HCl Doping Research Articles

Impact of hydrochloric acid doping on polyaniline conductivity and piezoelectric performance in polyaniline/bismuth oxyiodide nanocomposites

This study investigates the impact of hydrochloric acid (HCl) doping, ranging from 0.2 M to 1.25 M, on the conductivity of polyaniline (PANI) and the piezoelectric performance of polyaniline/bismuth oxyiodide (PANI/BiOI) nanocomposites (NCs). Two distinct methods for fabricating NCs based on PANI and bismuth oxyiodide (BiOI) are proposed. Two distinct methods for fabricating PANI/BiOI NCs are proposed, and their optical and electrical properties are systematically examined. The direct allowed energy bandgap of the NCs is found to be approximately 1.9 eV. The piezoelectric performance, attributed to the 2D Janus structure of BiOI, is explored in detail, with the bulk piezoelectric coefficient measured at 1.43 (65) pm/V. Sensitivity to pressure interaction reached 21.1 (92) mV/bar, and the generated power was 5.09 nW for air pressure excitation in a composite consisting of 37.5 wt% BiOI and 62.5 wt% PANI doped with 0.2 M HCl, fabricated in-situ. The results demonstrate precise control over key parameters, including the fabrication method, sample thickness, HCl doping concentration, and BiOI content, highlighting the significant potential for enhancing nanogenerator functionality. These findings provide valuable insights into improving the performance of piezoelectric materials for energy harvesting technologies.

Zn-doped bentonite catalysts for waste engine oil cracking: Thermal treatment offers a cleaner alternative to acid activation

This study investigates the cracking of waste engine oil (WEO) using bentonite clay (BC) activated through acid and thermal methods, as well as with Zn-doped BCs. Acid activation with 1 M HCl and Zn doping did not alter the BC catalyst’s structure. XRD and SAED analyses confirmed the crystallinity, while TEM showed partial destruction of the layered structure. XRF analysis indicated reduced Al and Si content upon Zn-doping due to high cation exchange capacity. Zn-doping decreased surface area and pore volume but increased acidic sites in acid-treated catalysts, although Zn suppressed these sites in calcined BC. Zn-doped catalysts displayed higher thermal stability. Cracking WEO at 450 °C for 45 min, with and without catalysts, yielded high liquid product recovery (72.6 %–82.8 %), primarily carboxylic acids and aromatics. This demonstrates the potential of Zn-doped BC as an effective catalyst for converting WEO into valuable products, aiding waste management and resource utilization.

PREPARATION AND CHARACTERIZATION OF NOVEL ES-PANI/GLUCOMANNAN COMPOSITE: STUDY OF CONDUCTIVITY

The synthesized of emeraldine-salt-polyaniline composites were synthesized using in situ chemical polymerization to form the ES-PANI-glucomannan composites and the ES-PANI-cellulose composites using the batch, and spray method. Polyaniline can be composed of glucomannan and cellulose matrics because they are abundant, cheap, and environmentally friendly. The Ammonium peroxodisulfate (APS) is used as an initiator for the process of oxidative polymerization of aniline and using HCl and HCOOH doping. Characterization of ES-PANI-Glucomannan and ES-PANI-Cellulose composites using FT-IR and conductivity test using LCR-meter. The ES-PANI-Glucomannan composite used the HCl doped batch method, and the conductivity values optimum ​​were 3,68 x 10-3 S/cm, the ES-PANI-Glucomannan composites used the HCOOH doped batch method, the conductivity values optimum ​​were 5,87 x 10-4 S/cm, the ES-PANI-Cellulose composites used the HCl doped batch method, the conductivity values ​​were 1,08 x 10-1 S/cm, the ES-PANI-Glucomannan composites used the HCl doped spray method, the conductivity values optimum ​​were 1,23 x 10-7 S/cm, and the ES-PANI-Glucomannan composites used the HCOOH doped spray method, the conductivity values ​​ optimum were 9,20 x 10-8 S/cm. The results of the study showed that the highest conductivity values ​​ were found for the ES-PANI-Glucomannan and ES-PANI-Cellulosa composites in the batch method of HCl, and HCOOH doping.

Effect of Ethanolamine and HCl on structural and optical properties of Nickel oxide thin films

In the present work, Nickel Oxide thin films were prepared by spin coating technique. The effects of Ethanolamine and HCl on structural and optical properties of NiO thin films are studied. The structural properties of NiO thin films were examined by X-ray Diffraction (XRD). The amorphous nature of NiO thin films were observed from XRD pattern. FESEM studies of the surface morphology of NiO thin films exhibits smooth and uniform surface with average particle size of 200 nm for Ethanolamine doping sample and 300 nm for HCl doping sample. The functional groups and surface roughness of NiO thin films were investigated by FTIR and 3 D Laser Profilometry. The surface roughness of the prepared samples increases with increasing thickness from 4.49 μm to 6.81 μm. The optical characteristics of the samples were determined by UV Visible Spectrophotometer. This results shows that the prepared NiO thin films exhibits high optical transparency.

Fabrication of conjugated triblock copolymer/single-walled carbon nanotubes composite films with enhanced thermoelectric performance

Aniline tetramer-b-polyethylene glycol-b-aniline tetramer (APA), a kind of conjugated triblock copolymer, has attracted attention in the thermoelectric (TE) conversion field owing to its typical n-type property, well-defined molecular structure and excellent dissolvability. Here, APA is used as n-type dopant for tuning the TE properties of the single-walled carbon nanotubes (SWCNTs), and APA/SWCNT TE composites are fabricated by a facile solution mixing method. Scanning electronic microscopy and transmission electron microscope, X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy, UV–Vis spectroscopy and thermogravimetric analysis are utilized to elucidate the morphology, elemental composition, structure and thermal stability of the composites, respectively. For one thing, APA provides enough negative charge at high temperature to convert the SWCNTs into n-type material, and a maximum Seebeck coefficient of −49.0 ± 0.3 μV/K at 125 °C for APA/SWCNT (40:100) was obtained. For another thing, HCl doping further improves the TE properties of APA/SWCNT, and the highest power factor of 106.3 μW/(m·K2) is obtained at 100 °C for APA/SWCNT (10:100). Therefore, this work provides a facile method using a new dopant APA to fabricate n-type APA/SWCNT composite with enhanced thermoelectric performance.

Graphene Aerogels for In Situ Synthesis of Conductive Poly(para-phenylenediamine) Polymers, and Their Sensor Application.

In this study, macroporous graphene aerogels (GAs) were synthesized by chemical reduction of graphene oxide sheets and were used as a support material for in situ synthesis of conductive poly(para-phenylenediamine) (p(p-PDA)). The in situ synthesis of p(p-PDA) in GA was carried out by using a simple oxidation polymerization technique. Moreover, the prepared conductive p(p-PDA) polymers in the networks of GAs were doped with various types of acids such as hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), phosphoric acid (H3PO4), respectively. The prepared GA and different acid-doped forms as GA/p(p-PDA) composites were characterized by FT-IR, TGA, and conductivity measurements. The observed FT-IR peaks at 1574 cm−1, and 1491 cm−1, for stretching deformations of quinone and benzene, respectively, confirmed the in situ synthesis of P(p-PDA) polymers within GAs. The conductivity of GAs with 2.17 × 10−4 ± 3.15 × 10−5 S·cm−1 has experienced an approximately 250-fold increase to 5.16 × 10−2 ± 2.72 × 10−3 S·cm−1 after in situ synthesis of p(p-PDA) polymers and with HCl doping. Conductivity values for different types of acid-doped GA/p(p-PDA) composites were compared with the bare p(p-PDA) and their undoped forms. Moreover, the changes in the conductivity of GA and GA/p(p-PDA) composites upon CO2 gas exposure were compared and their sensory potential in terms of response and sensitivity, along with reusability in CO2 detection, were evaluated.

Assembly of Conductive Polyaniline Microstructures by a Laser-Induced Microbubble.

Micropatterns of conductive polymers are key for various applications in the fields of flexible electronics and sensing. A bottom-up method that allows high-resolution printing without additives is still lacking. Here, such a method is presented based on microprinting by the laser-induced microbubble technique (LIMBT). Continuous micropatterning of polyaniline (PANI) was achieved from a dispersion of the emeraldine base form of PANI (EB-PANI) in n-methyl-2-pyrrolidone (NMP). A focused laser beam is absorbed by the EB-PANI nanoparticles and leads to formation of a microbubble, followed by convection currents, which rapidly pin EB-PANI nanoparticles to the bubble/substrate interface. Micro-Raman spectra confirmed that the printed patterns preserve the molecular structure of EB-PANI. A simple transformation of the printed lines to the conducting emeraldine salt form of PANI (ES-PANI) was achieved by doping with various acid solutions. The hypothesized deposition mechanism was verified, and the resulting structures were characterized by microscopic methods. The microstructures displayed conductivities of 3.8 × 10-1 S/cm upon HCl doping and 1.5 × 10-1 S/cm upon H2SO4 doping, on par with state-of-the-art patterning methods. High fidelity control over the width of the printed lines down to ∼650 nm was accomplished by varying the laser power and microscope stage velocity. This straightforward bottom-up method using low-power lasers offers an alternative to current microfabrication techniques.

Strong acid doping for the preparation of conductive polyaniline nanoflowers, nanotubes, and nanofibers

High-pressure CO2-supported aniline polymerization was thoroughly investigated with a focus on the effect of acid doping on the morphology of the prepared polyaniline (PANI). The polymerization was conducted using HCl at three different concentrations and H2SO4 as the doping agents. Self-assembled HCl-doped PANI nanoflowers (PANNFL) were synthesized for the first time by high-pressure CO2-supported polymerization in the presence of 2 M HCl. Furthermore, HCl-doped PANI nanotubes (HCl-PANNTs) and nanofibers (HCL-PANNFs), as well as sulfuric acid-doped PANI nanofibers (SUA-PANNFs), were successfully prepared by changing either the acidity of the reaction or the doping agent. With 0.1 M HCl doping, circular and rectangular cross-sectional HCl-PANNTs with a wall thickness of 40 nm were prepared. Upon increasing the acid concentration to 2 M HCl, the morphology of the PANI structures transformed from nanotubes to nanoflowers while retaining the same wall thickness. Further increasing the HCl concentration resulted in a mixture of nanosheet structures, and the amount of nanoflowers decreased. Additionally, 1.1 M H2SO4 doping produced nanofibers (SUA-PANNF) with an average fiber diameter of 45 nm. All the prepared PANIs had partially crystallized structure in the emeraldine salt form. Additionally, the crystallinities of the prepared HCl-PANI structures were higher than that of the SUA-PANI structure. It was clearly observed that the type of acid dopant and the acid concentration affected the polymerization yield (PY) and could control the electrical conductivity (EC). The highest EC, i.e., 3.7 S/cm, was exhibited by PANI prepared with 5 M HCl.

Improvement of open-circuit voltage of poly(3,4-ethylenedioxythiophene): Poly(styrenesulfonate)/α-CsPbI3 based device by mixing different concentrations of hydrochloric acid and hydroiodic acid additives

Abstract The open-circuit voltage (Voc) of all-inorganic perovskite solar cells (PSCs) based on poly(3,4-ethylenedioxythiophene): polystyrene sulfonate (PEDOT:PSS)/α-CsPbI3 architectures doped with hydroiodic acid (HI) is usually unsatisfactory. Herein, a sophisticated concentration ratio of HI and HCl additives were investigated to improve the Voc of the all-inorganic PSCs devices. The SEM and XRD results showed that perovskite thin films with fewer pinholes and higher crystallinity are fabricated. Furthermore, we found that the best Voc of 0.92 V and power conversion efficiency (PCE) of 5.69% were obtained with formed using a HCl volume percentage of 6 vol%, which is higher than α-CsPbI3 solar cells with pristine HI additives (0.87 V of Voc). It is believed that take a minute quantity HCl doping at least for high-quality inorganic perovskite thin films growth and improves the Voc of PEDOT:PSS/α-CsPbI3 PSCs device.

Rhenium Diselenide (ReSe2) Near-Infrared Photodetector: Performance Enhancement by Selective p-Doping Technique.

In this study, a near‐infrared photodetector featuring a high photoresponsivity and a short photoresponse time is demonstrated, which is fabricated on rhenium diselenide (ReSe2) with a relatively narrow bandgap (0.9–1.0 eV) compared to conventional transition‐metal dichalcogenides (TMDs). The excellent photo and temporal responses, which generally show a trade‐off relation, are achieved simultaneously by applying a p‐doping technique based on hydrochloric acid (HCl) to a selected ReSe2 region. Because the p‐doping of ReSe2 originates from the charge transfer from un‐ionized Cl molecules in the HCl to the ReSe2 surface, by adjusting the concentration of the HCl solution from 0.1 to 10 m, the doping concentration of the ReSe2 is controlled between 3.64 × 1010 and 3.61 × 1011 cm−2. Especially, the application of the selective HCl doping technique to the ReSe2 photodetector increases the photoresponsivity from 79.99 to 1.93 × 103 A W−1, and it also enhances the rise and decay times from 10.5 to 1.4 ms and from 291 to 3.1 ms, respectively, compared with the undoped ReSe2 device. The proposed selective p‐doping technique and its fundamental analysis will provide a scientific foundation for implementing high‐performance TMD‐based electronic and optoelectronic devices.

The influence of HCl on the evaporation rates of H2O over water ice in the range 188 to 210 K at small average concentrations

Abstract. The evaporation flux Jev(H2O) of H2O from HCl-doped typically 1.5 µm or so thick vapor-deposited ice films has been measured in a combined quartz crystal microbalance (QCMB)–residual gas mass spectrometry (MS) experiment. Jev(H2O) has been found to show complex behavior and to be a function of the average mole fraction χHCl of HCl in the ice film ranging from 6×1014 to 3×1017 molecule cm−2 s−1 at 174–210 K for initial values χHCl0 ranging from 5×10-5 to 3×10-3 at the start of the evaporation. The dose of HCl on ice was in the range of 1 to 40 formal monolayers and the H2O vapor pressure was independent of χHCl within the measured range and equal to that of pure ice down to 80 nm thickness. The dependence of Jev(H2O) with increasing average χHCl was correlated with (a) the evaporation range rb∕e parameter, that is, the ratio of Jev(H2O) just before HCl doping of the pure ice film and Jev(H2O) after observable HCl desorption towards the end of film evaporation, and (b) the remaining thickness dD below which Jev(H2O) decreases to less than 85 % of pure ice. The dependence of Jev(H2O) with increasing average χHCl from HCl-doped ice films suggests two limiting data sets, one associated with the occurrence of a two-phase pure ice/crystalline HCl hydrate binary phase (set A) and the other with a single-phase amorphous HCl∕H2O binary mixture (set B). The measured values of Jev(H2O) may lead to significant evaporative lifetime extensions of HCl-contaminated ice cloud particles under atmospheric conditions, regardless of whether the structure corresponds to an amorphous or crystalline state of the HCl∕H2O aggregate.

Polyaniline/clay nanocomposites. A comparative approach on the doping acid and the clay spacing technique

Polyaniline/clay nanocomposites (PCNs) have been synthesized by oxidative polymerization of aniline by using two different clay treatment techniques (mechanical agitation and ultrasonication), as well as two different doping acids (hydrochloric acid – HCl – and dodecylbenzene sulfonic acid – DBSA –). The effect of both conditions on their chemical nature, structure and morphology has been studied by Raman spectroscopy, X-ray Diffraction (DRX), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). PCNs electrical conductivity was measured by the 4-probe technique. The results reveal that the type of clay treatment shows no impact on the PCNs morphology, but it does determine their final structure – either intercalation or exfoliation – which has a remarkable effect on the electrical conductivity. Moreover, the doping acid presented a strong influence on both morphology and electrical conductivity of the prepared PCNs. In this work, HCl doping and ultrasonication are highlighted as the optimal PCN synthesis conditions, since the highest electrical conductivity is reached with less time and energy consumption.

Wide-Range Controllable Doping of Tungsten Diselenide (WSe2) based on Hydrochloric Acid Treatment

In recent years, chemical doping based on the charge-transfer phenomenon has been actively studied for transition-metal dichalcogenide (TMD) materials owing to its simplicity and efficiency. However, these chemical-doping techniques have been controlled mostly in a high-doping-concentration (degenerate) regime, consequently limiting the use of the techniques to TMD devices. Herein we report on the wide-range-controllable p-type doping of WSe2 based on hydrochloric acid (HCl) treatment. The doping concentration was controlled broadly between 1.67 × 1011 cm–2 and 1.32 × 1012 cm–2 by adjusting the concentration of the HCl solution. We then confirmed that the performances of the WSe2-based transistor and photodetector devices were improved (increases in the threshold voltage, field-effect mobility, on-current, and photoresponsivity with the doping concentration). Finally, we alleviated the degradation of the HCl doping effects in air by providing protection from the moisture in the air by using poly(methyl me...

Doping-enhanced dipolar dynamics in ice V as a precursor of hydrogen ordering in ice XIII

Dielectric spectroscopy measurements are carried out in the temperature range from about 100 to 145 K on nominally pure ice V as well as on crystals doped with KOH and with HCl in order to investigate their reorientation dynamics at ambient pressure. The orientational glass transition temperature of pure ice V is detected at 123 K, in agreement with previous indications from calorimetry. KOH doped ice V displays an about 60-fold enhanced hydrogen dynamics and the dipolar relaxation induced by HCl doping is even by a factor of about 40 000 faster than that of the undoped material. The phase transition of HCl doped ice V to ice XIII is accompanied by a significant reorientational slowdown and a pronounced freeze-out of the electrical susceptibility. The results obtained near this transition are discussed in relation to other order/disorder ice pairs such as ice I/XI and ice XII/XIV.

Development of VOCs Gas Sensor Using PANi/PMMA Blend Film for Environment Monitoring

This work presents development of chemiresistor gas sensor based on polyaniline (PANi) blending with poly(methyl methacrylate) (PMMA) thin film for identification of volatile organic compounds (VOCs) relevant to environmental monitoring. The investigated VOCs are including acetone, methanol, ethanol and ammonia. The gas sensors are prepared by solution mixing between non-conducting form of PANi and PMMA in presence of NMP solution. The mixed solution is spun on aluminum interdigitated electrodes and converted into conducting form using HCl doping. Their sensitivity is measured at room temperature by applying constant voltage and measuring response current in the presence of target gases. The results show that PANi/PMMA blend film has higher surface roughness and porous structure leading to higher response to VOCs gases when compared to pure PANi thin film. The PANi/PMMA blend film exhibits the highest response to ammonia and the lowest to acetone vapor. It response shows little different between ethanol and acetone vapor. The different response characteristics to VOCs of PANi/PMMA blend film indicate that it can be used as active layer for room temperature VOCs sensor.

Dynamics enhanced by HCl doping triggers full Pauling entropy release at the ice XII-XIV transition.

The pressure–temperature phase diagram of ice displays a perplexing variety of structurally distinct phases. In the century-long history of scientific research on ice, the proton-ordered ice phases numbered XIII through XV were discovered only recently. Despite considerable effort, none of the transitions leading from the low-temperature ordered ices VIII, IX, XI, XIII, XIV and XV to their high-temperature disordered counterparts were experimentally found to display the full Pauling entropy. Here we report calorimetric measurements on suitably high-pressure-treated, hydrogen chloride-doped ice XIV that demonstrate at the maximum 60% of the Pauling entropy is released at the transition to ice XII. Dielectric spectroscopy on undoped and on variously doped ice XII crystals reveals that addition of hydrogen chloride, the agent triggering complete proton order in ice XIV, enhances the precursor dynamics strongest. These discoveries provide new insights into the puzzling observation that different dopants trigger the formation of different proton-ordered ice phases.

Synthesis, Characterization and Anticorrosion Performances Study of Different Acid Doping Polyaniline

Different polyaniline micro/nanostructures were prepared in by oxidative polymerization doped with different acids like citric acid (C6H8O7), H3PO4 and HCl. The samples were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and UV–Visible spectral techniques. The rod-like composites, microspheres and nanofiber of polyaniline could be synthesized by different doting. The corrosion studies were carried out on steel plates coated with epoxy coatings containing polyaniline prepared with acid doping and no acid doing. Corrosion protection of these epoxy coatings containing prepared polyaniline (PANI) on steel was studied by Tafel polarization test in 3.5wt% sodium chloride (NaCl) aqueous solution. The results indicated that coatings prepared from acid doped polyaniline particles were found to exhibit excellent corrosion resistance much superior to no acid doped PANI in aggressive environments, and the epoxy coating containing PANI obtained in HCl doping had the best performance of the corrosion protection in all systems under investigation. The possible protective mechanism of PANI was discussed.

One-pot synthesis of polyaniline doped with transition metal ions using H2 O2 as oxidant

Polyanilines (PANIs) doped with Zn2+ and Cu2+ were synthesized by H2O2 oxidative polymerization of aniline in the presence of corresponding metal chloride in solution. The products were characterized by elemental analysis, UV-Vis-NIR, FTIR and Raman spectroscopies. Scanning electron micrograph was employed to examine the morphology of PANIs fabricated in the presence of different transition metals. Experimental results showed that transition metal ions had been successfully incorporated into the polymer, and there was a strong interaction between the transition metal ions and the PANI chains. The electrical conductivity of PANI doped with Zn2+ and Cu2+ is 0.37 and 0.21 S/cm, respectively, which is higher than that of HCl doping PANI corresponding to 0.052 S/cm. The cyclic voltammetric study has indicated that incorporation of metal ions in PANI backbone results in increasing of specific capacitance compared to that of HCl doping PANI. Copyright © 2014 John Wiley & Sons, Ltd.

Ultrathin polypyrrole nanosheets doped with HCl as counter electrodes in dye-sensitized solar cells

Ultrathin polypyrrole nanosheets (UPNSs) were synthesized by chemical oxidation via organic single-crystal surface-induced polymerization (OCSP) using sodium decylsulfonate (SDSn) as a template. This process yields mass-producible, inexpensive materials that are suitable for flexible devices. UPNSs were deposited onto transparent, conductive oxide glasses for use as catalytic counter-electrodes (CEs) in dye-sensitized solar cells. These electrodes boast 94% transmittance against that of Pt CEs. Hydrochloric acid (HCl, 35 wt%), applied in the vapor state as a post-doping process, was used to improve the catalytic activity of the electrodes. This treatment enhanced the catalytic activity of UPNSs by increasing their conductivity by 8 S cm−1, with a 7.4% increase in the level of nitrogen doping. The Tafel polarization and impedance results support the enhancement of catalytic activity due to HCl doping. Dye-sensitized solar cells (DSSCs) employing the HCl-enhanced UPNS CEs showed a power conversion efficiency (AM 1.5, 100 mW cm−2) of 6.8%, which is 19.3% greater than the untreated case and comparable to that of Pt CE-based DSSCs.

Ammonia sensing by hydrochloric acid doped poly(m-aminophenol)–silver nanocomposite

Processable poly(m-aminophenol) (PmAP) was synthesized using ammonium persulfate oxidant in 0.6 M sodium hydroxide solution at room temperature. Then, in situ PmAP–silver nanocomposite film was obtained by casting PmAP film from dimethyl sulfoxide with silver hydroxide ammonia mixture at 140 °C. The nanocomposite film was doped with hydrochloric acid (HCl) by general solution doping technique. The undoped and HCl-doped films were characterized by ultraviolet visible spectroscopy, Fourier transformed Infrared spectroscopy, transmittance electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction analysis. Spectroscopic characterizations confirmed that the PmAP was doped by silver nanoparticles and it was further doped by HCl used. So, the synthesized PmAP–silver nanocomposite showed a conductivity of 1.01 × 10−6 S/cm, which was increased to 3.27 × 10−4 S/cm after HCl doping. The well dispersed silver nanoparticles with average size 130–150 nm was observed by SEM and TEM analysis. Unlike conventional ammonia sensor here, the resistivity of the nanocomposite film was decreased on exposure to ammonia gas and the sensing properties of the HCl-doped nanocomposite films were also reproducible. It can be seen that the % response of doped nanocomposite was unchanged while, the response time was decreased with increasing ammonia vapor concentrations in air. The ammonia-sensing characteristics of the HCl-doped nanocomposite film was explained on the basis of a proposed mechanism.