Simple synthesis of CuO/Ag nanocomposite electrode using precursor ink for non-enzymatic electrochemical hydrogen peroxide sensing

Abstract

Hydrogen peroxide (H2O2) is an integral part in many biological processes, and is often used in industry as oxidizing agent for bleaching pulp or paper, as disinfectant for wastewater treatment and can even be found in some cosmetics, such as hair bleaching or teeth whitening. Although applying low concentrations of H2O2 may potential help disinfect wounds, exposure of the skin or eyes to higher concentrations of H2O2 are hazardous and possibly carcinogenic. The United States National Institute for Occupational Safety and Health classifies exposure to concentrations above 75 ppm as immediately dangerous to life or health. The detection of H2O2 is therefore vital and has traditionally been done through methods such as titrimetry, spectrophotometry and chemiluminescence. However, since these methods are time-consuming and complicated, electrochemical detection has become the preferred method of detection. Enzyme based sensors display good performance and selectivity but struggle with stability issues and high cost, leading most recent research to be focused on nanomaterial based sensors. Herein we report a simple preparation method for a CuO/Ag composite electrode using precursor type ink without the need of a reducing atmosphere or high temperatures. Thermogravimetric analysis (TGA) showed that the precursor type ink completely decomposes when heated at 150 °C and Scanning Electron Microscopy revealed a connective network of particles around 250 nm in size. The electrodes were used to make an amperometric sensor and electrochemical analysis showed that the sensor had a linear response in a wide range (5-500 µM) and a low detection limit of 4.0 µM (S/N=3). Compared to the pure silver electrode, the addition of the copper precursor to the silver ink resulted in a significant improvement in the limit of detection of H2O2.