Identification of different tin species in SnO2 nanosheets with 119Sn solid-state NMR spectroscopy

doi:10.1016/j.cplett.2015.11.035

Chemical Physics Letters

Volume 643, January 2016, Pages 126-130

https://doi.org/10.1016/j.cplett.2015.11.035 Get rights and content

Highlights

•
Sn ions in 1st/2nd layer, and ‘bulk’ in SnO₂ nanosheets can be resolved with NMR.
•
NMR spectroscopy provides fine resolution that no other spectroscopy currently shows.
•
This approach based on NMR should be able to be extended to other diamagnetic metal oxides.

Abstract

¹¹⁹Sn solid-state nuclear magnetic resonance (NMR) spectroscopy was employed to investigate the structure of hydroxylated SnO₂ nanosheets. Three ¹¹⁹Sn resonances can be observed and assigned to Sn ions in the first layer, the bulk and the second layer from high to low frequencies with the help of density functional theory (DFT) calculations. The results suggest that ¹¹⁹Sn NMR spectroscopy can be a sensitive method to monitor the structure of SnO₂ based nanomaterials and extension of this approach to other diamagnetic metal oxides.

Graphical abstract

Tin ions in the first layer, second layer and ‘bulk-like’ environment of ultrathin SnO2 nanosheets can be distinguished by using ¹¹⁹Sn solid-state NMR spectroscopy.

Introduction

Nanostructured materials show different, often better properties from their bulk counterparts, which arise from their higher surface areas and sometimes electronic properties, and thus are used or have potential applications in energy storage, catalysis, biosciences and environmental management. In order to rationally design nanomaterials with improved performances, it is critical to understand their structure details, especially surface structure, and develop structure and property relationships [1], [2], [3], [4]. Although electron microscopy is the most important tool to determine the surface structure, the small volumes investigated under such methods may not be representative of the entire sample. Other characterization techniques such as Raman [5], infrared (IR) [6], [7], [8] and ultraviolet (UV) spectroscopy [9], X-ray photoelectron spectroscopy (XPS) [10], [11] and low energy electron diffraction (LEED) [12] can also be used to extract the structural information of nanomaterials, however, much lower resolution is achieved.

Recently we showed that ¹⁷O NMR spectroscopy, in combination with DFT calculations, can be an extremely sensitive probe to detect and resolve oxygen ions in oxide nanostructures [13]. For example, the 1st, 2nd and 3rd layer of ceria nanoparticles, oxygen ions in the bulk, as well as surface hydroxyl species. However, this approach requires surface selective isotopic labeling due to the low natural abundance of ¹⁷O. In principle, the NMR parameters (e.g., chemical shift) of any nucleus should be sensitive to its local structure and thus NMR spectroscopy of metal ions should also be a powerful method for investigations of surface structure of nanosized oxides. Since nanostructured tin dioxide (SnO₂) have remarkable electronic, electrochemical and optical properties which lead to a variety of applications, such as catalytic carrier [14], [15], lithium-ion batteries [16], [17], [18], solar cells [19] and gas sensors [20], [21], [22], [23], and ¹¹⁹Sn has relatively high gyromagnetic ratio (γ(¹¹⁹Sn) = 0.374γ(¹H)) and natural abundance (8.58%), we attempted to develop the new characterization method on the basis of ¹¹⁹Sn solid-state NMR spectroscopy on SnO₂ nanomaterials. Specifically, hydroxylated SnO₂ nanosheets were prepared and investigated because the well-defined nanostructures. We are able to demonstrate here that ¹¹⁹Sn NMR spectroscopy can also be a sensitive technique to monitor the surface structure of nanosized SnO₂. We find that the ¹¹⁹Sn chemical shifts can distinguish Sn ions in the first, second layer and ‘bulk’ environment in the nanosheets, thus can be used to follow the structure evolution of SnO₂ based materials in related applications..

Section snippets

Synthesis of SnO₂ nanosheets

In a typical synthesis process, 374 mg of the precursor SnCl₂·2H₂O was added into 100 mL mixture of ethanol and deionized water (volume ratio = 1:1). After magnetically stirred for 5 min, ammonia was slowly (0.5 mL/min) introduced into the mixture until the pH value reached 11. After vigorous stirring for 30 min, the obtained white turbid suspension was transferred into a 100 mL Teflon-lined autoclave, heated with magnetic stirring at 393 K for different time in an oil bath pan before it was rapidly

Results and discussion

The XRD pattern of as-obtained SnO₂ sample (Figure S2) can be indexed to rutile phase with a tetragonal structure (JCPDS No. 41-1445). The broad peak widths indicate the presence of nanosized crystallites. The TEM and HRTEM images of SnO₂ nanostructures are shown in Figure S3and Figure 1A, in which light and dark regions can be observed. The light regions, which are the majority of the sample, suggest planar thin sheets lying on the substrate, while dark regions imply that nanosheets may either

Conclusions

¹¹⁹Sn solid-state NMR spectroscopy, in combination with the DFT calculations, has been demonstrated to identify different Sn species in SnO₂ nanosheets. The resonances at −585, −604 and −618 ppm can be assigned to Sn ions in the 1st layer, ‘bulk-like’ environment and 2nd layer in the hydroxylated nanosheets, respectively. The relatively large chemical shift differences found in different species suggest ¹¹⁹Sn NMR chemical shift is a sensitive structural probe. The results also suggest that NMR

Acknowledgements

This work is supported by National Basic Research Program of China (2013CB934800), National Natural Science Foundation of China (NSFC) (21222302, 20903056 and 21322307), NSFC – Royal Society Joint Program (21111130201), Program for New Century Excellent Talents in University (NCET-10-0483), Fundamental Research Funds for the Central Universities (1124020512), National Science Fund for Talent Training in Basic Science (J1103310) and a Project Funded by the Priority Academic Program Development

References (33)

A. Ayeshamariam et al.
Spectrochim. Acta A
(2014)
P. Chetri et al.
J. Alloys Compd.
(2015)
I. Hannus et al.
J. Mol. Struct.
(1995)
J.H. Kwak et al.
Science
(2009)
Q. Fu et al.
Science
(2010)
H.G. Yang et al.
Nature
(2008)
G.V. Lier et al.
Chem. Phys. Lett.
(2000)
R.G. Pavelko et al.
Phys. Chem. Chem. Phys.
(2010)
K. Nejati
Cryst. Res. Technol.
(2012)
S. Shah et al.
J. Mater. Chem.
(2012)

C.W. Cheng et al.

ACS Nano

(2009)

M. Kwokaa et al.

Thin Solid Films

(2005)

S.Y. Ho et al.

Cryst. Growth Des.

(2009)

M.S. Hettenbach et al.

Surf. Sci.

(2001)

M. Wang et al.

Sci. Adv.

(2015)

A. Kowal1 et al.

Nat. Mater.

(2009)

Cited by (15)

A review of <sup>17</sup>O isotopic labeling techniques for solid-state NMR structural studies of metal oxides in lithium-ion batteries
2024, Magnetic Resonance Letters
Recent advances in utilizing ¹⁷O isotopic labeling methods for solid-state nuclear magnetic resonance (NMR) investigations of metal oxides for lithium-ion batteries have yielded extensive insights into their structural and dynamic details. Herein, we commence with a brief introduction to recent research on lithium-ion battery oxide materials studied using ¹⁷O solid-state NMR spectroscopy. Then we delve into a review of ¹⁷O isotopic labeling methods for tagging oxygen sites in both the bulk and surfaces of metal oxides. At last, the unresolved problems and the future research directions for advancing the ¹⁷O labeling technique are discussed.
Hyperpolarization transfer pathways in inorganic materials
2021, Journal of Magnetic Resonance
Citation Excerpt :
The surface spectrum of SnO2 is characterized by three notable peaks corresponding to different sites. These signals can be observed in hydroxylated SnO2 nanosheets and have been assigned to different atomic layers [33]. The bulk-like 119Sn is at −604 ppm (B) and the first and second atomic layer, respectively, were assigned chemical shifts of −585 ppm (S1) and −618 ppm (S2).
Dynamic nuclear polarization can be used to hyperpolarize the bulk of proton-free inorganic materials in magic angle spinning NMR experiments. The hyperpolarization is generated on the surface of the material with incipient wetness impregnation and from there it is propagated towards the bulk through homonuclear spin diffusion between weakly magnetic nuclei. This method can provide significant gains in sensitivity for MAS NMR spectra of bulk inorganic compounds, but the pathways of the magnetization transfer into the material have not previously been elucidated. Here we show how two-dimensional experiments can be used to study spin diffusion from the surface of a material towards the bulk. We find that hyperpolarization can be efficiently relayed from surface sites to multiple bulk sites simultaneously, and that the bulk sites also engage in rapid polarization exchange between themselves. We also show evidence that the surface peaks can exchange polarization between different sites in cases of disorder.
Sol-gel synthesis of sno2 nanoparticles doped with zr+4/cd+2 and co-doped with f: Their structural, optical and electrical properties
2021, Materials Today: Proceedings
Citation Excerpt :
EDS analysis has shown incorporation of dopant ions into SnO2 network Fig. 3. Solid state 119Sn MAS NMR spectroscopy is an important tool for study the different chemical environment around Sn+4 ions in SnO6 polyhedra of casitarite structure of SnO2 [28–30]. To analyze presence of different chemical environment around tin in SnO2, 119Sn MAS NMR spectra of one of the doped samples (4) along with pure SnO2 synthesized with similar route have been recorded and are shown in Fig. 4.
Some nanoscale particles of SnO₂ doped with Zr⁺⁴ (1), Zr⁺⁴ and co-doped with F⁻ (2), Cd⁺² (3) and with Cd⁺² and co-doped with F⁻ (4) have been prepared by sol–gel technology in basic medium using SnCl₂·2H₂O as precursor in isopropanol as solvent. Structural analysis by XRD patterns have shown formation of particles at nanoscale and retention of tetragonal rutile structure in SnO₂ network. This fact was further confirmed by ¹¹⁹Sn MAS NMR spectroscopy. SEM images have shown formation of various geometrical patterns. In the IR spectra, O-Sn-O absorption bands appeared at their expected positions. UV–Vis spectroscopy has shown an increase in optical band gap. Photoluminescence spectra of all these derivatives are found to be almost similar, again indicated retention of tetragonal rutile SnO₂ framework. I-V curves are non-linear showing schottky contacts in the material.
Relationship between tin environment of SnO<inf>2</inf> nanoparticles and their electrochemical behaviour in a lithium ion battery
2021, Materials Chemistry and Physics
Citation Excerpt :
The shoulder line is observed for solvo and hydrothermal materials at about −610 ppm. Chen et al. reported that this peak is derived from surface Sn species that are close to absorbed water molecules and hydroxyl groups [38]. This is consistent with the observation of the Sn–OH bond identified by infrared for solvo and hydrothermal materials.
SnO₂ nanoparticles were synthetized in three different ways (solvothermal, hydrothermal, sol-gel) and heat-treated under argon at 600 °C to obtain different physico-chemical characteristics (texture, structure and surface chemistry) determined by X-ray powder diffraction (XRD), infrared spectroscopy (FTIR), ¹¹⁹Sn solid state Nuclear Magnetic Resonance (NMR), Electron Spin Resonance (ESR), scanning electron microscopy (SEM) and 77 K nitrogen sorption. When used as electrode material in a lithium ion battery, their electrochemical properties were evaluated by galvanostatic measurements. Among crystallinity, particle size, specific surface area and associated porosity, hydroxyl groups and paramagnetic centers, only the last two parameters appear as determinants of electrochemical performance. Solvothermal and hydrothermal syntheses lead to the presence of certain hydroxyl groups in the oxide whereas sol-gel one prevents their formation but forms paramagnetic species. The hydroxyl groups favour a good coulombic efficiency and an interesting reversibility of the conversion process. Paramagnetic species limit the electrochemical process. Their elimination by a heat-treatment at 1000 °C under argon improves the electrochemical properties. Understanding the key factors to favour SnO₂-based materials allows to obtain capacities of about 900 mAh.g⁻¹ over 5 cycles.
Highly efficient removal of U(VI) by the photoreduction of SnO<inf>2</inf>/CdCO<inf>3</inf>/CdS nanocomposite under visible light irradiation
2020, Applied Catalysis B: Environmental
Citation Excerpt :
Fig. 1B shows the FTIR spectra of the samples. For SnO2, the broad absorption bands appearing at 567 and 679 cm−1 are assigned to SnO antisymmetric vibrations and the absorption band at 1037 cm−1 is consistent with the previously reported overtone and combination bands of bulk cassiterite [27,28]. The bands appearing at ∼1630 cm−1 in all curves are related to the adsorbed H2O molecules.
Reducing soluble U(VI) to insoluble U(IV) is an ideal strategy to collect/remove uranium in water. In this work, a new way is reported to achieve this reduction through a photocorrosion-related photocatalysis process of SnO₂/CdCO₃/CdS (SCC) under visible light irradiation. The mechanism is systematically studied and discussed through a variety of characterization methods, such as X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Mott-Schottky test, etc. The matching of energy band ensures the separation of photoelectrons and holes, which results in the decrease of charges’ recombination rate and the enhancement of photoreduction activity. The reduction process can be efficiently performed in the ternary complex of SCC in that the photo-generated holes are consumed by oxidization of S²⁻ to S⁰ on CdS in SCC. Furthermore, uranium extraction could be achieved by SCC without any protective gases or electronic sacrificial agent, which shows great advantages in applications of U(VI) collection/removal.
Efficient solid acid catalysts based on sulfated tin oxides for liquid phase esterification of levulinic acid with ethanol
2018, Applied Catalysis A: General
Citation Excerpt :
Thus we suggest that the calcination of the precursor SnO2.xH2O gel at 500 °C resulted in formation of the inactive β-form which has less bound water [43]. The progressive increase of crystallite size with increasing temperature is also documented in the literature [46]. The 119Sn NMR spectra of samples SO42−/SnO2(100) and SO42−/SnO2(140) synthesized by sulfating of SnO2 precursors obtained without calcination step (SnO2(100) and SnO2(140)) show that the sulfation procedure resulted in disappearance of the signal at −601 ppm and in the appearance of new peaks at −769 ppm and −786 ppm (Fig. 7).
Tin oxide nanomaterials prepared by hydrothermal synthesis at 100 °C or 140 °C with or without template and further calcination step were modified with sulfate groups by post synthesis treatment. The catalysts were characterized by X-ray powder diffraction (XRD), N₂ physisorption, UV Vis spectroscopy, TG analysis, XPS and solid state NMR spectroscopy. The acidity of the materials was characterized by temperature programmed desorption (TPD) of ammonia. The catalytic performance of nanosized SnO₂ catalysts and their sulfated analogues was studied in levulinic acid (LA) esterification with ethanol. Sulfated materials show significantly higher activity compared to non-sulfated ones. It was found that the synthesis parameters (temperature, template) for preparation of the parent SnO₂ nanoparticles influence significantly their textural properties and have a pronounced effect on the structural characteristics of the obtained sulfated tin oxide based materials and their catalytic performance in levulinic acid esterification. Skipping the calcination step during the preparation of parent SnO₂ samples synthesized without template resulted in the formation of new, highly crystalline phase based on hydrated tin(IV) sulfate [Sn(SO₄)₂.xH₂O], tin(IV) bisulfate [Sn(HSO₄)₄.xH₂O] and/or tin(IV) pyrosulfate [Sn(S₂O₇).xH₂O] species in the sulfated nanomaterials with superior catalytic performance. The formation of this new and catalytically very active phase not reported so far in the literature for sulfated tin oxide-based materials is discussed. The catalytically active sites for esterification of levulinic acid with ethanol is suggested to result from the formation of strong Brønsted and Lewis acid sites with high density in the newly registered phase. The results indicate that the chemical structure and catalytic performance of the obtained sulfated tin oxide based materials strongly depend on the treatment of the SnO₂ nanoparticles before the sulfation procedure.

View all citing articles on Scopus

¹: These authors contributed equally.

View full text

Identification of different tin species in SnO2 nanosheets with 119Sn solid-state NMR spectroscopy

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Synthesis of SnO2 nanosheets

Results and discussion

Conclusions

Acknowledgements

Spectrochim. Acta A

J. Alloys Compd.

J. Mol. Struct.

Science

Science

Nature

Chem. Phys. Lett.

Phys. Chem. Chem. Phys.

Cryst. Res. Technol.

J. Mater. Chem.

ACS Nano

Thin Solid Films

Cryst. Growth Des.

Surf. Sci.

Sci. Adv.

Nat. Mater.

Identification of different tin species in SnO₂ nanosheets with ¹¹⁹Sn solid-state NMR spectroscopy

Synthesis of SnO₂ nanosheets