Nano textured core-shell carbide-derived carbon particles for electrochemical energy storage and electrocatalysis (COSH-CDC)

在这个项目中，我们将基于我们最近开发的一种新的两步合成方法来合成用于电化学应用的核/壳杂化材料。使用金属碳化物粉末，我们的方法是首先通过氯化实现颗粒材料外部的部分转化为碳化物衍生碳(CDC)。第二步采用焙烧剩余的核心(产生用于储能应用的金属氧化物)，或第二步氯化(产生与用于电催化的外壳非常不同的孔隙率的碳核心)。碳化物部分转化为CDC的关键是使用均匀分布的NiCl2，在精确调整的化学计量比中产生高度可控的原位氯气生成。使用不同的金属碳化物，即TiC、VC、NbC和Mo2C，使我们能够设计不同的金属氧化物核心(用于储能)或不同的核心孔隙率(用于电催化)。最近两个PI的联合工作证实了两种核/壳设计的可行性，即金属氧化物/CDC和CDC/CDC核壳颗粒。然而，对结构/性质相关性和电化学性质的测量仍然缺乏系统和全面的了解。将Etzold Group(TU Darmstadt)和Presser Group(INM Saarbrücken)在合成、电化学能量存储和电催化方面的关键专业知识带到Etzold Group(TU Darmstadt)和Presser Group(INM Saarbrücken)的关键专业知识中，我们将能够创造协同附加值，并为参与项目的博士生提供一个充满活力的协作研究环境，以拓宽他们的知识，使其超越选定的电化学应用。我们的核/壳粒子的电化学能量存储将利用金属氧化物核心的高电荷存储能力，这只能由于介孔碳壳的高导电性而得到利用。通过这种方式，不需要添加额外的导电添加剂，并且可以实现可能的高功率处理。拥有金属氧化物核心和碳壳也不同于目前大量的混合材料工作，其中金属氧化物生长在碳衬底的顶部。我们将在水和非水电解液中研究杂化材料的氧化还原活性和锂离子的嵌入能力。在电催化方面，铂将沉积在具有石墨化和介孔外壳以及微孔和非晶核的分级结构的碳上。研究了特殊碳结构对燃料电池阴极(氧化还原反应)和阳极(氢氧化反应；甲醇氧化反应)反应的影响。因此，由于核心促进了催化剂的高分散性，从而有助于催化剂的活性，因此预期性能会得到改善，而外壳的介孔改善了传质，并利用其石墨化特性降低了欧姆电阻。

In this project, we will synthesize core/shell hybrid materials for electrochemical applications, based on a novel two-step synthesis that we have recently developed. Using a metal carbide powder, our approach is to first achieve partial transformation of the outer part of the granular material to carbide-derived carbon (CDC) by chlorination. The second step employs either calcination of the residual core (yielding metal oxide for energy storage applications), or a second chlorination step (yielding a carbon core with a porosity very different from the shell for electrocatalysis). The key of partial transition of carbide-to-CDC is the use of homogenously distributed NiCl2, yielding a highly controllable in situ formation of chlorine gas in a precisely tuned stoichiometric ratio. The use of different metal carbides, namely, TiC, VC, NbC, and Mo2C, enables us to design different metal oxide cores (for energy storage) or different porosities of the core (for electrocatalysis).Recent joint work of the two PIs has established the feasibility of both core/shell designs, namely, metal oxide / CDC and CDC/CDC core shell particles. Yet, a systematic and comprehensive understanding of structure/property correlations and surveying of the electrochemical properties is still missing. Bringing the key expertise of synthesis, electrochemical energy storage, and electrocatalysis of the Etzold Group (TU Darmstadt) and Presser Group (INM Saarbrücken), we will be able to create synergistic added value and provide for the project-involved PhD students a vibrant collaborative research environment to broaden their knowledge beyond a selected electrochemical application.Electrochemical energy storage of our core/shell particles will capitalize on the high charge storage capacity of the metal oxide core, which can only be utilized because of the high electrical conductivity of the mesoporous carbon shell. By this way, no additional conductive additive is required to be added and possibly high power handling can be enabled. Having a metal oxide core and a carbon shell is also different from a large amount of current hybrid material works, where the metal oxide is grown on top of the carbon substrate. We will investigate aqueous and non-aqueous electrolytes to study the hybrid materials' redox-activity and lithium ion intercalation ability.For electrocatalysis, platinum will be deposited on the hierarchically structured carbons with graphitic and mesoporous shell and microporous and amorphous cores. The influence of the special carbon architecture on cathode (oxidation reduction reaction) and anode site (hydrogen oxidation reaction; methanol oxidation reaction) fuel cell reactions will be studied. Thereby improved performance is expected as the core facilitates a high dispersion and thus activity of the catalyst, while the shell improves with its mesoporosity the mass transfer and reduces with its graphitic character the Ohmic resistance.