Polyelectrolytes/reduced graphene oxide assembled film as a promising NO2 gas sensing material

Abstract

The nitrogen dioxide (NO2) is a typical hazardous gas and there is an urgent demand to develop effective, sensitive and reproducible sensing materials for NO2 gas detecting. In this paper, [poly-(sodium4-styrenesulfonate) stabilized reduced graphene oxide/poly-(allylamine hydrochloride)]n nanocomposite film are prepared via layer-by-layer assembly technique. The assembled process was monitored by UV–Vis spectroscopy in the range from 200 nm to 800 nm. Absorption peaks located at 233 nm and 271 nm, and the optical energy band-gap was estimated as 4.57 eV. The film thickness was tested about 95 nm by AFM with 0.95 nm for each assembled circle, and it was featured 975 ± 10 MPa, 28 ± 2 GPa, 105–106 Ω/sq. in modulus, hardness and sheet resistance respectively. The assembled films were extremely sensitive to NO2 with response (ΔR/Ra) above 66% with a linear relationship ranged from 2 to 8 ppm and independent on thickness. The impact of relative humidity was also considered for the film towards 5 ppm of NO2 gas at a room temperature, presenting a decreasing response from 1.8 to 0.89 when the relative humidity reaches 80%. The polyelectrolytes/reduced graphene oxide composite films are promising for application as gas sensing materials.