Investigation of Ca substitution on the gas sensing potential of LaFeO₃ nanoparticles towards low concentration SO₂ gas

Abstract

The present work investigates the superior ability of LaFeO3 (LaFeO) and La0.8Ca0.2FeO2.95 (LaCaFeO) nanoparticles to detect 3 ppm SO2 gas. The influence of calcium substitution on the sensing behaviour of LaFeO has been studied. High resolution TEM images show that the particle sizes of LaFeO and LaCaFeO are less than 100 nm and SEM images show the agglomeration of interconnected nanoparticles. Both LaFeO and LaCaFeO crystallize in the orthorhombic crystal system with the space group Pbnm. Rietveld analysis of neutron diffraction data showed that LaCaFeO has lattice oxygen vacancies. In addition, magnetic refinements on both the samples have been carried out. The presence of lattice oxygen vacancies in LaCaFeO is qualitatively supported by Raman and XPS measurements. Electrical characterization showed increased conductivity for the LaCaFeO sample, influencing their sensing performance significantly. The LaCaFeO nanoparticles exhibit higher sensitivity, faster response time, rapid recovery time and good recyclability for sensing 3 ppm SO2 gas. This enhanced sensing behaviour is attributed to the increased oxygen vacancies in the lattice as well as the surface. As a consequence, increased active sites are created in LaCaFeO, promoting redox reaction between the analyte and the sensing material. The results demonstrated that while LaFeO is a good gas sensor, p-type substitution by Ca(2+) renders this material an improved resistivity based gas sensor to detect low concentration SO2.

LaFeO3 ceramics as selective oxygen sensors at mild temperature

“…LaFeO 3 -based ceramics were also reported to have good sensing properties towards many gases such as acetone, formaldehyde ethanol, SO 2 , NO 2 , CO, CH 4 , CO 2 and O 2 [4][5][6][7][8][9][10][11][12][13].…”

Assembly of ZIF‐67 Metal–Organic Framework over Tin Oxide Nanoparticles for Synergistic Chemiresistive CO2 Gas Sensing

“…The CO 2 gas sensing behavior of SnO 2 and SnO 2 @ZIF‐67 was studied by monitoring the resistance change in the presence and absence of the target gas. The samples in the form of pellets were placed in the probe station provided with a heat‐ and gas‐supplying channel controlled by a temperature control unit and mass flow controllers (MFCs), respectively . We tested the response of materials at a wide range of CO 2 concentrations, starting from 50 % to 500 ppm.…”

“…The samples in the form of pellets were placed in the probe station provided with ah eatand gas-supplying channel controlled by atemperature control unit and mass flow controllers (MFCs), respectively. [12] We tested the response of materials at aw ide range of CO 2 concentrations, starting from 50 %t o5 00 ppm. Argon gas was chosen both as ar eference and diluting gas.…”

High-sensitivity detection of H2S by In2O3/C composite prepared by inert-ambient sealed-tube pyrolysis

“…In overall reducing reaction between H 2 S gas and chemisorbed oxygen spices may be represented by the following equations [36,37] The above equation shows that the concentration of electrons increases as the H 2 S gas interacts with the adsorbed oxygen molecules. These electrons neutralize the holes present in In 2 O 3 /C, thus reducing the majority charge carriers.…”