Solid-Electrolyte Amperometric Sensor for Simultaneous Measurement of CO and CO₂ in Nitrogen

Abstract

A solid-state amperometric sensor based on yttria-stabilized zirconia (YSZ) for the simultaneous measurement of CO and CO2 concentrations in inert gases was fabricated. The designed sensor consists of two electrically isolated ceramic cells made of YSZ and equipped with Pt electrodes. Ceramic capillaries connecting an inner gas chamber of each cell with the outside atmosphere serve as diffusion barriers. One of the cells is intended for sensing CO, whereas the other is for sensing CO2 in the gaseous atmosphere. The electrochemical response of the sensor was studied in the temperature range of 600–750 °C in the presence of up to 10% of CO and CO2 in nitrogen. The limiting currents of the two cells were shown to rise linearly with the relevant carbon oxide concentration, and no perceptible cross-sensitivity effect toward the other carbon oxide was found. The sensor demonstrated high stability and reproducibility of results and good dynamic characteristics. The novelty of this research lies in the development of a simple, reliable and fast solid-oxide sensor for simultaneous sensing of CO and CO2 in inert gases, which can be used for the control of atmosphere in, for example, pharmaceutical, chemical, food storage industries.

Keywords

• amperometric sensor
• carbon monoxide
• carbon dioxide
• diffusion barrier
• YSZ electrolyte
• oxide-ion conductivity