A SnO2 shell for high environmental stability of Ag nanowires applied for thermal management

Since silver nanowires (AgNWs) show high infrared reflectance many studies present their applicability as thermal management products for various wearable textiles. However, their use for practical purposes is only partially evaluated, without focusing on improving their low atmospheric and liquid stability. This report describes a new approach for the topic and proposes a facile method of Ag nanowire passivation with a SnO₂ layer for high environmental stability and retention of high infrared reflectance. The one-step passivation process of AgNWs was carried out in the presence of sodium stannate in an aqueous solution at 100 °C, and resulted in the formation of core/shell Ag/SnO₂ nanowires. This study presents the morphological, chemical, and structural properties of Ag/SnO₂NWs formed with a 14 nm thick SnO₂ shell, consisting of 7 nm rutile-type crystals, covering the silver metallic core. The optical properties of the AgNWs changed significantly after shell formation, and the longitudinal and transverse modes in the surface plasmon resonance spectrum were red shifted as a result of the surrounding media dielectric constant changes. The passivation process protected the AgNWs from decomposition in air for over 4 months, and from dissolution in a KCN solution at concentrations up to 0.1 wt%. Moreover, the report shows the microwave irradiation effect on the shell synthesis and previously synthesised Ag/SnO₂NWs. The post-synthesis irradiation, as well as the SnO₂ shell obtained by microwave assistance, did not allow long-term stability to be achieved. The microwave-assisted synthesis process was also not fast enough to inhibit the formation of prismatic silver structures from the nanowires. The Ag/SnO₂NWs with a shell obtained by a simple hydrolysis process, apart from showing high infra-red reflectance on the para-aramid fabric, are highly environmentally stable. The presented SnO₂ shell preparation method can protect the AgNW''s surface from dissolution or decomposition and facilitate the designing of durable smart wearable thermal materials for various conditions.

The study presents a rapid method of SnO₂ shell formation on AgNWs for both high environmental stability and thermal management on para-aramid fabric.     

Dip-coating decoration of Ag2O nanoparticles on SnO2 nanowires for high-performance H2S gas sensors

SnO₂ nanowires (NWs) are used in gas sensors, but their response to highly toxic gas H₂S is low. Thus, their performance toward the effective detection of low-level H₂S in air should be improved for environmental-pollution control and monitoring. Herein, Ag₂O nanoparticle decorated SnO₂ NWs were prepared by a simple on-chip growth and subsequent dip-coating method. The amount of decorated Ag₂O nanoparticles on the surface of SnO₂ NWs was modified by changing the concentration of AgNO₃ solution and/or dipping times. Gas-sensing measurements were conducted at various working temperatures (200–400 °C) toward different H₂S concentrations ranging within 0.1–1 ppm. The selectivity of Ag₂O-decorated SnO₂ NW sensors for ammonia and hydrogen gases was tested. Results confirmed that the Ag₂O-decorated SnO₂ NW sensors had excellent response, selectivity, and reproducibility. The gas-sensing mechanism was interpreted under the light of energy-band bending by sulfurization, which converted the p–n junction into n–n, thereby significantly enhancing the sensing performance.

Ag₂O nanoparticles decorated on the surface of on-chip growth SnO₂ nanowires by a dip-coating method possessed excellent sensing performance for H₂S gas.     

A novel synthesis of silver nanowires by using 6-chlorohexylzinc bromide as an additive for low haze transparent conductive films

High-quality silver nanowires (AgNWs) with a small diameter of ∼20 nm and a length of ∼40 μm were prepared by using a novel organic 6-chlorohexylzinc bromide as an assistant additive. The diameter of as-synthesized AgNWs was confirmed to be strongly dependent on the dosage of 6-chlorohexylzinc bromide. Moreover, a two-dimensional (2D) transparent conductive film (TCF) with an excellent optical performance was fabricated by as-synthesized AgNWs, which has a 90.3% transmittance and low haze value of <1.0% at a sheet resistance of 48.7 Ω sq⁻¹.

Silver nanowires with a diameter of ∼20 nm and length of 40 μm were prepared by using 6-chlorohexylzinc bromide as an additive.     

A highly active Z-scheme SnS/Zn2SnO4 photocatalyst fabricated for methylene blue degradation

Herein, a highly active Z-scheme SnS/Zn₂SnO₄ photocatalyst is fabricated by a one-step hydrothermal route. The structure, composition, photoelectric and photocatalytic properties of the as-prepared photocatalysts are systematically researched. The results demonstrate that SZS-6 displays a good photocatalytic performance with an efficiency of 94.5% to degrade methylene blue (MB) under visible light irradiation (λ > 420 nm). And its degradation rate constant is up to 0.0331 min⁻¹, which is 3.9 and 4.4 times faster than SnS and Zn₂SnO₄, respectively. The formation of a Z-scheme heterojunction facilitates the separation and transfer of charges, which improves the degradation of MB. The Z-scheme charge transfer pathway of the SnS/Zn₂SnO₄ photocatalyst is verified by the shifted peaks of the X-ray photoelectron spectroscopy (XPS) spectrum, the relative position of the bandgap, work function as well as free radical trapping experiments. The photocatalytic mechanism for the degradation of MB by SnS/Zn₂SnO₄ is proposed.

Herein, a highly active Z-scheme SnS/Zn₂SnO₄ photocatalyst is fabricated by a one-step hydrothermal route.     

Growth mechanism of SnC2H4O2 nanowires prepared by the polyol process as SnO2 precursor nanowires

Tin oxide (SnO₂) nanowires are produced by the calcination of tin glycolate (SnC₂H₄O₂) nanowires, which are synthesized with tin oxalate (SnC₂O₄) and ethylene glycol via the so-called polyol process. In this study, the growth mechanism of SnC₂H₄O₂ nanowires was investigated by monitoring the synthesis using scanning and transmission electron microscopy. The length and diameter of the nanowires were 9.25 μm and 0.37 μm, respectively; the former increased at a rate of 1.85 μm h⁻¹ but the latter did not increase over time. Fourier-transform IR spectroscopy showed that the nanowires were composed of SnC₂H₄O₂ instead of SnC₂O₄. Changes in the components of the reaction solution were also confirmed by ¹H NMR, ¹³C NMR, and high-performance liquid chromatography. SnC₂H₄O₂ was formed by the substitution of the oxalate coordinated to tin by ethylene glycolate, which was produced by the deprotonation of ethylene glycol. In this reaction, oxalate gradually changed to formic acid and carbon dioxide, and SnC₂H₄O₂ grew as a nanowire through O–Sn–O bond formation. In addition, when ethylene glycol was mixed with 1,2-propanediol, branched SnC₂H₄O₂ nanowires were formed. The branching was due to the interference of the methyl group of 1,2-propanediol with the growth of bundle-type nanowires. The branched nanowires had a higher surface area-to-mass ratio than the bundled ones based on dispersion measurements. Knowledge of the growth mechanism and reaction conditions that affect morphology would be valuable in modifying the physical and electrical properties of metal oxide nanowires.

Tin oxide (SnO₂) nanowires are produced by the calcination of tin glycolate (SnC₂H₄O₂) nanowires, which are synthesized with tin oxalate (SnC₂O₄) and ethylene glycol via the so-called polyol process.     

Investigation of electronic properties of chemical vapor deposition grown single layer graphene via doping of thin transparent conductive films

It is a crucial challenge to obtain the desired electronic properties of two-dimensional materials for various ubiquitous applications and improvements in the existing technology. In this article, we have demonstrated the modulation in electronic features of the chemical vapor deposition (CVD) grown single-layer graphene (SLG) via wet doping of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS). The PEDOT:PSS is well known as conducting polymer and used as transparent conducting electrode in flexible organic electronic devices. The effect of doping on SLG samples were examined by Raman spectroscopy, electrical transport measurement, atomic force microscopy (AFM), and Kelvin probe force microscopy (KPFM). The Raman peaks position of doped samples provided sought evidence of p-type doping of SLG after the deposition of PEDOT:PSS films. The electrical measurement confirmed the p-type doping of SLG and also revealed enhanced carrier density and mobility of SLG after the deposition of PEDOT:PSS films. AFM micrographs revealed the homogeneous loading of PEDOT:PSS particles over the SLGs. Further, KPFM technique was used to estimate the work function modulation of SLG after PEDOT:PSS film deposition. Our investigation will be useful for understanding the device physics as well as improvement of photovoltaic devices based on PEDOT:PSS coated graphene.

The tuning of charge carrier of graphene is a potential step for the realization of multifunctional use in current electronic/optoelectronic devices.     

Fabrication of chemically stable hydrogen- and niobium-codoped ZnO transparent conductive films

H- and Nb-doped ZnO (HNZO) thin films were fabricated on glass substrates with radio frequency magnetron sputtering. The effect of the flow rate of H₂ has been investigated by analyzing the structural, optical, and electrical properties. The incorporation of H during the deposition of Nb-incorporated ZnO films significantly improved their crystallinity, conductivity, and transmittance. The crystallites of the HNZO films were preferentially oriented in the c-axis direction; the films possess high transmittance (approximately 85%) in the visible and near-infrared regions (400 to 1400 nm). The lowest room-temperature resistivity of the HNZO films was measured as 1.28 × 10⁻³ Ω cm. Such optical and electrical properties along with the remarkable chemical stability of the HNZO films make them a promising candidate for applications in solar cells.

H- and Nb-doped ZnO (HNZO) thin films were fabricated on glass substrates with radio frequency magnetron sputtering.     

One-step synthesis of ultra-long silver nanowires of over 100 μm and their application in flexible transparent conductive films

Silver nanowires (AgNWs) >100 μm and even 160 μm in length have been synthesized using a facile and rationally designed solvothermal method by heating preservation at 150 °C. The length of the as-synthesized AgNWs is over 4–5 times longer than those previously reported, while the diameter range is from 40 nm to 85 nm. A transparent conducting film (TCF) was fabricated using hydroxyethyl cellulose (HEC) as the adhesive polymer, and it achieved exceptional and stable optoelectronic properties. Its low sheet resistance of ∼19 Ω sq⁻¹ (on polyethylene terephthalate, PET) and high optical transmittance of ∼88% are superior to that of expensive indium tin oxide (ITO) films. More significantly, the AgNW network demonstrates excellent adhesion to PET substrates. This study indicates that ultra-long silver nanowires can serve as an alternative to ITO, which also demonstrates its potential application in flexible electronic devices.

Ultra-long silver nanowires (100–160 μm) were applied in flexible transparent conductive films showing low sheet resistance and high optical transmittance.     

Correction: A highly active Z-scheme SnS/Zn2SnO4 photocatalyst fabricated for methylene blue degradation

Correction for ‘A highly active Z-scheme SnS/Zn₂SnO₄ photocatalyst fabricated for methylene blue degradation’ by Yingjing Wang et al., RSC Adv., 2022, 12, 31985–31995, https://doi.org/10.1039/D2RA05519H.

The authors regret that an incorrect version of Fig. 1 was included in the original article. The correct version of Fig. 1 is presented below.Open in a separate windowFig. 1(a) XRD spectra, (b) XPS survey, (c) Zn 2p, (d) Sn 3d, (e) S2p and (f) O 1s spectra of samples.The authors regret that there was an error in the text in lines 5–10 in the right column on page 31987 of the original article. The text originally read, “The binding energy at 530.1 eV and 531.3 eV belongs to the oxygen atom coordinated with a metal atom (Sn–O–Sn) and (Sn–O–Zn), respectively.³⁷ The peak at 531.3 eV is attributed to oxygen in absorbed water, and the binding energy at 532.2 eV is attributed to the oxygen atoms on defect atoms.³⁷” This text should read, “The binding energy at 530.1 eV and 531.3 eV corresponds to the oxygen atom coordinated with a metal atom (Sn–O–Sn) and (Sn–O–Zn),³⁷ and the binding energy at 532.2 eV is attributed to the hydrated species O–H.³⁶”The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.     

Formation of a conductive overcoating layer based on hybrid composites to improve the stability of flexible transparent conductive films

A protective layer that can be applied on a flat flexible transparent conductive film was prepared by combining silica sol and organic polymer. (3-Glycidyloxypropyl)trimethoxysilane (GPTMS) was used as a precursor for the silica sol, which hydrolyzed under moisture to form silanol groups and self-condensed to form a sol under acidic conditions. Therefore, the organic polymer used was poly(4-styrenesulfonic acid) (PSSA), which is acidic and water-soluble; thus, the silica precursor can form a sol and can cause chemical condensation with the silica sol under thermal conditions. However, as this protective layer was insulating, there was difficulty in conducting electricity to the lower portion through the upper contact. Therefore, a small amount of conductive polymer, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), was added to the protective layer to make the overcoating layer itself conductive, thereby enabling electrical conduction to the underlying conductive film. The network structure of the overcoating layer surface could block oxygen and moisture, thus improving chemical stability. Therefore, under high-temperature and high-humidity conditions for 500 h, the sheet resistance increased by 145% before overcoating but increased by 33% after the overcoating layer was formed with appropriate thickness. In addition, the bonding strength of the surface was further improved. Peel-off occurred after applying a pencil having hardness of 5B or more before the overcoating treatment; however, after the overcoating treatment, no damage was caused by a pencil having hardness of 5H or less. Consequently, the overcoated conductive film maintained flexibility and transparency; it also exhibited desirable electrical characteristics, improved chemical stability, and excellent scratch resistance.

A protective layer that can be applied on a flat flexible transparent conductive film was prepared by combining silica sol and organic polymer.     

Mechanism of surface treatments on carbon nanotube transparent conductive films by three different reagents

Transparent conductive films (TCFs) were fabricated via a spray-coating method with a solution prepared by dispersing single-walled carbon nanotubes (SWCNTs) in deionized water with sodium dodecylbenzene sulfonate (SDBS) as surfactant. We explored the mechanism of HNO₃ treatment by treating TCFs with different reagents. After being treated with different concentrations of reagents by HNO₃, HCl, and NaNO₃ to lower the sheet resistance of TCFs, the properties of TCFs were further characterized by a UV-VIS spectrophotometer, a four-point probe method, atom force microscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. In this study, we conclude that the HNO₃ treatment results in a decrease in the sheet resistance of the TCFs due to the combined effect of acidity and oxidizability. The strong interaction of the strong acidity and strong oxidizing property of HNO₃ causes the SDBS to be removed. To further improve the film conductivity of the TCFs, the experimental conditions of the HNO₃ treatment were optimized.

Comparative studies of sheet resistance and transmittance of CNT-TCFs treated by three different reagents were performed. The mechanism of an oxidation effect for removal of SDBS in CNT-TCFs by nitric acid was suggested.     

ZnO/Ag/Ag2WO4 photo-electrodes with plasmonic behavior for enhanced photoelectrochemical water oxidation

Ag-based compounds are excellent co-catalyst that can enhance harvesting visible light and increase photo-generated charge carrier separation owing to its surface plasmon resonance (SPR) effect in photoelectrochemical (PEC) applications. However, the PEC performance of a ZnO/Ag/Ag₂WO₄ heterostructure with SPR behavior has not been fully studied so far. Here we report the preparation of a ZnO/Ag/Ag₂WO₄ photo-electrode with SPR behavior by a low temperature hydrothermal chemical growth method followed by a successive ionic layer adsorption and reaction (SILAR) method. The properties of the prepared samples were investigated by different characterization techniques, which confirm that Ag/Ag₂WO₄ was deposited on the ZnO NRs. The Ag₂WO₄/Ag/ZnO photo-electrode showed an enhancement in PEC performance compared to bare ZnO NRs. The observed enhancement is attributed to the red shift of the optical absorption spectrum of the Ag₂WO₄/Ag/ZnO to the visible region (>400 nm) and to the SPR effect of surface metallic silver (Ag⁰) particles from the Ag/Ag₂WO₄ that could generate electron–hole pairs under illumination of low energy visible sun light. Finally, we proposed the PEC mechanism of the Ag₂WO₄/Ag/ZnO photo-electrode with an energy band structure and possible electron–hole separation and transportation in the ZnO/Ag/Ag₂WO₄ heterostructure with SPR effect for water oxidation.

Ag-based compounds are excellent co-catalyst that can enhance harvesting visible light and increase photo-generated charge carrier separation owing to its surface plasmon resonance (SPR) effect in photoelectrochemical (PEC) applications.     

Highly elastic and flexible transparent conductive films derived from latex copolymerization: P(SSNa-BA-St)/PEDOT/graphene

We reported an innovative transparent, elastic and flexible conductive composite materials P(SSNa-BA-St)/PEDOT/graphene which were prepared by using P(SSNa-BA-St) latex as template for PEDOT polymerization and graphene doping. This P(SSNa-BA-St)/PEDOT/graphene film exhibited highly transparent, good water resistance, low moisture adsorption, highly elastic and highly conductive properties, which can serve as a practical approach to fabricate the flexible, conductive and transparent films for wearable and implantable electronic devices, and photovoltaic cells.

We reported an transparent, water resistant, and flexible conductive materials P(SSNa-BA-St)/PEDOT/graphene and their conductivity are due to the large surface area to polymerize the extended PEDOT chain on the nanoparticles.     

Synthesis of a grape-like conductive carbon black/Ag hybrid as the conductive filler for soft silicone rubber

Conductive silicone rubber (CSR) is an outstanding stretchable conductive composite due to its excellent mechanical properties and stable conductivity. In this paper, silver nanoparticles were deposited on carbon black (CB) through a reduction reaction. The uniform dispersion of silver particles on the surface of CB as well as the grape-like branch structure of hybrid particles was formed by the condensation reaction of the hydroxyl groups of CB with (3-mercaptopropyl) trimethoxysilane (KH-590), along with the interattraction between sulfhydryl groups of KH-590 and silver ions. This sulfhydryl modified conductive carbon black/Ag hybrid filler (SMCB@Ag) avoided the high processing viscosity of CSR caused by the hydroxyl groups of CB. The percolation threshold of CSR made from SMCB@Ag was 5.5 wt% according to the percolation equation. With the addition amount of SMCB@Ag increasing to 10 wt%, the conductivity of CSR increased from 10⁻⁵ to about 10¹. Moreover, the conductivity of this CSR showed excellent stability with extension of storage time and increase of stretching-recovery cycles.

Schematic of the fabrication procedure of SMCB@Ag with the grape-like structure.     

Ultralow power consumption gas sensor based on a self-heated nanojunction of SnO2 nanowires

The long duration of a working device with a limited battery capacity requires gas sensors with low power consumption. A self-heated gas sensor is a highly promising candidate to satisfy this requirement. In this study, two gas sensors with sparse and dense SnO₂ nanowire (NW) networks were investigated under the Joule heating effect at the nanojunction. Results showed that the local heating nanojunction was effective for NO₂ sensing but generally not for reduction gases. At 1 μW, the sparse NW sensor showed a good sensing performance to the NO₂ gas. The dense SnO₂ NW network required a high-power supply for gas-sensitive activation, but was suitable for reduction gases. A power of approximately 500 μW was also needed for a fast recovery time. Notably, the dense NW sensor can response to ethanol and H₂S gases. Results also showed that the self-heated sensors were simple in design and reproducible in terms of the fabrication process.

We realize the local self-heated nanojunction in nanowires for ultralow power consumption gas sensor by a simple design and fabrication process.     

Z-scheme BiVO4/Ag/Ag2S composites with enhanced photocatalytic efficiency under visible light

The Z-scheme BiVO₄/Ag/Ag₂S photocatalyst was fabricated via a two-step route. The as-prepared samples were characterized by XRD, FE-SEM, HRTEM, XPS and UV-vis diffuse reflectance spectroscopy. The results of PL and photocurrent response tests demonstrate that the ternary BiVO₄/Ag/Ag₂S composites had a high separation and migration efficiency of photoexcited carriers. As a result, the ternary photocatalyst exhibits enhanced photocatalytic activity for decomposing Rhodamine B (RhB) under LED light (420 nm) irradiation. The results of trapping experiments demonstrate both h⁺ and ˙OH play crucial roles in decomposing RhB molecules. Additionally, the energy band structures and density of states (DOS) of BiVO₄ and Ag₂S were investigated via the density functional theory (DFT) method. Finally, a Z-scheme electron migration mechanism of BiVO₄ → Ag → Ag₂S was proposed based on the experimental and calculated results.

The Z-scheme BiVO₄/Ag/Ag₂S photocatalyst was fabricated via a two-step route.     

Dual role of Ag nanowires in ZnO quantum dot/Ag nanowire hybrid channel photo thin film transistors

High mobility and p-type thin film transistors (TFTs) are in urgent need for high-speed electronic devices. In this work, ZnO quantum dot (QD)/Ag nanowire (NW) channel TFTs were fabricated by a solution processed method. The Ag NWs play the dual role of dopant and providing the charge transfer route, which make the channel p-type and enhance its mobility, respectively. The best sample yields an on/off ratio (I_on/I_off) of 5.04 × 10⁵, a threshold voltage (V_T) of 0.73 V, a high field effect mobility (μ_FE) of 8.69 cm² V⁻¹ s⁻¹, and a subthreshold swing (SS) of 0.41 V dec⁻¹. Owing to the strong ultraviolet (UV) absorption and photo-induced carrier separation ability of ZnO QDs and the fast carrier transport of Ag NWs, the devices acquire a high external quantum efficiency (EQE) and ultra-fast response under 365 nm UV illumination. The UV-modulated ZnO QD/Ag NW hybrid channel photo TFTs have potential for future application in optoelectronic devices, such as photodetectors and photoswitches.

High mobility and p-type thin film transistors (TFTs) are in urgent need for high-speed electronic devices.     

Facile synthesis of SnO2 shell followed by microwave treatment for high environmental stability of Ag nanoparticles

This study describes a new method for passivating Ag nanoparticles (AgNPs) with SnO₂ layer and their further treatment by microwave irradiation. The one-step process of SnO₂ layer formation was carried out by adding sodium stannate to the boiling aqueous AgNPs solution, which resulted in the formation of core@shell Ag@SnO₂ nanoparticles. The coating formation was a tunable process, making it possible to obtain an SnO₂ layer thickness in the range from 2 to 13 nm. The morphology, size, zeta-potential, and optical properties of the Ag@SnO₂NPs were studied. The microwave irradiation significantly improved the environmental resistance of Ag@SnO₂NPs, which remained stable in different biological solutions such as NaCl at 150 mM and 0.1 M, Tris-buffered saline buffer at 0.1 M, and phosphate buffer at pH 5.6, 7.0, and 8.0. Ag@SnO₂NPs after microwave irradiation were also stable at biologically relevant pH values, both highly acidic (1.4) and alkaline (13.2). Moreover, AgNPs covered with a 13 nm-thick SnO₂ layer were resistant to cyanide up to 0.1 wt%. The microwave-treated SnO₂ shell can facilitate the introduction of AgNPs in various solutions and extend their potential application in biological environments by protecting the metal nanostructures from dissolution and aggregation.

This study describes a new method for passivating Ag nanoparticles (AgNPs) with SnO₂ layer and their further treatment by microwave irradiation.     

A green approach for the synthesis of novel Ag3PO4/SnO2/porcine bone and its exploitation as a catalyst in the photodegradation of lignosulfonate into alkyl acids

A novel Ag₃PO₄/SnO₂/porcine bone composite photocatalyst was successfully prepared via an ion exchange method, which can convert lignin derivatives into small molecular acids upon exposure to visible light at room temperature at ambient pressure. The composition characterization, optical absorption properties and photocatalytic activities of the Ag₃PO₄/SnO₂/porcine bone composites were thoroughly investigated. The certain role of each component of the composites in the degradation reaction was discussed: Ag₃PO₄ acted as the major active component, while SnO₂ and porcine bone as cocatalyst contributed to improve the photocatalytic activity and stability of Ag₃PO₄. The enhanced activity of the Ag₃PO₄/SnO₂/porcine bone composite may be attributed to the synergistic effect including the matched energy band structures of Ag₃PO₄ and SnO₂ for the decrease in the probability of electron–hole recombination and improved performance in the presence of hierarchical porous porcine bone (hydroxyapatite). This paper also analyzed the change of the molecular weight and structure of sodium lignin sulfonate in the photocatalytic reaction and discussed the possible photocatalytic mechanism of the photocatalyst composite, indicating that the benzene rings of guaiacol were oxidized into different alkyl acids (maleic acid, oxalic acid, formic acid and methoxy acetic acid).

A novel Ag₃PO₄/SnO₂/porcine bone photocatalyst was synthesized for mild depolymerization of lignosulfonate, providing a green approach to utilize lignin derivatives.     

Ultrasensitive and low detection limit of acetone gas sensor based on ZnO/SnO2 thick films

In this study, we synthesized ZnO/SnO₂ hybrid sensing nanostructures by a sol–gel method. The structures, composition and morphologies of the synthesized products were thoroughly studied by X-ray diffraction (XRD), field-emission electron scanning microscopy (FESEM) and transmission electron microscopy (TEM). After the gas sensing test, we found that the sensing performance of the ZnO/SnO₂ composite is improved obviously compared with that of single components ZnO and SnO₂. The response to 0.5 ppm acetone reaches 3.36, almost twice that of pure ZnO and SnO₂. Meanwhile, the detection limit can be reduced to the ppb level. The enhanced acetone sensing performance was mainly attributed to the formation of n–n heterojunctions and the synergistic effect of ZnO and SnO₂.

XRD patterns of ZnO/SnO₂ powders.