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，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将颗粒材料的外部部分转化为碳化物衍生碳（CDC）。第二步采用剩余核心的煅烧（产生用于储能应用的金属氧化物），或第二个氯化步骤（产生孔隙度与壳非常不同的碳核心用于电催化）。碳化物部分过渡到cdc的关键是使用均匀分布的NiCl2，在精确调节的化学计量比中产生高度可控的氯气原位形成。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芯（用于储能）或芯的不同孔隙率（用于电催化）。最近两个pi的联合工作已经确定了两种核/壳设计的可行性，即金属氧化物/CDC和CDC/CDC核/壳粒子。然而，系统和全面的了解结构/性质的相关性和电化学性质的测量仍然缺乏。结合Etzold集团（TU Darmstadt）和Presser集团（INM saarbr<e:1> cken）在合成、电化学储能和电催化方面的关键专业知识，我们将能够创造协同增值，并为参与项目的博士生提供一个充满活力的合作研究环境，以拓宽他们在选定的电化学应用之外的知识。我们的核/壳粒子的电化学储能将利用金属氧化物核的高电荷存储能力，这只能通过介孔碳壳的高导电性来利用。通过这种方式，不需要添加额外的导电添加剂，并且可能实现高功率处理。具有金属氧化物芯和碳壳的混合材料也不同于目前大量的混合材料作品，其中金属氧化物生长在碳衬底的顶部。我们将研究水电解质和非水电解质，以研究杂化材料的氧化还原活性和锂离子嵌入能力。对于电催化，铂将沉积在具有石墨和介孔壳以及微孔和无定形核的分层结构碳上。研究特殊碳结构对阴极（氧化还原反应）和阳极（氢氧化反应、甲醇氧化反应）燃料电池反应的影响。因此，由于核心促进了高分散性，从而提高了催化剂的活性，而壳层通过其介孔改善了传质，并通过其石墨特性降低了欧姆电阻，因此有望提高性能。

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.