MWCNT and α-Fe2O3 embedded rGO-nanosheets based hybrid structure for room temperature chloroform detection using fast response/recovery cantilever based sensors

This paper presents a simple, novel and cost effective process to synthesize MWCNTs and alpha-Fe2O3 embedded in rGO sheet layers, which is found to be a highly selective and sensitive material for the detection of chloroform vapours in room temperature conditions. The nanocomposite rGO- MWCNT- alpha-Fe2O3 has showed enhanced chloroform vapour sensing performance characteristics compared to rGO- alpha-Fe2O3 and pure alpha-Fe2O3 which have been reported earlier. The MWCNTS alongwith rGO sheets provide improved sensitivity mainly due to a high surface area (49 m(2)/g and 72 m(2)/g) with doping of nanotubes in the composite matrix as compared to other established counterparts like alpha-Fe2O3 (12.6 m(2)/g) and rGO- alpha-Fe2O3 (19.05 m(2)/g). The nanocomposite films also show a faster response (2 s at 1 ppm) and recovery time (1 s at 1 ppm) due to a high diffusivity of vapours into the structure owing to the 3-Dimensional nature of the nano-composite structure which makes the directly exposed area multifolds. The material is suitably immobilized on SU-8 based nanocantilever platform which show enhanced deflection upto 250 ppb vapour detection. The nanocomposite functionalised cantilever are further tested with other types of volatile organic compounds and the sensor is found to show a high selectivity towards chloroform. The presence of trace volatile organic compounds (VOC) in human breath is a very common way of detection of malignancy and thus this sensor may eventually help in such recognition in the near future.