Assembly of 2D-MoS2 with graphene layer for highly sensitive and selective gas detection at room temperature

Two-dimensional (2D) graphene has been regarded as a promising gas sensing material operated in room temperature. However, practical use of pure graphene as a gas sensor still faces problems owing to its insufficient sensitivity, selectivity and stability. In the present study, 2D-molybdenum disulfide (2D-MoS2) were successfully assembled with graphene oxide (GO) with the assistance of poly (diallyl dimethylammonium chloride) (PDDA). The intercalation of PDDA and stacking of 2D-MoS2 significantly expand the interlayer spacing of GO from 0.77 nm to 1.44 nm in the GO-PDDA-MoS2 composite. The rGO-PDDA-MoS2 sensing chip could be obtained by in-situ reduction of GO-PDDA-MoS2 pre-coated on an interdigital electrode in hydrazine vapor. The sensor exhibited excellent sensitivity, selectivity and stability for H2S and NO detection with a limit detection as low as 3 ppb and 5 ppb, respectively. The enhanced sensing performance could be ascribed to the increased gas accessibility and specific binding site resulted from the introduction of PDDA and 2D-MoS2. Furthermore, its potential application in the diagnosis of respiratory disease was demonstrated. Exhaled breath (EB) spiked with 50 ppb NO and 15 ppb H2S for simulating EB of asthma patients could be successfully discriminated from the normal EB.