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This review delivers a summary of the recent advances in polyaniline based electrocatalyst for direct methanol fuel cell applications. Today’s world is urging for global energy due to the fossil fuel diminution and ecological contamination which is overthrown by the direct methanol fuel cell. Amongst the conducting polymers, polyaniline has a significant role in the direct methanol fuel cell. Due to the high conductivity, unique redox properties, high flexibility, better solubility, reasonable stability, ease synthesis, and low cost. The nanocomposite of polyaniline with other electrochemically active materials such as metallic compounds and carbonaceous materials as well as nitrogen-doped carbon materials derived from PANI based nanocomposite were in detailly discussed in this review.

Amine-functionalized silica sorbents have been widely investigated for post-combustion CO2 capture at low temperature. In previous studies, amine-functionalized silica sorbents were prepared using a synthetic hierarchically porous silica, which is not commercially available in large quantities, because porous silica support structures strongly influence CO2 capture performance. Here, we propose a feasible and facile fabrication method for amine-functionalized silica sorbents using 3-aminopropyltrimethoxy silane (APTS) and fumed silica (FS), where APTS serves as both an active material and a binder. The APTS-functionalized FS sorbents have large amounts of active amino groups and porous structures and demonstrate good multicycle stability with excellent CO2 capture performance. In addition, cetyltrimethylammonium bromide was found to improve the diffusion pathway of CO2, leading to enhanced CO2 capture capacity because of the suppression of excessive condensation during preparation. Therefore, the APTS-functionalized FS sorbents could be cost- and energy-efficiently prepared using a novel one-pot synthesis method; the resulting sorbents exhibit excellent CO2 capture performance.

SnO2 thin-film gas sensors were easily created using the ion sputtering technique. The as-deposited SnO2 thin films consist of a tetragonal SnO2 phase and densely packed nanosized grains with diameters of approximately 20−80 nm, which are separated by microcracks. The as-deposited SnO2 thin film is well crystallized, with a dense columnar nanostructure grown directly onto the alumina material and the Pt electrodes. The grain size and thickness of SnO2 thin films are easily controlled by varying the sputtering time of the ion coater. The responses of the SnO2 thin-film sensors decrease as the SnO2 film thickness is increased, indicating that a negative association exists between the sensor response and the SnO2 film thickness due to gas diffusion from the surface. The SnO2 thin-film sensor, which was created by ion sputtering for 10 min, shows an excellent sensor response (Ra/Rg where Ra is the electric resistance under air and Rg is the electric resistance under the test gas) for detecting 1 ppm H2S at 350°C.

In neurotransmission process, dopamine (DA) is the key molecule. Hence, the detection of dopamine plays a vital role in the primary diagnosis of diseases which is related to the irregular levels of dopamine. In this study, we proposed the electrochemically deposited Graphene Nanosheets-Polydiphenylamine-Silica (GRNS-PDPA-SiO2) modified nanohybrid electrode for an amperometric detection of dopamine. The electrochemical oxidation of DA ensures the catalytic activity of the prepared nanohybrid composites by chronoamperometry (CA) method. The nanohybrid electrode shows linear response towards DA (1–5 μM) in the presence of phosphate buffer solution (PBS at pH 7.0) with the regression co-efficient (R2) of 0.98. Low detection limit with superior sensitivity of dopamine was achieved as 0.1 μM and 0.66 μA μM−1cm−2 respectively. The structural morphology and the chemical homogeneity of the materials were confirmed by scanning electron microscope with EDX analysis. The molecular vibration and electrochemical performances were recorded through Fourier-transform infrared spectroscopy (FTIR) and cyclic voltammetry (CV). The adopted GRNS-PDPA-SiO2 modified electrode resulted in excellent sensitivity, high selectivity claims its realistic applications in the highly clinical diagnostics.

Amperometric sensor of polydiphenylamine (PDPA)/phosphotungstic acid (PTA)/zinc oxide (ZnO) on glassy carbon (GC) nanohybrid composite electrode (GC/PDPA/PTA/ZnO) fabricated via facile electrochemical deposition method. The structural geometry and surface morphology were recorded by X-ray diffraction spectrometer (XRD) and scanning electron microscopy (SEM). Electro-catalytic properties and performances of nanohybrid composite were recorded by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry (CA) methods. PTA-assisted PDPA/ZnO-ME shows linear steady-state response towards glucose with superior sensitivity of 20.30 μA μM−1 cm−2, lowest detection limit 0.1 μM, and rapid response less than 2 s. The improved electro-catalytic performance towards glucose by GC/PDPA/PTA/ZnO is due to the combined existence of diphenoquinone diamine (DPDI2+) and phosphotungstic acid anion which provides a higher electro-catalytic active spots leads to more electron transport pathway for the oxidation of glucose. Interference analyses confirm the prepared nanohybrid sensor is best apt for glucose detection claims its practical biomedical application.

An amperometric urea biosensor was fabricated using Indium tin oxide (ITO) coated Polydiphenylamine (PDPA)/ Phosphotungstic acid (PTA)/Graphene (Gra) hybrid nanocomposites modified electrode (ITO/PDPA/PTA/Gra-ME) by an electrochemical-deposition technique. Scanning Electron Microscopy (SEM) and Atomic Force microscopy (AFM) techniques were used to capture the surface morphology and surface coating thickness of nanocomposite sandwiched electrodes. Electro-catalytic performances of modified hybrid electrodes were examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA) techniques. ITO/PDPA/PTA/Gra-ME exhibits a good linear response to urea concentration over the range of 1–13 μM along with a correlation coefficient of 0.999, good sensitivity (1.085 μA/μM cm2) and at a low response time (5 s). The enhanced electro-catalytic activity of ITO/PDPA/PTA/Gra-sandwich towards urea was owing to the synergistic contribution of tungsten atoms (phosphotungstic acid anion), diphenoquinone diamine (DPDI2+) form of PDPA/Graphene that enhances the fast electron transfer rate. Also, interfering analytes were studied to ensure the fabricated sensor is best suitable for practical applications.

Until now, SnO2 nanowires have been directly grown on alumina substrates with Au or Au-coated Pt electrodes by a thermal evaporation method using Sn or SnO2 powders under vacuum. However, in this study, SnO2 nanowires were successfully synthesized on the Pt phase of an alumina substrate by a thermal evaporation method using dibutyltin oxide [DBTO, (C4H9)2SnO] even at atmospheric pressure, resulting in nanowire networks between the Pt phases. Ar with 1% O2 was used as carrier gas with a flow rate of 100 mL/min at 900 °C (heating rate of 25 °C/min). The SnO2 nanowires consisted of straight and branched nanowires, and exhibited a SnO2 phase with a tetragonal structure. Both the DBTO and evaporation temperature play an important role on the synthesis of SnO2 nanowires at atmospheric pressure. The SnO2 nanowire sensor fabricated by an evaporation method showed a sensor response of ~ 500 for 0.05 ppm of NO2, being ~ 10 times greater than that of a SnO2 nanoparticle sensor. Furthermore, the SnO2 nanowire sensor showed excellent repeatability and selectivity for NO2 in the presence of SO2, Cl2, and H2S.

Electrochemical-deposition method was engaged to prepare Fluorine doped Tin oxide (FTO) modified Polydiphenylamine (PDPA)/Phosphotungstic acid (PTA)/Manganese dioxide (MnO2) nanohybrid (FTO/PDPA/PTA/MnO2-ME) Electrode. Nanocomposites structural analysis, morphology, and molecular vibrational studies were characterized through X-ray diffractometer (XRD), Scanning Electron Microscope (SEM) and Fourier Transform Infra read Spectroscopy (FTIR). Recorded XRD and FTIR pattern authenticates the existence of PDPA, PTA, and MnO2 structures. Cyclic voltammetry (CV) studies performed using electrochemical workstation shows very high specific capacitance value of 514.77 Fg−1 at 5 mVs−1 for the modified hybrid electrode system. The superior capacitive performance, cyclic stability of FTO/PDPA/PTA/MnO2 electrode was attributed due to the existence and fast reversible multi‐electron redox response of tungsten atoms in PTA along with PDPA-MnO2 synergistic interaction that augments the electron transfer processes.

This work reports the synthesis, characterization, and antimicrobial activity of polyaniline/polyvinyl alcohol (PANI/PVA) and polydiphenylamine/polyvinyl alcohol (PDPA/PVA) co-polymer nanocomposite films. Initially, chemical oxidative polymerization was employed to synthesis PANI and PDPA by oxidizing aniline (AN) and diphenylamine (DPA) in the presence of ammonium peroxydisulfate (APS) as an oxidant. A trace amount of prepared PANI and PDPA were used to prepare nanocomposite films by solution casting technique, using PVA as a stabilizer. Surface morphological studies reveal the impregnated amorphous structure of PANI and PDPA size in the range of ~ 50–150 nm. Fourier transform infrared (FTIR) examines to confirm the presence of PANI, PDPA, and PVA in nanocomposite film. Disk diffusion approach was adopted to study the antimicrobial activity of PANI/PVA and PDPA/PVA nanocomposite films.

Herein, a novel Poly (melamine) have been successively electrodeposited on glassy carbon electrode and decorated by Pd nanoparticles (Pd NPs) subsequently to fabricate Poly (melamine) – Pd nanocomposite. Structural geometry, morphological view, and elemental composition analysis were ensured by X-ray diffractogram, scanning electron microscope, and X-ray photoelectron spectroscopy. The electrodeposited Poly (melamine) (PME) material depicts an interconnected nano rod (50 nm) morphology leads to a nano exploder (~150 nm) arrangement. Spherical shaped Pd decorated PME morphology was obtained for GC\PME-Pd NPs composite (150 nm). The electrocatalytic activity of the fabricated anode electrocatalyst was examined by cyclic voltammetry, electrochemical impedance spectroscopy and chronoamperometry methods. The modified GC\PME-Pd NPs composite electrode validates superior electrocatalytic behaviour towards methanol and ethanol oxidation in alkaline background. Besides, the electrochemical surface area and electrocatalytic behaviour make it a greater anode catalyst towards methanol and ethanol oxidation. The synergic effects amid the Poly (melamine)-Pd NPs composite enhances the catalytic activity, mechanical stability on the electrocatalysis of methanol and ethanol oxidation reaction superior than modified Poly (melamine) electrode. Hence, the fabricated anode electrocatalyst is proficient to get realistic approach towards the progression in the direct alcohol (methanol and ethanol) oxidation reaction in direct alcohol fuel cells (DAFCs) applications.

The search for novel nanostructures towards multifunctional applications is the main objective of numerous researches in progress. This review article mainly centres the recent research updates in the synthesis, properties, advantages and applications of polyaniline (PANI) nanofibers (NFs) based on electrospinning technique. Among various nano structured conducting polymers (CPs) based NF architecture, PANI is in spotlight drawing too much attention among the scientific communities owing to the exceptional and enhanced characteristic features. This PANI based NFs were attained from the precursor polymer solution by engaging electrospinning technique has been notorious as a direct and facile route via the utilization of strong electrostatic field. Owing to its excellent physicochemical and electrochemical properties, E-spinning NFs based on polyaniline (PANI) becomes the most important novel material towards the emerging advancements such as NF based supercapacitor, sensor devices, scaffold materials and conductive tissue engineering, water filtration and purification, solar cells and so on. Though, the processability of PANI is quite tough in comparison with other CPs, mostly due to its firm structure of backbone with high conjugation level. To meet the demanding specifications towards the applications, the challenges in the E-spinning of PANI NF were explored and led to the progress in the electrospun based nanocomposites or hybrids and their blends. Thus, to explore more and to ignite the state-of-the-art progress, this review manuscript highlights a short review and understanding on the recent research efforts and escalation in the applications of E-spun PANI NFs in various fields such as supercapacitor, sensor, biomedical, and corrosion applications along with the fundamentals, theory, general working principle, and future prospects and challenges ahead of E-spinning.

Polyaniline (PANI) is one of the important materials in conducting polymers (CPs) for significant applications in devices due to its unique properties such as high electrical conductivity, flexibility, and economical price. In this work, novel and eco-friendly green synthesis of polyaniline Nanorod (PANI-NR) were developed by solar irradiation approach in acidic medium without the aid of any surfactant and template. As characterized by morphology studies, the average diameter of PANI-NR is approximately 200–250 nm and length is 2–2.5 µm. The elemental analysis and structural geometry of PANI-NR are examined through EDX, Mapping, and XRD studies. The electrochemical properties were investigated using CV, GCD, and EIS techniques. The electrochemical performance of Cyclic voltammetry analysis shows the redox peaks which confirms the PANI-NR has excellent electrical conductivity. A specific capacitance of 25 F/g at 10 mV/s scan rate by CV studies and 106 F/g at 1 A/g current density by GCD studies is observed for One-Dimensional (1D) PANI-NR as an electrode material for supercapacitor. Also, it shows remarkable cyclic retention and stability. These results indicate that PANI-NR is expected to have better electrochemical performance in energy storage applications.