Fabrication of room temperature H_2 gas sensor using pure and La: ZnO with novel nanocorn morphology prepared by sol-gel dip coating method

摘要

Nanostructured ZnO thin films with different lanthanum concentration (0, 1, 3, 5 and 10 wt%) were fabricated by sol-gel dip coating method on glass substrates. The effect of La incorporation on structural, morphological and H_2 gas sensing (room temperature) properties of the ZnO thin films was studied. Thermal behaviour of the xerogel of pure ZnO was studied by thermo gravimetric analysis/differential thermal analysis. The structural property of the films was analyzed by powder X-ray diffraction method and which revealed the presence of hexagonal structure. It emphasized that the film became (002) textured upon the 3 wt% of La incorporation onwards. The surface morphology was examined by field emission scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (EDX) and it substantiated that all the films have uniform distribution of particles with novel corn like morphology. Obviously, the length of nanocorn increases with the increase of La. The elemental composition was studied by EDX spectroscopy. Photoluminescence (PL) spectra revealed that La: ZnO thin films showed a blue shift and an enhanced PL intensity over that of the pure ZnO. The H_2 gas sensitivity of the pure and La: ZnO thin films were studied towards the concentration of 1,000 ppm. 1 wt% of La incorporated ZnO thin film showed a high sensitivity (51 %) than the pure and the higher La concentration. The increase and decrease of H_2 gas sensitivity of pure ZnO upon La incorporation is also discussed in this paper.