Room Temperature Ionic Liquids Assisted Green Synthesis of Nanocrystalline Porous SnO₂ and Their Gas Sensor Behaviors

Abstract

Nanocrystalline porous tin dioxide (SnO2) materials have been obtained employing room temperature ionic liquids (1-hexadecyl-3-methylimidazolium bromide, C16MimBr) as a template via a green sol−gel method at ambient temperature followed by a suitable thermal treatment. These materials have been thoroughly characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, FTIR, and nitrogen adsorption−desorption. A careful tuning of heat-treatment procedures allowed the preparation of SnO2 functional materials with Brunauer−Emmett−Teller surface areas ranging from 38 to 140 m2 g−1, an average pore size between super-micropore (1−2 nm) and mesopore (10 nm) range, and a mean particle size from 3.0 to 10.0 nm. The applications in gas sensors for the nanostructures reveal that the obtained SnO2 materials exhibit highly sensitive, fast-responding, reproducible, and size selective sensing behaviors. The sensor characteristics were discussed in relation to the architectures of the materials, which disclose that the gas-sensor properties are strongly structure-dependent.

Template-free synthesis of hierarchical porous SnO2

“…Figure 3a, b exhibits the high-resolution XPS spectra corresponding to Sn 3d and O 1s for the nanocrystalline porous SnO 2 . It appeared as a spin-orbit doublet at *486.4 eV (3d5/2) and *495.0 eV (3d3/2), which was in agreement with the reported value in the literature [30]. In the case of the O 1s peaks, a shoulder at *531.5 eV is observed with the main peak at *530.3 eV.…”

Preparation of Inorganic Materials Using Ionic Liquids

“…[240,241] Although the synthesis of metal oxides in ionic liquids or mixed solutions containing ionic liquids has just begun, the number of publications in this direction is much more than that on the synthesis of silicas using ionic liquids because of the diversity of metal oxides. Typical examples include the synthesis of TiO 2 , [47,48,[242][243][244][245][246][247][248][249][250][251][252][253][254][255] ZnO, [43,[256][257][258][259][260][261][262][263][264][265][266] CuO, [267][268][269][270][271] Cu 2 O, [272] Fe 2 O 3 , [273,274] NiO, [275] ZrO 2 , [276] Co 3 O 4 , [277,278] CeO 2 , [279,280] SnO 2 , [281,282] PbO, …”

Trimodally porous SnO2 nanospheres with three-dimensional interconnectivity and size tunability: a one-pot synthetic route and potential application as an extremely sensitive ethanol detector

“…Li et al 21 reported that the gas responses of mesoporous SnO 2 -based sensors to hydrogen and carbon monoxide increase as the size of the pores increase from 1 to 10 nm. Vuong et al 22 also reported that the hydrogen response of nanocrystalline SnO 2 thin Potential of SnO 2 spheres with trimodal pores J-W Yoon et al films increases as the mesopore size increases.…”

“…Knudsen diffusion depends on the molecular weight (or size) of the gas, and thus the size of the mesopores can be tuned to discriminate between gases with different sizes. 21,44 In addition, controlling the macropores, mesopores and micropores is extremely important for increasing or optimizing the accessibility of gases and ions to the surfaces of a material. From this perspective, the realization and tuning of multimodal pores with a high level of control over their size, distribution, volume and interconnectivity in the present study could provide a general solution for improving the performance of many energy and environmental applications, such as Li-ion batteries, 45 supercapacitors, 46 catalysts 47,48 and gas sensors.…”