Expanding the Environmental Frontiers of Operando Metrology for Advanced Device Materials Development

开尔文勋爵（Lord Kelvin）有句名言：“当你不能测量它，当你不能用数字表达它时，你的知识是贫乏的，令人不满意的。”这对于今天的纳米技术来说是最正确的。新兴材料如二维过渡金属二硫化物（TMD）化合物提供了令人兴奋的广泛机会，从新型（光电）电子器件到能量存储和催化能量转换。对于后者，像二硫化钼这样的tmd材料已经显示出很高的催化活性，并且作为富含地球的电催化剂提供了巨大的潜力，例如将废弃的二氧化碳转化为工业相关的化学品/燃料，并可持续地产生氢气，即作为可持续、清洁的未来经济战略的最重要的过程。然而，TMD催化剂在反应过程中会发生显著的化学和结构变化，其高催化活性的机制仍不清楚。我们目前在材料合成方面的知识同样贫乏。人们对tmd是如何生长的，以及如何大规模控制这些材料的结构和性能知之甚少。这些挑战和缺乏理解是许多新兴材料的共同问题。其中一个关键原因是，它们通常只能在“事后”阶段得到解决和充分表征，我们只能推测在与工业相关的“现实世界”条件下，究竟是什么机制实际控制着生长或材料的功能。该提案旨在在工业相关的高温反应气氛下对新型材料（如tmd）进行真正的操作特性描述，通过对其设计和功能的基本理解，对其未来的使用产生变革性影响。我们的重点将是电子显微镜和光谱学，特别是扫描电子显微镜和x射线光电子能谱，这是现代科学中最广泛和最通用的表征技术之一，在学术界和工业界的所有学科中都得到了应用。它们具有高（近）表面灵敏度，使它们成为分析表面和界面结构和化学的有力工具。然而，低能电子也会被气体分子强烈散射，因此所有这些技术通常都是在高真空或受限的环境条件下进行的。我们提出了新的环境电池方法，可以灵活地实施许多基于电子的技术，以克服这些限制，并在前所未有的工业相关工艺条件范围内实现高空间和/或化学分辨率的直接表征，温度高达1000℃，反应性气体或液体环境。该提案建立在曼彻斯特，剑桥和钻石光源/哈维尔最近的战略设备投资基础上，并与市场领先的工业合作伙伴一起，我们的愿景是开拓多种方法，开辟新的相关，多模态操作探测能力，适用于广泛的领域，包括有机半导体，电池/能源研究，催化和生命科学。这也将与模拟和理论联系起来，以达到新的理解水平和预测能力。应用于TMD材料，这种能力将使我们能够在工业相关的反应堆条件下直接询问TMD成核和生长，开发新的制造工艺，包括迄今为止大部分未开发的金属化合物。这将进一步使我们首次系统地研究反应条件下的TMD催化剂模型。特别是，我们建议探索像NbS2这样的金属tmd，因为与半导体MoS2不同，它们的催化活性可以扩展到整个基面上，为设计具有低过电位和高电流密度的新型电催化剂开辟了新的方向。

Lord Kelvin famously stated "when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind". This holds none more true than for nanotechnology today. Emergent materials such as 2D transition metal dichalcogenide (TMD) compounds offer exciting, wide opportunities from novel (opto-) electronic devices to energy storage and catalytic energy conversion. For the latter, TMDs materials like MoS2 have shown high catalytic activity and offer large potential as earth abundant electro-catalysts to for instance convert waste CO2 into industrially relevant chemicals/fuels and to generate hydrogen sustainably, i.e. processes of utmost significance as strategies for a sustainable, clean future economy. However, TMD catalysts can undergo significant chemical and structural changes during reactions, and the mechanisms that give the high catalytic activity remain largely unknown. Our knowledge is currently equally meagre in terms of materials synthesis. There is very little understanding how TMDs actually grow and hence how the structure and properties of these materials can be scalably controlled. These challenges and lack of understanding are common to numerous emerging materials. One key reason for this is that they typically can only be resolved and adequately characterised at a "post-mortem" stage, and we are left to speculate what mechanisms actually govern growth or material functionality at industrially relevant "real-world" conditions.This proposal aims at true operando characterisation of novel materials like TMDs under industrially relevant reactive atmospheres at elevated temperatures, to have a transformative impact on their future use by developing a fundamental understanding of their design and functionality. Our focus will be on electron microscopy and spectroscopy, in particular scanning electron microscopy and X-ray photoelectron spectroscopy, which are among the most wide-spread and versatile characterisation techniques in modern science, used across all disciplines in academia and industry. They are endowed with high (near-)surface sensitivity, making them powerful tools for analysing the structure and chemistry of surfaces and interfaces. However, low-energy electrons are also strongly scattered by gas molecules, and therefore all these techniques are conventionally performed under high vacuum or restricted environmental conditions. We propose new environmental cell approaches that can be flexibly implemented for the many electron-based techniques to overcome these restrictions, and enable direct characterisation at high spatial and/or chemical resolution across an unprecedented range of industrially relevant process conditions for temperatures as high as 1000C and in reactive gaseous or liquid environments. The proposal builds on recent strategic equipment investment at Manchester, Cambridge and the Diamond Light Source/Harwell, and together with market-leading industrial partners our vision is to pioneer versatile approaches that open up new correlative, multi-modal operando probing capability applicable to a wide range of fields including organic semiconductors, battery/energy research, catalysis and life sciences. This will also link to simulation and theory to achieve new levels of understanding and predictive power. Applied to TMD materials, this capability will allow us to directly interrogate TMD nucleation and growth at industrially relevant reactor conditions, to develop new manufacturing processes including for so far largely unexplored metallic compounds. This will further allow us for the first time to systematically study model TMD catalysts under reaction conditions. In particular, we propose to explore metallic TMDs like NbS2, as unlike to semiconducting MoS2, their catalytic activity could extend over the entire basal plane, opening new directions to design novel electro-catalysts with low overpotential and high current densities.