Nanoporous Tin Dioxide Research Articles

Stability improvement for dried droplet pretreatment by suppression of coffee ring effect using electrochemical anodized nanoporous tin dioxide substrate.

A novel nanoporous analytical platform is reported to improve the stability of the dried droplet method (DDM). This nanoporous platform was made of tin dioxide (Np SnO2) substrate by electrochemical anodization from tin (Sn) slide. The DDM is a widely used sample pretreatment in analytical chemistry that involves placing a droplet of solution onto the substrate and drying for analytical testing. However, during the droplet drying process, the solutes would converge at the droplet edge and cause inhomogeneous solutes distribution. This is the coffee ring effect (CRE). The Np SnO2 has irregular nanopores, which allows droplet solutions to penetrate into the substrate rather than spreading out, effectively suppressing CRE. Theoretical models were built to explain the formation of CRE on blank tin (Sn) substrate and suppression of CRE on Np SnO2. Better results were obtained in detecting lithium (Li) using the Np SnO2 by laser-induced breakdown spectroscopy (LIBS). The line scanning results indicated that the Li emission line (670.8nm) intensities on Np SnO2 substrate had lower relative standard deviation (RSD = 3.3%) than those on Sn substrate (RSD = 31.5%), which illustrate suppression of CRE and stability improvement on Np SnO2 substrate. Furthermore, Licalibration curves were built for LIBS with DDM. The curve using Np SnO2 substrate had better linearity (R2 = 0.997), higher precision (RSD = 4.2%), and higher sensitivity (LOD = 0.13mg/L) than that by Sn substrate (R2 = 0.954, RSD = 17%, and LOD = 1.21mg/L). All in all, the anodic Np SnO2 substrate can suppress CRE in DDM and hence improve the stability and precision of subsequent analysis. Graphical abstract.

Effect of hydrolysis ratio on structural, optical and electrical properties of SnO2 nanoparticles synthesized by polyol method

Using the polyol method and a thermal post-treatment, nanoporous tin dioxide (SnO2) were prepared at different hydrolysis ratio (h = n (H2O)/n (Sn)). The influence of the hydrolysis ratio on the structural, textural, optical and electrical properties of SnO2 nanopowders was investigated by employing a set of various techniques including Fourier Transform Infra-Red spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), Energy Dispersive X-ray spectroscopy (EDX), Scanning Electron Microscopy (SEM), Nitrogen Sorption Porosimetry and Impedance Spectroscopy. FTIR and EDX studies revealed that SnO2 species were obtained. Nanocrystallites of cassiterite, i.e. rutile-like tetragonal SnO2 structure, were formed after annealing in air at 700 °C and the average crystallite size increased from 12.8 to 29.1 when the hydrolysis ratio rose from 17 to 24. Moreover, TEM, SEM, and N2 sorption porosimetry investigations indicated that the sample prepared for h = 17 was composed of an aggregated network of almost spherical nanoparticles, the morphology and sizes of which changed with the increase in the hydrolysis ratio to h = 24 and the mesoporosity of which was found to be linked to the interparticle space. Moreover, this increase in mean nanoparticle size was accompanied by a decrease in the band gap value from 3.4 eV (h = 17) to 3.16 eV (h = 24). Finally, bulk conductivity dependence with temperature was found to follow an Arrhenius law for samples annealed at 700 °C with an activation energy of 0.65 eV for h = 17, 0.69 eV for h = 20 and 0.71 eV for h = 24 that is typical of SnO2 nanopowders.

Micrometer-sized nanoporous tin dioxide spheres for gas sensing

We report the synthesis of mesoporous tin dioxide (SnO 2) materials with well-defined particle morphology. The products consist of uniform spheres with a diameter of 5 μm. The spheres are hierarchically porous with two distinct pore modes of 5.0 nm and 52 nm, respectively. This special porosity is the result of a synthesis procedure which involves a ‘hard templating’ (nanocasting) process. The product forms an approximately homogeneous monolayer of spheres on a sensor substrate and shows promising response to methane gas with low cross-sensitivity to water. The structural properties and gas-sensing performance are compared with a mesoporous SnO 2 material without defined morphology, prepared by a ‘soft templating’ procedure.

Alkynylorganotins, versatile precursors of class II hybrid materials

AbstractIn the field of functional organic–inorganic hybrid materials, recent trends in the chemistry based on trialkynylorganotins 1 and organically bridged α,ω‐bis(trialkynyltin) compounds 2 are reviewed. Compounds 1 reacted with non‐porous silica and nanoporous tin dioxide powders to yield hydrophobic, lipophobic or perylene dye‐modified oxide materials. The formation of MoxideOSnC bonds and the release of three molecules of alkyne led to the irreversible chemisorption of 1, the reaction rate and the chain loading depending on the electronic demand and the bulkiness of the organic group grafted. Furthermore, self‐assembled tin‐based class II hybrid materials were spontaneously formed by hydrolysis of 2 under homogeneous conditions as the two tin atoms were bridged through a rigid or a semi‐rigid linker. Subsequent thermal treatment of these hybrids under an oxygen flow at 400–500 °C furnished nanoporous tin dioxide materials consisting of a porous network of aggregated cassiterite tin dioxide particles. An unusual polymodal distribution of mesopore sizes was found in the case of the sample prepared from the hybrid containing the diphenylene spacer. Copyright © 2007 John Wiley & Sons, Ltd.

Bridged Polystannoxane: A New Route toward Nanoporous Tin Dioxide

Hydrolysis and condensation under acidic conditions of bis(triprop-1-ynylstannyl)p-phenylene 1, p-xylene 2, or butylene 3 precursors yielded bridged polystannoxanes in the form of xerogels after being dried under reduced pressure. The gels were amorphous and nonporous with very low specific surface areas. Thermal treatment of the xerogels in air at 400−500 °C resulted in nanocrystalline nanoporous cassiterite tin dioxide materials, which have been thoroughly characterized by elemental analysis, FTIR, TGA−MS, powder XRD, and N2 adsorption porosimetry. The calcined materials consisted of a porous network of aggregated nanoparticles with a nanoporosity stemming from the interparticle space. A careful tuning of the precursor nature and the calcination conditions enabled the synthesis of materials with Brunauer−Emmet−Teller surface areas ranging from 40 to 150 m2 g-1, a mean pore size between 3.5 and 12 nm, and an average particle size of 5 to 25 nm. Starting from precursor 1 appeared to be the best strategy to obtain pure nanocrystalline tin dioxide materials with good textural properties for applications, with the p-phenylene bridge being easily removed by calcination.

Tin Dioxide Materials Chemically Modified with Trialkynylorganotins: Functional Nanohybrids for Photovoltaic Applications

Surface modification of nanoporous tin dioxide materials with fluorinated or perylene units is achieved with trialkynylorganotin compounds (see figure). Irreversible chemisorption occurs in solution at room temperature, yielding an organic layer at the oxide surface via the cleavage of the three tin–alkynide bonds of the precursor and the formation of Snbulk–O–Sn–C linkages. The dye-sensitized nanohybrids are suitable for solar-energy conversion devices.

Dye-Sensitization of Tin Dioxide via the Functionalization of Oxide Surfaces with Trialkynylorganotins

AbstractThe surface modification of nanoporous tin dioxide materials was achieved with trialkynylorganotin(IV) (C4H9-C=C)3Sn-(CH2)n(C10H20) (n = 4,6)1 endowed with a perylene dye to yield powders containing up to 0.13 mmol.g-1 of perylene unit or dye-modified thin films. Irreversible chemisorption occurred in solution at room temperature to give perylene dye grafted at the oxide surface via the cleavage of the three tin-alkynide bonds of the precursor and the formation of Snbulk-O-Sn-Cdye linkages. The photoelectrochemical cells made with the 1-modified films demonstrated maximum incident photon to current efficiency (IPCE) as high as 18% at 430 nm under white light illumination. The performances of the cells were interpreted in terms of the intrinsic properties of tin dioxide and aggregation of the perylene dye.