SnO2 Nanosheets Research Articles

A Single MEMS Sensor Based on SnO₂ Nanosheets for Selective Gas Identification

A Single MEMS Sensor Based on SnO₂ Nanosheets for Selective Gas Identification

Construction of direct Z-scheme Sn3O4/WO3 heterostructure photocatalyst for enhanced Congo red degradation and Cr(Ⅵ) reduction performance

The development of well-designed architectures is crucial in accelerating the transport of photon-generated carriers in composite photocatalysts. In this study, a direct Z-scheme Sn3O4/WO3 (SW) photocatalyst was successfully fabricated utilizing a straightforward hydro/solvothermal approach, where Sn3O4 nanosheets (NSs) grew in-situ onto WO3 nanorods (NRs) uniformly. The optimal SW-2 composite exhibits a remarkable reduction rate of 93.5 % for Congo Red (CR) within 40 min, with a rate constant (k) of 0.075 min−1. This performance surpasses that of pristine Sn3O4 and WO3, which have rate constants of 0.027 min−1 and 0.018 min−1, respectively. Additionally, the SW-2 composite effectively removes 89.2 % of Cr(VI) over 100 min, achieving a k value of 0.019 min−1, which is higher than that of Sn3O4 (0.013 min−1) and WO3 (0.001 min−1). Furthermore, the photocatalytic degradation performance of the recovered samples retains their photocatalytic degradation performance after five consecutive experimental cycles, indicating excellent durability. The enhanced photocatalytic performance can be attributed to the construction of a direct Z-scheme heterostructure, which not only broadens the spectral response range, bur also ensures efficient separation of photoexcited carriers and fosters robust photo-redox capacity within the composite. This study is expected to provide some valuable insights into the design and synthesis of Z-scheme heterojunction photocatalysts, aimed at addressing pressing environmental pollution challenges.

High-responsivity photoelectrochemical ultraviolet photodetector based on SnO2 nanosheets-Ga2O3

Abstract Tin oxide (SnO2) has garnered significant attention for its high spectral selectivity when used as an ultraviolet photodetector. In this study, SnO2 nanosheets (NSs) were synthesized via a hydrothermal method, followed by spin-coating a layer of Ga2O3 thin film to construct a heterojunction photoelectrochemical ultraviolet photodetector (PEC UV PD). Initially, we investigated the effect of precursor composition on the properties of the Ga2O3 thin films. It was observed that the thickness of the films increased with higher precursor concentrations, while the optical bandgap decreased. Based on these findings, we successfully fabricated the SnO2 NSs-Ga2O3 PEC UV PD. Electrochemical analysis revealed that as the precursor concentration used for spin-coating Ga2O3 increased, the device's responsivity and detectivity initially increased and then decreased. After optimization, the device prepared with a 0.2M Ga(NO3)3 solution spin-coated on SnO2 exhibited excellent spectral selectivity (R 265nm/R 420nm ~ 4472), a responsivity of 4.86 mA W-1, and a detectivity of 2.72×109 Jones. This study demonstrates that coating Ga2O3 is an effective approach to constructing high-performance SnO2-based UV PDs.

Engineering of in-plane SnS2–SnO2 nanosheets heterostructures for enhanced H2S sensing

In-plane heterostructures has attracted considerable interest due to exceptional electron transport properties, high specific surface area, and abundant active sites. However, synthesis of in-plane SnS2–SnO2 heterostructures are rarely reported, and the deep investigation of the fine structure on reactivity is of great significance. Here, we propose partial in-situ oxidation strategy to construct the in-plane SnS2–SnO2 heterostructures and the surface properties, the ratio of two components can be finely tuned by precisely adjusting the treatment temperature. In particular, the SnS2–SnO2 heterostructures formed after annealing of SnS2 nanosheets at 350 °C exhibits a unique electronic structure and surface properties due to rich grain boundaries, which exhibits excellent gas sensing performance to H2S (Ra/Rg = 169.81 for 5 ppm H2S at 160 °C, fast response and recovery dynamic (41/101 s), excellent reliability (σ = 0.01) and sensing stability (φ = 0.11 %)). Notably, the in-plane heterostructures endow the material with abundant grain boundaries and effectively regulates the electronic structure of the Sn p-orbital, which facilitate the formation of active oxygen species (O−(ad)), thus contributing to the sensing performance. Our work provides a promising platform to design in-plane heterostructures for various advanced applications.

Fast diffusion and stable topotactic reaction in single crystal conversion anode

Conversion electrodes typically have high theoretical specific capacity, but mostly suffer large structural changes during charge/discharge and result in poor cycling stability. The optimization of the polycrystalline materials is the mostly used strategy, however, these polycrystalline materials are intrinsically vulnerable to grain-boundary (intergranular) fracture caused by the anisotropic volume change during sodiation/desodiation, resulting in rapid impedance growth and capacity decay. Herein, we propose an alternative pathway to design single-crystal materials as potential conversion anodes. As an example, SnO2 with different crystallinities is successfully synthesized via solvothermal methods and compared to determine the implications of different crystallinity for the electrochemical properties of conversion anodes. It is demonstrated that the single-crystal SnO2 not only has faster Na+ diffusion dynamics but also maintains structural stability via topotactic reaction. Further optimization of the electron conduction and structural robustness is realized by uniformly covering a graphitic carbon shell on the surface of single-crystal SnO2 nanosheets. The modified single-crystal SnO2 exhibits a high reversible capacity of 436.2 mA h g–1 and maintains a high capacity of 257.1 mA h g-1 and remarkable capacity retention of about 98.9% after 9000 cycles at 5000 mA g-1. The deep understandings of the topotactic reaction in single crystal conversion anode in this work provide a theoretical foundation and new direction for further developing electrode materials with excellent electrochemical performance, especially high rate capabilities, and long cyclability.

General synthesis of porous metal oxides nanosheets for gas sensing by gradient crystallization induced spatial confinement approach

Inorganic-template synthesis of crystalline porous metal oxides nanosheets with fantastic properties is a powerful approach, but it is limited in the systems with strong interaction between inorganic crystals and guest species. Here, we report a gradient crystallization induced spatial confinement method to achieve a general synthesis of porous metal oxides nanosheets regardless of host–guest interaction. Taking the synthesis of porous SnO2 nanosheets as an example, the freezing of KCl/SnCl2 aqueous solution induces the gradient crystallization of lamellar ice and KCl structure, and subsequently expelled KCl/SnCl2 crystals can be limited in the confined region to form the ice/SnCl2/KCl sandwich structure. Followed by freeze-drying, calcination and water washing, the porous SnO2 nanosheets structure can be obtained. Notably, this general method enables the synthesis of functional porous nanosheet with specific designed component and surface properties, and the obtained porous Pt-SnO2 nanosheets with abundant accessible active sites and lower d-band center exhibit superior gas sensing performance to 3-hydroxy-2-butanone.

Facile synthesis of porous Au-decorated SnO2 microflowers with abundant oxygen vacancies for trace VOCs detection

Hierarchical Au-decorated SnO2 (Au@SnO2) microflowers with a porous structure were successfully synthesized. The preparation process involves in a hydrothermal method, calcination treatment, as well as modification. The hierarchical structure consisted of a large number of porous, uniform nanosheets. Excellent gas-sensing performances were demonstrated by the gas sensors fabricated using Au@SnO2 microflowers, for detecting volatile organic compounds (VOCs). In particular, for the accurate and fast detection of formaldehyde, the 2%Au-decorated SnO2 microflowers sensors showed a strong sensing response (76.5) for formaldehyde (100 ppm) at 140 °C, approximately three times higher than that (28.2) observed for the pure porous SnO2 microflowers. The response and recovery times (10 s/16 s) were shorter than those (12 s/25 s) of the pure SnO2, respectively. The detection limit for the 2%Au@SnO2 sensor was 19.03 ppb. The sensing mechanism of Au@SnO2 sensors was also investigated. Favorable porous 3-dimensional structure, high catalytic activity, and electron sensitization effect of Au nanoparticles (NPs) improved the gas-sensing performance. Furthermore, the catalytic activity of Au NPs was maximized due to their uniform distribution on the surface of each porous SnO2 nanosheet. The Au-decorated SnO2 microflowers sensors have great potential for the accurate, fast, and highly sensitive response detection of formaldehyde gas.

Interface engineering of SnO2 to enhance the cycle stability of WO3 and Prussian blue for complementary electrochromic smart windows and energy storage

The interface mismatch between electrochromic materials and conductive layer seriously affects the cycle stability of electrochromic smart windows (ESW). However, it is difficult to improve the interface matching at the same time because of the different physical and chemical properties of anode and cathode materials. In this work, SnO2 nanosheets are used as the interface modification layer between electrochromic materials and conductive layer. SnO2 interface engineering significantly can improve the cycle stability of WO3 film and Prussian blue (PB) film. The WO3/SnO2-PB/SnO2 complementary ESW exhibits a high optical modulation of 60.2 % at 633 nm, fast response time (bleached/colored time = 8.5/2.5 s), and coloration efficiency of 91.7 cm2 C−1. The WO3/SnO2-PB/SnO2 device can still maintain an optical modulation of 45.2 % after 2000 cycles, suggesting excellent long cycle stability. And the device shows the energy storage of 5.06 mF cm−2 at 0.1 mA cm−2, which can improve energy efficiency. The excellent electrochromic properties and energy storage suggests that SnO2 interface engineering has a good application prospect in multi-functional ESW with excellent cycle stability.

Tannic acid induced surface functional strategy to synthesize Ni-doped SnO2 nanosheets for enhanced HCHO sensing

Surface functionalization is a promising strategy to modulate the electronic and surface properties of metal oxide semiconductors. Here, we report a tannic acid (TA) induced surface functional strategy to synthesize Ni-doped SnO2 nanosheets. Benefiting from the abundant polyphenolic and catechol groups, the linkage of TA not only exhibit high affinity to various substrate, but also show powerful chelating ability to metal ions. Hence, Ni ions can be highly dispersed on the SnO2 nanosheets via TA, TA linkage also can prevent the aggregation of Ni ions during pyrolysis, and Ni substitution in SnO2 crystals can be obtained. As a proof-of-concept demonstration, the TA-Ni/SnO2 sensor is fabricated to detect HCHO, and exhibit superior sensing performance at low working temperature of 80 °C (Ra/Rg = 184.3), excellent sensing selectivity and long-term stability. Detail experimental and theoretical calculation demonstrate the highly dispersed Ni substitution active sites facilitate the generation of surface O2–(ad) species, and the electronic structure also can be modulated to exhibit high affinity to HCHO, hence, the synergistic effects contribute to the enhanced sensing performance. Our work paves the way for versatile surface functionalization to synthesize advanced materials for application in catalysis and sensing field.

Fabrication of Liquid-Metal Printed 2D Tin Oxide Nanosheets for Optoelectronic Applications

Liquid-metal printed processes have been recently developed as a novel strategy to grow ultrathin 2D oxide materials, which are transferred from liquid-metal surfaces to substrates. In this study, we fabricated liquid-metal printing 2D tin oxide (SnO) nanosheets on SiO2/Si and glass substrates. A large lateral-sized 2D SnO nanosheets of >100 µm and a thickness of approximately 6.3 nm was fabricated. The 2D SnO nanosheets exhibited a strong optical absorption in the ultraviolet and violet region and its bandgap was estimated to be approximately 2.9 eV. The 2D SnO nanosheets on glass substrates with patterned gold electrodes generated a photocurrent under ultraviolet (UV) light irradiation, demonstrating a potential for optoelectronic applications such as UV detectors.

The ammonia modified ZIF-8@SnO2 core-shell nanosheets for improved the sensitivity and selectivity of NO2

For NO2, a gas that is widely used and harmful, domestic and foreign researchers have done a lot of work to develop a sensor with low detection limit and low humidity sensitivity to achieve efficient detection of NO2. In this work, first of all, dense and uniform SnO2 nanosheets were grown in situ on the surface of Al2O3 ceramic tube by hydrothermal method. Then, the ZIF-8@SnO2 porous composite gas-sensitive material was constructed by solvent thermal method. With the advantages of the ZIF-8 porous screening framework, the permeation of different gases can be selectively controlled, and the adsorption efficiency of NO2 gas can be enhanced through the modification of ammonia to improve the selectivity of NO2. The results show that the response of the Modified-ZIF-8@SnO2 sensor is significantly enhanced, and the selectivity is greatly improved at low operating temperature. At 140 °C, the response of Modified-ZIF-8@SnO2 to 50 ppm NO2 gas is as high as 61, which is about 18.4 times higher than that of SnO2 nanosheets and about 16.3 times higher than that of ZIF-8@SnO2. Meanwhile, the anti-interference ability of the Modified-ZIF-8@SnO2 sensor to humidity has been improved. This work provides a new idea for improving the selectivity and humidity insensitivity of gas sensors.

Enhanced formaldehyde sensing performance employing plasma-treated hierarchical SnO2 nanosheets through oxygen vacancy modulation

Effective utilization of nanostructured metal-oxides with surface engineering is often overlooked during fabrication of gas sensors. The paper reports preparation of flower-like tin oxide nanosheets (average thickness = 12 nm) enriched with oxygen vacancies towards enhanced formaldehyde detection. The proportion of oxygen vacancy was increased using argon-plasma treatment (power = 100 W) with varied time durations (0, 2, 4, 7, 10 min). A detailed material characterization confirmed the structural property and oxygen vacancy content in the samples. A comparative sensing performance was analyzed among different fabricated sensor devices based on plasma exposure duration. Superior sensing behavior was registered from sensor S_7 comprising of sample with 7 min plasma exposure having maximum oxygen vacancy content of 53.16 % (relative). Sensor S_7 was considered optimum, which showed a response of 24.19 in presence of 10 ppm of formaldehyde which was 8.6 times greater than the sensor (S_0) without plasma exposure. Remarkably, sensor S_7 exhibited high sensitivity, fast kinetics, excellent reversibility, notable repeatability, and admirable selectivity, along with 34 ppb as limit of detection. Additionally, the sensing mechanism is adequately discussed based on the surface interaction, electronic sensitization and associated redox reactions. The demonstrated work emphasizes an efficacious approach toward developing upgraded gas sensor devices for widespread applications.

Surface chemistry altering electronic behaviour of liquid metal-derived tin oxide nanosheets.

Possessing excellent electronic properties and high chemical stability, semiconducting n-type two-dimensional (2D) tin dioxide (SnO2) nanosheets have been featured in sensing and electrocatalysis applications recently. Derived from non-layered crystal structures, 2D SnO2 has abundant unsaturated dangling bonds existing at the surface, providing interfacial activity. How the surface chemistry alters the electronic properties of 2D SnO2 nanomaterials remains unexplored. In this study, we synthesised ultra-thin 2D SnO2 nanosheets using a liquid metal (LM) touch printing technique and investigated experimentally and theoretically how the interactions of organic solvents composed of alkyl and hydroxyl groups with the surface of LM-derived 2D SnO2 modulate the electronic properties. It was found that alkane solvents can physically absorb onto the SnO2 surface with no impact on the material conductivity. Alcohol-based solvents on the other hand interact with the SnO2 surface via chemical absorptions primarily, in which oxygen atoms of hydroxyl groups in the alcohols form bonds with the surface atoms of SnO2. The binding stability is determined by the length and configuration of the hydrocarbon chain in alcohols. As representative long-chain alcohols, 1-octanol and 1-pentanol attach onto the SnO2 surface strongly, lowering the binding energy of Sn4+ and reducing the electron transfer ability of SnO2 nanosheets. Consequently, the electronic properties, i.e. conductivity and electronic mobility of SnO2 nanosheet-based electronic devices are decreased significantly.

In2O3-SnO2 Hedgehog-Like nanostructured heterojunction for acetone detection

The In2O3-SnO2 heterojunction nanostructures resembling hedgehogs were synthesized through hydrothermal method and physical stirring for acetone detection. SEM and TEM characterization showed that the composites were SnO2 nanosheets (NSs) assembled into a flower-like morphology with In2O3 particles grown in situ on the NSs. The In2O3-SnO2 sensor has excellent vapor sensitivity compared to pure SnO2. At an optimal temperature of 260 ℃, the In2O3-SnO2 sensor achieves a response value of 19.4 for acetone vapors at a concentration of 100 ppm. The composites still exhibit excellent gas-sensitized performance at low concentration (100 ppb). The improved gas-sensitized performance of In2O3-SnO2 composites is attributed to the sea urchin-like nanoflower morphology enriched with oxygen vacancies and the formation of n-n heterojunctions. To further substantiate its enhancing mechanism, the adsorption behavior of acetone molecules on the fabricated composite material was investigated through the utilization of density functional theory (DFT). This study confirms the enhanced gas sensing performance of In2O3-SnO2 heterojunction composites towards acetone and elucidates the enhancement mechanism by DFT calculations.

Porous SnO2 nanosheets for room temperature ammonia sensing in extreme humidity.

Gas sensors based on tin dioxide (SnO2) for the detection of ammonia (NH3) have become commercially available for environmental monitoring due to their reactive qualities when exposed to different gaseous pollutants. Nevertheless, their implementation in the medical field has been hindered by certain inherent drawbacks, such as needing to operate at high temperatures, lack of selectivity, unreliable operation under high-humidity conditions, and a lower detection limit. To counter these issues, this study created 2D nanosheets of SnO2 through an optimized solvothermal method. It was found that tuning the precursor solution's pH to either neutral or 14 led to aggregated or distributed, uniform-size nanosheets with a higher crystallinity, respectively. Remarkably, the SnO2 nanosheet sensor (SNS-14) displayed a much lower response to water molecules and specific reactivity to ammonia even when subjected to reducing and oxidizing agents at 25 °C due to the micropores and chemisorbed oxygen on the nanosheets. Furthermore, the SNS-14 was seen to have the highest sensitivity to ammonia at 100 ppm, with rapid response (8 s) and recovery times (55 s) even at a high relative humidity of 70%. Its theoretical detection limit was recorded to be 64 ppt, better than any of the earlier SnO2-based chemiresistive sensors. Its exceptional sensing abilities were credited to its optimal crystallinity, specific surface area, defects, chemisorbed oxygen, and porous structure. NH3-TPD measurements and computational simulations were employed to understand the ammonia interaction with atomistic details on the SnO2 nanosheet surface. A real time breath sensing experiment was simulated to test the efficacy of the sensor. Reaching this advancement is an achievement in bypassing past boundaries of SnO2-centered sensors, making it feasible to detect ammonia with enhanced precision, discrimination, dependability, and velocity for probable usages in medical diagnostics and ecological surveillance.

A fast response hydrogen sensor based on the heterojunction of MXene and SnO2 nanosheets for lithium-ion battery failure detection

During the process of lithium-ion battery failure, the discharge of hydrogen indicates that the electrolyte has leaked and is being electrolyzed, which is a sign of thermal runaway in lithium batteries. In this work, stannic oxide (SnO2) nanosheets was formed by high-temperature calcination and compounded with Ti3C2Tx (MXene) in different proportions. The morphology, microstructure and element composition of the material were characterized. The sensing response of MXene-SnO2 for hydrogen (H2) at the most suitable temperature was explored. The test results show that compared with single SnO2, MXene-SnO2 composite sensor has higher response, shorter response/recovery time, stable repeatability and excellent selectivity. Finally, through density functional theory (DFT) calculation, it may be caused by the microstructure of SnO2 and MXene synergism in the effect of forming heterostructures between the two materials in response to hydrogen gas.

Strongly Coupled Ag/Sn–SnO2 Nanosheets Toward CO2 Electroreduction to Pure HCOOH Solutions at Ampere-Level Current

HighlightsThe strongly coupled Ag/Sn–SnO2 nanosheets (NSs) were prepared via a versatile electrochemical template strategy, and the generated electron-enriched Sn sites promote the formation of *OCHO and alleviate the energy barriers of *OCHO to *HCOOH.Ag/Sn–SnO2 NSs afford a superior activity toward CO2 electroreduction with current densities up to 2000 mA cm‒2 and near-unity selectivity for formate production.Ag/Sn–SnO2 NSs as the cathode in a membrane electrode assembly with porous solid electrolyte reactor enable the direct production of ~ 0.12 M pure HCOOH solution for 200 h.

Ultra-large Sn3O4 nanosheets with Sn2+ defect for highly efficient hydrogen sensing

Hydrogen (H2) is the cleanest energy but also dangerous, thus the real-time detection of H2 leakage is crucially important. Herein, we develop ultra-large micro-sized Sn3O4 nanosheet hierarchies via a facile hydrothermal method using polyvinyl pyrrolidone as a regulating agent. Structural analyses reveal the as-prepared Sn3O4 nanosheets are single-crystalline with {010}-facet exposure and Sn2+-deficiency. When examined as gas sensing materials, the {010}-faceted Sn2+-deficient Sn3O4 nanosheets demonstrate highly efficient H2 sensing with excellent selectivity/response (two times higher than those for NO2, SO2, H2S, and H2O) and stability upon long-term testing (over 37 days). The sensor displays fast response /recovery times of 9.4/24 s to 10 ppm H2 at a low working temperature of 150 °C, and even well responds to 50 ppb H2 with a theoretical limit of detection (LOD) of 0.54 ppb. The excellent H2 sensing performance of the Sn3O4 nanosheets has been verified by the first-principle calculation based on density functional theory (DFT), suggesting that the Sn2+-deficient {010} surface of Sn3O4 provides abundant adsorption sites for hydrogen molecules. Moreover, we demonstrate the practical application of Sn3O4 sensor embedded into a miniaturized deployable module, which realizes the real-time on-line H2 monitoring with excellent repeatability and selectivity for long-term operation.

Sn3O4 nanosheets with N-doped carbon coating for high performance lithium storage

Tin-based oxides are promising anode materials for lithium ion batteries (LIBs) in virtue of their many advantages including high capacity, abundant reserves and environmental friendliness. Yet, previous studies mainly focus on the SnO2-based anodes for lithium storage. Considering that the mixed valence and layered crystal structure of Sn3O4 may lead to better lithium storage properties, Sn3O4-based anode material is designed and synthesized through a facile hydrothermal method in this work. The as-prepared Sn3O4 nanosheets are coated with N-doped carbon layers (∼15 nm) on both sides through dopamine polymerization and subsequent polydopamine carbonization to solve the issues of poor intrinsic electronic conductivity and drastic volume change during LiSn alloying/dealloying, which have hindered their application in LIBs. With the structural and composition advantages brought by the thick N-doped carbon layers, the Sn3O4@NC nanosheets delivered a remarkable reversible capacity (1222 mAh g−1 after 50 cycles at 200 mA g−1) and excellent rate performance when applied in LIB as anode material, owing to the improved electrical conductivity and strengthened structure stabilities. Importantly, we demonstrate a convenient strategy to realize carbon coating in the fabrication of Sn3O4-based anode materials, which could inspire the development of other Sn3O4-based anode materials with excellent lithium storage properties.

Instant‐in‐Air Liquid Metal Printed Ultrathin Tin Oxide for High‐Performance Ammonia Sensors

AbstractLiquid metal‐based printing techniques are emerging as an exemplary platform for harvesting non‐layered 2D materials with a thickness down to a few nanometres, leading to an ultra‐large surface‐area‐to‐volume ratio that is ideal for sensing applications. In this work, the synthesis of 2D tin dioxide (SnO2) by exfoliating the surface oxide of molten tin is reported which highlights the enhanced sensing capability of the obtained materials to ammonia (NH3) gas is reported. It is demonstrated that amperometric gas sensors based on liquid metal‐derived 2D SnO2 nanosheets can achieve excellent NH3 sensing performance at low temperature (150 °C) with and without UV light assistance. Detection over a wide range of NH3 concentrations (5–500 ppm) is observed, revealing a limit of detection at the parts per billion (ppb) level. The 2D SnO2 nanosheets also feature excellent cross‐interference performance toward different organic and inorganic gas species, showcasing a high selectivity. Further, ab initio DFT calculations reveal the NH3 adsorption mechanism is dominated by chemisorption with a charge transfer into 2D SnO2 nanosheets. In addition, a proof of concept for prototype flexible ammonia sensors is demonstrated by depositing 2D SnO2 on a polyimide substrate, signifying the high potential of employing liquid metal printed SnO2 for realizing wearable gas sensors.