The Sensing Mechanism Study of Potentiometric NO2 Sensor Based on Varying WO3 Electrode Thickness

Abstract

In order to understand the NO2 sensing mechanism, YSZ-based (Y2O3-doped ZrO2 electrolyte) potentiometric sensors with varying WO3 sensing electrode thickness were investigated. The NO2 sensing performances were evaluated at 500 °C, 550 °C and 600 °C. All sensors showed linear relationships between voltage response and NO2 concentration. The sensor with moderate WO3-SE thickness (34.9 μm) exhibited higher sensitivity than any other sensors with thinner or thicker WO3-SE. This behavior was attributed to different gas adsorption sites and a different degree of catalytic decomposition of NO2 to NO occurring at the WO3 (Pt)/YSZ interface.