Potentiometric Sensor Based on Chromium Vanadate Sensing Electrode for High Temperature Ammonia Detection

Abstract

Mixed-potential sensors using CrVO4 sensing electrodes were prepared for monitoring ammonia at high temperatures. NH3 sensitivity for the sensors sintered at 800 °C, 850 °C and 900 °C were −56.5, −75.0 and −32.1 mV/decade respectively for the NH3 above 10 ppm. High sintering temperature strengthens the bond of electrode and electrolyte, thus increasing the amount of TPB sites. Thinner electrode weakens the heterogeneous catalytic consumption of NH3. More reaction sites combined with higher NH3 concentration result in greater sensitivity for 850 °C-sintered sensor. 900 °C sintering leads to decomposition of CrVO4 into Cr2O3 and V2O5, which exhibits low NH3 sensitivity. In operating temperature range of 500 °C–600 °C, NH3 detection limit is 2 ppm. The sensor shows the biggest responses at 500 °C, but the optimum NH3 sensitivity of −75.0 mV/decade was obtained at 550 °C for the concentrations higher than 10 ppm. For the oxygen of 4–10 vol %, response is less affected by the change of oxygen content, the influence of water vapor with content of 5–6 vol % could also be ignored. The characteristics of high NH3 selectivity, sensitivity, long-term stability and anti-interference performances indicate that it is meaningful to use CrVO4 for ammonia detection in exhaust.

Detection of NH3 gas using CrVO4 nanoparticles

“…This could be attributed to a minor quantity of unspent precursor or a possible formation of a byproduct as the impurity in CrVO 4 [48]. However, most of the diffraction pattern matches the crystal structure of CrVO 4 -I [43].…”

“…Several vanadium-based bimetallic oxides, including rare earth and transition metal vanadates such as CeVO 4 , BiVO 4 , and InVO 4 , have been developed to detect NH 3 , showing good performance [40][41][42]. Among them, CrVO 4 has recently been used to detect NH 3 as a high-temperature potentiometric sensor that shows exquisite selectivity, albeit at a high operating temperature [43]. .…”

Selective detection of NO using the perovskite-type oxide LaMO3 (M = Cr, Mn, Fe, Co, and Ni) as the electrode material for yttrium-stabilized zirconia-based electrochemical sensors

“…The solid electrolyte (YSZ) serves as an oxygen ion conductor, and the electrochemical redox reaction between the electrode and the solid electrolyte generates an electrical signal. [16][17][18] The performance of the sensors is related to the electrolytes, sensitive materials, and a three-phase boundary (TPB) composed of the electrolytes and sensitive materials. Over the past few decades, research on YSZ electrochemical sensors has mainly focused on improving their sensitivity, selectivity, and stability by designing and developing sensitive materials and constructing highperformance reaction interfaces.…”

YSZ-based NO2 Mixed Potentiometric Sensor with Three-Dimensional Ordered Porous Structure

“…Over the past few decades, yttrium-stabilized zirconia (YSZ)based mixed-potential sensors have been extensively studied and optimized, with methods to improve the sensor's sensitivity mainly focused on two aspects: preparing new sensing electrodes and modifying the three-phase reaction boundary. [8][9][10][11][12][13] The types of sensing electrodes mainly include oxides and composite oxides, such as nickel oxide (NiO), tungsten oxide, and nickel cobaltite. 2,3,[14][15][16] Among the single oxides reported to date, NiO exhibits the best sensitivity.…”