Nanocomposite Based Gas Sensor Research Articles

Simulation performance of inkjet-printed polyaniline–graphene oxide nanocomposite based gas sensor

Simulation performance of inkjet-printed polyaniline–graphene oxide nanocomposite based gas sensor

Carbon and graphene based nanocomposites for gas sensors—Current state and advances

After the discovery of carbon nanoforms, carbon nanotube (one dimensional) and tube like nanostructure and graphene (two dimensional) nanosheets have gained immense research curiosity. Further nanotechnological developments have moved towards the formation of carbon nanotube nanocomposites and graphene nanocomposites. For the purpose, various matrices including thermoplastic polymers and conjugated polymers have been used. Methodology is the systematic gathering of the literature and development of a novel review outline, theme, and discussions regarding the discussed topics. Hence, varying conjugated polymers such as polyaniline, polythiophene, poly(3,4-ethylenedioxythiophene), and nonconjugated nylon, poly(ethylene glycol), etc. have been processed using techniques like in situ, solution, electropolymerization, spin coating, etc. In sensors, the nanocomposites need to develop fine nanoparticle dispersion, network formation, and interfacial interactions ultimately supporting the electron or charge transfer in these nanomaterials desirable for the recognition of the gaseous species. Moreover, interactions of the nanocomposite with the analyte molecules define the sensing capabilities of the nanomaterials. Consequently, nanocarbon nanocomposite based gas sensors have been analyzed for conductivity, change in resistance, sensitivity, selectivity, response time, detection limit, and other desirable properties. For future designs, it is recommended to develop high-tech combinations of conjugated polymers like polythiophene derivatives using functional forms of graphene and carbon nanotube. In addition, use of advanced manufacturing techniques like 3D/4D printing and spin coating must be applied to form efficient sensors. In conclusions, this manuscript presents not only comprehensive but also comparative analysis on different gas analysis parameters such as detection limit, concentration, response time, etc. for various nanocomposite sensors. Lastly, the encounters in preparing and applying graphene/carbon nanotube sensors, associated utilizations, and possible future prospects have been discussed.

ZnO Intercalated PVA-PEDOT:PSS Composite Nanofiber for Detection of Ammonia Gases

Keywords: Ammonia, Electrospinning, and Zinc OxideThe matter of air pollution has dramatically risen the worldwide concern on detecting of hazardous gases present in the atmosphere because they are highly detrimental to human health [4,5]. Additionally, the detection and monitoring of such harmful gases is necessary for process control in the industry as well as the general safety of the environment. Zinc oxide (ZnO) is an n-type semiconductor with a wide direct bandgap width (3.37 eV), high excitation binding energy (60meV), high electron mobility, thermal stability, and excellent electrical properties [1]. Other promising materials for gas-sensing applications encompass single elements, silicon and tellurium-based materials and organic semiconductors. The sensing materials that are of intense research interest are conducting polymers such as polyaniline (PANI), polypyrrole (PPy) and poly(3,4-thylenedioxythiophene) (PEDOT) used in the fabrication of polymer-based gas sensors [2]. Its capability to work at low operating temperatures while maintaining high sensitivity leads to the synergistic effect when in combination with metal oxides to produce high-performance gas sensors. They are very appealing in terms of energy saving as they do not need an additional source of heat, consequently reducing the operating cost, simplifying the fabrication process, and extending the lifespan of the device [3]. In this work, ZnO intercalated PVA-PEDOT:PSS composite nanofiber as a sensing layer was prepared by electrospinning method. This material was characterized both morphologically and structurally by X-ray diffraction analysis, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy and thermogravimetric analysis. The results from TEM and SEM show well distribution of ZnO particles in the polymer matrix. The gas measurement results reveal that the fabricated ZnO loaded PVA-PEDOT:PSS composite sensor exhibits excellent gas response (63%) to ammonia gas in 100 ppm gas concentration at 120 °C. Acknowledgment This research was supported by the research grant 021220CRP0122 “Development of highly sensitive MOS based nano-film gas sensors” from Nazarbayev University. References S. Bhati, M. Hojamberdiev, and M. Kumar, “Enhanced sensing performance of ZnO nanostructures-based gas sensors: A Review,” Energy Reports, vol. 6, pp. 46–62, 2020.Yan, Y. et al. (2020) “Conducting polymer-inorganic nanocomposite-based Gas Sensors: A Review,” Science and Technology of Advanced Materials, 21(1), pp. 768–786.Zhang, J. et al. (2015) “Nanostructured materials for room-temperature gas sensors,” Advanced Materials, 28(5), pp. 795–831.C. Eze, E. Schaffner, E. Fischer, T. Schikowski, M. Adam, M. Imboden, M. Tsai, D. Carballo, A. von Eckardstein, N. Künzli, C. Schindler, and N. Probst-Hensch, “Long-term air pollution exposure and diabetes in a population-based Swiss cohort,” Environment International, vol. 70, pp. 95–105, 2014.C. Shim, J. Han, D. K. Henze, M. W. Shephard, L. Zhu, N. Moon, S. K. Kharol, E. Dammers, and K. Cady-Pereira, “Impact of NH3 emissions on particulate matter pollution in South Korea: A case study of the seoul metropolitan area,” Atmosphere, vol. 13, no. 8, p. 1227, 2022. Figure 1

MXene/MoS2 nanosheet/polypyrrole for high-sensitivity detection of ammonia gas at room temperature

MXenes have recently emerged as innovative 2D materials with potential for gas-sensing applications. In this study, we produced a polypyrrole (PPy)-coated MXene/MoS2 nanocomposite-based gas sensor for ammonia detection at room temperature. MXene-loaded MoS2 nanocomposites with loose heterogeneous architectures were produced via a one-step hydrothermal technique based on an electrostatically ordered self-assembly. An etched MXene surface with evenly wrapped MoS2 nanosheets created a highly synergistic metal–semiconductor-like contact, producing an anti-blocking layer that had a trapping effect on electrons produced via NH3 sensing. PPy was polymerized in situ on the surface of the MXene/MoS2 composite, producing a self-supporting structure. The MXene/MoS2/PPy nanocomposite-based sensor exhibited response values approximately five times greater than sensors based on pure MXene when exposed to 100 ppm of ammonia at room temperature. Furthermore, the sensor could detect ammonia at concentrations as low as 10 ppm and presented a response of 2.08 at room temperature. The MXene/MoS2/PPy nanocomposite-based sensor also demonstrated long-term stability, high response and recovery rates, good humidity tolerance, and high selectivity for ammonia.

Ammonia Sensing Properties of SnS₂/SnO₂ Nanocomposite-Based Gas Sensor by SnS₂ Annealing

Tin disulfide has been demonstrated effective for ammonia detection, while its potential application has been seriously limited by high working temperature and low sensitivity. In this article, SnS2/SnO2 nanocomposites are prepared through a two-step method. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis show that the material would be transformed from SnS2 to SnS2/SnO2 composites by increasing annealing temperature. Gas testing results have shown that SnS2/SnO2 nanocomposites exhibit high sensitivity and good stability to ammonia, and the response to 100-ppm ammonia at 80 °C can reach 5.91. The sensor response was relatively stable at the target gas concentration. The high response of SnS2/SnO2 composites to ammonia at low temperatures might be due to SnS2 surface defects and heterostructure. From the perspective of atom and energy, adsorption energy has been simulated and calculated by the first principle analysis, to some extent, which proved that SnS2/SnO2 nanocomposite can improve the response to ammonia gas.

A review: electrical and gas sensing properties of polyaniline/ferrite nanocomposites

PurposeThis paper aims to study the various developments taking place in the field of gas sensors made from polyaniline (PANI) nanocomposites, which leads to the development of high-performance electrical and gas sensing materials operating at room temperature.Design/methodology/approachPANI/ferrite nanocomposites exhibit good electrical properties with lower dielectric losses. There are numerous reports on PANI and ferrite nanomaterial-based gas sensors which have good sensing response, feasible to operate at room temperature, requires less power and cost-effective.FindingsThis paper provides an overview of electrical and gas sensing properties of PANI/ferrite nanocomposites having improved selectivity, long-term stability and other sensing performance of sensors at room temperature.Originality/valueThe main purpose of this review paper is to focus on PANI/ferrite nanocomposite-based gas sensors operating at room temperature.

Improvement in NO2 Gas Sensing Properties of Semiconductor-Type Sensors by Loading Pt into BiVO4 Nanocomposites at Room Temperature.

In the present study, we report the first attempt to prepare a conducive environment for Pt/BiVO4 nanocomposite material reusability for the promotion of sustainable development. Here, the Pt/BiVO4 nanocomposite was prepared using a hydrothermal method with various weight percentages of platinum for use in NO2 gas sensors. The surface morphologies and structure of the Pt/BiVO4 nanocomposite were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). The results showed that Pt added to BiVO4 with 3 wt.% Pt/BiVO4 was best at a concentration of 100 ppm NO2, with a response at 167.7, and a response/recovery time of 12/35 s, respectively. The Pt/BiVO4 nanocomposite-based gas sensor exhibits promising nitrogen dioxide gas-sensing characteristics, such as fast response, highly selective detection, and extremely short response/recovery time. Additionally, the mechanisms of gas sensing in Pt/BiVO4 nanocomposites were explored in this paper.

Enhanced n-butanol sensing performance of SnO2-based gas sensors by doping In2O3 via co-precipitation method

A series of In2O3-SnO2 nanocomposites were synthesized with a facile hydrothermal co-precipitation method and calcination after-treatment at 400 °C. The crystal phase structure, morphology, and elemental composition were characterized by X-ray powder diffraction and field emission scanning electron microscopy with energy dispersive spectroscopy. In2O3-SnO2 nanocomposite-based gas sensors were fabricated, and their potential applications were assessed by testing gas-sensing properties systematically. The results exhibited that a small amount of In2O3 dopant improved the dispersion and increased the specific surface area of SnO2 nanomaterials. Besides, the gas response towards n-butanol gas was promoted and the working temperature was decreased by doping In2O3. In particular, the 1.5 %In2O3-SnO2 nanocomposites-based sensor showed an excellent response of 76.5 towards 50 ppm n-butanol gas at 140 °C. The binding energies of the Sn 3d in nanocomposites varied with the changed doping dosage of In through XPS analysis. The enhanced n-butanol sensing performance of the fabricated In2O3-SnO2 sensors at low operating temperature may be due to a synergistic effect between In2O3 and SnO2.

Room-Temperature Benzene Sensing with Au-Doped ZnO Nanorods/Exfoliated WSe2 Nanosheets and Density Functional Theory Simulations.

A gold-doped zinc oxide (Au-ZnO)/exfoliated tungsten diselenide (exfoliated WSe2) nanocomposite-based gas sensor toward benzene with high sensing properties was demonstrated. Epoxy resin was used as the matrix of the Au-ZnO/exfoliated WSe2 nanocomposite sensor. The straw-shaped Au-ZnO was synthesized by the hydrothermal method, and WSe2 nanosheets (NSs) were prepared via hydrothermal and liquid-phase exfoliation methods. The properties of Au-ZnO/exfoliated WSe2 nanoheterostructures constructed by self-assembly technology have been confirmed via a series of characterization methods. The benzene-sensing performances of sensors were tested at 25 °C. Compared with Au-ZnO, WSe2, and their composites, the Au-ZnO/exfoliated WSe2 sensor has a significant performance improvement, including a higher response and linear fit degree, better selectivity and repeatability, and faster detection rate. The significantly enhanced sensing properties of the Au-ZnO/exfoliated WSe2 sensor can be ascribed to the doping of Au nanoparticles, the increase in the specific surface area and adsorption sites of NSs after exfoliation, and the cooperative interface combination of the ZnO/WSe2 heterojunction. Furthermore, the sensitivity mechanism of the composite sensor to benzene was explored by density functional theory simulations.

Construction of MoO3/MoSe2 nanocomposite-based gas sensor for low detection limit trimethylamine sensing at room temperature

In this paper, MoO3/MoSe2 nanocomposite was constructed by an improved hydrothermal and spin coating method for fabricating trimethylamine (TMA) gas sensor. The surface morphology and microstructure of the prepared materials were analyzed by XRD, XPS, SEM and TEM characterization methods. The microstructural characterization results demonstrated that the MoO3/MoSe2 nanocomposite had been successfully synthesized, in which the MoSe2 had a flower-shaped structure, and MoO3 had a rod-shaped structure. At the same time, the MoSe2 surface exhibited periodic honeycomb structure. The gas sensitivity experimental results showed that the proposed MoO3/MoSe2 sensor had excellent TMA sensing performance at room temperature, including high response capability, low detection limit (20 ppb), short response/recovery time (12 s/19 s), long-term stability, good repeatability and outstanding selectivity. The heterostructure of MoO3/MoSe2 had made outstanding contributions to the enhanced TMA gas sensing performance at room temperature.

Electrochemical MoOx/Carbon Nanocomposite-Based Gas Sensor for Formaldehyde Detection at Room Temperature

A nanocomposite comprised of molybdenum oxide and highly conductive carbon (MoOx/Carbon) was deposited onto a screen-printed gold electrode (SPGE) to be employed as a gas sensor for the detection of formaldehyde gas. First, the carbon surface was modified by acid treatment to introduce oxygen-containing groups and promote the efficient anchorage of the molybdenum precursor by surface organometallic chemistry (SOMC). Then, once the MoOx/Carbon composite was deposited onto the SPGE, a Nafion layer was added to act as a solid-state ionic electrolyte. Fourier-transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA) were used to verify the carboxylated surface of carbon after the acid treatment. Scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectrosand inductively coupled plasma optical emission spectrometry (ICP-OES) were also employed to confirm the success of the SOMC synthesis. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to investigate the interaction of the nanocomposite with formaldehyde at room temperature. The nanocomposite gas sensor showed an enhanced electrical current response when increasing the concentration of formaldehyde, with a limit of detection as low as 60 ppb and sensitivity of 5.13 μA ppm−1. Additionally, the nanocomposite sensor demonstrated high selectivity to formaldehyde when compared to other volatile organic compounds (VOCs).

Novel Ag-SnO2-βC3N4 ternary nanocomposite based gas sensor for enhanced low-concentration NO2 sensing at room temperature

Herein, a novel gas sensor based on Ag nanoparticles, tin oxide and carbon nitride nanocomposite (Ag-SnO2-βC3N4) was fabricated and its utility towards room-temperature NO2 gas sensing was investigated. TheAg-SnO2-βC3N4 ternary nanocomposite was characterized with transmission electron microscopy (TEM), Energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) etc. The ternary heterojunction based sensor responded strongly to low concentrations of NO2 gas at room-temperature. For 5 ppm NO2 concentration, an excellent response time of 27.2 s for 90 % of response was achieved with higher recovery time of 110.5 s. The ternary nanocomposite sensor showed synergistic response which is ∼1.14 times and ∼1.9 times of that of the SnO2-C3N4 and pristine SnO2 sensors, respectively. The superior sensitivity of the ternary nanocomposite sensor is attributed to the higher conductivity and catalytic activity of the Ag-SnO2-βC3N4 ternary nanocomposite. The enhanced sensing properties of Ag-SnO2-βC3N4 sensor were discussed from the points of SnO2-βC3N4 n-n heterojunction and Ag-SnO2-βC3N4 Schottky contact on the basis of depletion layer model.

Facial fabrication of an inorganic/organic thermoelectric nanocomposite based gas sensor for hydrogen detection with wide range and reliability

A novel method for fabrication of a thermochemical hydrogen (TCH) gas sensor composed of platinum (Pt)-decorated graphene sheets and a thermoelectric (TE) polymer nanocomposite was investigated. The hydrogen sensing characterization for the device included gas response, response time (T90), recovery time (D10), and reliability testing, which were systematically conducted at room temperature with a relative humidity of 55%. Here, the Pt-decorated graphene sheets act as both an effective hydrogen oxidation surface and a heat-transfer TE polymer nanocomposite having low thermal conductivity. This property plays an important role in generating output voltage signal with a temperature difference between the top and bottom surfaces of the nanocomposite. As a result, our TCH gas sensor can detect the range of hydrogen from 100 ppm to percentage level with good linearity. The best response and recovery time revealed for the optimized TCH gas sensor were 23 s and 17 s under 1000 ppm H2/air, respectively. This type of sensor can provide an important component for fabricating thermoelectric-based gas sensors with favorable gas sensing performance.

Improved gas sensing performance of Al doped ZnO/CuO nanocomposite based ammonia gas sensor

Pure ZnO nanoparticles (NPs), ZnO/CuO and Al-ZnO/CuO nanocomposites (NCs) were prepared using co-precipitation followed by sol–gel method. The structural and morphological properties of resulting materials were characterized by X-ray diffraction (XRD), micro Raman, high-resolution transmission electron microscope (HRTEM) and scanning electron microscope (SEM) respectively. The XRD results confirmed that the ZnO-CuO composite is formed without the presence of any ZnO-CuO alloy. The gas sensing performance of pure ZnO, ZnO/CuO and Al-ZnO/CuO nanocomposites towards ammonia gas at room temperature was investigated. The gas sensing results revealed that the Al-ZnO/CuO nanocomposite based gas sensor has superior gas sensing properties like, high response, good stability, and fast response (14s) and recovery (9 s) time towards 500ppm (parts per million) ammonia gas at room temperature compared to pure ZnO and ZnO/CuO based sensors. Further the gas sensing performance of Al-ZnO/CuO sensor towards different volatile organic compound (VOC) gases was tested.

Enhanced Low-Temperature Response of PPy-WO3 Hybrid Nanocomposite Based Gas Sensor Deposited by Electrospinning Method For Selective and Sensitive Acetone Detection

In this paper, PPy-WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> hybrid nanocomposites with different weight percentages of WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanoparticles (5-40%wt) dispersed in polypyrrole (PPy) matrix were prepared and utilized as a new sensing material for acetone detection. PPy-WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> hybrid nanocomposite were deposited on interdigitated electrode by the electrospinning technique. WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanoparticles and PPy-WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanocomposites sensor were characterized by X-ray diffraction and field emission scanning electron microscopy, respectively. The presence of WO3 in PPy matrix was confirmed by EDAX. The resistance changes of different nanocomposites in exposure to acetone and methanol in three temperature (70 °C, 90 °C, and 110 °C) was tested and the results were compared with polypyrrole-based sensor. It was found that enhanced acetone sensing properties of PPy-WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> nanocomposite films strongly influenced by the WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> weight percentage and temperature. Comparing with PPy-based sensor, prepared PPy-WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> hybrid nanocomposite films exhibit excellent acetone vapor sensing properties at low temperature. The detection limit of PPy-WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (20%) hybrid nanocomposite sensor is about 16 times better than PPy sensor and it shows fast response (<; 5 s) toward acetone vapor at operating temperature of 90 °C. As a result, PPy-WO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> hybrid nanocomposite sensor can be a good candidate for high performance acetone detection.

In2O3–graphene nanocomposite based gas sensor for selective detection of NO2 at room temperature

In this paper, well-controlled synthesis of In2O3-reduced graphene oxide (In2O3–rGO) nanocomposites by hydrothermal method was demonstrated. The structural, morphological, chemical composition studies of the In2O3–rGO nanocomposites were carried out, evidencing a homogeneous dispersion of In2O3 on the rGO nanosheets. The sensor based on the In2O3–rGO nanocomposites exhibited excellent selectivity, high response, and relatively short response and recovery time for detection of NO2 at room temperature. The excellent sensing properties were resulted from the composition and structure advantages of the In2O3–rGO nanocomposites.

Organic-inorganic hybrid nanocomposite-based gas sensors for environmental monitoring.

Organic-inorganic hybrid nanocomposite-based gas sensors for environmental monitoring.

Phase transformation-dependent sensing performance of multi-walled carbon nanotube–alumina nanocomposite-based gas sensors

Alumina (Al2O3) exists in three different phases having different physical properties. In view of this fact, a systematic study has been carried out for the first time to investigate how its various phases influence the sensing performance of a MWCNTs–alumina nanocomposite based trace level gas sensor. A series of composite sensing film were prepared by dispersing MWCNTs in alumina solution followed by a sol–gel process, where the phase of alumina is controlled by specific temperatures set for an annealing process. The analysis revealed that porosity as well as the surface area varies from phase to phase in the composite film and it is the key factor which governs the sensing performance. Brunaur, Emmet and Teller (BET) analysis showed the significant increase in specific surface area of the composite film when boehmite (β-phase) was transformed into γ-phase. X-ray diffraction (XRD) results confirmed the presence of γ-, mixed δ- θ- and α-alumina phases when the annealing temperature of the composite film raised from room temperature to 450°C, 800°C and 1000°C respectively. Field emission scanning electron microscopy (FESEM), BET and Atomic force microscopy (AFM) techniques were employed to examine the resultant porous structure and surface area of the annealed composite films in various phases. The composite having γ-alumina phase (annealed at 450°C) was found to have maximum response, where the composite having α-alumina phase (annealed at 1000°C) had the least.

Cobalt Oxide-Tin Oxide Composite: Polymer-Assisted Deposition and Gas Sensing Properties

A cobalt oxide - tin oxide nanocomposite based gas sensor on an <TEX>$SiO_2$</TEX> substrate was fabricated. Granular thin film of tin oxide was formed by a rheotaxial growth and thermal oxidation method using dc magnetron sputtering of Sn. Nano particles of cobalt oxide were spin-coated on the tin oxide. The cobalt oxide nanoparticles were synthesized by polymer-assisted deposition method, which is a simple cost-effective versatile synthesis method for various metal oxides. The thickness of the film can be controlled over a wide range of thicknesses. The composite structures thus formed were characterized in terms of morphology and gas sensing properties for reduction gas of <TEX>$H_2$</TEX>. The composites showed a highest response of 240% at <TEX>$250^{\circ}C$</TEX> upon exposure to 4% <TEX>$H_2$</TEX>. This response is higher than those observed in pure <TEX>$SnO_2$</TEX> (90%) and <TEX>$Co_3O_4$</TEX> (70%) thin films. The improved response with the composite structure may be related to the additional formation of electrically active defects at the interfaces. The composite sensor shows a very fast response and good reproducibility.

Nanocomposites of sub-10 nm SnO2 nanoparticles and MWCNTs for detection of aldrin and DDT

The preparation of materials with size and porosity in the nanometre range is of technological importance for a wide range of sensing applications. Here, the ultrasensitive detection of Persistent Organic Pollutants (POPs), i.e., Aldrin and DDT, has been investigated using a sub-10 nm SnO2/MWCNT nanocomposite-based gas sensor. The features of prepared nanocomposites are carefully studied using SEM, TEM, and Raman spectroscopy. The sensing material shows a very attractive improved sensitivity compared to a conventional SnO2 sensor. One major advantage of this sensing material is the stable attachment between SnO2 nanoparticles and carbon nanotubes. Accordingly, facile preparation, high sensitivity, long-term stability, and nanoscale effects in this composite can create novel avenues and applications for fabricating important POPs sensors.