Preparation of Antimony Oxide in Different Media and Its Effect on the pH Measurement

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 sb_2o_3 and sb_2o_5, in a low field near an open circuit potential (ocp). xps results showed that the sb_2o_3 and sb_2o_5 ratio was almost similar in acidic medium, whereas sb_2o_5 was dominant in phosphate solution. all the prepared 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 sb_2o_5 formation.