Facile synthesis of SnO2 hierarchical porous nanosheets from graphene oxide sacrificial scaffolds for high-performance gas sensors

Facile synthesis of metal oxide semiconductors with controllable and novel nanostructures has attracted tremendous attentions due to their crucial importance in gas detection. In this work, we report the design and synthesis of tin oxide hierarchical porous nanosheets (SnO2 HPNSs) via a graphene oxide (GO) assisted hydrothermal route, where the GO flakes act as scaffolds and fluoride ions (F−) act as etchant to control the attachment growth of SnO2 nanosheets. Highly wrinkled SnO2/reduced graphene oxide nanosheets (such as SnO2/rGO-5.0 mg) have been achieved with a proper addition amount of GO powders. The wrinkled ultrathin nanosheets are subsequently converted to the SnO2 HPNSs after annealing at 500 °C in air, which are composed of the network interconnected SnO2 nanosheets (or nanoparticles). Moreover, the SnO2 HPNSs based gas sensors exhibit greatly enhanced ethanol sensing performance, with high response (77.1-100 ppm) and good selectivity at an optimum operating temperature of 250 °C, compared with the bare SnO2 nanosheets (4.0-100 ppm, at 275 °C). A possible gas-sensing enhancement mechanism based on this novel hierarchical architecture is discussed.