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This 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.

PANI/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.

This 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.

The main purpose of this review paper is to focus on PANI/ferrite nanocomposite-based gas sensors operating at room temperature.

This work aims to prepare and characterize of protective anticorrosion phosphate-doped polyaniline (PANI) nanocomposite coatings for stainless steel (SS) in chloride solution.

PANI composite coatings were electrodeposited from aqueous sulfuric acid solution containing monomer and Al₂O₃ nanoparticles using cyclic voltammetry technique. Doping by phosphate was done by aging the coated steels for different periods (1–168 h) in phosphate solution. The polymer film composite was investigated by Fourier-transform infrared spectroscopy and scanning electron microscopy techniques. Potential-time, anodic polarization and electrochemical impedance spectroscopy were used to study the protection efficiency of the coatings.

The Al₂O₃ nanoparticles were incorporated into the deposited PANI layer but they decreased the deposition of polymer. The nanoparticles and the phosphate anions enhanced the protective PANI layer for passivation and protection of SS in the chloride solution.

The replacement of counter anions by phosphate ions improved significantly the PANI and its nanocomposite as protective coating of SS in chloride solution.

The aim of this study is to investigate the humidity-sensing of polyaniline–zinc oxide (PANI–ZnO) nanocomposites. Humidity sensor has wide applications in drug industries, food industries and domestic purpose to regulate the humidity level.

PANI–ZnO composites were prepared by in situ polymerization method, and further humidity response was tested by using a two-probe sensor setup.

PANI-ZnO composites surface were modified by using camphor sulphonic acid. DC conductivity is due to the hopping of polorans. Thermal coefficient value varies from 1.7 to 2.3. The 30 weight per cent composite shows high sensitivity among other composites.

These composites can be used only at room temperature or moderate temperature, i.e. below 280°C.

The composites are prepared in tetrapod shape that has a large surface area and more stability. Therefore, these materials would be the replacement for conventional materials.

These sensors have many applications in food and drug preservation, domestic purposes, etc.

This work is original, and not being considered for publication elsewhere. In this work, the charge transport properties were evaluated based on the resistivity change when samples were exposed to humidity.

This study aims to investigate the ammonia-sensing performance of polyaniline/polyethylene oxide (PANI/PEO) and polyaniline/polyethylene oxide/zinc oxide (PANI/PEO-ZnO) composite nanofibers at room temperature.

Gas sensor structures were fabricated using microfabrication techniques. First, onto the SiO₂ wafer, gold electrodes were fabricated via thermal evaporation. PANI/PEO nanofibers were produced by the electrospinning method, and the ZnO layer was deposited by using radio frequency (RF) magnetron sputtering on the electrospun nanofibers as a sensing layer. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffraction were performed to characterize the analysis of nanofibers. After all, gas sensing analysis of PANI/PEO and PANI/PEO/ZnO nanofibers was conducted using an experimental setup at room temperature conditions. Furthermore, the impact of humidity (17%–90% RH) on the sensor resistance was actively investigated.

FTIR analysis confirms the presence of functional groups of PANI, PEO and ZnO in nanofiber structure. SEM micrographs demonstrate beads-free, thinner and smooth nanofibers with ZnO contribution to electrospun PANI/PEO nanofibers. Moreover, according to the gas sensing results, the PANI/PEO nanofibers exhibit 115 s and 457 s response time and recovery time, respectively. However, the PANI/PEO/ZnO nanofibers exhibit 245 s and 153 s response time and recovery time, respectively. PANI/PEO/MOx composite nanofibers ensure stability to the NH₃ gas owing to the high surface/volume ratio and decrease in the humidity dependence of gas sensors, making gas sensors more stable to the environment.

In this study, ZnO was deposited via RF magnetron sputtering techniques on PANI/PEO nanofibers as a different approach instead of in situ polymerization to investigate and enhance the sensor response and recovery time of the PANI/PEO/ZnO and PANI/PEO composite nanofibers to ammonia. These results indicated that ZnO can enhance the sensing properties of conductive polymer-based resistive sensors.

Polypyrrole (PPy) and PPy/metal oxide nanocomposites were synthesized by oxidative polymerization process, and its corrosion protection ability was studied by immersion test and electrochemical corrosion studies in 1 per cent HCl and 3.5 per cent NaCl solution.

The prepared composites were loaded in acrylic resin and subsequently coated on a mild steel surface. The characterization of the polymer composites using FT-IR, UV-vis, XRD and FE-SEM with EDS analysis confirmed the interaction between PPy and metal oxide nanoparticles. The PPy nanoparticles were less protected on the mild steel, but the nanocomposite coating with metal oxide nanoparticles dramatically increased the corrosion resistance.

According to the corrosion protection ability of the coating, it was demonstrated that the acrylic resin coating composed of PPy/metal oxide nanocomposites was highly efficient in protecting the mild steel compared to the PPy nanoparticles. The highest protection efficiency was obtained by PPy/TiO2 nanocomposites with acrylic resin coating.

To the best of the authors’ knowledge, this paper consists of original, unpublished work which is not under consideration for publication elsewhere and that all the co-authors have approved the contents of this manuscript and submission.

This paper aims to investigation of processes for Pb²⁺ elimination from water/wastewater as a significant public health issue in many parts of world. The removal of Pb²⁺ ions by various nanocomposites has been explained from water/wastewaters. ZnO-based nanocomposites, as eco-friendly nanoparticles with unique physicochemical properties, have received increased attention to remove Pb²⁺ ions from water/wastewaters.

In this review, different ZnO-based nanocomposites were reviewed for their application in the removal of Pb²⁺ ions from the aqueous solution, typically for wastewater treatment using methodology, such as adsorption. This review focused on the ZnO-based nanocomposites for removing Pb²⁺ ions from water and wastewaters systems.

The ZnO-based nanocomposite was prepared by different methods, such as electrospinning, hydrothermal/alkali hydrothermal, direct precipitation and polymerization. Depending on the preparation method, various types of ZnO-based nanocomposites like ZnO-metal (Cu/ZnO, ZnO/ZnS, ZnO/Fe), ZnO-nonmetal (PVA/ZnO, Talc/ZnO) and ZnO-metal/nonmetal (ZnO/Na-Y zeolite) were obtained with different morphologies. The effects of operational parameters and adsorption mechanisms were discussed in the review.

The findings may be greatly useful in the application of the ZnO-based nanocomposite in the fields of organic and inorganic pollutants adsorption.

The present study is novel, because it investigated the morphological and structural properties of the synthesized ZnO-based nanocomposite using different methods and studied the capability of green-synthesized ZnO-based nanocomposite to remove Pb²⁺ ions as water contaminants.

The current review can be used for the development of environmental pollution control measures.

This paper reviews the rapidly developing field of nanocomposite technology.

The purpose of this study is to investigate the presence of silicon dioxide (SiO₂) nanoparticles in o-toluidine monomer as a reactant and ammonium persulfate as an oxidant to obtain the poly(o-toluidine) (POT)/SiO₂ nanocomposites by oxidative polymerization method.

Fourier transformation infrared spectroscopy, X-ray diffraction and field emission scanning electron microscopy were used to characterize the structural properties of the composite. POT/SiO₂ nanocomposites were mixed with acrylic resin through a solution mixing method and the composites were coated onto the surface of mild steel. Electrochemical measurements were used to determine the corrosion protection efficiency (P.E.%) of polymer composite coatings using 3.5% NaCl solution as corrosion environment.

The results obtained reveals that the POT/SiO₂/acrylic resin composite coatings have got higher corrosion P.E.% than that of POT/acrylic resin coatings.

The formation of uniformly passive layer in the POT/SiO₂ composite was used to enhance the P.E.% on mild steel surface. The POT/SiO₂/acrylic resin nanocomposites showed effective anticorrosive behavior on mild steel in 3.5% NaCl solution.

Regular monitoring of bacteria, especially Escherichia coli, in wastewater is crucial to ensure the maintenance of public health. Amperometric detection proves to be a fast, sensitive and economically viable solution for E. coli enumeration. This paper reported a prototype amperometric sensor based on PANI-ZnO-NiO nanocomposite thin films prepared by sol–gel method and irradiated with gamma ray. The purpose of this study is to investigate the sensor performance of PANI-ZnO-NiO nanocomposite thin films to detect E. coli in water.

The films were varied with different compositions of ZnO and NiO by using the formula PANI-(ZnO)_1-x-(NiO)_x, with x = 0.2, 0.4, 0.6 and 0.8. PANI-ZnO-NiO nanocomposite thin films were characterized by using X-ray diffraction (XRD) and atomic force microscopy (AFM) to study the crystallinity and surface morphology of the films. The sensor performance was conducted using the current–voltage (I-V) measurement by testing the films in clean water and E. coli solution.

XRD diffractograms show the peaks of ZnO (1 0 0) and NiO (1 0 2). AFM analysis shows the surface roughness, and the grain size of PANI-ZnO-NiO thin films decreases when the concentration ratios of NiO increased. I-V curves show the difference in current flow, where the current in E. coli solution is higher than the clean water.

PANI-(ZnO)_1-x-(NiO)_x nanocomposite thin film with the highest concentration of ZnO performed the highest sensitivity among the other concentrations, which can be used to indicate the presence of E. coli bacteria in water.

Inorganic oxide addition can be synergistically beneficial in organic coatings if it can impart anti-corrosion properties and also act as an additive to enhance physical and/or chemical properties. The aim of this study was to evaluate the anti-corrosion benefits of nano nickel zinc ferrite (NZF) in the polymer film.

The time-dependent anti-corrosion ability of NZF (0.12-1.0 per cent w/w NZF/binder), applied on API 5L X-80 carbon steel, was characterized by electrochemical techniques such as open circuit potential, electrochemical impedance spectroscopy, linear polarization resistance and potentiodynamic. Characterization of corrosion layer was done by removing coatings after 216 h of immersion in 3.5 per cent w/v NaCl. Optical microscopy, field emission scanning electron microscopy and X-ray diffraction techniques were used to characterize the corroded surface.

Corrosion measurements confirm the electrochemical activity by metallic cations on the steel surface during corrosion process which results in improvement of anti-corrosion properties of steel. Moreover, surface techniques show compact corrosion layer coatings and presence of different metallic oxide phases for nanocomposite coatings.

The suggested protection mechanism was explained by the leaching and precipitation of metallic ion on the corroded surface which in turn slowed down the corrosion activity. Furthermore, improvement in barrier properties of rubber-based coatings was confirmed by the enhanced pore resistance. This work indicates that along with a wide range of applications of NZF, anti-corrosion properties can be taken as an addition.

The purpose of this paper was to research the influence of polyaniline/montmorillonite (PANI/OMMT) composite powder content on the corrosion protection of epoxy (EP) coating.

The polyaniline/montmorillonite/epoxy (PANI/OMMT/EP) coatings containing different contents of PANI/OMMT composite powder were prepared on steel. The corrosion protection performances of PANI/OMMT/EP coatings in 3.5 per cent NaCl solutions were investigated by electrochemical impedance spectroscopy. The barrier property of coatings was examined using water absorption analysis. The structure and crosslink density of coatings were examined using scanning electron microscopy and differential scanning calorimetry, respectively.

The PANI/OMMT composite powder could enhance the barrier properties of the EP coating and reduce the corrosion rate of the steel beneath the coating. The coating showed the best corrosion protection performance when 3 per cent PANI/OMMT powder was added to the coating.

The research clarified the influence of PANI/OMMT content on the corrosion protection of coating from two aspects: one is the barrier performance of the coating; the other is the corrosion inhibitors for metal substrate.