Anchoring ultrafine Pd nanoparticles and SnO2 nanoparticles on reduced graphene oxide for high-performance room temperature NO2 sensing

In this paper, we demonstrate room-temperature NO 2 gas sensors using Pd nanoparticles (NPs) and SnO 2 NPs decorated reduced graphene oxide (Pd-SnO 2 -RGO) hybrids as sensing materials. It is found that ultrafine Pd NPs and SnO 2 NPs with particle sizes of 3–5 nm are attached to RGO nanosheets . Compared to SnO 2 -RGO hybrids, the sensor based on Pd-SnO 2 -RGO hybrids exhibited higher sensitivity at room temperature , where the response to 1 ppm NO 2 was 3.92 with the response time and recovery time being 13 s and 105 s. Moreover, such sensor exhibited excellent selectivity , and low detection limit (50 ppb). In addition to high transport capability of RGO as well as excellent NO 2 adsorption ability derived from ultrafine SnO 2 NPs and Pd NPs, the superior sensing performances of the hybrids were attributed to the synergetic effect of Pd NPs, SnO 2 NPs and RGO. Particularly, the excellent sensing performances were related to high conductivity and catalytic activity of Pd NPs. Finally, the sensing mechanism for NO 2 sensing and the reason for enhanced sensing performances by introduction of Pd NPs are also discussed.