Understanding CO2 Reduction Catalysts

如果我们要找到提高催化效率的障碍在哪里，并了解和开发绕过这些障碍的方法，那么监测原位和操作中材料的合成和催化性能的需要至关重要。光电子能谱是一种应用广泛的多学科技术，广泛用于研究材料表面的组成和化学性质。这是一种超高压技术，这意味着不可能研究固气界面和相应的反应性。高压光电子能谱（hipes）处于先进表面表征技术的前沿，因为它现在允许在与技术应用高度相关的近环境压力下测量表面化学和物理。标准光电子能谱是在UHV （10- 9mbar）压力范围内进行的，而hipes测量是在大于10mbar的压力范围内进行的。这意味着可以在高度相关的条件下监测表面反应（例如，作为压力，温度，湿度，酸度的函数）；与传统光谱仪的强烈还原条件形成鲜明对比的是，传统光谱仪不仅不能提供动态信息，而且实际上可能改变所研究系统的表面化学性质。我们的目标是使用hipes技术来研究铜纳米颗粒和二氧化碳之间的表面化学反应。通过监测气固界面的相互作用，我们旨在确定催化活性位点的性质，并提出基于证据的铜上CO2还原机制。我们将研究表面化学作为温度、共吸附物（如水和O2）和ph的函数。我们希望更详细地了解这些纳米催化剂，提高催化效率，或发现新的催化剂，从而实现碳捕获和利用技术的经济可行性。

The need to monitor the synthesis and catalytic performance of materials in-situ and in-operando is of critical importance if we are to find where the barriers to increased catalytic efficiency are, and understand and develop methodologies to circumvent them. Photoelectron spectroscopy (PES) is a widely used multidisciplinary technique widely used to study the composition and chemistry of material surfaces. It is an UHV technique, meaning that it is not possible to investigate the solid-gas interface and consequential reactivity. High-pressure photoelectron spectroscopy (HiPPES) is at the forefront of advanced surface characterization techniques as it now allows the measurement of surface chemistry and physics at near-environmental pressures that are highly relevant for technological applications. Whereas standard photoelectron spectroscopy is performed in the UHV (10-9 mbar) pressure range, HiPPES measurements are performed at pressures greater than 10 mbar. This means that surface reactions can be monitored under highly relevant conditions (e.g. as a function of pressure, temperature, humidity, acidity); in stark contrast to the strongly reducing conditions of a conventional spectrometer which not only provide no dynamic information, but may also actually alter the surface chemistry of the system under study. We aim to use the HiPPES technique to the surface chemistry taking place between copper nanoparticles and CO2. By monitoring the interactions of the gas-solid interface we aim to determine the nature of catalytic active sites, and propose evidence-based mechanisms for the reduction of CO2 on copper. We will study the surface chemistry as a function of temperature, co-adsorbates (such as water and O2) and pH. We hope to understand these nanocatalysts in greater detail, to raise the catalytic efficiency, or to discover new catalysts, thereby enabling the economic viability of carbon capture and utilisation technologies.