Ligand-assisted deposition of ultra-small Au nanodots on Fe2O3/reduced graphene oxide for flexible gas sensors

The development of flexible room-temperature gas sensors is important in environmental monitoring and protection. In this contribution, by using 1-octadecanethiol (ODT) as a surface ligand, Au nanodots (NDs) with ultra-small size of similar to 1.7 nm were deposited on the surface of alpha-Fe2O3/reduced graphene oxide (rGO). The Au ND-ODT/alpha-Fe2O3/rGO composite was fabricated into flexible gas sensors, which could detect NO2 gas down to 200 ppb at room temperature. Compared with alpha-Fe2O3/rGO, Au ND-ODT/alpha-Fe2O3/rGO showed enhanced sensing performance because of the beneficial effects of Au NDs, including facilitating the adsorption of NO2 molecules and forming ohmic-like contact with rGO and alpha-Fe2O3. In addition, the sensing performance of the composite was also influenced by the surface ligands of the Au NDs. Ligands with less polar terminal groups were found to be beneficial to charge transfer in the sensing film. Moreover, Au ND-ODT/alpha-Fe2O3/rGO-based flexible sensors showed negligible performance deterioration under moderately bent conditions, suggesting their potential to be used in portable and wearable devices.

Automated summary

This study developed flexible room-temperature gas sensors by depositing ultra-small Au nanodots on the surface of alpha-Fe2O3/reduced graphene oxide composite. The sensors showed enhanced NO2 detection performance and resistance to bending due to the beneficial effects of Au nanodots. The choice of surface ligands for the Au nanodots also played a role in influencing the sensing performance of the composite.