Studying the layered hydroxide electrode materials with in situ transmission electron microscopy

Abstract

Abstract: In this project, electroactive and multifunctional nanomaterials based on alpha nickel hydroxide will be characterized, with potential application in the most essential and urgent areas of scientific and technological performance, such as energy conversion and storage, and amperometric sensors. For this, the nanoparticles (NPs) of a-Ni(OH)2 and a-Ni0.95V0.05(OH)2 planned and prepared in the FAPESP 2018/16896-7 project will be characterized by in situ transmission electron microscopy (in situ TEM) using liquid cell TEM. In situ TEM has become a popular technique for observing reactions at the nanoscale dimension compared with other in situ techniques like atomic force microscopy and various X-ray methods. TEM not only has the advantage of having both high temporal and spatial resolution, it also provides direct visualization of any changes in structural, morphological or elemental distribution at the nanoscale. The development of enclosed liquid cells has allowed the in situ TEM imaging of liquid phase reactions, opening up fields from electrochemistry to cell biology, yielding essential information for understanding fundamental processes. Having said that, it is fully understood the need for the characterization of ±-Ni(OH)2 and/or a-NiV based on nanomaterials by the in situ TEM technique, since it will be extremely important for understanding the improvement of the alpha phase stability, as well as the increased specific capacity and electrocatalytic activity of NPs prepared. In summary, with the liquid cell TEM it will be possible to obtain, for the first time, crystallographic information from the alpha phase of ultra-small NPs, observe possible phase changes (conversion from ± to ² phase) and correlate the improvements in electrocatalytic activity for OER in function of charge-discharge cycles, and during the electro-oxidation of glucose or drugs.