Fabrication of chemiresistive gas sensors based on multistep reduced graphene oxide for low parts per million monitoring of sulfur dioxide at room temperature

The proposed multistep reduction of graphene oxide includes two-step reduction process. The graphene oxide is reduced by hydrazine hydrate followed by further reduction with low energy nitrogen ion beam implantation technique. From the Raman spectra, reduction of graphene oxide samples has been estimated on the basis of Tuinstra and Koenig relation. FT-IR studies have shown the removal of oxygen functional groups such as epoxy, hydroxyl and carboxylic on reduction. Ion implantation has enhanced electrical conductivity and specific surface area of graphene oxide on reduction. Besides reduction, the second step has modified the surface morphology of the samples making them more appropriate for gas adsorption. The sample with higher implantation dose (1015 ions/cm2) exhibits promising potential for room temperature chemiresistive SO2 gas sensor at ppm levels as low as 5 ppm with reasonable response, selectivity and stability.