Selective molecular sieving by tailoring the etch hole dimensions of rGO in rGO-ZnO nanotubes based hybrid structure

The present paper concerns the selectivity improvement of the gas sensor devices by incorporating the molecular sieving effect through tailoring the dimensions and numbers of etch holes in the reduced graphene oxide (rGO) layer of rGO-ZnO nanotubes based hybrid device structure. The etch holes on rGO layer act as an effective molecular sieve, where target vapor having larger molecular size can't penetrate through the etch holes. Thus, the numbers and dimensions of etch holes were tailored in rGO-ZnO NTs based hybrid structure by tuning the reduction temperature of rGO. Two types of binary hybrid devices viz. sample 1 (treated at 200°C temperature) and sample 2 (treated at 400°C temperature) were investigated. Consequently, for proof of concept, two different alcohols vapors (i.e. methanol and ethanol) having different molecular size, were used as a test species. The experimental results confirms that, for smaller etch hole dimensions, the nanoscale perforation of rGO excludes larger molecules but allows smaller molecules to pass through it and thus can act as a molecular sieve.