Analytical and Bioanalytical Electrochemistry

Analytical and Bioanalytical Electrochemistry

Preparation of antimony oxide in different media and its effect on the pH measurement

Document Type : Original Article

Authors
1 Central Department of Chemistry, Tribhuvan University, Kathmandu, Nepal
2 Central Department of Chemistry, Tribhuvan University, Kirtipur, Kathmandu, Nepal
3 Department of Chemistry, Prithivi Narayan Campus, Tribhuvan University, Pokhara, Nepal
4 Central Dept. of Chemistry, Tribhuvan University, Kirtipur, Kathmandu, Nepal.
Abstract
A thin film of antimony-oxide on an antimony electrode (Sb-Sb-oxide) is a simple, robust, and low-cost electrode for pH measurement. This study reports on the effect of different electrolytic media on forming a thin-film of Sb-oxide by electrochemical methods and its stability for pH measurements. An antimony electrode was obtained by the melting and solidification of antimony powder. Sb-oxide, thus obtained by electrochemical methods, was characterized by X-ray Photoelectron Spectroscopy (XPS). The cyclic voltammetry (CV) study revealed a complex oxide formation mechanism. This mechanism could be interpreted as a stepwise formation of different Sb species, such as Sb2O3 and Sb2O5, in a low field near an open circuit potential (OCP). XPS results showed that the Sb2O3 and Sb2O5 ratio was almost similar in acidic medium, whereas Sb2O5 was dominant in phosphate solution. All the prepared Sb-Sb-oxide electrodes showed a linear electromotive force (e.m.f.) in pH 2-10, giving a slope of 0.049- 0.052 V/pH at room temperature (RT). The electrodes gave an excellent pH response, and hence they can be used in standard laboratory experiments where the accuracy of ±0.02 pH is required. However, Sb-oxide obtained in phosphate buffer solution of pH 7 showed a lower electrode sensitivity and lower stability due to dominant Sb2O5 formation.
Keywords

Volume 13, Issue 1
August 2021
Pages 127-138

  • Receive Date 07 November 2020
  • Revise Date 30 December 2020
  • Accept Date 31 July 2021