title: Normal-pressure microwave rapid synthesis of hierarchical SnO₂@rGO nanostructures with superhigh surface areas as high-quality gas-sensing and electrochemical active materials.
abstract: Hierarchical SnO2@rGO nanostructures with superhigh surface areas are synthesized via a simple redox reaction between Sn(2+) ions and graphene oxide (GO) nanosheets under microwave irradiation. XRD, SEM, TEM, XPS, TG-DTA and N2 adsorption-desorption are used to characterize the compositions and microstructures of the SnO2@rGO samples obtained. The SnO2@rGO nanostructures are used as gas-sensing and electroactive materials to evaluate their property-microstructure relationship. The results show that SnO2 nanoparticles (NPs) with particle sizes of 3-5 nm are uniformly anchored on the surfaces of reduced graphene oxide (rGO) nanosheets through a heteronucleation and growth process. The as-obtained SnO2@rGO sample with a hierarchically sesame cake-like microstructure and a superhigh specific surface area of 2110.9 m(2) g(-1) consists of 92 mass% SnO2 NPs and ∼8 mass% rGO nanosheets. The sensitivity of the SnO2@rGO sensor upon exposure to 10 ppm H2S is up to 78 at the optimal operating temperature of 100 °C, and its response time is as short as 7 s. Compared with SnO2 nanocrystals (5-10 nm), the hierarchical SnO2@rGO nanostructures have enhanced gas-sensing behaviors (i.e., high sensitivity, rapid response and good selectivity). The SnO2@rGO nanostructures also show excellent electroactivity in detecting sunset yellow (SY) in 0.1 M phosphate buffer solution (pH = 2.0). The enhancement in gas-sensing and electroactive performance is mainly attributed to the unique hierarchical microstructure, high surface areas and the synergistic effect of SnO2 NPs and rGO nanosheets.
authors.affiliation: School of Materials Science and Engineering, Zhengzhou University, 100 Science Road, Zhengzhou 450001, P.R. China. dlchen@zzu.edu.cn zhangray@zzu.edu.cn.
authors.forename: Li
authors.initials: L
authors.lastname: Yin
authors.forename: Deliang
authors.initials: D
authors.lastname: Chen
authors.forename: Xue
authors.initials: X
authors.lastname: Cui
authors.forename: Lianfang
authors.initials: L
authors.lastname: Ge
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.forename: Lanlan
authors.initials: L
authors.lastname: Yu
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.forename: Rui
authors.initials: R
authors.lastname: Zhang
authors.forename: Guosheng
authors.initials: G
authors.lastname: Shao