Construction of rGO-SnO2 heterojunction for enhanced hydrogen detection

Sandwich-structured rGO-SnO2 nanocomposites comprising of reduced graphene oxide (rGO) nanosheets and SnO2 nanoparticles were prepared by a simple refluxing reaction, and its hydrogen sensing performance was investigated. The structural characterization confirmed that the ultra-fine cylindrical SnO2 nanoparticles with length of ∼ 15 nm and diameter of ∼ 5 nm were loaded on the surface of rGO nanosheets. BET surface area of rGO-SnO2 nanocomposite enhanced as the amount of GO increased. Additionally, the increase in the amount of GO effectively inhibited the disproportionation reaction of Sn2+ during the annealing process. When the mass ratio of GO to SnO2 was higher than 1.0 wt%, the disproportionation reaction of Sn2+ was completely suppressed and all Sn-related products were changed into SnO2 phases. The 1.0 wt% rGO-SnO2 nanocomposites based gas sensor showed the highest response of 11.88 to 500 ppm H2 at 225 °C, with fast response/recovery times of 2 s/19 s and a detection limit of lower than 5 ppm. Especially, the sensor showed good reproducibility, selectivity, moisture resistance, and long-term stability. H2 sensing mechanisms of rGO-SnO2 nanocomposites were discussed based on the experimental data and gas-sensing reaction theory.