Due to the considerable importance of preventing and treating diseases, efficient detection methods are required to monitor levels of ascorbic acid (AA) in beverages, foods, dietary supplements, and ...biological fluids. In this work, an efficient, easy handling, low cost, and simple fabrication process for non‐enzymatic electrochemical sensors was fabricated through the carbonization of a graphene oxide filled biomass‐derived polymer poly(furfuryl alcohol) (PFA/GO), as sustainable alternative, using a high throughput CO2 laser‐scribing process. The laser power was found to determine the physicochemical properties of the resulting graphene‐like electrodes. As an electrochemical sensor, devices presented a detection limit of 1.0 μmol cm2 L−1 with good reproducibility towards AA oxidation. For real sample measurements, recovery rates between 97 and 113 % were found in commercial vitamin‐C tablet. Analysis of AA in synthetic sweat presented good intra‐electrode reproducibility and limit of detection of 1.3 μmol cm2 L−1.
Direct laser writing of graphene oxide‐biomass‐derived poly(furfuryl alcohol) (PFA/GO) electrode allowed the preparation of a non‐enzymatic electrochemical sensor. The PFA/GO‐3.88 W sensor showed good figures of merit, such as low detection limit, sensitivity, stability and anti‐interference performance. It exhibited good ability to detect ascorbic acid in vitamin C tablets and synthetic sweat.
The aim of this work was to prepare a flexible nanocomposite from ultra-fine titanium oxide (
TiO
2
) growth on carbon fibre via microwave-assisted hydrothermal synthesis (MHS) and to evaluate its ...photocatalytic properties. The
TiO
2
nanoparticles were directly grown on the carbon fibre (CF). Thus, a study comparing the conventional titania coating
vs.
the MHS were performed. The significant layer interaction as a function of the coating method on the visible and dark dye photodegradation performance was observed. Techniques such as X-ray diffraction, electron microscopy (field-emission scanning electron microscope (FESEM)), Raman spectroscopy, among others were used aiming to characterize the different route samples. This study reports a reproducible and single method to manufacture of nanocomposites through the growth of
TiO
2
nanoparticle on CF by MHS that allow controlling the thickness layer. Similar procedure of synthesized nanocomposite could be applied in different chemical compositions to advanced applications, based on the electrochemical nanostructure.
The Cover Feature illustrates the use of a biomass‐derived polymer for the direct laser writing fabrication of carbon‐based electrodes for a non‐enzymatic electrochemical sensor of ascorbic acid. ...More information can be found in the Research Article by L. Fernandes Loguercio et al.
Carbon-based hybrid structures have attracted much attention due to their superior chemical, thermal, mechanical and electrical properties. A 3D sponge-like structure based on reduced graphene ...oxide/carbon nanotubes decorated with zinc sulfide synthetized by a hydrothermal micro-wave assisted synthesis (MHS) was produced and its chemical, structural, morphological and electrochemical properties evaluated as electrodes for supercapacitor devices. XRD confirmed the structure of the nanocomposite, XPS was performed to examine the chemical state of the compounds. The morphology analysis realized by FESEM confirmed the success of the proposed methodology to produce the rGO/MWCNTf-ZnS nanocomposites revealing good homogeneity. The electrochemical properties were studied by cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge/discharge. It was observed that the increase of MWCNTf-ZnS content increased the specific capacitance and reduced the resistivity of the 3D hybrid structure, reaching 95 F g−1, thus, approaching the ideal electric double layer storage capacitor behavior in samples containing MWCNTf-ZnS.
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•An efficient method to produce 3D nanocomposite of reduced graphene oxide/carbon nanotubes coated with zinc sulfide.•A simple procedure to prepare a two-electrode cell device was demonstrated.•The device showed near to ideal capacitor behavior.
The development of new materials and systems capable of storing energy efficiently with a fast power delivering has been the subject of several studies. Many techniques and instruments are used for ...the characterization of these systems. Some involve the use of electrochemical techniques, such as cyclic voltammetry and electrochemical impedance spectroscopy, while others use instruments specially developed for this purpose. In this study, we provide a simple and functional supercapacitor characterization system using a programmable sourcemeter with an embedded scripting language. For the validation of the system, commercial capacitors and supercapacitors devices based on activated carbon and manganese dioxide were used. In a few steps, the system is capable of efficiently determine the main parameters used in the characterization of supercapacitors, for instance, specific capacitance, specific energy density, specific power density and equivalent series resistance. From the data collected, the system can also determine the stability and performance of supercapacitors, which are fundamental parameters used in the development of new electrodes for energy storage devices. Keywords: electrochemical characterization; energy storage devices; programmable sourcemeter; supercapacitors
The production of biodiesel generates high amounts of glycerol as a byproduct. Thus, alternatives to reuse this byproduct need to be investigated. In this study, we evaluated the valorization of ...glycerol through a catalytic process with nickel/vanadium supported on γ-Al2O3 in different compounds, followed by the electrochemical characterization for energy storage of carbon-based materials (coke) produced during the catalytic reaction. The structural, morphological and compositional properties of the catalysts and carbon-based materials were investigated by X-ray diffraction, N2-physisorption, thermogravimetric analysis, Raman spectroscopy, inductively coupled plasma mass spectroscopy, scanning electron microscopy and high-resolution transmission electron microscopy. The glycerol reaction generated acrolein, dihydroxyacetone and methanol as main products. The addition of nickel to the catalyst increased the selectivity for methanol by ca. 44% for the catalytic cracking; while for the vapor reforming is observed a higher H2 production. The use of the coke residues for energy storage was investigated through cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. A maximum specific capacitance of 7.3 F g−1 at 3.75 mA g−1 was achieved, attributed to the high surface area, ease of access of the electrolyte ions to the entire surface of the electrode. This research reveals a zero-waste approach for the glycerol valorization reaction.
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•This research describes a zero-waste approach for the glycerol valorization reaction.•The valorization of glycerol through a catalytic process with nickel/vanadium supported on γ-Al2O3 is studied.•The residues generated were applied as electrodes for supercapacitors, with a near to ideal EDLC behavior;•A total glycerol conversion was achieved generating methanol as main product.•The production of H2 was detected during the glycerol cracking process.
This study sought to evaluate the caries inhibition effect, and physical-chemical properties reached by the addition of β-TCP nanoparticles doped with antimicrobial agents to orthodontic adhesive ...bonding brackets.
A commercially available orthodontic bonding adhesive, YSticker Ortho (YO - Yller Biomateriais) was modified by adding β-TCP nanoparticles doped with antimicrobial agents at 10% by weight. The experimental groups were: TB (Transbond XT -unmodified orthodontic bonding adhesive, control), YO (YSticker Ortho modified with β-TCP), YOβ-TCP@AgNP (YO modified with β-TCP + Silver nanoparticles), YOβ-TCP@TRI (YO modified with β-TCP + triclosan), YOβ-TCP@CHX (YO modified with β- TCP + chlorhexidine gluconate) and YOβ- TCP@BAC (YO modified with β-TCP + benzalkonium chloride). Bonded brackets were submitted to antimicrobial evaluation by modified direct contact test using Streptococcus mutans, and the antibiofilm effect in a microcosm model followed by shear bond strength test. Changes in the integrated mineral loss (ΔS), in situ degree of conversion, water sorption, and solubility, were also evaluated. Statistical comparisons were conducted at a 5% significance level.
All experimental groups containing β-TCP nanoparticles doped with antimicrobial agents significantly inhibited bacterial growth. For bond strength, no difference was observed between TB and YO groups except for YOβ- TCP@CHX which resulted in the lowest values of bond strength. The orthodontic adhesive type did not dramatically affect the in situ degree of conversion, (ΔS), water sorption, and water solubility.
β-TCP nanoparticles doped with antimicrobial agents addition hold promise as a novel orthodontic adhesive bonding bracket. Possessing great caries inhibition potential with good mechanical properties.
•Addition of β-TCP nanoparticles doped with antimicrobial agents in the formulation of orthodontic adhesives was proposed.•The nanoparticles addition did not hamper the physicochemical or mechanical properties.•β-TCP nanoparticles doped with antimicrobial agents granted great antimicrobial features to the orthodontic adhesives.
The development of new materials and systems capable of storing energy efficiently with a fast power delivering has been the subject of several studies. Many techniques and instruments are used for ...the characterization of these systems. Some involve the use of electrochemical techniques, such as cyclic voltammetry and electrochemical impedance spectroscopy, while others use instruments specially developed for this purpose. In this study, we provide a simple and functional supercapacitor characterization system using a programmable sourcemeter with an embedded scripting language. For the validation of the system, commercial capacitors and supercapacitors devices based on activated carbon and manganese dioxide were used. In a few steps, the system is capable of efficiently determine the main parameters used in the characterization of supercapacitors, for instance, specific capacitance, specific energy density, specific power density and equivalent series resistance. From the data collected, the system can also determine the stability and performance of supercapacitors, which are fundamental parameters used in the development of new electrodes for energy storage devices. DOI: http://dx.doi.org/10.17807/orbital.v11i2.1374
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