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In-situ studies of electrocatalysts using Near-Ambient Pressure

使用近环境压力对电催化剂进行原位研究

基本信息

批准号：
1879317
负责人：
金额：
--
依托单位：
University of Manchester
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-1879317
关键词：
situ studies electrocatalysts using Near

项目摘要

Current fuel cell technology requires the use of large amounts of platinum as an electrocatalyst. This is the major barrier to the widespread adoption of fuel cells - there simply isn't enough platinum in the world. It is therefore critical to find replacement catalysts made of earth-abundant elements. Graphene doped with Nitrogen (N-graphene) has recently been shown to show great promise as an electrocatalyst for the Oxygen Reduction Reaction (ORR). However the chemical nature and location of the active sites (N dopants occupy several inequivalent sites on the graphene lattice) are still under debate and the reaction mechanism is completely unknown. This project will develop a new in-situ technique which will allow us to follow the surface chemsitry at the electrode/electrolyte interface of N-graphene electrocatalysts during operation. X-Ray photoelectron Spectroscopy (XPS) is a powerful probe of surface chemistry. X-Rays are fired at a sample and the resulting photoelectrons detected. Their energy is characteristic of the elements present and their chemical environment. It is surface sensitive, as only electrons generated near the surface escape and are detected. Studying the electrode/electrolyte interface in-situ using XPS is challenging for two reasons. Firstly, this interface is buried by electrode on one side and electrolyte on the other. Secondly, XPS is a high vacuum technique, so samples containing a liquid electrolyte cannot be studied. This project will make use of cutting-edge instrumentation available at Manchester, Near-Ambient Pressure XPS (NAP-XPS). This new instrument can study samples in high pressures, allowing the study of samples containing liquid water. By using a single layer of graphene as an electrode, photoelectrons can escape through the electrode and be detected. This will allow us to study the electrode/electrolyte interface while the catalyst is in operation. The project will consist of three parts: Control and optimise the growth of N-doped graphene. Using Chemical Vapour Deposition (CVD), you will grow single-layer graphene doped with N atoms. Using a combination of XPS and atom-resolved microscopy, you will investigate how growth conditions affect the N dopant concentration and type. Develop and optimise the in-situ electrochemical cell. Our group has developed an in-situ electrochemical cell based on an ultathin graphene membrane. Proof-of principle has been demonstrated but significant optimisiation is required to make it a viable research tool. Working with other group members and collaborators, you will help optimise this system using N-graphene as a test system. Measure the ORR in-situ. By monitoring the chemical state of the N dopants during the ORR, we will learn about intermediate species, gain insight into the reaction mechanism and poisoning/deactivation mechanisms. By using the insight gained from this and the control over graphene doping learned in part 1, we can then optimise our N-graphene for maximum catalytic performance.

目前的燃料电池技术需要使用大量的铂作为电催化剂。这是燃料电池广泛采用的主要障碍--世界上根本没有足够的铂。因此，寻找由富含地球的元素制成的替代催化剂至关重要。近年来，掺氮石墨烯(N-石墨烯)在氧还原反应(ORR)的电催化中显示出巨大的应用前景。然而，活性中心的化学性质和位置(N掺杂占据了石墨烯晶格上的几个不同的位置)仍然存在争议，反应机理也完全未知。本项目将开发一种新的原位技术，使我们能够在操作过程中跟踪N-石墨烯电催化剂电极/电解液界面的表面化学。X射线光电子能谱(XPS)是一种功能强大的表面化学探针。X射线被发射到样品上，并检测到产生的光电子。它们的能量是存在的元素及其化学环境的特征。它是表面敏感的，因为只有在表面附近产生的电子逃逸并被探测到。使用XPS原位研究电极/电解液界面具有挑战性，原因有两个。首先，该界面一侧为电极，另一侧为电解液。其次，XPS是一种高真空技术，因此不能研究含有液体电解液的样品。该项目将利用曼彻斯特近环境压力XPS(NAP-XPS)提供的尖端仪器。这种新仪器可以在高压下研究样品，从而可以研究含有液态水的样品。通过使用单层石墨烯作为电极，光电子可以通过电极逃逸并被检测到。这将使我们能够在催化剂运行时研究电极/电解液界面。该项目将包括三个部分：控制和优化N掺杂石墨烯的生长。使用化学气相沉积(CVD)，你将生长出掺杂N原子的单层石墨烯。结合使用XPS和原子分辨显微镜，您将研究生长条件如何影响N掺杂浓度和类型。现场电化学池的研制和优化。我们团队开发了一种基于超薄石墨烯薄膜的原位电化学电池。原则的证明已经得到证明，但需要进行重大的优化，才能使其成为可行的研究工具。与其他小组成员和合作者一起工作，您将使用N-石墨烯作为测试系统来帮助优化该系统。原位测量ORR。通过在ORR过程中监测N掺杂的化学状态，我们将了解中间物种，深入了解反应机理和中毒/失活机理。通过利用从这一点获得的洞察力和在第一部分中学到的对石墨烯掺杂的控制，我们可以优化我们的N-石墨烯，以实现最高的催化性能。