Electrochemical exsolution of Ag nanoparticles from AgNbO3 sensing electrode for enhancing the performance of mixed potential type NH3 sensors

Abstract

An electrochemical exsolution process was developed to prepare AgNbO3/Ag composite sensing electrode (e-ANO-SE) applied in NH3 sensor with mixed potential mode. The effects of the applied voltages and times on the microstructure and the sensing performance of the SE were investigated. After the cathodic polarization of the ANO-SE at 400 ℃ and 2 V for only 200 s in Ar, Ag metal nanoparticles are formed and finely distributed on the surface of the ANO-SE particles. The sensor using e-ANO sensing electrode fabricated by electrochemical exsolution treatment exhibits enhanced sensing signal (electrical potential V), improved sensitivity (-80.1 mV/decade) and lowered detection limit (10 ppm) at 400 ℃ over against ANO-SE based sensor. In addition, the sensor based on e-ANO sensing electrode displays excellent sensing performance, reproducibility, selectivity and long-term stability due to Ag exsolution. This electrochemical exsolution method provides a new rout for preparation of high performance sensing electrode for solid electrolyte type sensors.