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The use of humidity sensors in environmental monitoring application such as the creation of safe, comfortable, and cost-effective environment has been the subject of interest right from the beginning. The current study is focused on the organic–inorganic composite material as humidity sensor. Polyaniline (PANI) and its composites with copper oxide (PANI-CuO) doped with sulfuric acid (H2SO4) are prepared by the in-situ polymerization method. Structural features are investigated by different techniques including Ultraviolet/Visible (UV/Vis), X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric analysis (TGA), and Scanning Electronic Microscopy (SEM). The structural characterizations confirm the emeraldine salt (ES) form of the PANI doped with H2SO4. The conductivity measurements are recorded by using a four-probe conductivity meter, which indicates higher conductivity of the composites as compared to neat PANI. The cyclic voltammetry of the synthesized PANI and its composites with CuO is performed to study the redox properties. The humidity sensing properties in terms of measurement of capacitance are studied by using an LCR meter, which show the linear increase in the capacitance of the prepared composites. The sensor shows fast response and recovery with high stability.

Eco-friendly inhibitors have attracted considerable interest due to the increasing environmental issues caused by the extensive use of hazardous corrosion inhibitors. In this paper, environmentally friendly PDG-g-PANI/Al2O3 composites were prepared by a low-cost inverse emulsion polymerization for corrosion inhibition of mild steel (MS) and stainless steel (SS). The PDG-g-PANI/Al2O3 composites were characterized by different techniques such as X-ray diffraction (XRD), UV/Vis, and FTIR spectroscopy. XRD measurements show that the PDG-g-PANI/Al2O3 composite is mostly amorphous and scanning electron micrographs (SEM) reveal a uniform distribution of Al2O3 on the surface of the PDG-g-PANI matrix. The composite was applied as a corrosion inhibitor on mild steel (MS) and stainless steel (SS), and its efficiency was investigated by potentiodynamic polarization measurement in a 3.5% NaCl and 1 M H2SO4 solution. Corrosion kinetic parameters obtained from Tafel evaluation show that the PDG-g-PANI/Al2O3 composites protect the surface of MS and SS with inhibition efficiencies of 92.3% and 51.9% in 3.5% NaCl solution, which is notably higher than those obtained with untreated epoxy resin (89.3% and 99.5%). In particular, the mixture of epoxy/PDG-g-PANI/Al2O3 shows the best performance with an inhibition efficiency up to 99.9% on MS and SS. An equivalent good inhibition efficiency was obtained for the composite for 1M H2SO4. Analysis of activation energy, formation enthalpy, and entropy values suggest that the epoxy/PDG-g-PANI/Al2O3 coating is thermodynamically favorable for corrosion protection of MS and exhibits long-lasting stability.

Transition-metal sulfides with nanostructured features grown on a conductive substrate have been suggested as a promising alternative to precious metal-based electrocatalysts for energy conversion ...

A polybenzopyrrole@nickel oxide (Pbp@NiO) nanocomposite was synthesized by an oxidative chemical one-pot method and tested as an active material for hybrid electrodes in an electrochemical supercapattery device. The as-prepared composite material exhibits a desirable 3D cross-linked nanostructured morphology and a synergistic effect between the polymer and metal oxide, which improved both physical properties and electrochemical performance. The unprocessed material was characterized by X-ray diffraction, FTIR and UV–Vis spectroscopy, scanning electron microscopy/energy disperse X-ray analysis, and thermogravimetry. The nanocomposite material was deposited without a binder on gold current collectors and investigated for electrochemical behavior and performance in a symmetrical two- and three-electrode cell setup. A high specific capacity of up to 105 C g−1 was obtained for the Pbp@NiO-based electrodes with a gravimetric energy density of 17.5 Wh kg−1, a power density of 1925 W kg−1, and excellent stability over 10,000 cycles.

Due to the environmental and production problems of emulsion, it is important to efficiently separate oil-water emulsion to meet the refinery requirement and clean up oil spills. Synthesis of a universal demulsifier is not an easy task because the physical properties of crude oil vary, which makes its characterization and demulsification procedure difficult. To overcome this problem, hydrophilic and magnetically recoverable poly (methyl methacrylate-acrylic acid)/iron oxide magnetic composite nanoparticles ((P(MMA-AA)/Fe

The development of biocompatible, cost effective and more efficient materials to control or inhibit the growth of microorganisms in necessary to fight against resistant microbes. Here, we demonstrate the synthesis of nickel oxide-incorporated polyaniline/polyvinyl alcohol (PANI/PVA/NiOx) composite material by single-step polymerization and its application as antibacterial agent. The composite films were characterized using UV-visible spectroscopy (UV-Vis), Thermogravimetric analysis (TGA), Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). UV-Vis spectra revealed the enhancement in absorption properties of PANI/PVA/NiOx with optimum 5% incorporation of NiOx. TGA results indicated slightly enhanced thermal stability of the PANI/PVA/NiOx composite film as compared to PANI/PVA. FTIR spectra for composites revealed the existence of NiOx in polymers. However the crystallinity of PANI/PVA was not much affected. The antibacterial activity of the prepared composites was examined against four different gram negative bacteria, Salmonella, Shigella, Pseudomonas and Escherichia coli (E. coli). The composite exhibited excellent antibacterial activity against E. coli, Salmonella and Shigella while pseudomonas showed some resistance. Based on the results, PANI/PVA/ NiOx (5%) composite showed the highest activity against the tested bacterial strains, thus showing its potential to be used as an effective antibacterial agent.

Reduced graphene oxide/poly(pyrrol-co-thiophene) (RGO/COP), prepared by facile in-situ oxidative copolymerization, is reported as a new hybrid composite material with improved supercapacitance performance as compared to the respective homopolymers and their composites with RGO. The as-prepared hybrid materials were characterized with ultraviolet&ndash, visible (UV&ndash, Vis) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. The electrochemical behavior and energy storage properties of the materials were tested by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrostatic impedance spectroscopy (EIS) techniques in 0.5 M H2SO4. The specific capacitance (Csp) for RGO/COP calculated from the CV curve was 467 F/g at a scan rate of 10 mV/s. While the Csp calculated from the GCD was 417 F/g at a current density of 0.81 A/g. The energy density calculated was 86.4 Wh/kg with a power density of 630 W/kg. The hybrid composite exhibits good cyclic stability with 65% capacitance retention after 1000 cycles at a scan rate of 100 mV/s. The present work brings a significance development of RGO/COP composites to the electrode materials for pseudocapacitive application.

Reduced graphene oxide/poly(pyrrol-co-thiophene) (RGO/COP), prepared by facile in-situ oxidative copolymerization, is reported as a new hybrid composite material with improved supercapacitance performance as compared to the respective homopolymers and their composites with RGO. The as-prepared hybrid materials were characterized with ultraviolet–visible (UV–Vis) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. The electrochemical behavior and energy storage properties of the materials were tested by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD), and electrostatic impedance spectroscopy (EIS) techniques in 0.5 M H2SO4. The specific capacitance (Csp) for RGO/COP calculated from the CV curve was 467 F/g at a scan rate of 10 mV/s. While the Csp calculated from the GCD was 417 F/g at a current density of 0.81 A/g. The energy density calculated was 86.4 Wh/kg with a power density of 630 W/kg. The hybrid composite exhibits good cyclic stability with 65% capacitance retention after 1000 cycles at a scan rate of 100 mV/s. The present work brings a significance development of RGO/COP composites to the electrode materials for pseudocapacitive application.

We present an efficient, highly selective and binder free non-enzymatic glucose sensor based on polyaniline@copper-nickel (PANI@CuNi) nanocomposite. PANI@CuNi nanocomposites with different loading ratio of nanoparticles (1: 025, 1: 0.33, 1: 05 and 1: 1) were prepared by mixing solution of PANI, synthesized through inverse emulsion polymerization method, and CuNi nanoparticles, synthesized through polyol process. The as prepared PANI@CuNi nanocomposites were coated on glassy carbon substrate without binder for non-enzymatic glucose sensing. A considerable increase in the active surface area of the electrode occurred after coating of this material. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and chronoamperometry demonstrated that PANI@CuNi nanocomposite with 1: 0.5 ratio could be a good choice to be used as electrode material for non-enzymatic glucose sensing. The PANI@CuNi modified electrode exhibited high sensitivity (1030 μA mM−1 cm−2), good lower detection limit (0.2 μM) and a linear range of 5.6 mM (R2 = 0.992) with additional advantage of excellent selectivity, high stability and effective detection in real blood samples.

For the first time, chloroform and 2-butanol were used as solvent systems for the preparation of ZrO2–PANI and CeO2–PANI composites. Solubility of the synthesized composites was studied in chloroform, N-methyl-2-pyrrolidinone (NMP), and in mixture of toluene + 2-propanol (2:1). XRD and cyclic voltammetry data showed that the ZrO2–PANI and CeO2–PANI composites possess both crystalline and amorphous domains indicating some sort of conductivity. TGA results showed that ZrO2–PANI composite have a better thermal stability than pure PANI; however, CeO2–PANI composite has lower thermal stability than pure PANI. The conjugated unsaturated structure of PANI is responsible for the enhanced photocatalytic properties of ZrO2–PANI and CeO2–PANI. Photocatalytic results showed that, at photolysis time of 60 min, rhodamine B (RhB) dye was degraded up to 34 and 35% by ZrO2–PANI and CeO2–PANI, respectively. The degradation products of RhB were quantified by LC–MS and GC–MS, and accordingly, a detailed pathway was proposed.

The behaviour of gold electrode modified with polyaniline/graphene oxide composites (PGO) was studied for electrochemical and charge storage properties in aqueous acidic media. The surface of gold electrode was modified with aqueous slurry of PGO by using Carboxymethyl cellulose (CMC) as binder. The intercalation of polyaniline in the GO layers, synthesized by in situ polymerization was confirmed by scanning electron microscopy (SEM). The electrochemical behaviour and charge storing properties were investigated using cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS). A high specific capacitance of 1721 F g−1 was obtained for PGO with 69.8% retention of capacitance even after 1000 voltammetric cycles in the potential range of 0–0.9 V at 20 mV s−1. EIS indicated low charge transfer resistance (Rct) and solution resistance (Rs) values of 0.51 Ω and 0.07 Ω, respectively. This good performance of PGO coated electrode is attributed to the use of CMC binder which generate a high electrode/ electrolyte contact area and short path lengths for electronic transport and electrolyte ion.

This study reports the one-step in situ synthesis of a hematite–tungsten oxide (α-Fe2O3–WO3) composite on fluorine-doped tin oxide substrate via a simple hydrothermal method. Scanning electron microscopy images indicated that the addition of tungsten (W) precursor into the reaction mixture altered the surface morphology from nanorods to nanospindles. Energy-dispersive x-ray spectroscopy analysis confirmed the presence of W content in the composite. From the ultraviolet–visible spectrum of α-Fe2O3–WO3, it was observed that absorption began at ∼ 600 nm which corresponded to the bandgap energy of ∼ 2.01 eV. The α-Fe2O3–WO3 electrode demonstrated superior performance, with water oxidation photocurrent density of 0.80 mA/cm2 (at 1.6 V vs. reversible hydrogen electrode under standard illumination conditions; AM 1.5G, 100 mW/cm2) which is 2.4 times higher than α-Fe2O3 (0.34 mA/cm2). This enhanced water oxidation performance can be attributed to the better charge separation properties in addition to the large interfacial area of small-sized particles present in the α-Fe2O3–WO3 nanocomposite film.

We report the utilization of polyaniline (PANI), co-doped with DBSA and sulfuric acid (PANI/DBSA/H2SO4), as a novel and promising electrode material for aqueous supercapacitors. The co-doped PANI/DBSA/H2SO4 salts were characterized by in situ conductance measurements, in situ UV–vis spectroelectrochemistry, cyclic voltammetry (CV) and UV–vis NIR spectroscopy. Elemental analysis of the synthesized PANI salt revealed its remarkable (50%) doping level while intrinsic viscosity indicated its highest molecular weight. Furthermore, PANI salt with best set of properties was tested for application in supercapacitors. For this purpose a systematic study was carried out in selected acidic electrolytes (HClO4, H2SO4, and H3PO4) by employing CV, Galvanostatic Charge-Discharge (GCD), and Electrochemical Impedance Spectroscopy (EIS). Different parameters such as applied potential limits, current density as well as type and concentration of electrolytes were optimized. The kinetics of the electrochemical degradation as well as specific capacitance of the PANI film was determined in the above mentioned electrolytes, which helped in choosing the appropriate conditions and electrolyte for the maximum exploitation of this material for supercapacitor. All the results suggest 0.5 M HClO4, along with other optimized parameters, as the most appropriate electrolyte solution. The PANI film showed electroactivity even after 6000 cycles applied through cyclic voltammetry. A capacitance retention of 57% after 1000 charge discharge cycles was observed in this electrolyte. Similarly, the film exhibited a specific capacitance value of 516 F g−1 with a relatively high energy density and power density of 34 W h kg−1 and 11.51 K W kg−1, respectively. As compared with the literature, the prepared polymer can be used as an electrode material for supercapacitors.

Photoelectrochemical (PEC) based immunosensors are important bioanalytical tools for the label free detection of hepatitis C (HCV) antibodies as the photocurrent in the external circuit which is the response signal is not effected intrinsically by the excitation stimulus of light. Therefore, in this article, the facile development of label-free photoelectrochemical (PEC) immunosensor for the detection of hepatitis C (HCV) anticore mAbs 19D9D6 (1 NLB monoclonal antibodies) is reported. The photoactive ZnO was applied as matrix which was further doped with Sn in order to enhance the PEC properties for constructing the PEC immunosensor through immobilization of truncated recombinant HCV core nucleocapsid polypeptide antigen (residues 13–40) corresponding to immunodominant region as biolayer for immunospecific interaction. Morphological analysis was carried out using Scanning electron microscopy (SEM). X-ray diffraction (XRD) was performed for the structural analysis of the pure ZnO and Sn doped ZnO matrix. Optical properties were evaluated using the UV–visible spectroscopy that was further used to attain Mott–Schottky plot, Tauc plot and Urbach plot that explained in detail the PEC enhancement in terms of the energy band gap (Eg). The results depicted a significant red shift in the light absorption by Sn-doped ZnO electrode due to band shrinkage. Defect sites induced due to doping also hinders the photo-generated electron-hole pair recombination. Consequently, the photocurrent density of Sn doped ZnO electrode increased approximately two fold when subjected to illumination. The insulative layer formation at the semi-conductor solution junction resulted in a significant decrease in the photocurrent density that was successfully applied to monitor the immunospecific interaction between the antigen and antibody. PEC immunosensor has the linear detection range from 0.006 to 60 ng mL-1 anticore mAbs 19D9D6 (1 NLB monoclonal antibodies) concentration with 0.53 pg mL-1 (S/N = 3) detection limit as a function of photocurrent decrement which is low for enhancing the sensitivity to effectively measure the antibody. The as prepared PEC immunosensor displayed high selectivity and stability due to which it can be rendered as capable photoelectrochemical scheme for protein detection in the point of care medical diagnosis.

The eco-friendly and cost-efficient synthesis of polyaniline (PANI) is one of the perplexing tasks in the research horizons of conducting polymers while keeping the desired properties unaffected. The present work reports an eco-friendly and comparably cost-efficient pathway for the synthesis of corrosion-resistant, thermally stable, and highly soluble PANI salt using coconut oil as a novel dispersion medium. The PANI salt was optimized by varying the reaction parameters, such as concentration of monomer, oxidant, surfactant, and solvent. The UV/Visible spectra indicated absorption peaks in the range of 344–353, 424–433, and 740–779 nm. The FTIR analysis of PANI salt reveals the stretching of the benzenoid and quinoid rings at 1460 and 1559 nm respectively. X-ray diffraction shows peaks on 2Ө at 19° and 25° which are the characteristic peaks of PANI. PANI salt was found to be soluble in several organic solvents such as 2-propanol, n-Methylpyrolidinone (NMP), and highly soluble in chloroform and Dimethyl sulfoxide (DMSO) up to 7.6 and 6.9% respectively. SEM images and TGA analysis of PANI confirmed the porous morphology like cauliflower and quite thermally stable up to 538 °C respectively. The layer of synthesized PANI shows remarkable corrosion inhibiting behavior on the surface of mild steel which reduces the rate of corrosion up to 82%. Hence, boost up the global economy.

The interaction of colloidal species is prominently governed by their surface properties. The adsorption of charged proteins at the surface of the Polyaniline nanotubes (PN) results in the electrostatic interactions which can be moulded by controlling the surrounding zeta potential. The zeta potential of PN as a function of pH, charge density and ionic strength was determined and the results are duly explained by 1-pK model and Grahame model as empirical data fits well to these models. Similarly, the surface charge and zeta potential of the 1 NLB antibodies were also determined which later on explained the adsorption of 1 NLB antibodies on PN in aqueous media. The isoelectric point (IEP) of PN showed variation as function of surface coverage by adsorbed 1 NLB antibody mass. These results were utilized to fabricate a label-free impedimetric immunosensor aimed at the detection of hepatitis C (HCV) 1 NLB monoclonal antibodies (anticore mAbs 19D9D6). The bioactive interfacial layer was attained by the immobilization of 1 NLB monoclonal antibodies at the PN which were later on spin coated on ITO substrate for fabricating impedimetric immunosensor. The impedimetric immunosensor shows linear response range of 01 ng mL−1 to 200 ng mL−1 of HCV core antigen concentration with detection limit of 0.02 ng mL−1 (3σ/S). The charge transfer resistance change (Rct) showed an absence of the prominent change depicting the stability of the impedimetric immunosensor whereas the sensitivity of sensor was found to be 12.215 Ω mL ng−1.

Catalytic oxidation of organic volatile compounds (VOCs) is considered superior to conventional methods because very low concentration of VOCs can also be oxidized and removed at low temperatures without consumption of addditional fuel and introduction of NOx compounds into the environment. Herein, the synthesis of MnO2 nanoparticles on bentonite (Bent) support in the presence of CuO for catalytic oxidation of m-xylene is reported. The synthesized materials were analyzed with FT-IR, XRD, and TEM analysis for structural and morphological characterization. XRD and TEM analysis indicated the formation of δ-MnO2 with sheet structure on Bent surface. Temperature-programmed reduction (H2-TPR) of hydrogen was used to investigate catalytic performance of δ-MnO2 towards oxidation of m-xylene at different temperatures. The catalytic activity was strongly dependent on the δ-MnO2 content in the synthesized material. 100 % oxidation of m-xylene with observed with 10% Mn content at temperature below than 325 oC. Intersetingly introduction of CuO greatly improved the catalytic activity of Mn-Bent materials. The presence of Cu in Mn-Bent has greatly reduced the temperature for complete oxidation of m-xylene. In this case100% conversion of m-xylene was observed at 250 oC.

Polyaniline and zinc oxide nanoparticles were successfully synthesized through inverse emulsion polymerization method and hydrothermal method respectively. For ammonia gas sensing using LCR meter thin film of the composite was fabricated by using spin coater. The functional groups, morphological, optical, structural properties of zinc oxide nanoparticles, polyaniline (emeraldine salt) and composites were investigated by FTIR spectroscopy, Scanning electron microscopy (SEM), UV- Visible spectroscopy and XRD analysis. The formation of ZnO particles of different shapes in the nano range was confirmed from UV-visible and XRD analysis. UV visible spectrum shows the formation of nanoparticles of ZnO. Thin film of Polyaniline/zinc oxide composites were deposited on the surface of copper interdigitated electrode. The fabricated device showed sensitivity to ammonia gas (NH3) at ambient temperature (300 K). It was observed that the resistance is decreases with the increase of volume of ammonia gas. The electrical properties were also investigated of the different concentration of nanocomposite. Optimum sensing response was achieved with PANI in the presence of 50 wt% ZnO nanoparticles. It may also be inferred from this study that the solution mixing process to produce composites has promising future if handled carefully.

A thin film of poly(o-aminophenol), POAP, has been used as a sensor for various types of toxic and nontoxic gases: a gateway between the digital and physical worlds. We have carried out a systematic mechanistic investigation of POAP as a humidity sensor; how does it sense different gases? POAP has several convenient features such as flexibility, transparency, and suitability for large-scale manufacturing. With an appropriate theoretical method, molecular oligomers of POAP, NH and O functional groups and the perpendicular side of the polymeric body, are considered as attacking sites for humidity sensing. It is found that the NH position of the polymer acts as an electrophilic center: able to accept electronic cloud density and energetically more favorable compared to the O site. The O site acts as a nucleophilic center and donates electronic cloud density toward H2Ovap. In conclusion, only these two sites are involved in the sensing process which leads to strong intermolecular hydrogen bonding, having a 1.96 Å bond distance and ΔE ∼ −35 kcal mol–1. The results suggest that the sensitivity of the sensor improved with the oxidization state of POAP.

Ion diffusion rate and contact surface area of conducting polymers increased by composite formation with nanometric-size materials make them promising materials in the fabrication of energy storage devices. In this work, electronically conducting polyaniline and manganese oxide (PANI/MnO2) nanofibrous composites were electrochemically co-deposited on stainless steel from binder-free electrolyte solution. Structural characterization and morphological characterization of the materials were performed with Fourier-transformed infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). SEM images show fibrous micro/nano-architecture of the composites with cluster networking structure having 200–500 nm length and 100–200 nm diameter. Electrochemical and energy storage properties of the as-synthesized materials were investigated with cyclic voltammetry (CV), galvanostatic charge discharge curves(GCDC), and potentiostatic electrochemical impedance spectroscopy (PEIS) without any binders. Electrochemical measurements as well as galvanostatic charge discharge curves at 1 mA constant current have shown maximum specific capacitance of 149 F/g for the composite prepared with 0.15 M MnSO4 in the co-deposition bath. The composites retain 67% specific capacitance even after 400 cycles, indicating the stability of synthesized composite. PEIS confirms the pseudocapacitive nature of the synthesized composites.

This paper reports on the synthesis and characterization of poly(2-methylaniline), PmA, a derivative of a very fascinating electronically conducting polymer polyaniline. PmA was synthesized in its salt form by one pot emulsion polymerization route using DBSA and sulfuric acid as co-dopants. Fourier transform infrared spectroscopy and Ultraviolet visible spectroscopic analysis confirmed formation of conducting emeraldine salt form of PmA. These PmA salts showed good redox reversibility and high purity. Thermogravimetric analysis revealed very good thermal stability up to 520 °C which is the highest reported thermal stability for PmA so far. Potentiodynamic polarization measurements clearly revealed that the PmA acts as corrosion protective coating on stainless steel with the protection efficiency of 55.59%.