High-performance mixed-potential NH3 sensor based on molten-salt-synthesized CoWO4 sensing electrode for middle-low temperature operation

High-quality CoWO 4 sensing electrodes (SE) were synthesized via a facile and green molten salt method to develop high-performance NH 3 sensors. XRD, SEM, and TEM were employed to systematically characterize the phase composition and morphology of the products obtained under various synthesis conditions. The superior sensing performance of the CoWO 4 -SE (prepared at 350 ℃ for 60 min) was maintained throughout the 250–450 ℃ operating range. Specifically, at an optimal temperature of 300 ℃, the sensor exhibited a high response of −66.5 mV to 100 ppm NH 3 , a sensitivity of −47 mV/decade, and a low limit of detection (LOD) of 5 ppm. Furthermore, the sensor exhibited strong performance in terms of repeatability and selectivity for common interfering gases. Electrochemical analyses, such as polarization and Tafel measurements, confirmed that the mixed potential theory operated in the sensing mechanism.