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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.

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The CNT-ZnO nanocomposites were synthesized by addition of commercially available MWCNT during growth of ZnO nanoparticles employing a wet chemical route. These nanocomposites were then spin coated and characterized using X-ray diffraction, scanning electron microscopy, current-voltage characteristics and O2 (5-20%) / NO2 (2-20 ppm) gas sensing at 250°C operating temperature in N2 atmosphere (0.4±0.03 mbar). The addition of CNT in ZnO is found to increase the sensitivity for both O2 and NO2 gas sensing. The 0.1 wt % CNT addition in ZnO is observed to appreciably enhance the NO2 gas sensitivity while 1.0 wt % CNT addition in ZnO showed highest sensitivity for O2 gas detection.