Fabrication of LaFeO₃ and rGO-LaFeO₃ microspheres based gas sensors for detection of NO₂ and CO

Abstract

In the present report, gas sensing devices based on LaFeO 3 and rGO-LaFeO 3 were fabricated by a photolithography technique. The X-ray diffraction, Raman spectra and FT-IR results confirm the formation of a perovskite phase and composite. XPS and TEM give the chemical compositions for both products. The higher roughness, greater surface area (62.1 m 2 g À1 ), larger pore size (16.4 nm) and lower band gap (1.94 eV) of rGO-LaFeO 3 make it a suitable candidate to obtain high sensitivity. The gas sensing performance of the devices was investigated for various concentrations of NO 2 and CO gases at temperatures of 200 and 250 C. It was observed that the rGO-LaFeO 3 based device exhibited a high relative response (183.4%) for a 3 ppm concentration of NO 2 at a 250 C operating temperature. This higher response is attributed to the large surface area, greater surface roughness, and numerous active sites of rGO-LaFeO 3 . The gas sensing properties investigated show that rGO-LaFeO 3 is an excellent candidate for an NO 2 sensor.

Autocombustion‐Promoted Synthesis of Lanthanum Iron Oxide: Application as Heterogeneous Catalyst for Synthesis of Piperidines, Substituted Amines and Light‐Assisted Degradations

“…Usually, this peak is considered to be the characteristic of Fe 3 + ions in their oxide form. [83,84] Additionally, the presence of La and Fe in + 3 oxidation state was ascertained with the literature. Besides this, the analysis of the binding energy value in the range of 500-550 eV showed the two assymetric peaks (Figure 9(c)), declaring the presence of oxygen in two different valence states, out of them the one at 528.7 eV belongs to the lattice oxygen which means that it serves for the LaÀ O and FeÀ O bonds of the LFO lattice structure whereas the another one at 531.1 eV seems to be due to the adsorbed hydroxyl group (from the atmospheric moisture) on the surface of LFO.…”

Characteristics of porous spherical LaFeO3 as ammonia gas sensing material

“…[36] The two weak peaks at 1506 and 1398 cm -1 are assigned to the asymmetric stretching of the carbonates. [37] The FT-IR spectra of PS-LFO shows a sharp peak at 542 cm -1 , confirming the presence of a perovskite phase which usually appears in 500-700 cm -1 range [38] The 542 cm -1 band is the characteristic band of the octahedral FeO6 group in LFO, suggesting the existence of Fe-O stretching vibration. [39] Figure 1: XRD pattern of PS-LFO Figure 3 showed the N2 adsorption-desorption isotherm of the porous spherical LFO.…”

Socio-economic demands and challenges for non-invasive disease diagnosis through a portable breathalyzer by the incorporation of 2D nanosheets and SMO nanocomposites

“…Relative response: ratio of resistance of the sensor in the ambient atmosphere to the resistance to the exposure of acetone of varying concentration. 57 S ¼ (R a /R g ) À 1…”

“…Sensitivity: change in relative response with respect to the change in gas concentration. 57 Selectivity: measure of the relative response of other interfering biomarkers with respect to acetone.…”