In Situ X-ray Absorption Spectroscopy of Metal/Nitrogen-doped Carbons in Oxygen Electrocatalysis

Metal/nitrogen-doped carbons (M−N−C) are promising candidates as oxygen electrocatalysts due to their low cost, tunable catalytic activity and selectivity, and well-dispersed morphologies. To improve the electrocatalytic performance of such systems, it is critical to gain a detailed understanding of their structure and properties through advanced characterization. In situ X-ray absorption spectroscopy (XAS) serves as a powerful tool to probe both the active sites and structural evolution of catalytic materials under reaction conditions. In this review, we firstly provide an overview of the fundamental concepts of XAS and then comprehensively review the setup and application of in situ XAS, introducing electrochemical XAS cells, experimental methods, as well as primary functions on catalytic applications. The active sites and the structural evolution of M−N−C catalysts caused by the interplay with electric fields, electrolytes and reactants/intermediates during the oxygen evolution reaction and the oxygen reduction reaction are subsequently discussed in detail. Finally, major challenges and future opportunities in this exciting field are highlighted.</p

Overcoming Diffusion Limitation of Faradaic Processes Property Performance Relationships of 2D Conductive Metal Organic Framework Cu3 HHTP 2 for Reversible Lithium Ion Storage

Faradaic reactions including charge transfer are often accompanied with diffusion limitation inside the bulk. Conductive two dimensional frameworks 2D MOFs with a fast ion transport can combine both charge transfer and fast diffusion inside their porous structure. To study remaining diffusion limitations caused by particle morphology, different synthesis routes of Cu 2,3,6,7,10,11 hexahydroxytriphenylene Cu3 HHTP 2 , a copper based 2D MOF, are used to obtain flake and rod like MOF particles. Both morphologies are systematically characterized and evaluated for redox active Li ion storage. The redox mechanism is investigated by means of X ray absorption spectroscopy, FTIR spectroscopy and in situ XRD. Both types are compared regarding kinetic properties for Li ion storage via cyclic voltammetry and impedance spectroscopy. A significant influence of particle morphology for 2D MOFs on kinetic aspects of electrochemical Li ion storage can be observed. This study opens the path for optimization of redox active porous structures to overcome diffusion limitations of Faradaic processe

A Collaboration for Exploring Fundamental Property Performance Relationships for Electrochemical Energy Storage

This invited Team Profile was created by Jens Matthies Wrogemann. He and his collaborators at the MEET Battery Research Center, the Helmholtz Zentrum Berlin für Materialien und Energie GmbH HZB , and Paderborn University recently published a research article about property performance relationships of 2D conductive metal organic frameworks. Flake and rod like shaped particles were evaluated to investigate the impact of the particle morphology of MOFs on electrochemical Li ion storage. By optimization of the particle morphology, the diffusion limitation of the Faradaic process can be significantly reduce