Corrosion protection of aluminum alloy by epoxy coatings containing polyaniline modified graphene additives

In the study, polyaniline/reduced‐graphene oxide (PANI‐RGO) composites, fabricated by loading 2, 5, and 8wt% graphene oxide, was prepared by in‐situ emulsion polymerization and reduction. They are characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, and scanning electron microscopy. Epoxy coatings adding PANI and PANI‐RGO composites were coated on the surface of AA5083 Al alloy. The anticorrosion performance of the coatings is measured by electrochemical impedance spectroscopy and potentiodynamic polarization curve in 3.5wt% NaCl solution. The results demonstrate that the epoxy/PANI‐RGO coating exhibits a better protection against AA5083 alloy corrosion compared with the epoxy/PANI coating. Enhancement of the passivation performance of PANI was obtained by the addition of RGO into epoxy/PANI coating system.     

Sonochemical synthesis of PANI-BiVO4-GO semiconductor nanocomposite highly efficient visible-light photocatalytic performance

Abstract

Polyaniline/Bismuth Vanadate/Graphene Oxide (PANI-BiVO₄-GO) or BGPA composite was prepared by sonochemical deposition of bismuth vanadate-graphene oxide (BiVO₄) nanoparticles on the surface of polyaniline (PANI). The best photocatalytic degradation performance was obtained by 5wt% BGPA composites for MB, RhB, and SO dyes, which is approximately 4 times higher than that of 1% BGPA. Meanwhile, the photocatalytic stability of BiVO₄ was significantly improved by introducing PANI into the PANI-BiVO₄-GO composite. The dramatic promotion of the photocatalytic degradation performance and the photocatalytic stability can be attributed to the formation of a heterojunction free electron between PANI and BiVO₄-GO. The existence of those extra free electrons can dramatically enhance the efficiency of the photogenerated electrons, which accelerate the transfer of photogenerated holes from BiVO₄-GO to PANI, and therefore inhibit the self-oxidation of BiVO₄.     

Tungsten Nitride,Well‐Dispersed on Porous Carbon: Remarkable Catalyst,Produced without Addition of Ammonia,for the Oxidative Desulfurization of Liquid Fuel

Polyanilines (pANIs), loaded with phosphotungstic acid (PTA), are pyrolyzed to get WO₃ or W₂N (≈6 and ≈7 nm, respectively), which is well‐dispersed on pANI‐derived porous carbons (pDCs). Depending on the pyrolysis temperature, WO₃/pDC, W₂N/pDC, or W₂N‐W/pDCs could be obtained selectively. pANI acts as both the precursor of pDC and the nitrogen source for the nitridation of WO₃ into W₂N during the pyrolysis. Importantly, W₂N could be obtained from the pyrolysis without ammonia feeding. The obtained W₂N/pDC is applied as a heterogeneous catalyst for the oxidative desulfurization (ODS) of liquid fuel for the first time, and the results are compared with WO₃/pDC and WO₃/ZrO₂. The W₂N/pDC is very efficient in ODS with remarkable performance compared with WO₃/pDC or WO₃/ZrO₂, which is applied as a representative ODS catalyst. For example, W₂N/pDC shows around 3.4 and 2.7 times of kinetic constant and turnover frequency (based on 5 min of reaction), respectively, compared to that of WO₃/ZrO₂. Moreover, the catalysts could be regenerated in a facile way. Therefore, W₂N/pDC could be produced facilely from pyrolysis (without ammonia feeding) of PTA/pANI, and W₂N, well‐dispersed on pDC, can be suggested as a very efficient oxidation catalyst for the desulfurization of liquid fuel.     

聚乙烯醇对芳纶复合纱聚苯胺导电层耐久性影响

为提高聚苯胺导电层与基材之间的黏结牢度,以聚乙烯醇为共混高聚物,通过连续原位聚合法在对位芳纶纱线表面形成聚乙烯醇/聚苯胺导电层,制备得到芳纶/聚苯胺/聚乙烯醇复合导电纱。分析了导电纱的结构与性能,并研究了聚乙烯醇对聚苯胺导电层耐水洗和耐磨性的影响。结果表明:适量添加聚乙烯醇有助于提高导电纱导电层的结构规整性及电导率,随着聚乙烯醇质量分数的提高,导电纱的电导率呈先上升后下降的趋势,当聚乙烯醇占苯胺的质量分数为4.30%时,制得的复合导电纱线的电导率最高,达到(1.120±0.198) S/cm;聚乙烯醇的添加和质量分数的提高,有助于聚苯胺导电层耐水洗性及在较小外力作用下的耐磨性的提高。     

Optimization of waste quail eggshells as biocomposites for polyaniline in ammonia gas detection

A simple, cost-effective, and novel chemical sensor for ammonia (NH₃) gas detection was developed from polyaniline (PANI)/quail eggshell (QES) composites. QES is a natural waste enriched in calcium carbonate. In this work, pure PANI was synthesized from chemical oxidation method and PANI/QES composites were prepared from physical mixing of QES with the synthesized PANI at different mass ratio. A series of complementary techniques including Fourier transform infrared and ultraviolet-visible spectrometers, scanning electron microscope with energy dispersive detection coupled with mapping, thermogravimetric analysis, and X-ray diffractometer were used to characterize the physicochemical and textural properties of the biocomposites. From the results, PANI/QES composite with a mass ratio of 1 exhibited the lowest NH₃ detection limit of 5.24 ppm with a linear correlation coefficient (R²) of close to unity (0.9932) between the signal and NH₃ gas concentration. As a whole, the PANI/QES biocomposites synthesized from this work exhibited excellent selectivity toward NH₃ gas even in the presence of other gas impurities, such as acetone, ethanol, and hexane. For the sensor reusability, the PANI/QES biocomposites can be reused in the application of NH₃ gas detection for at least 4 cycles.     

Studies on one‐dimensional polyanilines prepared with n‐dodecylbenzenesulfonic and camphorsulfonic acids

Anilinium salts complexed with n‐dodecylbenzenesulfonic acid (DBSA) and camphorsulfonic acid (CSA) were found to self‐assemble into cylindrical micelles with bigger diameters than those complexed with only DBSA or CSA. These cylindrical micelles were polymerized into one‐dimensional copolyaniline nanotubes (PANIDBSACSA) via emulsion polymerization, demonstrating various morphologies depending on the ratio of DBSA to CSA. The UV?visible?NIR spectra of neat PANICSA and PANIDBSACSAs illustrate significant free carrier tails in the NIR region and conductivity 10–20 times higher than that of neat PANIDBSA whose UV?visible?NIR spectrum does not illustrate significant carrier tails. When the number of moles of DBSA is equivalent to or exceeds that of CSA in the polymerization mixture, SEM and TEM micrographs of the PANIDBSACSAs reveal that they have larger diameters than that of neat PANIDBSA. Besides, some of the surfaces of the big nanotubes were implanted and mounted with lots of small nanofibers of neat PANICSA polymerized from some of the CSA‐complexed aniliniums which were excluded from the cylindrical micelles before polymerization. TGA thermograms of PANIDBSACSAs show an intimate relationship between thermal deprotonation and the DBSA to CSA ratio. X‐ray diffraction patterns demonstrate a layered structure arrangement of polyaniline molecules of all one‐dimensional nanofibers. © 2015 Society of Chemical Industry     

Polyaniline–13X zeolite composite‐supported platinum electrocatalysts for direct methanol fuel cell applications

We successfully synthesized 13X zeolite using a hydrothermal method. Then, composites of polyaniline (PANI) with 13X zeolite and PANI–13X with platinum were prepared by chemical oxidative polymerization and chemical reduction, respectively. Field emission scanning electron microscopy, X‐ray diffraction, Raman spectroscopy and Brunauer–Emmett–Teller techniques were used to characterize the PANI–Pt and PANI–Pt–13X composites. Further, the electrocatalytic activity towards methanol oxidation of the synthesized catalysts was explored using cyclic voltammetry in 1 mol L^?1 CH₃OH + 0.5 mol L^?1 H₂SO₄ solution. From the obtained results, PANI–Pt–13X shows superior performance compared to PANI–Pt towards methanol oxidation and electrical conductivity. Hence, the 13X zeolite‐incorporated PANI–Pt composite could be an efficient catalyst for direct methanol fuel cell applications. © 2019 Society of Chemical Industry     

Improving ultraviolet light photocatalytic activity of polyaniline/silicon carbide composites by Fe-doping

It was aimed to prepare polyaniline (Pani) composites, including silicon carbide (SiC) nanofibers doped with iron (Fe) ions. The Fe-doping of SiC was performed to enhance the photocatalytic activity of the composites through the separation of photoexcited mobile charge carriers. For comparison purposes, Pani composites were also prepared with undoped SiC nanofibers. The composite samples were characterized by FTIR, XRD, SEM, EDX, and UV–Vis spectroscopies. Experiments on photocatalytic degradation of methylene blue under ultraviolet light irradiation revealed that Pani/SiC-Fe composites exhibited higher photocatalytic activity when compared with Pani/SiC composites. Almost 22% dye removal was obtained within 300 min with the Pani composite, containing 15 wt.% SiC-Fe. FTIR, XRD, SEM, EDX, and UV–Vis spectroscopies demonstrated that SiC nanofibers were successfully doped with iron ions and incorporated into the polyaniline matrix. The original aspect of this study was to research the photocatalytic activity of polyaniline composites containing Fe-doped SiC nanofibers. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48524.     

Morphology‐dependent electrochemical performance of nitrogen‐doped carbon dots@polyaniline hybrids for supercapacitors

In this work, the binary N‐CDs@PANI hybrids were fabricated by introducing zero‐dimensional nitrogen‐doped carbon dots (N‐CDs) into reticulated PANI. Firstly, N‐CDs were prepared by one‐pot microwave method, and then, the N‐CDs were introduced into in situ oxidative polymerization of aniline (ANI) monomer. The N‐CDs with abundant functional groups and high electronic cloud density played a significant role in guiding the polyaniline‐ordered growth into intriguing morphologies. Moreover, morphology‐dependent electrochemical performances of N‐CDs@PANI hybrids were investigated and N‐CDs improve static interaction and enhance the special capacitances in the N‐CDs@PANI hybrids. Especially, the specific capacitance of PC4 hybrid can reach 785 F g^?1, which exceed that of pure PANI (274 F g^?1) at current density of 0.5 A g^?1 according to three‐electrode measurement. And the capacitance retention of the PC4 hybrid still keeps 70% after 2000 cycles of charge and discharge. The N‐CDs@PANI hybrids can have potential applications in electrode materials, supercapacitors, nonlinear optics, and microwave absorption.