PANI Nanocomposite Research Articles

Polyaniline as a dual flame retardant and electrostatic dissipative additive in polyethylene nanocomposites

AbstractPolyolefins, such as polyethylene (PE), are highly flammable and electrically insulative, limiting their applicability. The study explored the flame‐retardancy and electrical conductivity of PE/polyaniline (PE/PANI) nanocomposites containing undoped PANI, PANI doped, and co‐doped with various acids and PANI modified with a double layered hydroxide or ammonium polyphosphate (APP). The nanocomposites were synthesized through in situ chemical oxidative polymerization of aniline and compression molding. Flame retardancy was evaluated using UL 94 tests and cone calorimetry. All nanocomposites, except the de‐doped PANI nanocomposite, attained a UL 94 V2 rating. Cone calorimeter results showed that PANI doped with H3PO4 reduced the peak heat release rate by 20% compared to neat PE, whereas co‐doping PANI with H3PO4 and phytic acid reduced it by 31%. The nanocomposites exhibited volume resistivity for suitable for electrotactic dissipation applications but showed marginally reduced mechanical properties. This study demonstrates the potential to develop electrostatic dissipative and flame‐retardant PE nanocomposites incorporating PANI.Highlights PE/PANI nanocomposites were synthesized. PANI doped with H3PO4 reduced the peak HRR by 20%. Co‐doping PANI with H3PO4 and phytic acid further reduced peak HRR. Nanocomposites attained a UL 94 V2 rating. PE/PANI nanocomposites were electrostatic dissipative.

Synthesis and characterisation of PANI and PANI-NiO nanocomposite for promising supercapacitor application

Synthesis and characterisation of PANI and PANI-NiO nanocomposite for promising supercapacitor application

Selective and Sensitive Detection of Ammonia at Room Temperature by the WS2-PANI Nanocomposite on a Flexible Paper-Based Sensor with Cost-Effective Chemically Expanded Graphite Ink Electrodes

Selective and Sensitive Detection of Ammonia at Room Temperature by the WS₂-PANI Nanocomposite on a Flexible Paper-Based Sensor with Cost-Effective Chemically Expanded Graphite Ink Electrodes

In situ synthesis of long tubular water-dispersible polyaniline with core/shell gold and silver@graphene oxide nanoparticles for gas sensor application

Gold nanoparticles (Au NPs) with graphene oxide (GO) shell (Au@GO), silver nanoparticles (Ag NPs) with GO shell (Ag@GO), and gold silver nanoparticles (AuAgNPs) with GO shell (AuAg@GO) were synthesized employing a cationic surfactant. The prepared core@shell structures were used for in situ synthesis of long tubular polyaniline structures employing cetyl trimethyl ammonium bromide (CTAB) as a soft template. This process led to a notable enhancement in the tubular nanostructure of PANI, extending its length beyond 10 μm, in the case of using core/shell Au@GO, Ag@GO, and AuAg@GO structures. To evaluate their applicability and compatibility, the dispersibility of these nanocomposites was assessed in three distinct solvents: water, dimethyl sulfoxide (DMSO), and N-Methyl-2-pyrrolidone (NMP). Subsequently, the dedoping of PANI within the prepared nanocomposites was scrutinized using UV–Visible (UV–Vis) spectroscopy, which revealed a reduction in the I750/I315 ratio from 1.00 to 0.66 when subjected to water and NMP solvents, respectively. Notably, the dedoping of the AuAg@GO/PANI nanocomposite was predominantly observed in NMP, attributable to the presence of hydrogen bonding interactions and the basic properties of NMP. In terms of ionic conductivity, it was observed that the prepared nanocomposite exhibited its highest conductivity in a water-based medium, registering at 1982 μs. Furthermore, the AuAg@GO/PANI nanocomposite exhibited superior sensing capabilities in comparison to PANI-based gas sensor devices, particularly when exposed to acetone, CO2, NO2, and H2S. Remarkably, at room temperature (25 °C), the AuAg@GO/PANI nanocomposite displayed rapid response and recovery times, with values of 279 s, 431 s, 335 s, and 509 s for 1 ppm concentrations of CO2, NO2, H2S, and acetone, respectively. The sensitivity of these sensors towards acetone, CO2, NO2, and H2S, was quantified by analyzing the slope of the response versus the target gas concentration, revealing the AuAg@GO/PANI nanocomposite to exhibit the highest sensitivity, particularly towards NO2.

Nb-Ta3N5 protected with PANI nanocomposite for enhanced photocatalytic water-splitting towards hydrogen production under visible light irradiation

The photocatalytic production of hydrogen (H2) from water to convert solar energy to chemical energy is a promising way to solve energy crisis issues. In this study, we synthesized niobium-doped tantalum nitride protected by polyaniline (Nb-Ta3N5@PANI) for visible light photocatalytic water-splitting. Nb was successfully doped into Ta3N5 lattice confirmed by XRD. Nb as a dopant increases e−- h+ pair separation by acting as an intermediate band between the valence band (VB) and conduction band (CB) of Ta3N5. PANI works as a conducting polymer to further improve the photogenerated e− and h+ charge transfer. XRD, UV–vis, FT/IR, and FE-SEM were used to confirm their structure and properties. Based on our modification, the optimal solar H2 evolution on the Nb-Ta3N5@PANI photocatalyst reaches 71.3 mmol/g, ca. 3.1 folds that of the Ta3N5 photocatalyst.

An antifouling electrochemical biosensor based on chondroitin sulfate-functionalized polyaniline and DNA-peptide conjugates for cortisol determination in body fluids.

An antifouling electrochemical biosensor was constructed based on chondroitin sulfate (CS)-functionalized polyaniline (CS/PANI) and DNA-peptide conjugates that is capable of assaying cortisol directly in human fluids. First, a CS-doped PANI nanocomposite (sensing substrate) was electrodeposited onto a bare glassy carbon electrode to promote electron transport, providing the sensing signal from high peak currents of PANI to improve the sensitivity of the biosensor. Dendritic DNA-peptide conjugates were assembled onto the CS/PANI by exploiting the highly specific and strong interactions between biotin and streptavidin, which amplified the sensing signals toward cortisol. The integration of the DNA-peptide conjugates into the CS/PANI nanocomposite ensured that the biosensor had a synergistic antifouling effect and was capable of detecting cortisol directly in body fluids (sweat, saliva, and tears). When assaying cortisol levels, the biosensor exhibited a linear range over the cortisol concentrations of 1 × 10-12-1 × 10-7 M and a low limit of detection (0.333 × 10-12 M). In the detection of cortisol in real samples, the relative standard deviation (RSD) of the biological samples ranged from 2.94 to 4.23%, and the recovery were calculated to be in the range 95.2-103.2%.

Wearable Gas Sensor Based on Reticular Antimony-Doped SnO2/PANI Nanocomposite Realizing Intelligent Detection of Ammonia within a Wide Range of Humidity.

Wearable gas sensors demonstrate broad potential for environmental monitoring and breath analysis applications. Typically, they require a highly stable and high-performance flexible gas sensing unit that can work with a small, flexible circuit to enable real-time accurate concentration analysis and prediction. This work proposes a flexible gas sensor using antimony-doped tin dioxide composite polyaniline as the sensing material for room-temperature ammonia detection over a wide humidity range. The sensor exhibits high sensitivity (response value at 33.1 toward 100 ppm ammonia at 70% relative humidity), excellent selectivity, and good long-term and mechanical stability. The increased sensitivity is due to a reduction in the hole concentration of polyaniline in air, achieved through compositing and doping. Subsequently, regression analysis equations are developed to establish the relationship between the gas concentration and sensor response under varying environmental humidity conditions. The sensor was integrated with a small, low-power circuit module to form a wearable smart bracelet with signal acquisition, processing, and wireless transmission functions, which could achieve early and remote warning of gas leakage in different humidity environments. This research demonstrates a promising approach to designing high-performance, high-stability, and flexible gas sensors and their corresponding wireless sensing systems.

Fabricating ternary α-Fe2O3 nanoparticles-polyaniline-graphite nanoplatelets nanocomposite with enhanced photoelectrochemical activity for potential use as peroxidase mimic as well as photocatalyst

Ternary nanocomposite based on the polyaniline (Pani), α-Fe2O3 nanoparticles (α-Fe2O3 NPs) and graphite nanoplatelets (GnP) [Pani/α-Fe2O3/GnP] (PFG) was prepared through a stepwise chemical route of synthesis. The flat band potential Vfb is found to be − 0.31, − 0.42 and − 0.78 V vs. Ag/AgCl as reference electrode under continuous illumination for the bare α-Fe2O3 NPs, Pani and PFG ternary nanocomposite. Incase of the potential application of the PFG ternary nanocomposite as a peroxidase-like mimic, the catalysis data was fitted according to the Michaelis−Menten kinetic model in order to evaluate the kinetic parameters of the Michaelis−Menten constant (Km) and maximum velocity (vmax) which were found to be 9.73 × 10−6 M, 1.26 × 10−6 M/sec and 6.51 × 10−5 M, 3.15 × 10−6 M/sec for α-Fe2O3 NPs and Pani whereas for PFG ternary nanocomposite, it was observed to be 7.12 × 10−5 M and 9.44 × 10−7 M/sec, respectively, depicting the fact that lower H2O2 concentration was required in order to acquire maximum reaction velocity incase of H2O2 as substrate. For TMB as substrate, the PFG ternary nanocomposite (2.75 ×10−4 M) displayed lower value of value of Km signifying its higher affinity for TMB as compared to HRP (1.24 ×10−8 M). Furthermore, the Allura Red dye degradation under visible light irradiation was carried out that resulted in the photocatalytic rate of 9.74 × 10−2 min−1 for PFG ternary nanocomposite which is high as compared to 1.56 × 10−2 min−1 for α-Fe2O3 NPs and 2.41 × 10−2 min−1 for pure Pani at 1 ppm concentration.

Supporting electrolyte enhanced supercapacitance of acetic acid doped reduced graphene oxide/nickel hydroxide/polyaniline nanocomposites

The rapidly enhanced electrolytic intercalation bringing about 101 % higher energy storage in rGO, Ni(OH)2 and PANI (GNP) nanocomposite in comparison with 1 M H2SO4 is achieved using the 0.4 M CH3SO3H (MSA) as supporting electrolyte for 0.4 M H2SO4 (SA). Ensuing the established fact of acid insoluble Ni(OH)2 in our earlier study, the further work on Ni(OH)2 containing composites in the presence of acid electroytes has proven its stability in MSA as well. The GNP exhibited increase in specific capacitance (Cs) on increasing the cycles of energy storage and delivery in different acid electrolytes but the enhancement in the presence of MSA is higher. The superior results were achieved from the supercapacitor device containing GN51P (rGO 3.70 %: Ni(OH)2 51.86 %: PANI44.44 %) and SA + MSA, which are, Cs of 381.67 F g−1, specific capacity (Q) of 458.01 C g−1, E of 76.33 W h kg−1 and a specific power of 3.3109 kW kg−1 at 1 A g−1. The GN51P exhibited increasing Cs even after 10,000 cycles at 400 mV s−1. The real time applications of the GNP composites are also experimented satisfactorily.

Iron Doped Titania/Polyaniline Composite: An Efficient Electrocatalyst for Hydrogen Evolution Reaction in Acidic Medium

The development of noble metal-free catalyst for hydrogen evolution reaction (HER) is the primary challenge in fuel production to replace fossil fuels. Here, we have synthesized Fe-doped TiO<sub>2</sub>/PANI nanocomposite via facile in situ polymerization method and studied its electrocatalytic activity towards HER. The composite catalyzes HER efficiently with an overpotential value of -180 mV vs. RHE in 0.5 M H<sub>2</sub>SO<sub>4</sub> solution to achieve the current density of 10 mA cm<sup>-2</sup> and also possesses unique stability of 8 h. However, a unique balance of PANI content must be maintained to draw the maximum efficiency from the conjuncture of active Fe-doped TiO<sub>2</sub> particles and PANI. The catalytic efficiency of PANI is upgraded by interfacial electronic coupling with Fe-doped TiO<sub>2,</sub> due to which the antibonding states of nitrogen atom got occupied, leading to a weaker interaction between adsorbate hydrogen and catalyst surface and enhancing the rapid desorption of H<sub>2</sub>.

TiO2/Bi2O3/PANI nanocomposite materials for enhanced photocatalytic decontamination of organic pollutants

• TiO 2 /Bi 2 O 3 /PANI nanocomposites were synthesized. • Materials characterized for structural, morphological and optical characteristics. • Nanocomposites employed for RhB and Triclopyr photocatalytic degradation. • Close contact between TiO 2 , Bi 2 O 3 and PANI promotes interfacial charge transfer. • holes are the prominent ROS for the degradation of RhB; holes and O 2 ∙ - for TC. In this present work, TiO 2 /Bi 2 O 3 /PANI nanocomposites were synthesized and employed as photocatalyst for the degradation of organic pollutants i.e. Rhodamine B dye and Triclopyr pesticides. TiO 2 /Bi 2 O 3 /PANI nanocomposites were characterized with the help of various advanced instrumentation techniques including X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), photoluminescence (PL), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) analysis. The absorption in the visible wavelength region (λ > 400 nm) increased with increasing PANI amount accompanied by π → π ∗ transition. The close contact between TiO 2 , Bi 2 O 3 and PANI promotes the interfacial charge transfer and significantly improved photocatalytic performance under the irradiation of visible LEDs. Among the prepared nanocomposites, the sample containing 5 wt. % PANI of TiO 2 /Bi 2 O 3 (TB(15)) was found to be most efficient photocatalyst and stable even after four cyclic runs for the degradation of organic pollutants. TB(15)/PANI(5) exhibited the lowest PL intensity, indicating the minimum reunion in the photoproduced electron-hole pairs, which was favorable to improve the efficiency of the photocatalyst for the removal of organic pollutants. The photodegradation rate of RhB and TC using TB(15)/PANI(5) photocatalyst reached to 99.6 % in 50 minutes and 76.1 % in 120 minutes under the visible LEDs irradiation respectively. Kinetics analysis of photocatalytic reaction obeys the pseudo first-order kinetic model with respect to concentration of organic pollutants with a regression coefficient value in the range of 0.941-0.999. The trapping experiments confirmed that holes are prominent species for the degradation of RhB, and holes and superoxide anion radical for photocatalytic degradation of TC. Finally, the mechanism of photocatalytic degradation using TiO 2 /Bi 2 O 3 /PANI nanocomposite was also proposed.

Enhanced sunlight-absorption of Fe2O3 covered by PANI for the photodegradation of organic pollutants and antimicrobial inactivation

• Fabrication of core–shell S-scheme heterojunction Fe 2 O 3 -PANI nanocomposite via simple solution method. • Booted photodegradation of diverse organic pollutants under sunlight. • The enhanced antimicrobial characteristics against various bacterial strains. • The improved charge carrier’s kinetics via S-scheme with PANI. • A promising material against bacterial disinfection and an excellent stable photocatalyst. The current study focused on preparing S-scheme heterojunction Fe 2 O 3 -PANI nanocomposite and pristine Fe 2 O 3 using surfactant-assisted sol–gel and polymerization routes. The structural conformation was assessed through XRD diffractograms that confirmed the Fe 2 O 3 phase in both samples. FTIR data traces the metal–oxygen and carbon-related bonds. PL results showed that the recombination rate is retarded in nanocomposite. TEM images confirmed the covering of PANI over Fe 2 O 3 . EDX mapping showed that Fe, C, N, and O were present in the grown nanocomposite. XPS study revealed the binding energies of constituent atoms. The optical energy bandgap 2.8 and 2.7 eV for Fe 2 O 3 and Fe 2 O 3 -PANI was observed through UV–Vis analysis. The photocatalytic test against methyl blue (MB), eosin yellow (EY), and methyl red (MR) dyes were executed for 50 min under direct sunlight. The Fe 2 O 3 -PANI showed 99.8, 98.5, and 99.6% degradation efficiency against MB, EY, and MR dyes, respectively, which was higher than Fe 2 O 3 . The recyclability assessment confirmed the reusability upto four cycles. The antimicrobial property against E. coli, P-aeruginosa, K-pneumoniae, S. aureus, and P. vulgaris bacterial strains revealed a higher response for Fe 2 O 3 -PANI with the zone of inhibition 30, 31, 31, 30, and 30 nm, respectively. The enhanced performance of Fe 2 O 3 -PANI is being credited to S-scheme heterostructure supported with PANI, which can hinder the recombination process and support electron/hole separation. The results indicated that the as-grown nanocomposite could be a promising candidate against bacterial disinfection and an excellent stable photocatalyst.

MoSe2‐PANI Nanocomposite as Supercapacitor Electrode Material: Optimization, Mechanism and Electrochemical Performance

AbstractIn this report, MoSe2‐Polyaniline (PANI) nanocomposite with different amounts of MoSe2 (0.05 g, 0.1 g and 0.2 g) were synthesized via in‐situ oxidative polymerization method. The morphology and wt % ratio of nanocomposites was studied using Field emission scanning electron microscopy (FESEM) and Energy dispersive X‐ray spectroscopy (EDX), respectively. Atomic and weight concentration of the nanocomposite was calculated using X‐ray Photoelectron Spectroscopy (XPS) and the results were in agreement with EDX analysis. The optimum nanocomposite as the electrode material for supercapacitor showed the highest specific capacitance of 463 F/g at a scan rate of 5 mV/s and retains ∼72 % specific capacitance after 3000 charge‐discharge cycles. The MoSe2‐PANI nanocomposite attains an energy density of 19.6 Wh/kg at a power density of 12.7 W/kg. The enhancement in the electrochemical activity of the MoSe2‐PANI electrode was achieved by using synergetic effects of electrical double‐layer capacitors (MoSe2 nanosheets) and pseudocapacitors (Polyaniline nanofiber). MoSe2‐PANI nanocomposite showed improved electron and ion transfer mechanism and improvement in the wettability of the electrode material. The thermogravimetric analysis (TGA) confirmed that the nanocomposite has improved thermal stability with mass loss of 28 %. The Brunauer‐Emmett‐Teller (BET) study confirm the high surface area (61.147 m2 g−1) and pore volume (8.595 cm3 g−1) as compared to their pristine samples. The outstanding electrochemical performance has proved that MoSe2‐PANI nanocomposite has a great potential to be an electrode material in energy storage devices.

Tuned MWCNT/CuO/Fe3O4/Polyaniline nanocomposites with exceptional microwave attenuation and a broad frequency band

In this study, novel quaternary MWCNT/CuO/Fe3O4/PANI nanocomposites were synthesized with three different weight ratios of CuO/Fe3O4/PANI to MWCNT (1:3), (1:4), and (1:5), where all of its components were synthesized separately and then combined in specific weight ratios. CuO/Fe3O4/PANI transmission electron microscopy (TEM) images revealed that most nanoparticles were in a CuO/Fe3O4 hybrid form, with a narrow size distribution uniformly dispersed in a polymer background. The TEM and scanning electron microscopy (SEM) images of the MWCNT/CuO/Fe3O4/PANI nanocomposite revealed that the MWCNT was uniformly coated with CuO/Fe3O4/PANI. All three nanocomposites samples demonstrated superior microwave attenuation performance in terms of reflection loss and absorption bandwidth. The minimum reflection losses for MWCNT/CuO/Fe3O4/PANI nanocomposites (1:3), (1:4), and (1:5) were 45.7, 58.7, and 85.4, 87.4 dB, respectively. The absorption bandwidths (RL ≤ −10 dB) of MWCNT/CuO/Fe3O4/PANI nanocomposites (1:3), (1:4), and (1:5) were 6, 7.6, and 6 GHz, respectively.

Investigation Photoluminescence Property of ZnO / PANI Nanocomposite Synthesized in​ [EtOHMIM+] [HSO4-] Ionic Liquid and CTAB Surfactant

In the present work, ZnO nanoparticles (NPs) were prepared using hydrothermal method with Trimethyl Ammonium Bromide (CTAB) as surfactant in 1- (hydroxyethyl)-3- methylimidazolium sulfate [EtOHMIM+] [HSO-] ionic liquid (IL). ZnO / PANI nanocomposite was prepared via in situ polymerization. The structures of the modified ZnO particles were characterized by X-ray diffraction, Raman spectroscopy and, scanning electron microscopy (SEM). The optical properties of (ZnO / PANI) nanocomposite were examined by photoluminescence (PL) analysis. XRD and, Raman analysis confirmed that pure ZnO (NPs) synthesized with (CTAB) in [EtOHMIM+] [HSO-] IL were formed. The addition of (CTAB) and [EtOHMIM+] [HSO-] IL does not change the ZnO phase but reduces the particle size of ZnO and converts shallow defects to deep defects. The SEM images of the ZnO / PANI nanocomposite showed the formation of hexagonal wurtzite ZnO (NPs) embedded in polyaniline matrix. The PL intensity of the ZnO / PANI nanocomposite is improved as compared to pure ZnO (NPs). This indicates that [EtOHMIM+] [HSO4-] IL may be acting as a dye, since it is constituted by an organic part, [EtOHMIM+]. This good performance indicates that the synthesised nanocompsite is promising material as photoanode in solar cells.

Comparison of catalytic and fuel additive properties of bimetallic nanoparticles and its composite: FeMnO3 and PANI-FeMnO3

A novel nanocomposite polyaniline-iron manganese oxide (PANI-FeMnO3) is successfully synthesized via in-situ chemical oxidative polymerization of aniline using ammonium persulfate (APS) as an oxidizing agent and FeMnO3 bimetallic nanoparticles. FeMnO3 bimetallic nanoparticles are prepared by a temperature-controlled solvothermal method to obtain desired morphology. The morphology of synthesized products is confirmed by SEM and STEM analysis. XRD analysis provided that bimetallic nanoparticles are highly crystalline however, nanocomposites have amorphous nature due to the presence of polymer. FTIR patterns of PANI and PANI-FeMnO3 nanocomposite have characteristic peaks at 1543 cm-1, indicating the electron delocalization in the conductive emeraldine form of PANI. Catalytic efficiency of the FeMnO3 bimetallic nanoparticles and PANI-FeMnO3 nanocomposites as catalysts in organic dyes and nitroarenes reduction is studied. Different parameters such as kapp, reduction time, percentage reduction and reduced concentration are performed to assess the catalytic activity of both catalysts. Among all substrates, highest kapp value is 0.186 min-1 for 2,4-DNP with PANI-FeMnO3 nanocomposite. Effect of type and orientation of functional groups, nature of bonds and steric hindrance on the reduction rate of substrates is also studied. The efficiency of FeMnO3 bimetallic nanoparticles and PANI-FeMnO3 nanocomposite as nano additives is also evaluated and compared by investigating the physical and combustion parameters of commercial diesel. Fuel efficiency is observed to be greatly enhanced by increasing the dosage of nano additives. The results indicate that the efficiency of PANI-FeMnO3 nanocomposite is greater than that FeMnO3 bimetallic nanoparticles.

Synthesis, characterisation and AC conductivity study of PANI/α-Fe2O3 nanocomposites

The disperse α-Fe2O3 in polyaniline matrix to form its nanocomposite enhances the structure and properties of PANI for wider applications. Present study reports the preparation of alfa iron oxide dispersed PANI nanocomposite (α-Fe2O3/PANI NC) with the help of oxidize agents APS by technique insitue method. t. Composite of PANI with 10%, 20 %, 30%, 40% & 50% of α-Fe2O3 has been synthesized by adding iron oxide powder gradually in the reaction mixture during oxidative polymerisation with APS. The composites were well characterized like as XRD,SEM,FTI. AC conductivity of the pure polyaniline & α-Fe2O3/PANI NC with 10%, 20%, 30%, 40% & 50% is studied as function of frequency. The value of ac conductivity increases as frequency increased from 1 KHz – 1MHz.

Ternary nanocomposite cathodes based on 3D graphene-Ag nanoparticle-polyaniline for hybrid electrochemical energy device

A ternary nanocomposite of three-dimensional graphene-silver nanoparticles-polyaniline (3DG-nAg-PANi) is prepared via an in-situ polymerization technique. The structural and morphological characterizations through X-ray diffraction, Fourier transform infrared, Raman spectroscopy and Field emission scanning electron microscopy confirmed the high purity 3DG-nAg-PANi nanocomposite. The prepared 3DG-nAg-PANi nanocomposite is used as a positive electrode with activated carbon as a negative electrode to fabricated asymmetric supercapacitor (ASC). The electrochemical performance studies revealed the outstanding performance of 3DG-nAg-PANi nanocomposite compared to its counterparts (3DG, PANi and 3DG-PANi). The maximum specific capacity is found for 3DG-nAg-PANi ternary nanocomposite (115.6 C g−1) compared with 3DG (71.6 C g−1), PANi (32.2 C g−1), and 3DG-PANi nanocomposite (47.2 C g−1), at a current density of 1 A g−1 in the standard three-electrode cell. The assembled ASC delivered maximum specific energy of 11.67 Wh kg−1 at a specific power of 300 Wkg−1 using 0.4 A g−1 of current density. The ASC is able to retain 92% of initial capacity after 5000 cycles at a current density of 2 A g−1. The electrochemical performance of the 3DG-nAg-PANi ternary nanocomposite reveals that it is a suitable candidate for electrodes in the energy storage systems.

Polyaniline and sulfonated graphene oxide supported bimetallic manganese cobalt oxides as an effective and non-precious cathode catalyst in air-cathode microbial fuel cells

This study examines the feasibility of the use of nanocomposite of polyaniline (PAni) grafted sulfonated graphene oxide (SGO) supported manganese cobalt oxide as a novel and effective cathode catalyst for single chamber microbial fuel cell (SC-MFC). The graphene oxide (GO) was sulfonated to SGO for the development of a significant increase in the hydrophilicity of GO to enhance the nano−catalyst dispersion. The structural properties of the prepared nanocomposite were studied by X-ray diffraction, X-ray photoelectron spectroscopy, and Raman spectroscopy. Morphological studies of the nanocomposite revealed a wrinkled paper−like structure of SGO and a spherical type structure of Mn−Co. Both cyclic voltammetry and electrochemical impedance spectroscopy showed a reduction current value of −1.04 mA, and charge-transfer resistance of 52.4 ohm, which exhibited a higher oxygen reduction reaction activity and good conductivity compared to Mn−Co/GO−PAni, Mn−Co/rGO−PAni and Pt/C catalyst. Electrochemical tests also suggest that the Mn−Co/SGO−PAni nanocomposite exhibited excellent durability among the other three cathodes. Furthermore, the MFCs equipped with Mn−Co/SGO−PAni nanocomposite modified electrode achieved power density of 1392.68 mW m−2 which is 2.89 times higher than state-of-art Pt/C (481.3 mWm−2). The Electrochemical studies also displayed a similar result. The significant increase in power generation with Mn−Co/SGO−PAni nanocomposite as a cathode catalyst indicates that it can be used as a promising, inexpensive electrocatalyst for the long-term operation for MFC.

Electrochemical Sensors for the Detection of Heavy Metals in Wastewater

Heavy metals are characterized by their high density, high toxicity, non-biodegradable, and poisoning even at low concentrations1. These can be present in irrigation water, wastewater or drinking water. Their accumulation can affect the natural ecosystems, crops and mainly the health of people2 , 3. The World Health Organization reported the reference values of lead 0.01 mg/l, cadmium 0.03 mg/l, mercury 0.006 mg/l, nickel 0.07 mg/l and arsenic 0.01 mg/l and showed the maximum limited of these chemicals in consumption water4.Electrochemical sensors have assumed an importance role in analytical chemistry, for easing collection data, fast, greatly sensitive, easy to handle, cheap and versatility5. There are already analytical methods that can detect heavy metals, however, these can only detect one metal per time, so the electrochemical method, in turn, can generate advantages for measuring metal ions simultaneously6. Moreover, many sensors use mercury which generates high toxicity when replacing the electrode. For this reason, it is necessary to develop materials that are more environmentally friendly as well as, it can detect heavy metals simultaneously.It is important that materials used as electrodes in electrochemical sensors have high surface reactivity and that their porosity can be modified, so the metal can be detected. It has been gaining momentum the of study carbon-modified electrodes in order to improve the sensitivity of electrochemical detection methods7. Carbon materials possess these characteristics and are starting to accomplish a leading role in nanotechnology field, with different structures such as carbon nanotubes, graphene, carbon dots, carbon cables, nanodiamonds8. The easy in situ data also provides an economic advantage over more expensive methods such as atomic absorption or spectroscopy. The function of carbon materials within the sensors is focused with the possibility of improving the accessibility of heavy metal atoms by modifying the surface porosity of the material and reflecting the detection the element. The carbon materials currently most studied are graphene due to its properties in electronic, mechanical, and thermal9.There are currently studies demonstrating the efficiency of graphene oxide and iron composite materials where there is a conductive phase and an insulator phase7. Furthermore, carbon nanotubes (CNTs) are cylindrically rolled graphene structures and depending on the characteristics of winding which generate different types of carbon allotropic conformation. They are used in the development of sensors especially in composite designs, due to their high conductivity, high specific surface area, and excellent thermal stability. Conductive polymers (e.g., polyaniline, polypyrrole and polythiophene) can be used to solve the non-uniformity of the distribution of carbon nanotubes on the surface10. Motaghedifard et al.10 synthesized PANI nanocomposite and sulfated zirconium oxide nanostructures and immobilized with carbon nanotubes on the surface of a glassy carbon electrode to trace measure of Cr(VI) in aqueous solution, and found that a limit of detection for Cr(VI) was 64.3 nmol/L. Other materials such as porous carbon materials from biomass resources with heteroatoms doped into the carbon matrix or metal composites have become research interesting for electrochemical sensors due to large specific surface areas, uniform porosity, and low cost11 , 1. For example, Qin et al. studied bacterial cellulose-metal composites as electrodes of the electrochemical sensor, which showed high sensitivity and selectivity toward target metals like Cd(II) and Pb(II)11.The techniques most used in electrochemical sensors are voltammetry, potentiometry, impedimetry, amperometry, and conductometry. The voltammetry measurement (ASV) method widely used for the detection of heavy metal ions (HMIs) due to its high selectivity, sensitivity, short detection time, and low-cost equipment12. However, the electrodes respond best depending on the metal ion to be measured (Cu+2, Cd+2, Zn+2)13. Xu et. at1 synthetized N,S co-doped porous honeycomb carbon (N,S-PHCC) as an electrode for detection of Pb(II) by DPASV. These materials showed a wider linear range (0.75 – 120 mg/L), higher sensitivity, and lower detection limit (0.064 mg/l) than those of other electrode-based carbon materials. Figure 1