High-Performance Limiting Current Oxygen Sensor Comprised of Highly Active La0.75Sr0.25Cr0.5Mn0.5O3 Electrode

Abstract

Zirconia-based limiting current oxygen sensor gains considerable attention, due to its high-performance in improving the combustion efficiency of fossil fuels and reducing the emission of exhaust gases. Nevertheless, the Pt electrode is frequently used in the oxygen sensor, therefore, it restrains the broader application due to the high cost. Quite recently, La0.75Sr0.25Cr0.5Mn0.5O3 (LSCM) has been reported to be highly active to catalyze oxygen reduction. Herein, with the intention of replacing the frequently used Pt, we studied the practicability of adapting the LSCM to zirconia-based limiting current oxygen sensor. Through comparing the electrocatalytic activity of LSCM and Pt, it is confirmed that LSCM gave analogous oxygen reactivity with that of the Pt. Then, limiting the current oxygen sensors comprised of LSCM or Pt are fabricated and their sensing behavior to oxygen in the range of 2–25% is evaluated. Conclusively, quick response/recovery rate (within 7s), linear relationship, and high selectivity (against 5% CO2 and H2O) in sensing oxygen are observed for the sensors, regardless of the sensing materials (LSCM or Pt) that are used in the sensor. Particularly, identical sensing characteristics are observed for the sensors consisting of LSCM or Pt, indicating the practicability of replacing the Pt electrode by adapting the LSCM electrode to future zirconia-based oxygen sensors.

Ti-Doped AgNbO3 as Novel Dense Diffusion Barriers of Limiting Current Oxygen Sensors

“…According to the obtained results of tests’ voltage sweep speed, the reaction durations for AgNb 0.8 Ti 0.2 O 3−δ and AgNb 0.7 Ti 0.3 O 3−δ to achieve 90% of their saturation were calculated to be 2 and 5 s, respectively, at 800 °C. These response times are equivalent to those observed in the previously described sensors with the limiting current . In real-world applications of oxygen sensors with limiting currents, the restricted space’s oxygen content is determined by the value of the limiting current.…”

“…The Ti 2p3 and Ti 2p1 peaks’ respective binding energies are 459.01 and 464.71 eV. As shown in Table , O 2 vacancy content is evaluated using the atomic percentage of O 1s obtained from the XPS spectra (Figure b–d) . As demonstrated in Table , the values of vacancy content are 0.55, 0.56, and 0.58, accordingly.…”

“…As shown in Table 1, O 2 vacancy content is evaluated using the atomic percentage of O 1s obtained from the XPS spectra (Figure 6b−d). 42 As demonstrated in Table 1, the values of vacancy content are 0.55, 0.56, and 0.58, accordingly. In brief, Ti-doping can enhance the oxygen vacancy formation in the lattice.…”

“…These response times are equivalent to those observed in the previously described sensors with the limiting current. 42 In real-world applications of oxygen sensors with limiting currents, the restricted space's oxygen content is determined by the value of the limiting current. The AgNb 0.8 Ti 0.2 O 3−δ oxygen sensor with a condensed barrier to diffusion limiting current mechanism exhibits an exceptional plateau in its steady-state current, where the value of its limiting current (log I L ) is directly proportional to 1000/T.…”