Toward Facile Preparation and Design of Mulberry ...

Polymer-Plastics Technology and Engineering

ISSN: 0360-2559 (Print) 1525-6111 (Online) Journal homepage: http://www.tandfonline.com/loi/lpte20

Toward Facile Preparation and Design of Mulberry-Shaped Poly(2-methylaniline)Ce2(WO4)3@CNT Nanocomposite and Its Application for Electrochemical Cd for Environment Remediation

2+

Ion Detection

Anish Khan, Aftab Aslam Parwaz Khan, Mohammed M. Rahman, Abdullah M. Asiri, Sulaiman Y. M. Alfaifi & Layla A. Taib To cite this article: Anish Khan, Aftab Aslam Parwaz Khan, Mohammed M. Rahman, Abdullah M. Asiri, Sulaiman Y. M. Alfaifi & Layla A. Taib (2017): Toward Facile Preparation and Design of Mulberry-Shaped Poly(2-methylaniline)-Ce2(WO4)3@CNT Nanocomposite and Its Application for 2+

Electrochemical Cd Ion Detection for Environment Remediation, Polymer-Plastics Technology and Engineering, DOI: 10.1080/03602559.2017.1329431 To link to this article: http://dx.doi.org/10.1080/03602559.2017.1329431

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Accepted author version posted online: 19 May 2017. Published online: 19 May 2017.

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Date: 13 July 2017, At: 03:37

POLYMER-PLASTICS TECHNOLOGY AND ENGINEERING https://doi.org/10.1080/03602559.2017.1329431

none defined

Toward Facile Preparation and Design of Mulberry-Shaped Poly(2-methylaniline)-Ce2(WO4)3@CNT Nanocomposite and Its Application for Electrochemical Cd2+ Ion Detection for Environment Remediation Anish Khana,b, Aftab Aslam Parwaz Khana,b, Mohammed M. Rahmana,b, Abdullah M. Asiria,b, Sulaiman Y. M. Alfaifia, and Layla A. Taiba a

Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah, Saudi Arabia; bChemistry Department, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia ABSTRACT

Novel hybrid material was prepared by adding slurries of poly(N-methylaniline) and cerium tungstate [Ce2(WO4)3] into a conical flask contained dispersed carbon nanotubes. It was characterized by scanning electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Electrical conductivity of poly(N-methylaniline)-Ce2 (WO4)3@carbon nanotube samples was determined using four-probe method. The thin layer of poly(N-methylaniline)-Ce2(WO4)3@carbon nanotube was fabricated onto glassy carbon electrode for a selective Cd2þ ion sensor. The calibration plot is linear (r2 ¼ 0.9917) over the large Cd2þ concentration ranges (1.0 nM–1.0 mM). The sensitivity, detection limit is ∼5.138 µA µM 1 cm 2 and ∼0.11 nM (signal-to-noise ratio, at a SNR of 3), respectively.

KEYWORDS

Cd2þ; conductivity; indicator electrode; membrane; nanomulberry composite; sol-gel

GRAPHICAL ABSTRACT

CONTACT Anish Khan [email protected] Center of Excellence for Advanced Materials Research, King Abdulaziz University, Jeddah 21589 P.O. Box 80203, Saudi Arabia. Color versions of one or more of the figures in this article can be found online at www.tandfonline.com/lpte.

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Introduction In recent years, concept of material science is top of the world research inspiration for advancement of the technology. In every engineered system, composites are valuable and necessary. Because of limitations of some physical and chemical properties such as low mechanical strength, processibility, high cost and poor flexibility, confined the use of conducting polymers in significant commercial impact. That is why, to improve the processibility of the conducting polymers, tremendous efforts have been done in the past years. To construct high density, electrochemical active energy devices, twodimensional materials are ideal. The mixing of polymer with nanoparticles has been practiced from a decades. To make good hybrid material suitable chemical and physical properties for potential applications in diverse field, it is necessary for combination of inherently organic conducting polymer with inorganic host[1–4]. Adding organic to inorganic, it has been found that subsequent composite has expanded chemical and mechanical properties with inherited one. Especially conducting polymer composite is the field that has been attracted both academicians as well as industrialists recently[5–10]. All the properties of the composite are superior as compared to polymer because of synergetic interaction between conducting polymer and inorganic filler[11–18]. Clay-reinforced resin, Bakelite, was synthesized in early 1900s and was first prepared mass produced conducting polymer nanocomposite that changed the soul of household materials. Up to early 1900s, the scientific community did not know about the nanocomposite yet when Toyota researchers made mica and nylon composite that had five-fold tensile strength and yield[19,20]. Insertion of monomer precursor into the inorganic host with high oxidation properties (FeOCl, V2O5, VOWO4) are mainly leading to the design of nanocomposites[21–24]. It was discovered by Dupre et al.[25] that insertion of sodium ion into interlayer space increases the kinetics and cyclability. Also one of the researches illustrates that the insertion of HCOOH and CH3COOH into the interlayer spaces induces the increased ionic diffusion coefficient[26] Additionally electrochemical sensors are the theme of research in the recent years[27,28]. That is why we need to enhance the membrane efficiency by modification using different functionalities that enables ion exchange simpler through membrane to the substrate[29,30]. Hetropolyacids have a great deal of interest since they have appealing molecular and electronic properties[31,32] that is why leads novel applications[33–35].

Tsai et al.[36] investigated the use of MWCNTs (multiwall carbon nanotubes) with Nafion to form a cation-exchange membrane for electroanalytical analysis of cadmium. Yi[37] reported an electrochemical method for the determination of trace levels of heavy metal based on a MWCNT film-coated glassy carbon electrode (GCE). Recent studies have reported that the addition of nanoparticles, especially metal nanoparticles, is efficient to improve the electroactivity and sensitivity of the modified electrode. Lu and Tsai[38] prepared a MWCNT alumina-coated silica nanocomposite-modified GCE for the determination of acetaminophen. Qu et al.[39] developed an electrochemical sensing platform based on magnetic loading of carbon nanotube and nano-Fe3O4 composite on electrodes. Recently, the bismuth-based chemically modified electrodes have been proven to be highly sensitive and reliable for trace analysis of Cd2þ in conjunction with anodic stripping voltammetry, due to the unique behavior of bismuth nanomodified electrodes being attributed to the formation of multicomponent alloys as well as the enhanced sensibility coming from the combination of the great properties of the nanostructured materials[40,41]. In this approach, it is an excellent cationic sensing application with poly(N-methylaniline) (P2MA)-Ce2 (WO4)3@CNT NCs/Nafion/GCE to confirm the electrical properties, which improved the development of frequent electronic and optoelectronic materials. P2MA-Ce2(WO4)3@CNT NCs/Nafion/GCE permit very sensitive transduction of the liquid/surface interactions to modify in the chemical properties. The significant prospect is observed in a variety of nanostructural orientation and morphologies, which offered different visions of modification of the toxic cadmium ions for sensing development. P2MA-Ce2(WO4)3@CNT NCs/ Nafion/GCE have been used to fabricate a simple and efficient Cd2þ sensor and assessed the chemical sensing performance selectively considering cadmium at room conditions. To the best of our knowledge, this is the first report for detection of Cd2þ with P2MA-Ce2(WO4) 3@CNT NCs/Nafion/GCE using simple, convenient, and reliable I-V technique with short response time.

Experimental Reagents and instruments 2-Methylene aniline was purchased from E. Merck, cerus nitrate from CDH while the sodium tungstate from Loba Chemie, tetradecyltrimethylammonium bromide (TTAB) from Sigma-Aldrich, ammonium persulfate (APS) from Merck was received.

POLYMER-PLASTICS TECHNOLOGY AND ENGINEERING

Monosodium phosphate, disodium phosphate, cadmium sulfate, 5% Nafion, aluminum nitrate, calcium nitrate, cobalt nitrate, chromium nitrate, copper chloride, mercuric chloride, magnesium chloride, nickel nitrate, stannous chloride, zinc chloride, arsenic chloride, silver nitrate, and all other chemicals were purchased from Sigma-Aldrich. All reagents and chemicals were of analytical grade. All these chemicals were used without any further purification. The main instrument used in the current studies was Fourier transform infrared spectroscopy (FTIR) spectrophotometer model 2000 which was from PerkinElmer, USA. Scanning electron microscope (SEM) was from JEOL JSM 6300 with link-Oxford-Isis X-ray analysis system (EDX). Deionized water was obtained from Milli-Q plus of Millipore, USA. For sonication, Elma Elmasonic 120v P180H was used. I-V technique was executed using Electrometer (Keithley, 6517A, Electrometer, USA) for measuring the current responses in two-electrode systems for target Cd2þ cations based on P2MA-Ce2 (WO4)3@CNT NCs/Nafion/GCE in buffer phase at room conditions, where fabricated GCE and Pd-wire were used as working and counter electrode, respectively. Synthesis of bulk P2MA-Ce2(WO4)3@CNTs Preparation method of bulk Ce2(WO4)3 was followed as presented in the literature. In brief, 100 mL 0.1 M sodium tungstate and 50 mL 0.1 M cerus nitrate were mixed together for 10 min in a 500-mL conical flask having a magnetic stirrer bar and then 0.1 g CNTs was mixed and stirred well with one drop of TTAB in the mixture and sonicated for nest 15 min, then APS (1 M in 1 M HCl) was added in the suspension, then N-methylaniline monomer of 10% (in 1 M HCl) was mixed dropwise containing APS and Ce2(Wo4)3 by continues stirring for 45 min. The color of the solution changed from brown to yellow and then greenish. All the intercalation compounds were stored at room temperature. This resultant composite gel was filtered and washed repeatedly by demineralized water (DMW) for until all impurities were washed away with trace of oxidant. It was than washed over P4O10 in the oven at or below 45°C. Several samples of P2MA-Ce2(WO4)3@CNT composite fiber were prepared for further studies. Electrical conductivity measurements The P2MA-Ce2(WO4)3@CNT nanocomposite sample was treated with 1 molar aqueous solution of HCl and washed with DMW to remove excess HCl. The sample material was dried completely between 40 and 50°C in an oven. Then 200 mg material was finely ground in a

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mortar pastel and pellets were made at room temperature with the help of a hydraulic pressure instrument at 25 kN pressure for 20 min. The thickness of pellet was measured by a micrometer. Four-probe electrical conductivity measurements with increasing temperatures (between 35 and 200°C) for the composite samples were performed on pressed pellets using a four in-line-probe DC electrical conductivity measuring technique. Fabrication of electrodes Phosphate buffer solution (PBS, 0.1 M, pH 7.0) is prepared by mixing 0.2 M Na2HPO4 and 0.2 M NaH2PO4 solution in 100.0 mL deionize (DI) water. GCE is made by P2MA-Ce2(WO4)3@CNT NCs with 5% ethanolic Nafion solution as a conducting agent. Subsequently it is moved into the air at room condition for 2 h until the film is completely uniform, stable, and dry. An electrochemical cell is mounted with P2MA-Ce2(WO4)3@CNT NCs/Nafion-coated GCE as a working electrode and Pd wire is used as a counter electrode. Cadmium solution (0.1 M) is diluted at different concentrations in DI water and used as a target chemical. Amount of 0.1 M PBS is kept constant in the small beaker as 5.0 mL throughout the chemical analysis. Analyte solution is prepared with different concentrations of cadmium from 1.0 nM to 0.1 M. The sensitivity is calculated from the slope of current versus concentration from the calibration plot by considering the active surface area of P2MA-Ce2 (WO4)3@CNT NCs/Nafion/GCE sensors. Keithley electrometer is used as a voltage source for I-V method in two-electrode system.

Results and discussions Preparation and characterization of P2MA-Ce2 (WO4)3@CNT The composite P2MA-Ce2(WO4)3@CNT was prepared by exfoliation intercalation sol-gel method. Ce2(WO4)3@CNT was prepared first and adsorption was done by high ultrasonication for 15 min. Each CNT was covered by Ce2(WO4)3 thick layer by physical bonding attached by hydrogen bonding provided by H2O, as it is a kind of week intermolecular force and sensitive for the applied external forces[42]. In the present case above technique was performed for the interaction of Ce2(WO4)3 by sonication later on by oxidative polymerization of N-methylaniline was done. The SEM photographs of P2MA-Ce2(WO4)3@CNT are shown in Figure 1a–c on different resolutions. As

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Figure 1. SEM Images of P2MA-Ce2(WO4)3@CNT nanocomposite at different magnification for morphology purpose.

one can observe that thick mulberry-like structures are seen clearly in the SEM images having shining appearance and at the same time some other bigger shaped structures are also seen, it may be due to the aggregation of the mulberry-like structure and it may happen because of polymer forbing. On the basis of these images, it could be said that the morphology of the

composite is entirely changed after the exfoliation of polymer with inorganic matrices and CNTs. On the basis of thermogravimetric analysis (TGA) trend (Figure 2) for the mulberry composite, only less than 8% weight loss was observed up to 150°C, the reason behind this is obviously the removal of external surface water molecules present in the composite[43]. Weight loss

Figure 2. Thermogravimetric study of P2MA-Ce2(WO4)3@CNT upto 1000°C in the nitrogen atmosphere.


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Figure 3. Fourier transform infrared studies of P2MA-Ce2(WO4)3 @CNT having different peaks.

Figure 4. X-ray studies of P2MA-Ce2(WO4)3@CNT showing different peaks in the material.

between 150 and 800°C was found about 3%, which showed the polymer part decomposition. The appearance of broad differential thermal analysis peak in the curve is explaining the exothermic phase change nature of decomposition between ∼100 and 800°C with some simultaneous side change reaction peaks. The FTIR spectra of the composite mulberry is given in Figure 3. Big intensity peaks in the FTIR spectrum of the composite at 1630 cm 1 show the presence of C=C[44,45]. The peak at 790 cm 1 is for the deformation out of plane mode for C–H. Meanwhile other peaks are also found in the same region that attributes for the ring stretching and deformation[46,47]. The FTIR spectrum of Ce2(WO4)3 shows the same number and positions at about 600–3200 cm 1. Because of polaron–polaron interaction, only ring deformation was observed between P2MA backbone and Ce2(WO4)3. It means that some of the molecules of constituents are not interact completely with the mulberry composite. The spectrum of P2MA-Ce2(WO4)3@CNT is some very small intensities of semicrystalline behavior that was measured in the X-ray diffraction (XRD) powder pattern shown in Figure 4. But one of the peaks is big at 25 for 2h that representing the nanocomposite structure of the material. Some of the peaks are also find at between angle 45 and 50° that may be for the Ce2(WO4)3 with very little intensity[48].

it beats challenges which are experienced in conventional methods of conductivity measurement (i.e., two probe), e.g., the rectifying nature of the metal–semiconductor contacts and the injection of minority carriers by one of the current-carrying contacts, which influences the capability of alternate contacts and modulates the conductance of the material, and so forth. The current–voltage data produced at increasing temperatures for the determination of electrical conductivity of the composite sample were processed for calculation of electrical conductivity using the following equation:

Electrical conducting behavior of P2MA-Ce2(WO4)3@CNTs mulberry composite Electrical conductivities of the pellets of P2MA-Ce2 (WO4)3@CNT composite samples were determined from the measurement of conductivity of the samples using four-probe method[49] of conductivity measurement for semiconductors. This is the most satisfactory method as

q ¼ q0 =G7 ðW=SÞ

ð1Þ

where q is corrected resistivity (ohm cm), q0 ¼ uncorrected resistivity (ohm cm), G7(W/S) is the correction factor used for the case of a nonconducting bottom surface, which is a function of W, the thickness of the sample under test (cm), and S, the probe spacing (cm); i.e., G7 ðW=SÞ ¼ ð2S=W Þln 2

ð2Þ

q0 ¼ V=I � 2p S; 1 r¼ q

ð3Þ ð4Þ

where I is the current (A), V is the voltage (V), and r ¼ DC electrical conductivity (s cm 1). Although the electrical conductivity measurements were done under ambient conditions, the composite samples were thoroughly dried before making the pellets and performing the electrical conductivity measurements. Hence, the contribution of protonic conductivity to the aggregate electrical conductivity because of the nearness of dampness ought to be least and need not be mulled over. The main constituents that make the composite electrically conductive are P2MA and CNTs. The

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Figure 5. Log conductivity of composite as prepared and HCl treated on increasing temperature from 30°C to 200°C.

conducting properties depend on the percolation behavior of the conducting phase. The electrical conductivity of the composite is due to oxidized PANI (polyaniline) maintained in its conductive state by PANI/Ce2(WO4)3 counter ions in excess. The variation of electrical conductivity (r) of the composite samples (prepared with 5% vol N-methylaniline concentration, with increasing temperatures (between 35 and 200°C) was investigated. On examination, it was observed that the electrical conductivities of the samples increase with the increase in temperature and the values are of the order of 10 3–10 2 S cm 1, i.e., in the borderline of conductor and semiconductor region. To determine the nature of the dependence of electrical conductivity on temperature, plots of log σ

versus 1000/T (K) are drawn (Figure 5) and they followed the Arrhenius equation similarly to other semiconductors[50]. The thermal stability of the composite material (HCl treated) in terms of DC electrical conductivity retention was studied under isothermal conditions (at 50, 80, 110, and 140°C) using 4-probe in-line DC electrical conductivity measurements at 30°C intervals. The electrical conductivity measured with respect to the time of accelerated aging is presented in Figure 5. It was observed that the electrical conductivity is quite stable at 50, 80, 110, and 140°C, which supports the fact that the DC electrical conductivity of the composites is sufficiently stable under ambient temperature conditions. The electrical conductivity decreases with time at 140°C, which may be attributed to the loss of dopant and the chemical reaction of dopant with the material. The material was also observed to be a stable material, i.e., the room temperature conductivity is negligibly affected by short-term exposure to laboratory air as is evident from Figure 6. The conductivity is higher as compared to the constituents, this may be due to the electron-donating property of the CNTs. The conductivity of the composite by self-doped polymerization (as prepared) increases by increasing temperature up to 120°C. This increase in conductivity with increase in temperature is the characteristics of “thermal activated behavior.”[51] The increase in conductivity could be due to the increase in efficiency of charge transfer between the composite chains and the dopant with increase in the temperature[52]. It is also possible that the thermal curing effects of the chain alignment of the polymeric inorganic composite leads to the increase in conjugation length and that brings about the increase in conductivity.

Figure 6. Original conductivity retention of the composite on exposure to the laboratory air.


Application: Detection of Cd2þ ions with P2MACe2(WO4)3@CNT NCs/Nafion/GCE The significant application of P2MA-Ce2(WO4)3@CNT NCs assembled onto GCE as cationic sensors (especially Cd2þ ions analyte in buffer system) has been executed for measuring and detecting target chemical. Enhancement of the P2MA-Ce2(WO4)3@CNT/Nafion/GCE as cationic sensors is in the initial stage and no other reports are available. The P2MA-Ce2(WO4)3@CNT/ Nafion/GCE sensors have advantages such as stability in air, nontoxicity, chemical inertness, electrochemical activity, simplicity to assemble, ease in fabrication, and chemosafe characteristics. As in the case of Cd2þ cation sensors, the incident of rationale is that the current response in I-V method of P2MA-Ce2(WO4)3@CNT/ Nafion/GCE considerably changes when aqueous Cd2þ ion analytes are adsorbed. The P2MA-Ce2(WO4)3 @CNT/GCE was applied for fabrication of cationic sensor, where Cd2þ ions were measured as target analyte. The fabricated surface of P2MA-Ce2(WO4)3 @CNT NCs sensor was prepared with conducting binders (5% ethanolic Nafion) onto the GCE surface. The fabricated GCE electrode was put into the oven at low temperature (35.0°C) for 2.0 h to make it dry, stable, and uniform the surface totally. The P2MA-Ce2(WO4)3 @CNT NCs/Nafion/GCE was used for the detection of Cd2þ ions in liquid phase. I-V responses were measured with P2MA-Ce2(WO4)3@CNT NC-coated thin film (in two-electrode system). In the experimental section, it was already mentioned that the Cd2þ ion-sensing protocol is using P2MA-Ce2(WO4)3@CNT NCs/Nafion/

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GCE-modified electrode. The concentration of Cd2þ ions was varied from 1.0 nM to 0.1 M by adding deionized water at different proportions. Here, Figure 7a is represented the I-V responses for bare-GCE (blue-dotted) and PANI-Ce-CNT P2MACe2(WO4)3@CNT NCs/Nafion/GCE (red-dotted) electrodes. In PBS system, the P2MA-Ce2(WO4)3@CNT NCs/Nafion/GCE electrode shows that the reaction is slightly decreased owing to surface inhibited by the presence of P2MA-Ce2(WO4)3@CNT NCs on bareGCE surface. A considerable enhancement of current value with applied potential is demonstrated with fabricated P2MA-Ce2(WO4)3@CNT NCs/Nafion/GCE in presence of target Cd2þ ion analyte, which is presented in Figure 7b. The red-dotted and green-dotted curves were indicated the response of the fabricated film before and after injecting 25.0 µL Cd2þ solution (1.0 nM) in 5.0 mL PBS solution, respectively. Significant increases of current are measured after injection of target component in regular interval. I-V responses to varying Cd2þ ion concentration on thin P2MA-Ce2(WO4)3@CNT NCs/Nafion/GCE were investigated (time delaying, 1.0 s; response time, 10 s) and presented in the Figure 7c. Analytical parameters (such as sensitivity, detection limit, linearity, and linear dynamic range, etc.) were calculated from the calibration curve (current versus concentration), which is presented in Figure 7d. A wide range of Cd2þ ion concentration was selected to study the possible detection limit (from calibration curve), which was examined in 1.0 nM to 0.1 M. The sensitivity was calculated from the calibration curve,

Figure 7. I-V responses of (a) Bare-GCE and P2MA-Ce2(WO4)3@CNT NCs/Nafion/GCE; (b) P2MA-Ce2(WO4)3@CNT NCs/Nafion/GCE (in absence and presence of Cd2þ ions; 1.0 nM); (c) Concentration variations (1.0 nM to 0.1 M) of Cd2þ ions, (d) Calibration plot of P2MA-Ce2(WO4)3@CNT NCs fabricated GCE (at þ0.5 V).

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which was close to ∼5.138 µA µM 1 cm 2. The linear dynamic range of the P2MA-Ce2(WO4)3@CNT NCs/ Nafion/GCE sensor was used from 1.0 nM to 0.1 M (linearly, r2: 0.9917), where the detection limit was calculated about 0.11 nM (ratio, 3 N/S). The P2MACe2(WO4)3@CNT NCs/Nafion/GCE was exhibited mesoporous behaviors, where the electrical resistance decreases under the presence of target Cd2þ ions in PBS phase. The film resistance was decreased gradually (increasing the resultant current) upon increasing the Cd2þ ion concentration in bulk system. Interference (for selectivity) was studied for Cd2þ ion sensor in presence of other chemicals like Cd2þ, Cu2þ, Ni2þ, Hg2þ, As3þ, Agþ, Fe2þ, Ca2þ, Al3þ, Co2þ, Mg2þ, Cr3þ, Sn2þ, Sn2þ, and Zn2þ using the P2MACe2(WO4)3@CNT NCs embedded on flat GCE (Figure 8a). The concentrations of all analytes are kept constant at 0.1 µM level in PBS system. Here, it is clearly demonstrated that the P2MA-Ce2(WO4)3@CNT NCs/ Nafion/GCE sensor is most selective toward Cd2þ ions compared with other chemicals. Cd2þ sensor probe was also tested in presence of dual or multiple cationic mixtures in similar analyte concentration (0.1 µM). It is concluded from these observations that the P2MA-Ce2 (WO4)3@CNT NCs/Nafion/GCE probe is most selective toward Cd2þ ion by obtaining the highest I-V response. The investigated results are included in the Figures S1 and S2 (Supporting information). The excellent selectivity is ascribed to the reasons that terminal functional groups have strong and stable interaction with Cd2þ resulting in the increase in the current response in I-V system. Dual or more complex matrixes were investigated in presence of various analytes with target matrix. To check the reproducibly and storage stabilities, I-V response for P2MA-Ce2(WO4)3@CNT NCs/ Nafion/GCE sensor was examined (Figure 8b). After each experiment, the fabricated P2MA-Ce2(WO4)3 @CNT NCs/Nafion/GCE substrate was washed

thoroughly with the PBS and observed that the current response was not significantly decreased. The sensitivity was retained almost same of initial sensitivity up to few days, after that, the response of the fabricated P2MA-Ce2(WO4)3@CNT NCs/Nafion/GCE electrode is gradually decreased. The Cd2þ ion sensor based on P2MA-Ce2(WO4)3@CNT NCs/Nafion/GCE is also displayed good repeatability as well as reproducibility with good stability for over week and no major changes in sensor responses are found. After a week, the cationic sensor response with P2MA-Ce2(WO4)3@CNT NCs/Nafion/GCE was slowly decreased, which may be due to the weak interaction between fabricated P2MACe2(WO4)3@CNT NCs active functional sides and Cd2þ ions. The significant result was achieved by P2MA-Ce2(WO4)3@CNT NCs/Nafion/GCE, which can be used as efficient electron mediators for the development of efficient cationic sensors. Actually the response time was around 10.0 s for the fabricated P2MA-Ce2 (WO4)3@CNT NCs/Nafion/GCE to reach the saturated steady state level. The higher sensitivity of the fabricated P2MA-Ce2(WO4)3@CNT NCs/Nafion/GCE can be attributed to the excellent absorption [assembly of NCs/Nafion/GCE] and P2MA-Ce2(Wo4)3@CNT adsorption ability [surface of P2MA-Ce2(WO4)3@CNT NCs/Nafion/GCE] and high catalytic activity of the n-P2MA-Ce2(WO4)3@CNT NCs. The estimated sensitivity of the fabricated sensor is relatively higher and detection limit is comparatively lower than previously reported chemical sensors based on other nanocomposite or nanomaterial-modified electrodes measured by I-V systems[53–57]. Due to P2MA-Ce2(WO4)3@CNT NCs/Nafion/GCE, it provides a favorable microenvironment for the Cd2þ cation detection with good quantity. The high sensitivity of P2MA-Ce2(WO4)3@CNT NCs/ Nafion/GCE provides high electron communication features which enhanced the direct electron transfer between the active sites of P2MA-Ce2(WO4)3@CNT

Figure 8. (a) Selectivity studied with various analytes using P2MA-Ce2(WO4)3@CNT NCs/Nafion/GCE. (b) Repeatibility study with P2MA-Ce2(WO4)3@CNT NCs/Nafion/GCE with fixed concentration of target analyte. Analyte concentration was taken at 0.1 µM. Potential range: 0 to þ1.5 V; Delay time: 1.0 s.


NCs and GCE. The P2MA-Ce2(WO4)3@CNT NCs/ Nafion/GCE system is demonstrated a simple and reliable approach for the detection of toxic chemicals. It is also revealed that the significant access to a large group of chemicals for wide range of environmental applications in healthcare fields.

Conclusion This article approach, preparation of a novel nanomulberry like composite, P2MA-Ce2(WO4)3@CNT with improve ion exchange capacity and thermal stability. In this study, we use simple sol-gel polymerization method for the preparation of P2MA-Ce2(WO4)3@CNT composite. This composite was characterized by various spectroscopic methods. We decided for the preparation of easily available PANI derivatives, and Ce2(WO4) 3@CNT is highly sensitive to be a guest for the PANI derivative. Composite was also used for the determination of four probe-electrical conductivity and found in the range of semiconductor. A very simple P2MACe2(WO4)3@CNT nanocomposite was applied for the detection of toxic cadmium ions using Nafion-bonded GCE electrode systems. Analytical performances of Cd2þ ions sensor using P2MA-Ce2(WO4)3@CNT NCs/ Nafion/GCE are investigated by reliable I-V method in terms of sensitivity and detection limit in short response time as well as reproducibility. This extensive research is performed in terms of preparation and characterization of P2MA-Ce2(WO4)3@CNT NCs and applied for the Cd2þ ion sensor using I-V method. The novel idea exhibits the high selectivity and fast detection for cadmium ion with the P2MA-Ce2(WO4)3@CNT NC-fabricated GCE probe. Potentially, the same concept might be applied to the creation of new sensors for monitoring other cationic ions. Hence, this approach is introduced a new route for efficient toxic heavy cationic sensor development in environmental and healthcare fields.

Acknowledgments We acknowledge the Center of Excellence for Advanced Materials Research (CEAMR) and Chemistry Department, King Abdulaziz University, Jeddah, for providing research facility.

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