SnO2 Nanocrystals Research Articles

Fabrication, structural characteristics, and influence of Bi3+ doping concentration on UV-vis spectra of Bi3+:SnO2 nanocomposite materials

The authors report the characteristics and optical properties of Bi3+-doped SnO2 quantum dots prepared bysol-gel and hydrothermal methods. The structure and morphology of the materials as a function of dopingconcentration were studied and analysed by X-ray diffraction (XRD) and scanning electron microscope(SEM). The structure of the material was assigned to the tetragonal crystal structures of the SnO2 rutile phase,reported in JCPDS Card No. 41-1445. With the increase of Bi3+ doping, the crystallinity of Bi-doped SnO2worsened. The average sizes of the SnO2 nanocrystals were within 3-8 nm. The effect of Bi3+ ion concentrationon the absorbance properties of the materials was investigated by UV-Vis absorption spectra. The absorbancedecreased with increasing the concentration of Bi3+ dopant in the SnO2 lattice. The bandgap width decreasedwith Bi3+ dopant concentration. All Bi3+-doped SnO2 samples presented an enlargement of the light absorptionrange due to a bandgap width decrease.

Crystal facets-controlled NiO/SnO2 p-n heterostructures with engineered surface and interface towards triethylamine sensing

Crystal facets engineering is an effective means to improve the gas sensing performance of metal oxides and has become a research hotspot recently. However, research on crystal facets engineering are mainly focused on single metal oxides semiconductor, there are still very limited report about the crystal facets engineering on the semiconductor p-n heterostructures. In the present study, NiO/SnO2 p-n heterostructures were constructed by wrapping SnO2 nanocrystals exposing different crystal facets with 2D porous NiO nanosheets networks. It was found that the heterostructures with coexisted SnO2 {221} and {110} crystal facets displayed a significantly improved triethylamine sensing performance with a high response value of 78.5 towards 100 ppm triethylamine, together with ultrafast response characteristics (< 3 s), excellent stability and selectivity. The related mechanism was described through theoretical calculation. On the one hand, {221} crystal facets had higher activity and provided more active sites for the surface adsorption of triethylamine. On the other hand, the strong electron interaction between {110} facets and NiO was favorable for efficient electron transfer in interface, which further enhanced the gas sensing activity of heterostructures. This study provides a new idea for improving the gas sensing performance of metal oxide heterostructures through collaborative optimization of surface and interface.

Size dependent photocatalytic activities of rod-shape SnO2 nanocrystals

Various rod-shape SnO2 nanocrystals of different sizes and shapes were synthesized to study the desirable morphology for photocatalytic applications. An optimal apparent photocatalytic rate constant of 0.0809/min−1 was achieved for smaller SnO2 nanorods with diameter of ∼2.9 nm and with length of ∼9.3 nm, which is attributed to suitable nanostructures and high crystallinity. Photocatalytic activities as a function of growth and evolution of SnO2 nanorods are revealed.

Enabling High‐Performance Sodium Battery Anodes by Complete Reduction of Graphene Oxide and Cooperative In‐Situ Crystallization of Ultrafine SnO2 Nanocrystals

The main bottleneck against industrial utilization of sodium ion batteries (SIBs) is the lack of high‐capacity electrodes to rival those of the benchmark lithium ion batteries (LIBs). Here in this work, we have developed an economical method for in situ fabrication of nanocomposites made of crystalline few‐layer graphene sheets loaded with ultrafine SnO2 nanocrystals, using short exposure of microwave to xerogel of graphene oxide (GO) and tin tetrachloride containing minute catalyzing dispersoids of chemically reduced GO (RGO). The resultant nanocomposites (SnO2@MWG) enabled significantly quickened redox processes as SIB anode, which led to remarkable full anode‐specific capacity reaching 538 mAh g−1 at 0.05 A g−1 (about 1.45 times of the theoretical capacity of graphite for the LIB), in addition to outstanding rate performance over prolonged charge–discharge cycling. Anodes based on the optimized SnO2@MWG delivered stable performance over 2000 cycles even at a high current density of 5 A g−1, and capacity retention of over 70.4% was maintained at a high areal loading of 3.4 mg cm−2, highly desirable for high energy density SIBs to rival the current benchmark LIBs.

SnO2 coated carbon nanospheres: Facile preparation and electrochemical performances as anode materials for lithium ion batteries

In this work, the SnO2/C nanocomposites as the anode material for lithium ion batteries (LIBs) were successfully prepared by ultrasonic dispersing of the hydrothermally-synthesized carbon nanospheres in SnCl2 solution and aging for a period of time and then calcination of the dried intermediates in an inert atmosphere. As demonstrated by the experimental results, the obtained SnO2/C nanocomposites were composed of SnO2 nanocrystals (∼10 nm) coated uniformly on the surface of amorphous carbon nanospheres with diameters ranging from 200 nm to 240 nm. The electrochemical test results show that the prepared SnO2/C nanocomposites exhibited higher reversible capacity than the carbon nanospheres, and better cycling performance than the SnO2 nanocrystals. The enhanced electrochemical performance of SnO2/C nanocomposites could be due to the fact that the coupling of SnO2 nanocrystals and carbon nanospheres could not only effectively improve the mobility of charge carriers, but also effectively inhibit the collapse of the SnO2 structure at the expense of a part of the capacity, thus resulting in better structural stability of the SnO2/C nanocomposites.

Three-Dimensional Plasmonic Photocatalyst Consisting of Faceted Gold Nanoparticles and Radial Titanium(IV) Oxide Heteromesocrystals

Radial heteromesocrystals (HEMCs) consisting of TiO2 nanorods (NRs) with (110) side walls were synthesized by the seed-assisted hydrothermal method using SnO2 nanocrystals (rad-TiO2 HEMCs). Au nanoparticles (NPs) with comparable sizes and amounts were loaded on rad-TiO2 HEMCs (Au/rad-TiO2 HEMCs) and commercial rutile TiO2 NPs (Au/TiO2 NPs) for comparison by the deposition–precipitation method. Transmission electron microscopic observation confirmed that the faceting of Au NPs is induced by the domain matching heteroepitaxy with a (111)Au//(110)TiO2 orientation, and the faceting probability of Au NPs on rad-TiO2 HEMCs (47%) is larger than that on TiO2 NPs (17%). As a test plasmonic photocatalytic reaction, aerobic oxidative decomposition of 2-naphthol was carried out using it as a model water pollutant. Au/rad-TiO2 HEMCs exhibit photocatalytic activity significantly higher than Au/TiO2 NPs with ∼90% of 2-naphthol decomposed within 15 min under the illumination of simulated sunlight (AM-1.5, 1 sun, λex > 430 nm). The high photocatalytic activity of Au/TiO2 HEMCs is ascribable to the plasmonic hot spots near the edges and corners of the faceted Au NPs enhancing light harvesting, hot-electron injection into TiO2, and charge separation in addition to the electrocatalytic activity of Au NPs for the two-electron oxygen reduction reaction. Further, the concentration gradient of electrons in the TiO2 NRs generated by the multiple light scattering between TiO2 NRs and the extremely large absorption coefficient of Au NPs can also enhance the charge separation.

Molten salt-assisted valorization of waste PET plastics into nanostructured SnO2@terephthalic acid with excellent Li-ion storage performance

Polyethylene terephthalate (PET) is one of the most widely used plastic materials, and therefore, its clean, efficient and low-cost valorization into high-value materials is of substantial economic and environmental interest. Here, for the first time, the utilization of molten salts for the facile, scalable and fast depolymerization of PET into terephthalic acid (C8H6O4) is reported. It is asserted that the simple heat-treatment of PET in molten KCl-LiCl containing SnCl2 in air leads to the green preparation of nanocrystalline terephthalic acid embedded with SnO2 nanocrystals, with an excellent performance as the anode of lithium ion batteries (LIBs). The structural, morphological, thermal, surface, electrical and electrochemical characteristics of plastic-derived nanocomposites are evaluated by various techniques. The sample prepared at 500 °C (PDN-500) contains 28.3 wt% SnO2, and exhibits an enhanced bulk electrical conductivity of 447.3 S m−1, and an excellent Li-ion storage capacity of 498 mAh g-1 after 500 cycles, corresponding to 1657 mAh per gram of SnO2. This performance is accompanied by an enhanced lithium ions diffusion coefficient of 8.51 × 10−10 cm2 s−1 recorded after 300 cycles, and a capacitive storage contribution of above 42 %. The sustainability of the presented molten salt approach is discussed from two complementary points of view, in terms of the clean conversion of waste plastics into high-performance anode materials for LIBs, as well as the facile and scalable depolymerization of PET, reducing the waste plastics in our environment. This article proposes an efficient and green strategy for the valorization of waste plastics into nanostructured SnO2@terephthalic acid for energy storage applications.

Self‐Standing 3D Hollow Nanoporous SnO2‐Modified CuxO Nanotubes with Nanolamellar Metallic Cu Inwalls: A Facile In Situ Synthesis Protocol toward Enhanced Li Storage Properties

AbstractSnO2 is regarded as a prospective anode material candidate for high energy density lithium‐ion batteries (LIBs). However, rapid structural degradation and low conductivity always bring about poor cycling stability and electrochemical reversibility, becoming critical dilemmas toward its practical application. To address these issues, herein, a facile multi‐step in situ synthesis protocol is developed to tactfully achieve self‐standing 3D hollow nanoporous SnO2‐modified CuxO nanotubes with nanolamellar metallic Cu inwalls (3D‐HNP SnO2/CuxO@n‐Cu) via chemical dealloying, heat treatment, electrochemical replacement, and selective etching. The results show that the unique 3D‐HNP SnO2/CuxO@n‐Cu as a binder‐free integrated anode for LIBs exhibits superior Li storage properties with high initial reversible capacity of 3.34 mAh cm−2 and good cycling stability with 85.6% capacity retention and &gt;99.4% coulombic efficiency after 200 cycles (capacity decay of only 0.002 mAh cm−2 per cycle). This is mainly attributed to the unique 3D hollow nanoporous configuration design composed of interlinked CuxO nanotubes modified by ultrafine SnO2 nanocrystals (4–10 nm) with two‐way mechanical strain cushion and nanolamellar metallic Cu inwalls with boosted electrical conductivity. This work can be expected to offer an original and effective approach for rational design and fabrication of advanced MOx‐based anodes toward high‐performance LIBs.

Semiconducting metamorphism in Cu2+ substituted structurally enriched SnO2 nanocrystals

The manuscript portrays structural, microstructural, and electrical characteristics of pristine and Cu2+ doped SnO2 nanocrystals [Sn(1-x)CuxO2 NCs, where x = 0, 0.05, and 0.10] synthesized using conventional sol–gel technique. X-ray diffraction (XRD) results revealed that all the compositions possess single phase tetragonal rutile-type crystal configuration with space group P4/2mnm as confirmed by Rietveld refinement studies. Microstructural characterizations depicted homogeneous grain distribution with well interlinked grains and it was observed that the average grain size decreased from 30.29 nm to 27.47 nm with increasing Cu2+ concentration and the findings were consistent with structural studies. The concentric rings marked with Miller planes (110), (101), (200), and (211) observed in Selected Area Electron Diffraction (SAED) pattern. Hall effect measurements depicted that the concentration and mobility decreased with Cu2+ thereby transforms the system from n-type semiconductor to p-type.

The Influence of Different Recombination Pathways on Hysteresis in Perovskite Solar Cells with Ion Migration

The impact of hysteresis on the power conversion efficiency (PCE) of perovskite solar cells (PSCs) still faces uncertainties despite the rapid development of perovskite photovoltaics. Although ion migration in perovskites is regarded as the chief culprit for hysteresis, charge carrier recombination pathways in PSCs are proposed to be necessary for the occurrence of hysteresis. Here, the impact of both bulk recombination and interface recombination on hysteresis in PSCs is investigated via drift–diffusion modeling. The simulation results demonstrate a direct correlation between recombination pathways and hysteresis in PSCs with ion migration. The simulation reveals that recombination pathways in PSCs will react to the variation in charge carrier distribution under different voltage scanning directions induced by ion migration in absorber layers, which leads to hysteresis in PSCs. Moreover, the hysteresis in normal (N-I-P) PSCs with different electron transport layers (ETLs) including sintered SnO2, SnO2 nano crystals and TiO2 is experimentally explored. The results demonstrate that multiple recombination pathways coupled with ion migration can lead to obvious hysteresis in fabricated PSCs which is consistent with simulation results. This work provides great insight into hysteresis management upon composition, additive and interface engineering in PSCs.

Surface Functionalization of Indium Tin Oxide Electrodes by Self-assembled Monolayers for Direct Assembly of Pre-synthesized SnO2 Nanocrystals as Electron Transport Layers

Surface Functionalization of Indium Tin Oxide Electrodes by Self-assembled Monolayers for Direct Assembly of Pre-synthesized SnO2 Nanocrystals as Electron Transport Layers

Cu-doped SnO2 nanoparticles: size and antibacterial activity investigations.

Nowadays, the use of self-cleaning surfaces is increasing globally, especially after the COVID-2019 pandemic, and the use of nanoparticles has been shown as a plausible option for this purpose. In the present study, Cu-doped SnO2 nanocrystals were successfully synthesized (in the copper content range of 0-30 mol%) using the polymeric precursor method. The structural, morphological, vibrational, and antibacterial activity were carefully studied to unveil the effect of copper ions on the properties of the hosting matrix, aiming at maximizing the usage of Cu-doped SnO2 nanocrystals. The results show fabrication of nanoparticles near their respective exciton Bohr diameter (5.4 nm for SnO2), however, monophasic SnO2 was observed up to 15 mol%. Above this limit, a secondary CuO phase was observed, as shown by the assessed X-ray diffraction (XRD), Fourier transform infrared, and Raman spectroscopy data. Furthermore, the redshift of the primary A1g vibrational mode of SnO2 is successfully described using the phonon-confinement model, demonstrating a good relationship between the Raman correlation length (L) and the crystallite size (〈D〉), the latter determined from XRD. Regarding the antibacterial activity, assessed via the disc-diffusion testing method (DDTM) while challenging two bacterial species (S. aureus and E. coli), our results suggest a rapid diffusion of the nanoparticles out of the paper disc, with a synergistic effect credited to the Sn1-xCuxO2-CuO phases contributing to the inhibition of the bacteria growth. Moreover, the DDTM data scales with cell viability, the latter analyzed using the Hill equation, from which both lethal dose 50 (LD50) and benchmark dose (BMD) were extracted.

Alkaline earth metal ion doping to enhance the light emission from Er3+:SnO2 nanocrystal Co-doped silica films.

Alkaline earth metal ions (Mg2+, Ca2+, Sr2+) have been introduced into Er3+:SnO2 nanocrystal co-doped silica thin films fabricated by a sol-gel method combined with a spin-coating technique. It is found that the incorporation of alkaline earth metal ions can enhance the light emission from Er3+ at the wavelength around 1540 nm and the strongest enhancement is observed in samples doped with 5 mol% Sr2+ ions. Based on X-ray diffraction, X-ray photoelectron spectroscopy and other spectroscopic measurements, the improved light emission can be attributed to more oxygen vacancies, better crystallinity and a stronger cross-relaxation process with the introduction of alkaline earth metal ions.

In situ growing fusiform SnO2 nanocrystals film on carbon fiber cloth as an efficient and flexible microwave absorber

Developing highly efficient flexible microwave absorber is of great significance for wearable electronics and aerospace applications. In this work, the fusiform SnO2 nanocrystals film in situ grown on flexible carbon fiber cloth is rationally designed and fabricated through combining air calcination and hydrothermal synthesis. X-ray photoelectron spectrum confirms fusiform SnO2 nanocrystals film and carbon fiber cloth are effectively integrated with strong chemical bonds of COSn. The as-prepared composite exhibits strong reflection loss of −49.1 dB (2.6 GHz) and wide effective absorption bandwidth of 5.8 GHz (11.6–17.4 GHz) with a thin matched thickness of 1.6 mm, surpassing to pure carbon fiber cloth and many SnO2/carbon-based microwave absorbers. The efficient performance originates from well-matched characteristic impedance and multifarious electromagnetic attenuation mechanisms, i.g., dipole orientation polarization, interfacial polarization relaxation, conductive loss, and multiple reflections/scatterings. Especially, differential charge density calculation reveals the uneven charge distribution at SnO2/C interface, which is believed to remarkably enhance interfacial polarization relaxation and contribute to microwave absorption. Our results illustrate that the ingenious integration of nanomaterials on carbon fiber cloth promises a way to achieve efficient and flexible microwave absorbers.

Chitosan modulated engineer tin dioxide nanoparticles well dispersed by reduced graphene oxide for high and stable lithium-ion storage

Tin based materials are widely investigated as a potential anode material for lithium-ion batteries. Effectively dispersing SnO2 nanocrystals in carbonaceous supporting skeleton using simplified methods is both promising and challenging. In this work, water soluble chitosan (CS) chains are employed to modulate the redox coprecipitation reaction between stannous chloride (SnCl2) and few-layered graphene oxide (GO), where the excessive restacking of the corresponding reduced graphene oxide sheets (RGO) has been effectively inhibited and the grain size of the in-situ formed SnO2 nanoparticles have been significantly controlled. In particular, the CS molecules are gradually detached from the RGO sheets with the GO deoxygenation process, leaving only a small quantity of CS remnants in the intermediate SnO2@CS@RGO sample. The final SnO2/CSC/RGO sample with significantly improved microstructure is synthesized after a simple thermal treatment, which delivers a high specific capacity of 842.9 mAh g−1 at 1000 mA·g−1 for 1000 cycles in half cells and a specific capacity of 410.5 mAh g−1 at 200 mA·g−1 for 100 cycles in full cells. The reasons for the good lithium-ion storage performances for the SnO2/CSC/RGO composite have been studied.

Near-infrared light emitting devices from Er doped silica thin films via introducing SnO2 nanocrystals

To get high performance light emitting devices on Si platform with emission wavelength at 1.55 μm is a challenge for future Si-based opto-electronic integration chips. In this paper, we fabricated near-infrared light-emitting devices based on Er/SnO2 co-doped silica thin films. The introduction of SnO2 nanocrystals with controllable size and density not only contributes to the near-infrared light emission enhancement of Er3+ ions at 1.55 μm, but also provides an effective carrier transport channel to realize efficient and stable electro-luminescence. The corresponding devices exhibit an external quantum efficiency of 5.4% at near infrared light region and the power efficiency is about 1.52 × 10−3. Our present work lays a solid foundation for facilitating Si-based light source towards practical application in the field of optoelectronic interconnection.

Enhanced sensitivity of SAW based ammonia sensor employing GO-SnO2 nanocomposites

A GO-SnO2 nanocomposites coated surface acoustic wave (SAW) device is proposed for sensing ammonia with extremely low concentrations. The GO-SnO2 nanocomposites with diameters of ∼4.3 nm was controllably synthesized in a hybrid solution system of oleic acid (OA) and oleylamine. We revealed that the SnO2 nanocrystals were uniformly immobilized on the GO surface and exhibited porous structures through the characterizations of TEM, SEM, XRD, and Raman. The gas adsorption in GO-SnO2 modulates the SAW propagation velocity, and the corresponding changes in phase/frequency can be collected as the sensing signal. A 200 MHz SAW device with the delay-line pattern was prepared by using the lithograph technique on the Y35°X quartz substrate. The GO-SnO2 was deposited on the SAW device by drip-coating, and the device was integrated in the phase detection circuit to build the ammonia sensor and experimentally characterized. Very low detection limit of 40 ppb and a high sensitivity of 0.098 mV/ppb with a fast response of less than 16.4 s were achieved at room temperature (25 °C). In addition, the developed sensing device exhibited excellent selectivity and stability, and the effects of ambient humidity and temperature on the sensing performance were also investigated.

Transition metal-doped SnO2 and graphene oxide (GO) supported nanocomposites as efficient photocatalysts and antibacterial agents.

In the present work, pristine and transition metal (TM) (W, Ag, Zn)-doped SnO2 nanocrystals using a facile sol-gel approach were synthesized. The grown products were anchored on graphene oxide (GO) sheets via a simple ultrasonication technique to fabricate binary nanocomposites. The structural, optical, and morphological properties of as-synthesized samples were studied by XRD, FTIR, Raman, EDX, UV-Visible, PL, and FE-SEM. The charge transferability of graphene oxide-based samples was investigated by EIS. The XRD exhibited the TM doping in SnO2 and the development of GO-based nanocomposite. FTIR data evidenced the existence of the metal-oxygen bonds. Raman spectra presented the optical phonon modes of SnO2 and the existence of oxygen vacancy defects. FE-SEM images demonstrated the anchoring of particles on the GO sheet, and EDX further approved the existence of desired dopants. The integration of SnO2 with TM doping remarkably reduced optical bandgap (3.65-3.10eV), which was further decreased (3.10-2.99eV) by making composite with GO. The photodegradation results exhibited that GO-based nanocomposites have the higher potential to degrade synthetic dyes (methyl red (MR), and methyl orange (MO) and SnZnO2/GO have shown superb photocatalytic performance after 80-min sunlight illumination (99.9% MR and 95.0% MO dyes) with the higher rate constant and superior stability up to 6th cycle against MR dye. The grown samples were tested for bacterial disinfection, and SnZnO2/GO sample showed a higher zone of inhibition towards S. aureus and K. pneumoniae bacteria strains. The greater charge transfer rate and lower recombination of charge carriers in GO-based composites were also observed by EIS and PL analysis. Moreover, the present article ascribed that the photocatalytic and antibacterial properties of bare SnO2 could be improved by TM doping and fabricating their composite with GO.

Efficient Perovskite Solar Cells Based on Tin Oxide Nanocrystals with Difunctional Modification.

Tin oxide (SnO2 ) nanocrystals-based electron transport layer (ETL) has been widely used in perovskite solar cells due to its high charge mobility and suitable energy band alignment with perovskite, but the high surface trap density of SnO2 nanocrystals harms the electron transfer and collection within device. Here, an effective method to achieve a low trap density and high electron mobility ETL based on SnO2 nanocrystals by devising a difunctional additive of potassium trifluoroacetate (KTFA) is proposed. KTFA is added to the SnO2 nanocrystals solution, in which trifluoroacetate ions could effectively passivate the oxygen vacancies (OV ) in SnO2 nanocrystals through binding of TFA- and Sn4+ , thus reducing the traps of SnO2 nanocrystals to boost the electrons collection in the solar cell. Furthermore, the conduction band of SnO2 nanocrystals is shifted up by surface modification to close to that of perovskite, which facilitates electrons transfer because of the decreased energy barrier between ETL and perovskite layer. Benefiting from the decreased trap density and energy barrier, the perovskite solar cells exhibit a power conversion efficiency of 21.73% with negligible hysteresis.

Improved resonant energy transfer and light emission from SnO2 nanocrystals and Er3+ embedded in silica films via Yb3+ co-doping

SiO2-SnO2:Er3+ thin films co-doped with Yb3+ ions have been prepared by the sol-gel method. By controlling the Yb3+ concentration, the enhanced Er3+-related near infrared (NIR) emission is achieved under 325 nm excitation. The energy transfer efficiency (ETE) from SnO2 to rare earth is investigated by photoluminescence decay curves. It is found that with the increase of Yb3+ ion concentration to 15 mol%, the ETE gradually increases to ∼68.7%. The comprehensive spectroscopic analysis results demonstrate that both improved ETE and a new energy transfer channel from SnO2 nanocrystals to Er3+ ions via the Yb3+ intermediate state contribute to the Er3+-related NIR emission enhancement.