Abstract
Chemical nanosensors based on nanoparticles of tin dioxide and graphene-decorated tin dioxide were developed and characterized to detect low NO(2) concentrations. Sensitive layers were prepared by the drop casting method. SEM/EDX analyses have been used to investigate the surface morphology and the elemental composition of the sensors. Photoactivation of the sensors allowed for detecting ultra-low NO(2) concentrations (100 ppb) at room temperature. The sensors showed very good sensitivity and selectivity to NO(2) with low cross-responses to the other pollutant gases tested (CO and CH(4)). The effect of humidity and the presence of graphene on sensor response were studied. Comparative studies revealed that graphene incorporation improved sensor performance. Detections in complex atmosphere (CO + NO(2) or CH(4) + NO(2), in humid air) confirmed the high selectivity of the graphene sensor in near-real conditions. Thus, the responses were of 600%, 657% and 540% to NO(2) (0.5 ppm), NO(2) (0.5 ppm) + CO (5 ppm) and NO(2) (0.5 ppm) + CH(4) (10 ppm), respectively. In addition, the detection mechanisms were discussed and the possible redox equations that can change the sensor conductance were also considered.