Webinar #4 - E-chem for TEM: Studying Catalyst Materials (Part 1)

Описание: DR. NATHALY ORTIZ PEÑA | IPGP / Université de Paris

Morphological and Structural Evolution of Co3O4 Nanoparticles Revealed by in Situ Electrochemical TEM during Electrocatalytic Water Oxidation

Herein we present the implementation of an in situ electrochemical Transmission Electron Microscopy (in situ EC-TEM) device to track the structural evolution of cobalt oxide nanoparticles in oxygen evolution conditions. In first instance, we developed a protocol not only for the sample deposition but also for the observation and data recording, to ensure that the in situ observations mimic as well as possible the lab-scale experiments. Different aspects that could affect the fidelity of the data compared with the ex situ experiments have been evaluated.

In summary, we studied the morphological transformation of cobalt oxide spinels in operational conditions for the oxygen evolution reaction. The study was performed after thorough evaluation of the role of the observation conditions, including electron dose, electrochemical conditions and electrolyte’s nature. Optimized conditions allowed direct tracking of the catalyst nanostructure in relation with the electrochemical measurements within the electrolyte. Post-mortem selected area diffraction, energy dispersive and electron energy loss spectroscopies of, both, in situ and ex situ electrode materials, permitted to complete the picture about the electronic state and phase transformation induced during the electrocatalytic process. It was possible for the first time to observe directly the gradual amorphization of Co3O4 nanoparticles at the water oxidation potential. Such amorphization reaches a plateau after the initial couple of minutes in the observation conditions. Although, the re-structuration is significant, the overall route of the efficiency seems to be preserved, from where this could be considered as an activation process.