Fabrication of a pH Sensor Based on Metal Oxide Nanoparticle and Ion Exchanging Surfaces

Abstract

The nanostructures of metal oxides are attractive and important for nanosensor research in the broad range of applications in various fields of biological, environmental and analytical chemistry. Due to their potential applications and special properties metal oxides nanoparticle have concerned considerable attention which are strongly related with their size, structure and morphology. Among the metal oxide, cupric oxide (CuO) is found to be one of the most popular oxide. Owing to its exceptional electrochemical activity and the possibility of promoting electron transfer at a low potential, availability, stability, good morphological and structural control of the synthesized nanostructures, CuO is a good candidate for pH sensing application. In this paper, an electrochemical pH sensor that has been fabricated using copper oxide modified glassy carbon electrode (CuO/GCE). The difference in peak potential shift while using CuO/GCE as pH sensor was measured using square wave voltammetry (SWV); and was found to be linear over the range of pH 3-9, with a sensitivity of 60 mVpl-f'. The sensor shows a potential drift of 1.97 —3.33 % after three hours of continuous use; and could retain 95% of its initial sensitivity after 1 week of use. The electrode was found to respond both in the presence and absence of oxygen, further expanding the potential applications to include it into de-oxygenated environments. This prototype has been tested in real samples and verified by using commercial pH meter. The CuO based sensor showed good sensitivity and long term stability that may show the way to develop a low cost solid state pH sensor for a wider range of applications.