MXene-based energy materials guided by 3D Atomic-Resolution Tomography

绿色能源转换设备，即燃料电池和制氢电解槽的效率取决于催化剂，即加速所需化学反应速度的材料。催化科学正在经历一场革命，科学家们被要求专注于提高耐用性和降低价格，而不仅仅是最大化活性。这样的基准只有通过发现新材料和在原子尺度上建立加工-结构-性能关系才能实现。MXenes于2011年被发现，是最新也是最不为人所知的二维(2D)材料。它们的名字来源于它们的母体Mn1AXn(MAX)相，其中M是早期过渡金属，A是A族元素，X是碳和/或氮，n=1-3。最近的理论论文预测了MXenes作为低成本催化剂应用于能源应用的适用性，但这些研究还没有强有力的实验验证。该项目旨在为能量转换应用量身定做MXenes，并使用原子探针断层扫描(APT)和高分辨率电子显微镜提取关于其稳定性的原子级结构和化学见解。Sokol小组将通过湿化学合成新型MXenes，而Eiliz小组将通过电镀以及最先进的2D图案和3D打印来处理MXenes。在罗森小组进行催化测试之前和之后，Raabe和Gault小组将使用APT和其他先进的分析技术来表征这些材料的化学和结构。热脱附光谱(TDS)将被用来检测催化剂中的氢和氧的残留量，以及确定MXene材料中氢原子与微结构陷阱之间的结合能。将与电子显微镜和APT进行关联，以确定氢捕获位置以及催化剂和材料性能如何受到影响。拉贝和埃利亚兹小组将研究氢和氧诱导的催化剂材料的降解，这将与APT的结果相关联，以更好地了解如何优化其寿命。因此，我们的团队将以不同的方式将一类新发现的材料(MXenes)的加工与催化测试和最先进的原子分辨率表征相结合，以应对我们这一代人面临的重大挑战之一。

The efficiency of devices for green energy conversion, i.e. fuel cells and electrolyzers for hydrogen generation, is dependent on catalysts, materials that accelerate the rate of desired chemical reactions. The catalytic sciences are undergoing a revolution as scientists are pushed to focus on improving durability and reducing price rather than just maximizing activity. Such benchmarks are only achievable by the discovery of new materials and establishing processing-structure-property relationships at the atomic scale. MXenes, discovered in 2011, are the latest and least understood two-dimensional (2D) materials. They derive their name from their parent Mn+1AXn (“MAX”) phases where M is an early transition metal, A is an A-group element, X is carbon and/or nitrogen, and n = 1–3. Recent theoretical papers have predicted the suitability of MXenes as low-cost catalysts for energy applications, but a robust experimental validation of these studies does not exist. This project aims to tailor MXenes for energy conversion applications, and extract atomic-scale structural and chemical insights about their stability, using atom probe tomography (APT) and high-resolution electron microscopy. The Sokol group will synthesize novel MXenes by wet chemistry, whereas the Eliaz group will process MXenes by electroplating as well as by state-of-the-art 2D patterning and 3D printing. APT and other advanced analytical techniques will be used by the Raabe and Gault groups to characterize the chemistry and structure of these materials, before and after catalytic testing by the Rosen group. Thermal desorption spectroscopy (TDS) will be used in order to detect residues of hydrogen and oxygen in the catalyst as well as to determine the binding energy between hydrogen atoms and microstructural traps in MXene-based materials. A correlation will be made with electron microscopy and APT to determine hydrogen trapping sites and how catalytic and material properties are influenced. The Raabe and Eliaz groups will study hydrogen- and oxygen-induced degradation of the catalyst materials, which will be correlated with results from APT to better understand how to optimize their lifetime. Thus, our team will combine processing of a newly discovered class of materials (MXenes) in different ways, with catalytic testing, and state-of-the-art atomic resolution characterization to tackle one of the grand challenges of our generation.