olga-evolutionofthe-2014.pdf (1.24 MB)
Download file

Evolution of the electrochemical capacitance of transition metal oxynitrides with time: the effect of ageing and passivation

Download (1.24 MB)
journal contribution
posted on 28.08.2014, 00:00 authored by Olga Kartachova, Y Chen, R Jones, Ying (Ian) ChenYing (Ian) Chen, H Zhang, Alexey Glushenkov
A number of transition metal nitrides and oxynitrides, which are actively investigated today as electrode materials in a wide range of energy conversion and storage devices, possess an oxide layer on the surface. Upon exposure to ambient air, properties of this layer progressively change in the process known as "ageing". Since a number of electrochemical processes involve the surface or sub-surface layers of the active electrode compounds only, ageing could have a significant effect on the overall performance of energy conversion and storage devices. In this work, the influence of the ageing of tungsten and molybdenum oxynitrides on their electrochemical properties in supercapacitors is explored for the first time. Samples are synthesised by the temperature-programmed reduction in NH3 and are treated with different gases prior to exposure to air in order to evaluate the role of passivation in the ageing process. After the synthesis, products are subjected to controlled ageing and are characterised by low temperature nitrogen adsorption, X-ray photoelectron spectroscopy and transmission electron microscopy. Capacitive properties of the compounds are evaluated by performing cyclic voltammetry and galvanostatic charge and discharge measurements in the 1 M H2SO4 electrolyte. © 2014 the Partner Organisations.

History

Journal

Journal of materials chemistry A

Volume

2

Issue

32

Pagination

12940 - 12951

Publisher

Royal Society of Chemistry

Location

London, Eng.

ISSN

2050-7488

eISSN

2050-7496

Language

eng

Publication classification

C Journal article; C1 Refereed article in a scholarly journal

Copyright notice

2014, Royal Society of Chemistry