Carbon Paint Research Articles

Off-Grid Electrogenerated Chemiluminescence with Customized p-i-n Photodiodes.

Electrochemiluminescence (ECL) is the generation of light induced by an electrochemical reaction, driven by electricity. Here, an all-optical ECL (AO-ECL) system is developped, which triggers ECL by the illumination of electrically autonomous "integrated" photoelectrochemical devices immersed in the electrolyte. Because these systems are made using small and cheap devices, they can be easily prepared and readily used by any laboratories. They are based on commercially available p-i-n Si photodiodes (≈1€unit-1), coupled with well-established ECL-active and catalytic materials, directly coated onto the component leads by simple and fast wet processes. Here, a Pt coating (known for its high activity for reduction reactions) and carbon paint (known for its optimal ECL emission properties) are deposited at cathode and anode leads, respectively. In addition to its optimized light absorption properties, using the commercial p-i-n Si photodiode eliminates the need for a complicated manufacturing process. It is shown that the device can emit AO-ECL by illumination with polychromatic (simulated sunlight) or monochromatic (near IR) light sources to produce visible photons (425nm) that can be easily observed by the naked eye or recorded with a smartphone camera. These low-cost off-grid AO-ECL devices open broad opportunities for remote photodetection and portable bioanalytical tools.

Fabrication of a carbon cloth-based FeS nanosystem for simultaneous removal of Cr(VI) and microplastics

As two kinds of environmental pollutants, hexavalent chromium (Cr(VI)) and microplastics could be simultaneously released into the environment through agricultural production, industrial wastewater, and domestic sewage, resulting in combined pollution. Therefore, it was an important challenge to remove both Cr(VI) and microplastics simultaneously and effectively reduce their environmental impacts. In this study, ferrous sulfide (FeS) was fabricated by hydrothermal treatment and uniformly loaded on the surface of carbon cloth (CC) by using the conductive carbon paint (CCP) to obtain a nanosystem named as CC/CCP/FeS. Therein, FeS could provide electrons and have a high reduction capability for Cr(VI). CC could decrease the impedance of the nanosystem to 30 Ω, accelerate the transfer of electrons, and effectively solve the agglomeration of FeS. Importantly, CC/CCP/FeS could remove both Cr(VI) and microplastics in water at the same time, after which the resulting system could be conveniently separated from the water. The removal efficiencies of CC/CCP/FeS with nine layers for Cr(VI) and microplastics could reach 96 and 100 % by filtration, respectively. Additionally, pot experiment results indicated that CC/CCP/FeS could promote the growth of water spinach and reduce its Cr content from 273 to 31 mg/kg. Therefore, this research provides an effective method to simultaneously remove Cr(VI) and microplastics, which may have a huge application prospect for industrial wastewater treatment.

Un estudio comparativo de diferentes compuestos de poli(3-hexiltiofeno)-carbono como capas transportadoras de huecos sobre la estabilidad de celdas solares de perovskita preparadas bajo condiciones ambientales

Hole transport layers (HTLs) play an important role in efficiency and stability of perovskite solar cells (PSCs).  Most of the highly efficient PSCs use spiro-OMeTAD doped with Li-TFSI as HTLs, which has to be prepared under inert atmosphere, because the hygroscopic feature of the lithium salt deteriorates the stability of PSCs under ambient conditions. In this work, we report a comparative study of the electrical and morphological properties of different poly(3-hexylthiophene) (P3HT) thin films: pristine, doped with FeCl3, and composites with carbon nanotubes (CNT) or reduced graphene oxide (rGO). Although the electrical conductivity of P3HT films is found to increase with any of those modification methods, the photovoltaic performance of PSCs is highly dependent on the modification agent. P3HT:FeCl3 reduces the photocurrent density of PSCs, while the addition of rGO in P3HT improves charge extraction and stability of PSCs. Furthermore, the insertion of conductive carbon paint between P3HT and the metal contact maintains the original efficiency of non-encapsulated PSCs after continuous illumination for 30 min. It is concluded that carbon modifications in P3HT based HTL can improve the stability of perovskite solar cells totally fabricated under ambient conditions.

Conductive carbon paint: An efficient way to electrodeposit metallic nanowires by using porous membranes

The present work demonstrates that conductive carbon paint, used for sample preparation in electron microscopy, can be a more straightforward and as-effective substitute for the metallic layer deposition usually used for the electrodeposition of metallic nanowires within porous membranes. AFM images demonstrated the good surface quality of the carbon layer. Raman spectroscopy confirmed the high crystallinity of carbon and high density of π-electrons. The electrical conductivity of the carbon layer was estimated using the linear sweep voltammetry technique. This new cathode was employed to grow continuous (Ni) and composition-modulated (Ni/Cu) nanowires within alumina templates, starting from aqueous solutions of Ni2+ and Cu2+ mixed salts. The obtention of metallic copper and nickel, and their separation can be readily observed by scanning electron microscopy and elemental mapping by EDS.

Conductive cross-section preparation of non-conductive painting micro-samples for SEM analysis

Scanning electron microscopy (SEM) is a common method for the analysis of painting micro-samples. The high resolution of this technique offers precise surface analysis and can be coupled with an energy-dispersive spectrometer for the acquisition of the elemental composition. For light microscopy and SEM analysis, the painting micro-samples are commonly prepared as cross-sections, where the micro-sample positioned on the side is embedded in a resin. Therefore, the sequence of its layers is exposed after the cross-section is polished. In common cases outside of cultural heritage, a conductive layer is applied on the polished side, but in this field, the measurements are mostly done in low-vacuum SEM (LV-SEM). Although the charging effect is reduced in LV-SEM, it can still occur, and can hardly be prevented even with carbon tape or paint. This work presents two conductive cross-section preparation methods for non-conductive samples, which reduce charging effects without impairing the sample integrity.

Coal tar-derived conductive pigment/polyvinylidene fluoride composite for Joule heating

The fast-increasing demand for high-performance carbon conductive paints has motivated the use of inexpensive precursors and easy-to-manufacture methods to scale up production. The performance of carbon conductive paints highly depends on the precursor types, carbonization conditions and the coordination between carbon pigment and binder. This work investigated the effect of precursors (by-products of coking industry including coal tar pitch, anthracene oil, naphthalene oil, and washing oil) on the structure and properties of carbon pigment, as well as the influences of binders polyvinylidene fluoride (PVDF), styrene-butadiene emulsion, and acrylic emulsion on the electrothermal properties and adhesion of carbon paint coating. The conductive pigment prepared from coal pitch has nano-sheet structure, high sp2 content, large sp2 cluster size and high disordered structure, resulting high carrier concentration and mobility, and low volume resistivity. The carbon conductive coating fabricated from coal pitch-based pigment and PVDF (PC-PVDF) has good electrothermal properties, excellent stability, low volume resistivity, good adhesion and corrosion resistance. The electrical conductivity of carbon-PVDF composites prepared from coal tar pitch, anthracene oil, naphthalene oil, and washing oil as precursors were 15.7, 3.0, 4.4, and 4.0 S/m, respectively. Coal pitch-derived conductive pigment-PVDF carbon coating exhibits excellent Joule heating performance, i.e., up to 147 °C at 20 V when heating at 122 °C/min, uniform temperature distribution, and excellent reusability. This work demonstrates the potential application of coal pitch-based pigment-PVDF coating for Joule heating.

A sodium hyposulfite fuel cell for efficient Cr(VI) removal

This work shows a strategy of reducing hexavalent chromium (Cr(VI)) by sodium hyposulfite (Na2S2O3) with self-generated electricity via a dual-chamber non-biological fuel cell (D-nBFC). Therein, Na2S2O3 was electro-oxidized on graphite felt (GF) at anode and Cr(VI) in strong acidic solution was electro-reduced at GF/CCP cathode (GF decorated with conductive carbon paint (CCP)). Additionally, an agar salt bridge, consisting of saturated KCl solution, was introduced to form complete circuit by offering ions. The results showed that Cr(VI) was reduced to trivalent chromium (Cr(III)) and the D-nBFC system could produce electricity in this process. This system could obtain a high Cr(VI) removal efficiency (97.0%), 110 μA maximum current, and 13.4 mW m−2 maximum power density in 4 h. In addition, the proposed system had high reusability after five cycles and the relative standard deviation was only 3.4% (n = 5). Thus, this D-nBFC system provides a promising and eco-friendly method for treatment of Cr(VI) pollution and generating electricity simultaneously, and also has potential application value for other heavy metals remediation.

Rapid remediation of Cd(II)-contaminated water using a magnetically collectable iron-based primary battery

Remediation of cadmium ion in polluted water suffers from high cost and low efficiency. Nanoscale zero-valent iron (NZVI) was able to extract Cd(II) from water effectively, but the liability to aggregate greatly limits its broad application. Herein, we develop a promising remedy (CCP@NZVI) for the rapid and efficient removal of Cd(II) in water by facile coating conductive carbon paint (CCP) on NZVI. Compared with NZVI alone, CCP@NZVI shows enhanced efficiency, achieving removal up to 95% in 5 min at a low dose (0.67 g/L). We demonstrated the validity of a build-in primary battery as the driving force for the removal of Cd(II). In water contaminated by Cd(II), NZVI acting as the anode tends to be oxidized to ferrous ion and transfers electron to CCP as the cathode, wherein dissolved O2 is reduced to OH- for interfacial Cd(II) precipitation. A panel of characterization techniques including scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray powder diffraction, and open circuit potential, have been used to analyze CCP@NZVI before and after the reactions, verifying the immobilization of absorbed Cd(II) in CCP@NZVI as Cd(OH)2. In addition, this method exhibits good stability against weak acid and coexisting anions with satisfactory biosafety. Importantly, the Cd-immobilized CCP@NZVI after treatment can be easily separated via weak magnetic field. This study provides a novel strategy to achieve rapid Cd(II) removal at low-cost and with collectability, which may have a tremendous application prospect in environment fields including water treatment and soil detoxication.

Long-term experience in anoxic wastewater treatment plants of planar MFC with Ce-doped cathodes

Planar MFC prototypes were constructed and experimented to operate as sensors of the anoxic condition in a denitrification tank of a wastewater treatment plant in Italy, during different times in 2018 – 2019. Electrodes were differently enriched with carbon paint containing nanotubes and CeO2 nanoparticles. Performances of different electrodes were compared. Results underline critical anoxic conditions in the tank, that caused a very low signal and phenomena of signal reversion during some period of the year. the activity of aerobic microorganisms and protozoa growing and grazing the bacteria on the electrodes strongly influenced the signal of the MFCs. The presence of nanoceria enhanced, for some extent, the MFC signal, both in presence of reversing trends and in absence of these phenomena. In absence of reversing trends, nanoceria enhanced the MFC voltage. Such signal trends from MFCs can give, in real-time, useful information to optimize the purification process without the necessity of frequent biological and chemical analyses.

EFFECT OF PIEZOELECTRICITY ON THE REACTIVITY OF NANOALUMINUM P(VDF-TrFE) ENERGETIC COMPOSITES

In this study, the effect of piezoelectricity on the sensitivity to ignition by laser radiation of 10% wt nanoaluminum/poly(vinylidene fluoride-trifluoroethylene) [nAl/P(VDF-TrFE)] composite films was investigated. Nanoaluminum particles were dispersed in P(VDF-TrFE) copolymer solution and cast into ~ 45 μm thick films. Ignition samples across which an electric field of 25 kV/mm could be applied were created by sputter coating gold electrodes on opposing sides of the film. Electrodes were coated on one side with a layer of carbon paint to absorb laser radiation. Samples were tested under four conditions: unmodified, unpoled with an applied electric field, poled without an electric field, and poled with an electric field. Results from this study indicate that both the application of an electric field and the activation of the piezoelectric properties of PVDF sensitize the composite as measured by a decrease in a mean time to ignition, with piezoelectricity activation sensitizing the composite to a greater degree than only an applied electric field.

Double perovskite Cs2AgBiBr6 radiation sensor: synthesis and characterization of single crystals

Single crystals of lead-free halide double perovskite Cs2AgBiBr6 sensor material manifest a remarkable potential for application in radiation detection and imaging. In this study, the purity and crystallinity of solution-grown Cs2AgBiBr6 single crystals with cubic Fmoverline{3}m symmetry have been corroborated by powder XRD measurements, while the single crystal XRD patterns reveal the dominant {111} lattice planes parallel to the sample surfaces. A wider range of lower resistivity values (106–109 Ωcm) was obtained from the I-V measurements compared to the 1.55 × 109–6.65 × 1010 Ωcm values from the van der Pauw method, which is typically higher for the Ag than for the carbon paint electrodes. Charge-carrier mobility values estimated from the SCLC method for the carbon paint-Cs2AgBiBr6 (1.90–4.82 cm2V−1 s−1) and the Ag-Cs2AgBiBr6 (0.58–4.54 cm2V−1 s−1) including the density of trap states (109–1010 cm−3) are comparable. Similar values of 1.89 cm2V−1 s−1 and 2.36 cm2V−1 s−1 are derived from the Hall effect measurements for a sample with carbon and Ag electrodes, respectively. The key electrical parameters including the X-ray photoresponse measurements indicate that the Cs2AgBiBr6 samples synthesized in this study satisfy requirements for radiation sensors.Graphical abstract

Simultaneously removal of Cr(VI) and Cd(II) from water using a flower-like primary battery nanosystem

In this study, a new flower-like primary battery nanosystem termed “Zn/CCP/ZIF-8” was prepared by depositing conductive carbon paint (CCP) and zeolitic imidazolate framework-8 (ZIF-8) on a zinc plate (Zn). Therein, CCP had good conductivity performance and adhesiveness, ZIF-8 and Zn/CCP/ZIF-8 possessed BET specific surface areas of 1909.5 and 1265.4 m2/g respectively. The results showed that the Zn/CCP/ZIF-8 nanosystem could effectively simultaneously adsorb hexavalent chromium (Cr(VI)) and bivalent cadmium (Cd(II)) from water. The system could promote the transfer of electrons from Zn to Cr(VI) and Cd(II) which were effectively reduced to trivalent chromium (Cr(III)) and cadmium (Cd), respectively. The resultant Zn/CCP/ZIF-8/Cr/Cd composite was then easily separated from water. The adsorption isotherm, kinetics, and thermodynamics of the prepared Zn/CCP/ZIF-8 for Cr(VI) and Cd(II) were investigated. An electrochemistry performance test proved that the Zn/CCP/ZIF-8 system was a primary battery. Notably, the Zn/CCP/ZIF-8 system substantially reduced the amounts of Cr(VI) and Cd(II) absorbed by zebrafish and water spinach, thus increasing food safety. The results of a rat test indicated that the Zn/CCP/ZIF-8 system possessed a high biosafety. This study provides a promising, eco-friendly, and facile method for the simultaneously treatment of Cr(VI) and Cd(II) contamination of water.

Paper Strip and Ceramic Potentiometric Platforms Modified with Nano-Sized Polyaniline (PANi) for Static and Hydrodynamic Monitoring of Chromium in Industrial Samples.

Screen-printed membrane sensors based on the use of paper and ceramic substrates are fabricated, characterized, and used for rapid batch and continuous monitoring of CrIII in the form of CrO42− in some industrial products and wastewater samples. Strips of paper and ceramic platforms (15 × 5 mm) were covered with conductive carbon paint and then modified with polyaniline (PANI) film, to act as an ion-to-electron transducer, followed by a drop casting of plasticized poly (vinyl chloride) (PVC) Rhodamine-B chromate membrane as a recognition sensing material. In a 5.0 mmol L−1 Trizma buffer solution of pH ~8, the fabricated paper and ceramic based membrane sensors exhibited a near Nernstian response for CrVI ion with slopes of −29.7 ± 0.5 and −28.6 ± 0.3 mV decade−1, limit of detection 2.5 × 10−5 and 2.4 × 10−6 mol L−1 (1.3–0.12 µg mL−1), and linear concentration range 7.5 × 10−3–5.0 × 10−5 and 7.5 × 10−3–1.0 × 10−5 mol L−1 (390-0.5 µg mL−1), respectively. Both sensors exhibited fast and stable potentiometric response, excellent reproducibility, and good selectivity with respect to a number of common foreign inorganic species. Impedance spectroscopy and chronopotentiometry data revealed a small resistance and a larger double layer capacitance due to the presence of the intermediate polyaniline (PAN) conductive layer. Furthermore, the formation of a water layer between the ion selective membrane (ISM) and the underlying conductor polymer and between the conducting polymer and the carbon conducting surface was greatly reduced. The developed disposable solid-contact potentiometric sensors offer the advantages of simple design, long term potential stability, flexibility, miniaturization ability, short conditioning time, and cost effectiveness that enable mass production. The sensors were successfully used for static and hydrodynamic measurements of total chromium in some leather tanning wastewater and nickel-chrome alloy samples. The results compare favorably with data obtained by atomic absorption spectrometry.

Protective Layers Based on Carbon Paint To Yield High-Quality Large-Area Molecular Junctions with Low Contact Resistance.

A major obstacle for transforming large-area molecular junctions into a viable technology is the deposition of a top, metallic contact over the self-assembled monolayer (SAM) without chemically damaging the molecules and preventing an interface-limited charge transport. Often a thin conducting layer is softly deposited over the SAM to protect it during the deposition of the metal electrode which requires conditions under which organic molecules are not stable. We report a new protective layer based on carbon paint which is highly conductive and has metallic-like behavior. Junctions made of SAMs of n-alkanethiolates supported by Au were characterized with both dc and ac techniques, revealing that carbon paint protective layers provide a solution to three well-known challenges in molecular junctions: series resistance of the leads, poor interface conductance, and low effective contact area related to the roughness of the interfaces. Transport is constant with coherent tunneling down to 10 K, indicating the carbon paint does not add spurious thermally activated components. The junctions have both high reproducibility and good stability against bias stressing. Finally, normalized differential conductance analysis of the tunneling characteristics of the junctions as a function of molecular length reveals that the scaling voltage changes with molecular length, indicating a significant voltage drop on the molecules rather than on the molecule–electrode interface. There is a clear inverse dependence of the scaling voltage on length, which we deduced has a tunneling barrier height of close to 2 eV. The paper establishes the reliability of carbon paint protective layers and provides a procedure for discriminating genuine molecular effects from interfacial contributions.

FlexTouch

In this paper, we present FlexTouch, a technique that enables large-scale interaction sensing beyond the spatial constraints of capacitive touchscreens using passive low-cost conductive materials. This is achieved by customizing 2D circuit-like patterns with an array of conductive strips that can be easily attached to the sensing nodes on the edge of the touchscreen. FlexTouch requires no hardware modification, and is compatible with various conductive materials (copper foil tape, silver nanoparticle ink, ITO frames, and carbon paint), as well as fabrication methods (cutting, coating, and ink-jet printing). Through a series of studies and illustrative examples, we demonstrate that FlexTouch can support long-range touch sensing for up to 4 meters and everyday object presence detection for up to 2 meters. Finally, we show the versatility and feasibility of FlexTouch through applications such as body posture recognition, human-object interaction as well as enhanced fitness training experiences.

Optimization of discharge triggering in micro-cathode vacuum arc thruster for CubeSats

The ignition and optimization of the pulsed micro-cathode triggerless vacuum arc thruster model are analyzed. To this end a simplified model of the thruster consisting of two rectangular electrodes on an alumina ceramic plate with a variable inter-electrode gap covered by a conductive film of carbon paint is considered. It is shown that after optimizing the inter-electrode gap, the electrical power and the value of the magnetic field parallel to the film surface, such an ‘idealized’ thruster model can provide up to 1.2–1.3 million pulses with a high degree of stability of ignition and a large amplitude of arc current. These findings may be used in designing long-life and durable low-power micro-cathode thrusters with rigidly fixed, unmovable electrodes. We also propose the concept of a modular thruster consisting of separate elementary consumable thrusters—the modular thruster lifetime increases with the number of these elementary thrusters.

3D high viscosity jetting of functional materials

Inkjet printing is one of the most suitable technologies to produce multi-material and multi-layered printed electronics due to its scalability, the wide range of substrates that it can accept and the possibility of mixing and combining numerous fluids in a single process. However, restrictions in material properties such as viscosity, typically below 25 mPa·s, limit the molecular weight of usable polymers and the solid content of inks. In some cases, this leads to volumetric shrinkage, longer post-process treatments and poor performance. Therefore, a high viscosity approach would widen the material catalogue for printed electronics without compromising the advantages of inkjet. In this work, drop-on-demand micro-dispensing valves that combine mechanic and pneumatic actuation were used to create 2D patterns and 3D structures of a conductive and non-Newtonian carbon paint. The combination of this functional material with a non-conductive photo-curable resin allowed the creation of more complex 3D geometries using the layer-by-layer approach typical from Additive Manufacturing. Printing parameters such as pneumatic pressure, valve closing speed, resolution and drying time are studied and optimised to produce multi-layered tracks, self-standing pillars and a functional demonstrator featuring a printed capacitive switch and an embedded commercial LED.

Implications for Migration and Social Connections in South-Central New Mexico Through Chemical Characterization of Carbon-Painted Ceramics and Obsidian

Magdalena Black-on-white ceramics from two sites (Gallinas Springs and Pinnacle Ruin) in west-central and southwestern New Mexico have been interpreted as evidence of a migration of Northern Pueblo groups from the Four Corners region into southwestern New Mexico during the thirteenth century. They also appear to be linked to sites with similar carbon-painted ceramics on the Rio Puerco of the east and beyond. An additional site (Roadmap Village) reveals import of Magdalena Black-on-white ceramics produced at Gallinas Springs as well as possible local production. Limited quantities of carbon paint ceramics have been found on El Paso Phase sites in south-central New Mexico that have previously been attributed to contemporaneous carbon-painted pottery produced at communities in the Galisteo Basin and the upper Rio Grande. Recent compositional analysis of carbon-painted ceramics from the Gallinas Springs, Pinnacle, and Roadmap sites has identified characteristic chemical signatures that suggest local production of carbon paint ceramics at all three sites and distribution of carbon paint ceramics from Gallinas Springs to Pinnacle and Roadmap in the eastern Black Range of southwestern New Mexico. Analysis of carbon paint ceramics from Madera Quemada, an El Paso Phase site in the Tularosa Basin indicates that the carbon paint wares found in El Paso Phase sites were acquired through trade connections from the Black Range rather than from more northern sources. The overall Magdalena Black-on-white production patterns are contrasted with the obsidian procurement data from the same sites to reveal a complex and divergent pattern.

Evaluating the thermal damage resistance of graphene/carbon nanotube hybrid composite coatings.

We study laser irradiation behavior of multiwalled carbon nanotubes (MWCNT) and chemically modified graphene (rGO)-composite spray coatings for use as a thermal absorber material for high-power laser calorimeters. Spray coatings on aluminum test coupon were exposed to increasing laser irradiance for extended exposure times to quantify their damage threshold and optical absorbance. The coatings, prepared at varying mass % of MWCNTs in rGO, demonstrated significantly higher damage threshold values at 2.5 kW laser power at 10.6 μm wavelength than carbon paint or MWCNTs alone. Electron microscopy and Raman spectroscopy of irradiated specimens show that the coating prepared at 50% CNT loading endure at least 2 kW.cm−2 for 10 seconds without significant damage. The improved damage resistance is attributed to the unique structure of the composite in which the MWCNTs act as an efficient absorber of laser light while the much larger rGO sheets surrounding them, dissipate the heat over a wider area.

Conductive carbon paint as an anode buffer layer in inverted CdS/Poly(3-hexylthiophene) solar cells

Hybrid solar cells have been prepared by deposition of thin films of cadmium sulfide (CdS) on transparent conductive glass substrates, followed by the formation of poly(3-hexylthiophene) (P3HT) coatings. Conductive carbon paint (CP) layer was applied on top of P3HT before the evaporation of gold (Au) as metal contact. When the P3HT film thickness (d) was smaller than 600nm, photovoltaic (PV) performance of the CdS/P3HT solar cells was enhanced with CP layer. In the case of d=305nm, the presence of CP layer increased the open-circuit voltage (Voc) from 335 to 710mV and the short-circuit current density (Jsc) from 1.23 to 1.42mA/cm2 as well. The analysis of current–voltage (I–V) curves in the dark of the same type of cells indicates that CP reduced the leakage current and metal contact resistance, and increased the rectification ratio. I–V curves of hole-only Metal-1/P3HT/Metal-2 devices suggest that the presence of CP facilitates hole-extraction from P3HT. The comparison of charge recombination times at CdS/P3HT interface suggests that without CP layer, Au atoms could reach areas near the interface and facilitates charge recombination process. It is concluded that conductive carbon not only improves the ohmic contact between P3HT and top metal but also impedes the diffusion of the evaporated metal atoms deep inside the polymer films. This leads to better PV performance of the CdS/P3HT solar cells.