Robust Type III Potentiometric Sensors for SOx Realized Via Fast Solid-State Potassium Ion Conductors

Abstract

Sulfur oxide gases (SOx) are among the most serious air pollutants that contribute to acid rain and have a significant impact on human health and the environment. The sensing and quantification of SOx is critical for industrial and environmental applications, such as monitoring air quality, controlling emissions from power plants and maritime vessels, as well as ensuring safety in industrial processes. However, conventional sensing methods are limited by prohibitive costs, complex hardware, and maintenance requirements. In this work, we present a novel potentiometric type III solid-state sensor for the sensing of SOx using fast and ambient stable potassium-ion (K+) conducting solid-state electrolytes (KSE). Several potentiometric sensors including (O2,Au|Ag|KSE|K2SO4|Pt|Au,SO2,O2), (O2,Au|Ag|KSE|K2SO4+LaNi0.6Fe0.4O3|Pt|Au,SO2,O2) and (O2,Au|Ag|KSE|LaNi0.6Fe0.4O3|Pt|Au,SO2,O2) were assembled and characterized by chronopotentiometry. This is the first demonstration of a type III potentiometric SOx sensor using solid-state K+ conductor, operational while both sensing and reference electrodes exposed to same gas mixture without the need for sealed and separated gas chambers. The sensors in this study, at 0-10 ppm SO2 concentration and temperature range of 300-500 ℃, exhibited high sensitivities (74-89 mV/dec), robust signal output (as high as 600 mV for 2 ppm of SO2), fast response times (as low as 2 minutes), and excellent stability in ambient condition. These sensors also demonstrated good selectivity towards SOx over other interfering gases such as CO2. The results of this study indicate that the proposed sensor has immense potential for technological applications such air quality monitoring in maritime applications. Figure 1