Graphene-based materials have emerged as new green broad-spectrum antibacterial agents with low bacterial resistance and sustained release properties. In the current work, a novel graphene-ZnO hybrid nanocomposite was prepared as an effective antibacterial weapon with a blade-like structure. Graphene oxide nanosheets decorated with ZnO nanospheres (GO/ZnO) were facilely prepared and controlled via a one-phase method. Nano-GO with 2 nm-thick sheets was prepared via a modified Hummers' procedure. A wet-chemical process was used to produce controlled 60 nm-ZnO nanospheres. Analytical methods such as field emission TEM and SEM microscopes were used to characterize the produced nanocomposites. Several gram-positive and gram-negative bacteria were used to test the anti-microbial activity of the developed materials. Through the microdilution method, GO/ZnO composites showed outstanding antibacterial activity with minimum inhibitory concentrations of 20 µg/mL for S. aureus, Bacillus subtilis, B. pertussis, as well as 40 µg/mL for H. pylori and P. aeruginosa. GO/ZnO nanocomposite’s bacterial resistance was mediated via nanoblade-edges, cellular rupture, and generation of reactive oxygen species. We concluded that a considerable quantity of oxidative stress created on the composite surface was involved in the bactericidal pathway and was responsible for eradicating the mature biofilm. ZnO NPs' dispersion in an aqueous solution was boosted by GO nanosheets, which also prevented aggregation and enhanced the anti-microbial performance.

In the present work, a novel sensitive sensor for hydrazine determination was introduced based on modifying a glassy carbon electrode with MoS2-QDs@Fe3O4/rGO nanocomposite. The synthesized MoS2-QDs@Fe3O4/rGO nanocomposite was analyzed by field emission scanning electron microscopy (FE-SEM), transmission electron microscope (TEM), FT-IR, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), vibrating-sample magnetometry (VSM), and Brunauer–Emmett–Teller (BET) technique. The proposed structure was confirmed by the above techniques. Cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry techniques were used for electrochemical investigations. The effective surface area of the modified electrode and the diffusion coefficient of hydrazine were obtained as 0.1213 cm2 and 4.42 × 10−6 cm2s−1, respectively. Finally, by using the DPV technique, was recorded the calibration curve for hydrazine. Under the optimized conditions, a linear range of 0.8–2190 µM, a limit of detection of 0.12 µM, Limit of Quantitation of 0.4 µM, and sensitivity of 0.0353μAμM−1 were obtained for hydrazine through the DPV technique using the proposed sensor.

To obtain even superior electromagnetic wave (EMW) absorption materials, research is currently focused on composite absorbers. The aim of this work is to prepare composite absorbers with multiple absorption mechanisms using 2D porous Ti3C2Tx MXene as a substrate. Here, porous Ti3C2Tx MXene nanosheets with a large layer spacing were formed through high-temperature molten salt treatment of layered Ti3C2Tx MXene nanosheets. Then, NiCo2O4 nanosheets were anchored onto the porous Ti3C2Tx MXene nanosheets through heat treatment, forming a heterogeneous structure of porous Ti3C2Tx MXene/NiCo2O4 (P-MXene/NiCo2O4). The heterogeneous interface between Ti3C2Tx MXene and NiCo2O4 nanosheets forms strong interfacial polarization, while NiCo2O4 connects the MXene layer to layer forming a conductive network structure. Furthermore, NiCo2O4 nanosheets suppress the self-stacking of porous Ti3C2Tx MXene nanosheets and improve impedance matching. As a result, P-MXene/NiCo2O4 offers excellent EMW absorption performance with a reflection loss (RL) value of − 64.7 dB at a matching thickness of 4.465 mm. This study provides a new idea for pretreating Ti3C2Tx MXene and constructing efficient composite absorbing materials for electromagnetic waves.

Graphene is a two-dimensional material with remarkable physicochemical characteristics. In particular, graphene is highly sensitive to its electronic and electrostatic environment. For these reasons, among various applications of graphene, its use as a sensitive material in field-effect transistors (FETs) is widely studied, especially for biodetection purposes. So, this review aims to introduce the reader to the state of the art of graphene-based materials for their applications in electrolyte-gated graphene field-effect transistors (EGGFETs) for biosensing applications. Among numerous ways to produce graphene-based materials for such devices, some of the most important, widely used methods are presented herein. After that, the working principle of graphene-based FETs is discussed and the various ways to tune graphene's electronic properties are presented. The fabrication methods are discussed, with an emphasis on inkjet printing which allows printing of EGGFETs from aqueous graphene oxide inks, providing that it is subsequently reduced to adjust the mobility of charge carriers and the doping state. Finally, some of the recent works concerning the use of FETs in biosensing applications are reviewed.

A sensing platform for the determination of chloramphenicol is put forward based on a nanocomposite of conductive polymer (polypyrrole), MWCNTs, and Ionic liquid (Ppy-MWCNTs-IL). The synthesized polypyrrole and its nanocomposite were characterized through FTIR spectroscopy, SEM, and HR-TEM. Polypyrrole possesses excellent conductivity compared to other insulating polymers and can be utilized to selectively interact with analyte through π-π interaction. MWCNTs are also known for their conductivity and high surface area which is essential for sensing purposes. The ionic liquid acts as a conductive binding agent which helps in preparing a uniform nanocomposite layer. Fabricated electrode gave excellent results for chloramphenicol with a detection limit of 8.94 μg L−1 and linear range of 30 – 700 μgL−1. Other analytical parameters such as repeatability and reproducibility (RSD 2.09 %) were also measured and found to be satisfactory. The stability of the nanocomposite film on the Indium tin oxide (ITO) electrode was attributed to the excellent film-forming capability of polypyrrole and ionic liquid that resulted in providing good shelf life (25 days). The fabricated sensor was further used to detect chloramphenicol in real water samples by spike recovery test.

Abstract not available

Role dopant anions and solvents in electropolymerized conducting polymers (CPs) on controlling the morphology of thin films and electrocatalytic activities to judge their suitability as low-cost counter electrodes (CE) of dye-sensitized solar cells ( DSSCs) was systematically investigated. Amongst various CPs such as polyaniline (PANI), polypyrrole (PPy), and PEDOT with sodium dodecyl sulfate (SDS) as a dopant, PEDOT was found to exhibit the best photovoltaic performance with a photoconversion efficiency (PCE) of 6.99 %. This was attributed to the best electrocatalytic activity due to the smallest ΔEp, most minor R1, and nano-morphology-assisted high surface area, as confirmed by CV, EIS, and FE-SEM investigations. Using PEDOT as CP, the nature of dopants such as SDS, TFSI, and ClO4 has also been found to control the electrocatalytic activities and the morphology of the fabricated thin films affecting overall photovoltaic performance DSSCs. Amongst the various CP-based CE fabricated using different dopants and solvents, PEDOT:TFSI thin films prepared in acetonitrile solvent and used as CE exhibited not only the best electrocatalytic activity as CE but also demonstrated the best photovoltaic performance with PCE of 7.0 %, which almost similar to that of DSSC utilizing Pt as CE with PCE of 7.1 %. Therefore, it was concluded that the nature of CP and dopant ions were vital factors in governing the electrocatalytic activities of the thin films to ensure their suitability as CE for optimal functioning and controlling the DSSC performance.

The present study has focused on designing and characterizing ten novel (SS1-SS10) hole transport materials (HTM) for perovskite solar cells (PSCs). The objective is to enhance power conversion efficiency (PCE) and improve these devices' durability. A systematic investigation has been carried-out to investigaye the optoelectronic properties of these HTMs. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) have been employed to analyze the structures and optical features of these designed HTMs. The calculations included the arrangement of frontier molecular orbitals (FMO), open-circuit voltages (Voc), the density of states (DOS), transition density matrix (TDM), power conversion efficiency (PCE), reorganizational energies of electrons and holes, charge transfer analysis, and molecular electrostatic potential (MEP). Newly designed molecules (SS1-SS10) exhibit promising optoelectronic features with narrower energy gap (ranges from 1.41 eV to 0.64 eV) and absorbed maximum absorption wavelength (546 nm) compared to the reference molecule which have a gap of 3.41 eV and wavelength of 414.88 nm. The designed molecules also have high open-circuit-voltage values of 0.92–1.08 and proficient hole and electron transport abilities making them strong candidates when blended with the polymer PC70BM. The computed value of R for λe is 0.0082. The lowest reorganisation energy for electrons appears in SS8, SS3, and SS5, showing strong charge mobility within the acceptor and donor sections. The reorganisation energy of hole (λh) for R was discovered to be 0.0060, among all the designed molecules SS6 has the highest λh value. The study highlights that efficient molecular design and strategy are necessary for developing desirable photovoltaic precursors best suited for perovskite organic solar cells. The modeled materials SS1-SS10 are recommended for future synthesis and development of cost-effective organic solar cell devices.

PEDOT:PSS is a conducting polymer with a wide variety of applications in the field of organic electronics. Over the past few years our group has developed PEDOT:PSS fibers with high electrical conductivity and robust mechanical properties, and we have observed changes in their properties that seemed to stem from seasonal changes in atmospheric relative humidity. In this work, we report the influence of relative humidity on the swelling, electrical conductivity and structure of wet-spun PEDOT:PSS fibers. The diameter of the fibers linearly increased with relative humidity up to the 70–80% range where the increase became exponential. The electrical conductivity reversibly decreased with increasing relative humidity with a similar linear and then exponential behavior. Additionally, an irreversible decrease (aging) in electrical conductivity was also observed. To gain more insight into the structural origin of these changes, wide angle x-ray scattering of the PEDOT:PSS fibers were gathered at different relative humidities in the 10–90% range so that the changes in structure could be observed in situ. On one hand, the lamella stacking distance of PEDOT and PSS chains increased linearly up to the 70–80% relative humidity range where the increase became exponential. On the other hand, the π-π stacking distance between PEDOT chains remained unaltered. We found that the changes in the lamella stacking distance were closely correlated to the changes observed for the diameter and electrical conductivity.

Nickel ferrite/coal-based carbon (NiFe2O4/CBC) composites were synthesized by using microwave irradiation and simple hydrothermal method. The effects of reaction conditions on particle size, morphology, magnetic, and microwave absorption properties of the NiFe2O4/CBC composites were systematically studied. In all NiFe2O4/CBC composites, NiFe2O4 microspheres with different shapes and sizes were anchored on the surface of CBC. By adjusting size of the NiFe2O4 particles, dielectric and magnetic properties of the NiFe2O4/CBC composites could be optimized simultaneously. For the NiFe2O4/CBC sample with the average particle size of NiFe2O4 to be 4.69 nm, when the thickness was 4.42 mm, the minimum reflection loss (RLmin) could reach − 63.15 dB at 9.89 GHz. Meanwhile, the maximum effective absorption bandwidth (EABmax) was 4.91 GHz (6.31–11.22 GHz) at a thickness of 5 mm, which almost covered the whole X-band. The s-shaped hysteresis loop of the sample revealed that it had typical superparamagnetic characteristics. The possible mechanism of microwave absorption was also discussed. Our NiFe2O4/CBC composites could be used as a new and efficient microwave absorption material.

In this work, a nanostructured electrode material based on copper metal decorated polyaniline nanowires (PANi NWs@Cu) was directly fabricated on a Pt (Pt/PANi NWs@Cu) microelectrode using a novel and effective two-step electrochemical procedure. Herein, the polyaniline nanowires were firstly electropolymerized on the Pt microelectrode using a cyclic voltammetry method, and the copper metal coated onto the polyaniline nanowires were fabricated via a chronoamperometry deposition to form the PANi NWs@Cu with an average diameter of 85 nm. The electrocatalytic activity showed that the as-synthesized PANi NWs@Cu can directly oxidize glucose in alkaline medium, which suggested that the PANi NWs@Cu can be applied as an artificial enzyme for development of a non-enzymatic electrochemical glucose sensor. Obtained results exhibits that the Pt/PANi NWs@Cu has the ability to directly detect glucose with a rapid response, high selectivity, good repeatability, excellent stability with a wide linear range of glucose concentration from 0.5 mM to 50.0 mM and a low detection limit of 94 μM. The developed Pt/PANi NWs@Cu-based electrochemical sensor also shows the ability to directly detect glucose in a 5% glucose intravenous infusion sample with an error of 1.21% from a labelled value.

Flexible or bendable energy storage devices have drawn great attention recently due to the great demand for the development of soft portable equipment. Conducting polymers (polypyrrole, polyaniline, polythiophene) are particularly interesting powder form candidates for active materials in such devices. A traditional slurry-based technology with low mass loadings (1 mg/cm2) is usually used. However, poor interparticle or particle-substrate connections influence the performance of devices during bending. Furthermore, increasing the mass loading (10 mg/cm2) of commercial-level electrode materials often has the problems of poor electrical and ionic conductivity, which will hinder their practical applications. The electrodeposition process of conducting polymers provides an alternate useful method to synthesize uniform and binder-free electrodes with high mass loadings. Here, electrochemically synthesized polypyrrole is proposed and investigated to increase the energy storage performance with high mass loadings. The electrodeposition polypyrrole electrode with a mass loading of 10 mg/cm2 demonstrates a competitive gravimetric capacitance of 265 F/g at a current density of 1 A/g. In the case of a symmetrical supercapacitor with E-PPy, the differences in the capacitance obtained with different electrode masses are insignificant (59.1 F/g for 2.4 mg/cm2 and 54.9 F/g for 10 mg/cm2). The assembled supercapacitor also possesses outstanding flexibility (as high as 96.3% capacitance retention at 2 A/g) upon bending to 140° for 10 cycles.

Lightweight, flexible and portable electronics, and wearable devices are recognized as the next-generation electronic devices. Rapid growth in the usage of such devices will add to electromagnetic interference (EMI) or EM pollution in an alarming magnitude. Hence, lightweight, hydrophobic, and flexible EMI shielding materials capable of effectively reducing EMI are urgently required. The present work reports fabrication of poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS) and polyvinylpyrrolidone (PVP) coated, carbonized electrospun polyacrylonitrile (PAN) nanofiber (CNF) and their flexible polydimethylsiloxane (PDMS) composites. The material showed excellent EMI shielding effectiveness of 44 dB in the frequency range of 8–26.5 GHz with a thickness of 0.06 mm due to the synergetic effect of CNF matrix, PEDOT: PSS, and PVP. It also exhibited a high absolute EMI SE of 5678 dB cm2 g−1 with low loading of PEDOT:PSS-PVP. Here, PEDOT:PSS-PVP/CNF shows EMI shielding through an absorption dominated mechanism rather than reflection. These findings indicate the potential of these composites as thin, flexible, hydrophobic, and lightweight EMI shielding materials for practical applications.

Metal basic carbonate materials (M-CH), which are employed as precursors of metal hydroxides/oxides, have recently popularity as battery-type electrodes due to their exceptional energy storage performance. However, a unitary metal basic carbonate is insufficient to meet today’s challenges. To make hybrid electrochemical capacitors, multiple-metals basic carbonate materials must to be designed and synthesized. Herein, a one-step hydrothermal method is used to produce Co basic carbonate doped with Ni and Zn (Co, Ni, Zn-CH). The results of X-ray diffractometer refinement demonstrate that following Ni, Zn co-substitution for Co ions, the crystal cell parameters of Co-CH drop. In a three-electrode system, such changes facilitate the electronic transfer, resulting in a high specific capacity of 91.80 mAh g−1 at 1 A g−1, a high rate performance of 52.42% at 20 A g−1, and a 5000-cycle stability of 91.85% at 10 A g−1. Furthermore, an assembled hybrid electrochemical capacitor (HEC) can provide an energy density of 36.10 Wh kg−1 at a power density of 1009.65 W kg−1 and a capacity retention of up to 91.93% after 5000 cycles. Two homemade hybrid electrochemical capacitors connected in series impressively maintain eight LEDs glowing for 30 min, demonstrating superior energy storage capability.

Camphorsulfonic acid doped polyaniline (PANI)-polystyrene (PS)-Graphene oxide (GO) nanocomposite films are synthesized by the solution casting technique, and the thickness obtained is approximately about ∼ 0.85 mm. The prepared composite films are investigated by X-Ray diffraction (XRD), Raman spectroscopy, and Transmission electron microscopy (TEM). The electrical conductivity is measured using the Four-probe technique, which yields the percolation threshold and critical exponent at 0.09 wt% and 0.6 respectively. The EMI shielding effectiveness (SE) of PANI-PS-GO composite films is investigated in the microwave of 8 – 12 GHz frequency range (X-band range) and shows significant results. The results demonstrate that the interfacial polarization and charge transformation between the polymer matrix and GO contribute to enhanced shielding efficiency in the composite. The EMI SE of the composite is found to be 40 dB for the PANI-PS-GO nanocomposite film containing 1.5 wt% GO. The obtained results recommend that the proposed polymer nanocomposite system can be of immense potential as an efficient candidate for the novel EMI shielding materials in the X-band frequency range.

Organic heterocyclic fused ring compounds possess remarkable nonlinear optical (NLO) amplitude, are potentially employed in optical computing and nano-photonics. Herein, ITTBCR1 was quantum chemically modified into a series of novel D-π-A configured NLO compounds (ITTBCD2-ITTBCD6) by substituting various efficient donor moieties. To investigate the electronic, photophysical, and NLO properties, ITTBCR1 and ITTBCD2-ITTBCD6 were subjected to density functional theory (DFT) and time-dependent DFT calculations at M06/6–311 G(d,p) level of theory. Frontier molecular orbital analysis (FMOs) illustrated that the newly designed chromophores exhibit smaller energy gaps (1.625–2.013 eV) compared to ITTBCR1 (2.384 eV). The global reactivity parameters estimated through Egap revealed higher softness (σ = 0.49–0.61 Eh) values, implying enhanced reactivity of ITTBCD2-ITTBCD6 compounds. An efficient push-pull mechanism disclosed positive charges on donors and π-spacers, while the acceptor moieties exhibited a negative charge. The presence of charge separation states and the substantial involvement of molecular orbitals in the charge transfer were explored by natural bond orbitals (NBOs), transition density matrix and density of states analyses. The UV-Vis study of the designed compounds displayed larger bathochromic shifts with wider absorption spectra. Also, a significantly large NLO behavior was found in all the novel entities (ITTBCD2-ITTBCD6), thus potentially employable as NLO materials. Inclusively, compound ITTBCD5 demonstrated highest linear polarizability (〈α〉 = 2.250 ×103 a.u.), and first hyperpolarizability (βtot = 70.155 ×104 a.u.), therefore proposed as the most proficient NLO material. Comparative study for NLO properties at various functional showed that at M06/6–311 G (d,p) significant NLO results could be obtained. The current investigation revealed that by controlling the type of donor motifs, numerous NLO compounds can be designed, which are equally productive in hi-tech NLO applications.

Electrochemical Energy Storage (EES) technologies are playing a significant role in the aspirations to decrease the usage of fossil fuels and move toward an environmentally conscious society. Due to the importance of EES technologies, more researchers are looking for an efficient and effective electrode material, which is the most important part of the EES system that possibly could result in much-needed advancements in the field. However, incoming researchers have a diverse backgrounds and as newcomers to the electrochemical community, they sometimes lack familiarity with the core concepts, well-established procedures, and methodologies that define the standards of the discipline. This issue's importance has been acknowledged, and various publications have been written to guide researchers in doing accurate evaluations. However, to the best of our knowledge, even though these publications demonstrate the methodologies and procedures for approaching the existing challenges none of them address the offered topic with an actual example. To address this gap, we present a step-by-step procedure for the electrochemical analysis of polypyrrole, a widely utilized conducting polymer with significant potential as an electrode material for supercapacitors and batteries.

The electrochemical performances of three types of polyaniline (PANI)-based films developed as pH-sensing electrodes were evaluated and compared. PANI emeraldine base (PANI-EB), PANI emeraldine salt (PANI-ES), and PANI-ES/polyvinyl acetate (PVAc) composite films were spin coated on fluorine-doped tin oxide (FTO) glass substrates to fabricate pH-sensing electrodes. The surface morphology, wetting properties, and electrochemical properties were characterized and compared. Unprotonated PANI-EB films had a regular structure with residual flakes, whereas protonated PANI-ES and PANI-ES/PVAc films exhibited globular and porous structures, respectively. All PANI-based films adhered well to the FTO substrate. Water contact angles indicated the hydrophobic characteristic of the PANI-EB films and the hydrophilicity of the PANI-ES films, which could affect their stability in buffered solutions of different pH. The PANI-ES/PVAc films exhibited improved stability because of the hydrophobic PVAc. The PANI-ES/PVAc electrodes exhibited a significantly higher pH sensitivity of 100 mV pH−1 than those of the single-component PANI-EB and PANI-ES electrodes (57 and 65 mV pH−1, respectively) in the pH range of 3.0–8.0, which could be attributed to the non-equilibrium protonation/deprotonation of nitrogen atoms in the PANI structure. Moreover, the PANI-ES/PVAc electrodes also exhibited good reproducibility and selectivity to H+ over certain other ions and molecules (e.g., glucose).

The emergence of drug-resistant bacteria threatens human health, and photodynamic therapy and photothermal therapy are promising methods to eliminate drug-resistant bacteria. However, the key to photodynamic and photothermal therapy is efficient photosensitizers, which are not fully developed. Herein, a novel cationic zinc aminophthalocyanine, zinc tetrakis(dimethyloctylammonium bromide) phthalocyanine (DMAZnPc-C8), is synthesized and investigated. The structures of the cationic zinc aminophthalocyanines are characterized by Fourier transform infrared spectrometer (FTIR), nuclear magnetic resonance hydrogen spectrum (1H NMR)，Mass spectrometry and X-ray spectroscopy. The singlet oxygen generation ability, photo-thermal properties and antibacterial properties against methicillin-resistant Staphylococcus aureus (MRSA) of cationic zinc aminophthalocyanine nanoparticles (DMAZnPc-C8 NP) in aqueous dispersion are investigated. The results show that the maximum ultraviolet absorption wavelength of DMAZnPc-C8 in DMSO is at 764 nm, and DMAZnPc-C8 shows good response to near-infrared light. DMAZnPc-C8 NP has good photo-thermal performance. After irradiation with an 808 nm laser (0.5 W/cm2) for 10 min, the temperature of DMAZnPc-C8 NP dispersion (0.05 mg/mL) is increased by 7.4 °C. And DMAZnPc-C8 NP has good singlet oxygen production capacity. DMAZnPc-C8 NP has excellent antibacterial effect against MRSA-resistant bacteria. When the concentration of DMAZnPc-C8 NP is 0.03 mg/mL, the growth of MRSA is almost completely inhibited after 10 min of laser irradiation at 808 nm (0.5 W/cm2), the antibacterial rate reach over 99 %. This study shows that cationic zinc aminophthalocyanine has promising application prospects in the field of anti-drug-resistant bacteria.

Bulk heterojunction organic photovoltaic cells (OPVs), which are based on anthracene-containing poly (p-phenylene-ethynylene)-alt-poly (p-phenylene-vinylene) (PPE-PPV) polymer denoted (AnE-PVstat) and phenyl C60 butyric acid methyl ester (PCBM). The active layer thickness was varied from 100 nm to 300 nm. The solar cell parameters and magnetoconductance (MC) effect were analyzed, and the results showed a positive MC effect (+MC) for active layer thicknesses of 100 nm, 150 nm, and 200 nm, while a negative MC effect (-MC) was observed for thicknesses of 250 nm and 300 nm. The Power conversion efficiency (PCE) of 4 ℅ was achieved for an active layer thickness of 200 nm. The triplet-doublet quenching (TQD) model was used to describe the MC effect, which is influenced by triplet-charge reactions on the current based on density matrix formalism using the Stochastic Liouville Equation. The dissociation and recombination rates of the T-D pairs increased with the thickness for thinner layers (100, 150, 200 nm) while decreased for thicker layers (250 nm and 300 nm).