，该反应速率的改善是降低成本膜电极组件（MEA）的主要途径，因为当前所需的MEA阴极上所需的PGM负载太高。较低的成本量将使燃料电池更广泛地渗透到现有市场和发展中的市场中，例如汽车。在目前，只有一种电化学方法可以探测MEA以外的气体扩散电极在高电流密度下的电催化行为。这是在库克纳克教授小组的帝国学院开发的浮动电极（FE）方法。 FE的原理如图1所示：电催化剂同时与气态反应物，水溶液和良好的电子导体（溅射金）接触。该技术的一个关键特征是它在研究离散的电催化剂团聚物和不同PGM负载的连续催化剂层之间弥合差距的能力，同时避免使用成熟的内部MEA MEA测试遇到的复杂问题。克里斯Zalitis（Chris Zalitis）显示了这种方法的可行性和实用性，并在内部购买了JMTC，但FE的应用引发了许多新问题，例如：1。为什么随着电极载荷的增加，ORR催化剂（PT/C）的质量活性显然显着降低？2。催化剂层接触（固体膜或水酸）的电解质内的质子传导如何限制ORR？3。是否可以确定地表明，尽管在低电流密度下相反的是真实的，但PT合金催化剂实际上在高电流中比仅PT的催化剂不那么活跃。这些问题的分解会涉及FCR群体的理解，以了解MAS的行为和免费工作，将重点介绍到以后的催化剂和催化性的问题，以此为基础设计。气相电催化剂系统。这些将包括在工业电化学过程的阴极中无处不在的氢进化反应，例如电氯化和使用PEM电解器从可再生能源产生氢的中心。此外，电化学系统的灵活性使使用间歇性可再生能源可以合成以外的有价值的化学物质（包括氨和小链碳氢化合物）。 FE允许在更现实的条件下以基本的方式研究这种高速率的气体消费或气体演化的电化学反应。