Electrochemical NO[sub x] Sensors Based on Interfacing Nanosized LaFeO[sub 3] Perovskite-Type Oxide and Ionic Conductors

Abstract

Electrochemical NO x sensors based on coupling different ionic conductors with perovskite-type LaFeO 3 as auxiliary phase were prepared. The ionic conductors used were yttria-stabilized zirconia that is an oxygen ion conductor and sodium superionic conductor whose charge carriers are sodium ions. Thick films of LaFeO 3 powders were deposited using a screen printing oil on one side of the solid electrolyte pellets, using powders having different grain sizes. The obtained sensors were wholly exposed to the same atmosphere. Electromotive force ͑emf͒, polarization curves, and amperometric measurements were performed in air and at different concentrations of NO 2 in air, at selected temperatures. Quite stable emf values and fast response times were obtained. The NO 2 response was much larger when powders with nanosized grains were used for the preparation of the electrodes. From polarization curves, all sensors showed a nonlinear behavior. The role played by the electrolyte/electrode interface was determined by electrochemical impedance spectroscopy measurements; exposure to NO 2 did not affect the bulk but only the electrolyte/ electrode interface.

YSZ-based electrochemical sensors: From materials preparation to testing in the exhausts of an engine bench test

“…Among the metal oxides previously studied 6,9,11,12 as sensing electrode for high temperature applications, WO 3 showed the best performance. A chemical method was set up to obtain pure WO 3 sub-micrometric powders.…”

Electrochemical Sensors: Fundamentals, Key Materials, and Applications

“…LaFeO 3 , which has been used as a semiconductor-type gas sensor [315,316], has also been used as an electrode with YSZ [255,263,317] or NASICON [317,318] electrolytes for potentiometric NO x sensors. Strontium (i.e., (La,Sr)FeO 3 [255,256,284]) or strontium and cobalt (i.e., (La, Sr)(Co,Fe)O 3 [275,280,309]) have been added to LaFeO 3 to improve electrode performance.…”

NO2 adsorption behaviour on LaFeO3 electrodes of YSZ-based non-nernstian electrochemical sensors

“…Some of the authors of this paper previously examined the sensing properties of electrochemical sensors based on coupling YSZ with p-type (LaFeO 3 ), n-type semiconducting oxides (WO 3 , In 2 O 3 ) and mixed ionic-electronic conductors (La x Sr 1-x FeO 3 ) [8][9][10][11][12]. The sensors were fabricated using either pellets or thick layers of YSZ to obtain devices in bulk and planar form.…”