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Solid-state and quasi-solid state electrolytes have been attracting the scientific community’s attention in the last decade. These electrolytes provide significant advantages, such as the absence of leaking and separators for devices and safety for users. They also allow the assembly of stretchable and bendable supercapacitors. Comparing solid-state to quasi-solid-states, the last provides the most significant energy and power densities due to the better ionic conductivity. Our goal here is to present recent advances on quasi-solid-state electrolytes, including gel-polymer electrolytes. We reviewed the most recent literature on quasi-solid-state electrolytes with different solvents for supercapacitors. Organic quasi-solid-state electrolytes need greater attention once they reach an excellent working voltage window greater than 2.5 V. Meanwhile, aqueous-based solid-state electrolytes have a restricted voltage window to less than 2 V. On the other hand, they are easier to handle, provide greater ionic conductivity and capacitance. Recent water-in-salt polymer-electrolytes have shown stability as great as 2 V encouraging further development in aqueous-based quasi-solid-state electrolytes. Moreover, hydrophilic conductive polymers have great commercial appeal for bendable devices. Thus, these electrolytes can be employed in flexible and bendable devices, favoring the improvement of portable electronics and wearable devices (376 references were evaluated and summarized here).

We report here molecular dynamics simulations combined with in situ experimental studies to understand the advantages and disadvantages of replacing conventional (salt-in-water, SiWE) aqueous-based electrolytes with very concentrated (water-in-salt, WiSE) systems in supercapacitors. Atomistic molecular dynamics simulations were employed to investigate the energetic, structural, and transport properties of aqueous electrolytes based on sodium perchlorate (NaClO4). Simulations covered the concentrations range of 1 mol dm−3 (1 mol kg−1) to 8 mol dm−3 (15 mol kg−1), demonstrating a significant increase in viscosity and density and reduction in ionic conductivity as the concentration reaches the WiSE conditions. A carbon-based symmetric supercapacitor filled with WiSE showed a larger electrochemical stability window (ESW), allowing to span the cell voltage and specific energy. Larger ESW values are possible due to the formation of a solvent blocking interface (SBI). The formation of ionic aggregates owing to the increasing cohesive energy in WiSE disturbs the hydrogen-bond network resulting in physicochemical changes in the bulk liquid phase. In addition, the molal ratio between water and ions is decreased, resulting in a low interaction of the water molecules with the electrode at the interface, thus inhibiting the water-splitting considerably.

Comprehensive electrochemical and operando Raman studies are performed to investigate the electrochemical stability window (ESW) of supercapacitors filled with normal (salt-in-water) and highly concentrated (water-in-salt, WiSE) electrolytes. Impedance and chronoamperometric experiments are employed and combined with cyclic voltammetry to correctly define the ESW for a WiSE-based device. The total absence of water-splitting resulted in phase angles close to -90° in the impedance data. It is verified that a 17 m NaClO

Raman probing of carbon electrode and electrolyte under dynamic conditions is performed here using different aqueous electrolytes to elucidate the fundamental events occurring in electrochemical supercapacitor during charge–discharge processes. The areal capacitance ranges from 1.54 to 2.31 mF cm−2 and it is determined using different techniques. These findings indicate that the Helmholtz capacitance governs the overall charge-storage process instead of the space charge (quantum) capacitance commonly verified for HOPG electrodes in the range of ~ 3 to 7 µF cm−2. Molecular dynamics simulations are employed to elucidate the origin of the reversible Raman spectral changes during the charge–discharge processes. A correlation is verified between the reversible Raman shift and the surface excesses of the different ionic species. A theoretical framework is presented to relate the effect of the applied potential on the Raman shift and its correlation with the surface ionic charge. It is proposed that the Raman shift is governed by the interaction of solvated cations with graphite promoted by polarization conditions. It is the first time that a comparative study on different aqueous electrolyte pH and cation ion size has been performed tracking the Raman spectra change under dynamic polarization conditions and contrasting with comprehensive electrochemistry and dynamic molecular simulations studies. This study shines lights onto the charge-storage mechanism with evidence of Kohn anomaly reduction in the carbon electrode during the reversible adsorption/desorption and insertion/extraction of ionic species.

We report here the activated carbon and cobalt hexacyanoferrate composite, which is applied as the electrode materials in symmetric supercapacitors containing a 1.0 M Na2SO4 aqueous electrolyte. This novel material combines high specific surface area and electrochemical stability of activated carbon with the redox properties of cobalt hexacyanoferrate, resulting in maximum specific capacitance of 329 F g−1 with large voltage working window of 2.0 V. Electrochemical studies indicated that cobalt hexacyanoferrate introduces important pseudocapacitive properties accounting for the overall charge-storage process, especially when I

We report on multi-walled carbon nanotubes (MWCNTs) and an activated carbon (AC) composite material as an electrode for electrical double-layer capacitors (EDLCs). Material flexibility, robustness, and electrical conductivity are features that come from the MWCNTs, while a high specific surface area is an AC's intrinsic property. We prepared different MWCNT : AC ratios in solutions, which were filtered to form a buckypaper. We investigated the specific capacitance, equivalent series resistance, working voltage window (WVW), and the specific energy and power. The best electrochemical findings were obtained for the MWCNT : AC ratio of 1 : 3 with a specific capacitance reaching the theoretical limit. A high working voltage window of 1.4 V was verified in aqueous solution. Simultaneously, the symmetric cells were able to cycle for more than one million cycles in fast charge–discharge galvanostatic tests with 93% capacitance retention. Finally, the main criticism regarding the self-supported electrode materials is the difficulty of welding. In this sense, we presented a particular welding process as proof of concept for electrode scalability. Overall, this novel electrode material exhibits a set of exciting properties, which we now tested in EDLCs.

We report a novel electrode for Li-O2 battery based on radially ordered multi-walled carbon nanotubes functionalized by acid and plasma pre-treatments without degrading its structure with improved wettability leading to more effective active sites. This electrode was used in a device with DMSO/LiClO4 as the electrolyte, presenting good discharge capacity result (2804 mA h g−1C). The defects on the nanotube structure were characterized with RAMAN and a correlation from defects and discharge capacity was observed indicating that the defects could provide larger number of effective regions for discharge products. Raman, FTIR and synchrotron X-ray diffraction characterization over the discharged electrode revealed a large formation of Li2CO3 as the main product, which is uncommon for this system. Further characterization of composition and morphology in time-elapsed discharge also supported a continuous carbonate formation. By limiting the discharge capacity to 500 mA h.g−1C, an improvement in the cycling was observed, however, the higher overpotential needed to decompose the discharge product limited the cell performance.

After a brief presentation of the major aspects involving supercapacitors, their fundamental aspects were reviewed with special emphasis on recent advances accounting for the electric double layer models proposed for porous carbon-based electrodes containing electrochemically active sub-nanometer pores. Despite these important considerations, the main focus of this review is concerned with the major difficulties found in trying to interpret the electrochemical findings obtained for porous electrodes in the presence and absence of a pseudocapacitance (e.g., Faradaic process) due to presence of distributed and dispersion capacitance effects. In this sense, we present a comprehensive analysis concerned with the misuse of the classic electrochemical methods initially proposed for the study of ideally flat and/or spherical electrodes that are commonly adapted to evaluate the specific capacitance exhibited by porous electrodes. We critically discussed the main pitfalls arising from the incorrect interpretation of the electrochemical findings obtained in the time and frequency domains using different electrochemical characterization methods. For the sake of reuniting our better understanding of the electrochemistry of porous electrodes used in supercapacitors, we investigated the most relevant and recent papers in the field. Finally, we highlight some specific electrochemical methodologies proposed for the study of porous electrodes and some guidelines to establish a laboratory protocol to collect the most relevant information about the supercapacitors are presented.

The use of technologies such as Internet of Things (IoT), data processing and blockchain have allowed companies to serve their customers with better quality, efficiency, reliability and in the shortest possible time. The growing adoption of electric vehicles on the market has increased the demand for batteries that may have numerous manufacturers. Life expectancy is affected on manufacture, but also on operational conditions. A large number of parameters have a role on battery's health and thousands of data need to be evaluated and combined. The present work investigates the scenario of the battery industry in order to implement a blockchain-based platform for the supply chain implementation thus allowing a better control on performance of batteries and environmental impact. To achieve this goal, the authors carried out a systematic review with the following steps: identification of relevant studies, evaluation and summary of similar studies, comparison and extraction of data from the papers. The main motivation of this work is the use of the literature for justifying the use of the blockchain technology to track batteries and for identifying the main challenges in the related markets that can be addressed by this technology. The results of this systematic review show that the development of a blockchain-based platform for battery tracking will allow for greater transparency across the entire supply chain: production, reuse, recycling, disposal. Trasparency and traceability prevent clandestine markets, misuse and release of pollutants. Adressing these topics forsters the successful implemention of electric vehicles in the market.

We report here density functional theory calculations and molecular dynamics atomistic simulations to determine the total capacitance of graphene-modified supercapacitors. The contributions of quantum capacitance to the total capacitance for boron-, sulfur-, and fluorine-doped graphene electrodes, as well as vacancy-modified electrodes, were examined. All the doped electrodes presented significant variations in quantum capacitance (ranging from 0 to ∼200 μF cm-2) due to changes in the electronic structure of pristine graphene. The graphene-modified supercapacitors show any appreciable effect on double-layer capacitance being virtually the same for all the devices investigated. The total differential capacitance was found to be limited by the quantum capacitance, and for all the systems, it is lower than the quantum capacitance over the entire voltage window. We found that the total capacitance can be optimized by considering an adequate modification to each electrode in the supercapacitor. In addition, we found that an asymmetric supercapacitor assembled with different doped electrodes, i.e. an F doped negative electrode and an N doped positive electrode, is the best choice for a supercapacitor since this combination results in better capacitance over the entire potential window.

Neutral aqueous electrolytes are known to promote corrosion of carbon coated aluminum current collectors used in electrochemical capacitors, limiting their applications on energy storage devices. Alternatively to the standard electrode manufacturing recipe, we have grown multi-walled carbon nanotubes as the active material on modified aluminum foils to avoid the corrosion of the latter in neutral aqueous solutions. Therefore, the purpose of the present study is the fabrication of a binary alloy that is resistant to corrosion in neutral aqueous solutions. In this sense, we modified standard aluminum foil current collectors by coating them with a thin nickel layer, which was converted on nickel-aluminum alloy (NixAl, x = 1 & x = 3) during the first heating steps of nanotubes growth on the current collector. This novel aluminum modified current collector is electrically conductive and very resistant to corrosion, which allows applying aluminum-based current collectors on aqueous-based electrochemical capacitors devices. To better investigate the electrochemical performance of carbon-based electrodes in aqueous filled coin cell devices, we performed several electrochemical studies using cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. Our results show specific electrode capacitance is up to ∼60 F g−1. After 85,000 (re)charge/discharge cycles, the cell operating on 0–1.5 V voltage range, indicate very long lifespan with no significant loss of specific capacitance and energy density. These results are unexpected for aluminum current collectors on supercapacitor or batteries. On the Ragone plot, our aqueous-based electrochemical capacitor is on supercapacitors region with fairly high power and energy densities.

We report an electrode material for supercapacitors composed of nickel oxide (NiO) nanoparticles supported onto radially oriented multi-walled carbon nanotubes (CNTs) using a stainless-steel fine-mesh as the support (AISI:CNT-NiO). CNT scaffolds showed a turbostratic multi-walled structure with an interplanar spacing of 0.32 ± 0.02 nm and a diameter of ∼20–100 nm. NiO nanoparticles exhibited a diameter of ∼2–7 nm. X-ray data confirmed the presence of NiO in the scaffold. A large pseudocapacitive voltage range of 2.0 V was obtained in a 1.0 M Li2SO4 aqueous solution. The main contribution to the overall pseudocapacitance is due to the presence of reversible solid-state surface Faradaic reactions involving the Ni(II)/Ni(III) redox couple. High specific capacitance values of ∼1200 F g−1 at 5 A g−1 for the AISI:CNT-NiO electrode were extracted from galvanostatic discharge curves. Considering the contribution of negative voltages, the specific power and energy determined using cyclic voltammetry exhibited values of ∼140 Wh kg−1 and ∼9 W kg−1, respectively, at 0.02 V s−1. A specific capacitance of ∼1028 F g−1 was obtained at this scan rate. Even after 40,000 cycles carried out under galvanostatic conditions, the symmetric coin cell remained stable with a very high coulombic efficiency of ∼99%, which is a remarkable result. Also, we attributed to carbon nanotubes an extraordinary stability as electron drain on the current collector. The morphology factor analysis revealed that 19% of the electrochemically active surface area is confined to the inner surface regions of the porous nanostructured active layer. A low value of 0.15 mΩ g was extracted for the equivalent series resistance. New insights are presented concerning the true meaning of negative voltages for coin cells. Interesting findings regarding the porous nature of electrodes were elucidated using the impedance technique.

Different nanostructured mixed metal oxide (MMOs) electrodes containing Sn, Ru, and Ir supported on titanium with the nominal composition Ti/[Sn0.5Ru(0.5−x)Ir(x)]O2 were prepared using the drop-coating method. SEM analysis revealed the presence of oxide islands in the microsized domains of ca. 50 μm separated from each other by cracks. On the contrary, analysis of the nanosized domains revealed the presence of nanostructures containing rectangular grains with an average diameter of ca. 200 nm. The discrepancy between the nominal and real oxide compositions was attributed to volatilization of Sn during the heat treatment. XRD analysis revealed a poor degree of crystallinity and an average crystallite size of 15 ± 4 nm. Different electrochemical studies revealed higher specific pseudocapacitances in the range of 175–222 F g−1 for the MMO containing 50 mol% Ir. The low values obtained for the morphology factor (0.11 ≤ φ ≤ 0.33) indicate a relatively narrow interval of 11–33% for the active surface regions confined to the inner surface regions of the oxide layers. The chronoamperometric findings obtained for short times (t ≤ 50 ms) permitted evaluation of the electrical double-layer capacitance (Cedl), with verified maximum values in the range of 68–75 F g−1 for the MMO containing 50 mol% Ir. On the contrary, the experimental findings obtained for long times (0.1 s ≤ t ≤ 3 s) revealed that the reversible solid-state Faradaic reactions did not exhibit a Fickian behavior. The impedance analysis revealed that MMOs exhibit a porous electrode behavior (De Levie’s model) permitting the determination of the pseudocapacitance and the resistance of the electrolyte inside the pores.

An electrode composed of highly defective nickel oxide (NiO) nanostructures supported on carbon nanofibers (CNFs) and immersed in an Li+-based aqueous electrolyte is studied using Raman spectroscopy under dynamic polarization conditions to address the charge-storage phenomenon. By this operando technique, the formation of Li2SO4·H2O during the discharge process is verified. At the same time, we observed the phase transformation of NiO to NiOOH. The Ni(OH)2/NiOOH redox couple is responsible for the pseudocapacitive behavior with intercalation of cationic species in the different Ni structures. A ‘substitutive solid-state redox reaction’ is proposed to represent the amphoteric nature of the oxide, resulting in proton intercalation, while the insertion of Li+ occurs to a less extent. The electrode material exhibits outstanding stability with 98% coulombic efficiency after 10 000 charge–discharge cycles. The excellent electrode properties can be ascribed to a synergism between CNFs and NiO, where the carbon nanostructures ensured rapid electron transport from the hydrated nickel nanoparticles. The NiO@CNF composite material is a promising candidate for future applications in aqueous-based supercapacitors. DFT simulation elucidates that compressive stress and Ni-site displacement lead to a decrease up-to 3.5-fold on the electron density map located onto the Ni-atom, which promotes NiO/Ni(OH)2/NiOOH transition.

Superior electrochemical performance, structural stability, facile integration, and versatility are desirable features of electrochemical energy storage devices. The increasing need for high‐power, high‐energy devices has prompted the investigation of manufacturing technologies that can produce structured battery and supercapacitor electrodes with optimized charge transport. While conventional electrode production techniques are becoming increasingly obsolete and incompatible with technological developments such as wearables and flexible electronics, additive manufacturing (AM) has emerged as one of several state‐of‐the‐art tools to produce 3D‐structured electrodes with morphology control, high yield, and scalability. Herein, a comprehensive review of the major AM technologies and most recent literature about designing and manufacturing electrode materials for batteries and supercapacitors is presented. A thorough discussion of research opportunities and challenges in this promising field is also presented to introduce the potential and importance of AM to current developments involving electrode materials.

It is common to find in the literature different values for the working voltage window (WVW) range for aqueous-based supercapacitors. In many cases, even with the best intentions of the widening the operating voltage window, the measured current using the cyclic voltammetry (CV) technique includes a significant contribution from the irreversible Faradaic reactions involved in the water-splitting process, masked by fast scan rates. Sometimes even using low scan rates is hard to determine precisely the correct WVW of the aqueous-based electrochemical capacitor. In this sense, we discuss here the best practices to determine the WVW for capacitive current in an absence of water splitting using complementary techniques such as CV, chronoamperometry (CA), and the electrochemical impedance spectroscopy (EIS). To accomplish this end, we prepare and present a model system composed of multiwalled carbon nanotubes buckypaper electrodes housed in the symmetric coin cell and soaked with an aqueous-based electrolyte. The system electrochemical characteristics are carefully evaluated during the progressive enlargement of the cell voltage window. The presence of residual Faradaic current is verified in the transients from the CA study, as well as the impedance changes revealed by EIS as a function of the applied voltage, is discussed. We verify that an apparent voltage window of 2.0 V determined using the CV technique is drastically decreased to 1.2 V after a close inspection of the CA findings used to discriminate the presence of a parasitic Faradaic process. Some orientations are presented to instigate the establishment in the literature of some good scientific practices concerned with the reliable characterization of supercapacitors.

A green chemical method is reported for the synthesis and functionalization of high surface area carbon-based materials for applications as electrodes in short-term energy storage devices, such as supercapacitors. The proposed method is focused on sustainable chemistry and engineering. Our results evidenced an excellent performance of electrochemical capacitor devices with a high lifespan over a wide working voltage with low equivalent series resistance. Great enhancement of electrode wettability and charge transfer at the electrode/electrolyte interface using oxygenated surface functional groups was obtained using the present method. Actually, the present findings are quite promising thus encouraging further investigations of this green-functionalization method for all other carbon-based materials, such as graphene, carbon nanotubes, doped-diamond, and so on.

A method for the direct electrodeposition of globular nano-hydroxyapatite (nHAp) onto reduced graphene oxide (RGO) is presented and a model for the specific growth preference is discussed. Results show that the carboxyl (carboxylic acid)/carboxylate functional groups attached directly to the RGO after oxygen plasma treatment were essential to accelerate the OH– formation and the deposition of globular nHAp crystals. High resolution scanning electron microscopy, energy dispersive X-ray and X-ray diffraction showed that homogeneous, highly crystalline, stoichiometric nHAp crystals, with preferential growth in the (002) plane direction, were formed without any thermal treatment. The nHAp/RGO composites were shown to be an appropriate surface for mesenchymal stem cell adhesion with active formation of membrane projections.

We present a simple, low cost, and fast method to produce free-standing nanohydroxyapatite/carbon-based scaffolds. We electrodeposited nanohydroxyapatite onto vertically aligned carbon nanotube flakes and reticulated vitreous carbon bars. We prepared a highly crystalline and homogeneous thin film without any post-thermal treatment, and our results evidence that we can control the nanohydroxyapatite crystal formation according to the substrate employed. Immersion tests using simulated body fluid showed that these new nanobiomaterials had in vitro bioactivity. The free-standing nanohydroxyapatite/carbon-based scaffolds have been shown to be a suitable surface for mesenchymal stem cell adhesion with active formation of membrane projections and cell monolayer formation.

Nowadays it is mandatory sustainable energy production and storage. In this scenario, supercapacitors play an important role as ultrafast energy storage devices with long lifetime and high efficiency features. The new era of these devices is based on new materials and electrolytes that are environment-friendly during manufacturing and applications. This paper presents a high surface area mesoporous Carbon (MC) material direct growth on aluminum current collector on an environment-friendly process. MC material showed specific capacitance of ~ 8 F g− 1 and impressive chemical stability. Prepared with two MC electrodes, low-cost cellulosic separator and aqueous neutral electrolyte, the supercapacitor coin cells presented very low equivalent series resistance, ~ 100% device storage and supply efficiency, then almost no Capacitance, Energy and Power lost after dozen thousand cycles (on the optimized cell). The Ragone plot contrasts our data with conventional capacitors, electric double-layer capacitor (EDLC) and batteries, fitting them well into the EDLC category. For our best understanding, the excellent electric contact of MC and Al current collector is the key parameter to achieve a minimal ESR, higher efficiency and longer lifetime. The detailed characterization of material and devices are presented herein, evidencing MC as promising materials for energy storage applications.

A novel and scalable method is reported to produce flexible and freestanding fabrics composed of high surface area activated carbon nanofibers (aCNF) for applications in supercapacitors. The electrochemical behavior of a symmetric supercapacitor using the aCNF electrodes and the operando Raman spectra study accomplished under polarization conditions are reported. The evolution of Raman spectra during polarization supported the aCNF stability and suggested the insertion of the HSO4− ions in carbon micropores. These findings evidenced a new symmetry at the aCNF/electrolyte interface, where electronic and ionic charges accumulate. The distributed capacitance in the time domain was studied by numeric differentiation of galvanostatic charge-discharge findings. The impedance behavior of the solid and liquid phases composing the aCNF/solution interface was modeled using a macro homogeneous description of two closely mixed phases represented by a single-channel transmission line incorporating the anomalous transport of the ionic charges in the disordered structure of aCNF. Electrochemical findings revealed outstanding charge-storage properties in neutral aqueous electrolyte resulting in long lifespan, low equivalent series resistance (12 mΩ g), high coulombic efficiency (∼99.8 %), a maximum distributed capacitance of 82 F g−1 (0.25 A g−1-1.1 V), maximum specific energy and power of 2.98 W h kg−1 and 72,672 W kg−1, respectively.

This study report on the physicochemical behavior exhibited by the composite material based on niobium pentoxide nanoparticles (Nb2O5) decorated graphene (Gr) and their promising electrochemical properties in neutral aqueous supercapacitors (SCs). The Nb2O5@Gr composite showed outstanding properties where Gr contributes to electrochemical stability and ultra-fast electronic transport, while Nb2O5 offers fast and reversible solid-state surface redox reactions. Nb2O5 also works as a protective surface blocker for the carbon scaffold. A new methodology is proposed to verify the electrocatalytic activity for electrolyte decomposition in SCs. It was verified the electrocatalytic activity decreased by 7% for water splitting in the presence of Nb2O5, which boosted the overall device characteristics for the energy-storage properties. The Nb2O5@Gr composite electrode increased the energy and power densities from 4 to 18 µWh cm−3 and 0.5 to 2 µW cm−3, respectively. In addition, the cell voltage increased from 0.4 to 0.6 V, while the areal capacitance changed from 27.5 to 150 µF cm−2, and the equivalent series resistance (ESR) underwent a three-fold reduction. These promising findings are associated with synergism between the Nb2O5 nanoparticles, which conferred a pronounced pseudocapacitive contribution, while the Gr worked as an efficient nanosized and localized current collector at the active redox surface sites. These results encourage future works to explore the exciting properties of the Nb2O5@Gr composite electrode in aqueous-based SCs. The distributed capacitance in the time domain was calculated to discriminate the electrostatic and faradaic charge-storage mechanisms occurring in electrical double-layer capacitors and pseudocapacitor devices, respectively.

Due to the pseudocapacitive charge storage, transition metal oxides occupy a prominent position as high-energy-density electrode materials for supercapacitors. Environmentally friendly, facile synthesis and earth-abundant precursor materials are highly desirable in the investigation of novel electrodes. We report the synthesis of a binder-free electrode composed of iron oxide (FeOx) nanoparticles supported on radially oriented multi-walled carbon nanofibers (CNF). Characterization studies revealed a homogeneous distribution of nanoparticles composed of α-Fe2O3 (hematite), γ-Fe2O3 (maghemite), and Fe3O4 (magnetite) phases on the CNF scaffold. A high specific pseudocapacitance of 239.2 F g−1 was verified for the iron oxides due to contributions of the reversible solid-state redox reactions involving the Fe(II)/Fe(III) redox couple. Likewise, this work also discusses in detail the charge storage mechanism involving the FeOx species. It is reported a facile synthesis of an electrode material with a pseudocapacitive behaviour, good cyclability, and low equivalent series resistance (e.g., 3.79 mΩ g). As seen, the composite electrode material is promising for the energy storage process in aqueous-based supercapacitors.

To date is emergent the development of novel coatings to protect erosion, especially to preventive dentistry and restorative dentistry. Here, for the first time we report the effectiveness of multi-walled carbon nanotube/graphene oxide hybrid carbon-base material (MWCNTO-GO) combined with nanohydroxyapatite (nHAp) as a protective coating for dentin erosion. Fourier transform Raman spectroscopy (FT-Raman), scanning electron (SEM), and transmission electron (TEM) microscopy were used to investigated the coatings and the effect of acidulated phosphate fluoride gel (APF) treatment on bovine teeth root dentin before and after erosion. The electrochemical corrosion performance of the coating was evaluated. Raman spectra identified that: (i) the phosphate (ν1PO43-) content of dentin was not significantly affected by the treatments and (ii) the carbonate (ν1CO32-) content in dentin increased when nHAp was used. However, the nHAp/MWCNTO-GO composite exposited lower levels of organic matrix (CH bonds) after erosion compared to other treatments. Interesting, SEM micrographs identified that the nHAp/MWCNTO-GO formed layers after erosive cycling when associate with APF treatment, indicating a possible chemical bond among them. Treatments of root dentin with nHAp, MWCNTO-GO, APF_MWCNTO-GO, and APF_nHAp/MWCNTO-GO increased the carbonate content, carbonate/phosphate ratio, and organic matrix band area after erosion. The potentiodynamic polarization curves and Nyquist plot showed that nHAp, MWCNT-GO and nHAp/MWCNT-GO composites acted as protective agents against corrosion process. Clearly, the nHAp/MWCNTO-GO composite was stable after erosive cycling and a thin and acid-resistant film was formed when associated to APF treatment.

Imipramine (IMP), a tricyclic antidepressant drug, is commonly prescribed for treatment of psychiatric patients suffering from different forms of depression. The appropriate amount of drug intake is crucial to ensure the optimum therapeutic effects minimizing severe collateral effects and toxicity. Therefore, the monitoring of imipramine is essential for its clinical applications. Herein, we report an electrochemical sensor based on a composite of ferrocenecarboxylic acid (FCA), β-cyclodextrin (CD), and oxidized multi-walled carbon nanotubes (f-CNT) modified glassy carbon electrode for detection of IMP at low potential. The electrochemical behavior of the proposed sensor was characterized by scanning electron microscopy, Raman spectroscopy, and cyclic voltammetry. The results show that imipramine determination using the proposed sensor occurs around 0 V vs Ag/AgCl in phosphate buffer pH 7.0. The calibration curves were obtained by cyclic voltammetry and differential pulse voltammetry, with linear ranges of 10 to 350 μmol L−1 and 0.1 to 10 μmol L−1, respectively. A detection limit of 0.03 μmol L−1 was obtained for the detection of IMP. The sensor was applied for IMP determination in psychotropic drugs and urine samples and the results show a recovery percentage between 99 and 101% for the analyte.

An electrochemical sensor based on functionalized multiwalled carbon nanotubes (MWCNTf) has been developed and applied for determination of anticancer drug flutamide in pharmaceutical and artificial urine samples. The electrode was prepared by modifying a glassy carbon electrode with MWCNTf, denoted herein as MWCNTf/GCE. The MWCNTf/GCE electrode exhibited high catalytic activity, high sensitivity, and high stability and was applicable over a wide concentration range for flutamide. The effects of the scan rate, pH, and nature of the electrolyte on the electrochemical behavior of flutamide on the MWCNTf/GCE were investigated. The results showed that this electrode presented the best square-wave voltammetric response to flutamide in Britton–Robinson buffer solution at pH 5.0 at frequency of 50 Hz and amplitude of 0.06 V. The proposed sensor presents a wide linear response range from concentration of 0.1 μmol L−1 up to 1000 μmol L−1 (or 27.6 μg L−1 up to 0.27 g L−1), with limit of detection, limit of quantification, and sensitivity of 0.03 μmol L−1, 0.1 μmol L−1, and 0.30 μA μmol−1 L, respectively. The MWCNTf/GCE electrode was successfully applied for determination of flutamide in pharmaceutical formulations and artificial urine samples, giving results in agreement with those obtained by a comparative method described in literature. A paired Student’s t-test revealed no statistical difference between the reference and proposed method at 95% confidence level. The average recovery for fortified samples was 101 ± 1%.

Osteoporosis is an osteometabolic disease, which promotes structural degradation of bone tissue and reduction of mineral density. We reported here a mechanical resistance assay from normal, osteopenic and osteoporotic trabecular vertebral bones of human cadavers. We performed a compressed test on ninety samples, evaluating Young's modulus and X-ray microtomography to measure bone volume fraction and trabecular thickness. This experimental data are employed for computing the orthotropic macroscopic behavior of vertebral trabecular bones using known analytical formulae that were obtained by Galka et al. (Arch Mech 51: 335-355, 1999) via an asymptotic homogenization model. A geometrical model with a periodic orthogonal plate-like structure is applied. The properties of the bone-trabecular mass are considered linear, homogeneous and orthotropic. Average values for all technical or engineering elastic properties are computed for three important regions of the trabecular bones corresponding to thirty individuals classified as normal, osteopenic or osteoporotic by calcaneus ultrassometry. This study could be useful for a better understanding of the elastic behavior of trabecular bones in human vertebral bodies, allowing an estimation of bone answer under stress in different directions and the risk of fracture associated with osteoporosis.HighlightsDescribing the elastic behavior of trabecular bones in human vertebral bodies at the micro and macroscopic.Allow a better estimation of the stress in different directions and risk of fracture associated with osteoporosis.Model request a very low computational cost.Offer a better understand the global effective coefficients of samples of trabecular bone, from the model of a periodic unit cell, in the format orthogonal plate-like structure with homogeneous bone mass.

No contexto de armazenamento de energia com grande potencia, devemos levar em consideracao a importância dos supercapacitores, este trabalho tem como finalidade melhorar a capacitância de supercapacitores adicionando a tecnica de calcinacao tentando obter oxidos de manganes no processo de producao destes supercapacitores e realizar medidas in-operando para determinar as variacoes quimicas que ocorreram nos eletrodos dos supercapacitores.

Nowadays, being able to store and recover energy quickly is becoming increasingly more important for different applications. This Study report on novel electrode material composed of MWCNTs directly synthesized over a fine aluminum foil in CVD then functionalized with Nitric Acid and placed in Coin cells. The electrolyte used was an aqueous solution of Lithium Sulfate 1Mol/L with Sonicator-scattered Pani. This Material showed a good lifetime, solid electric potential stability until 2V and improved Capacitance going up to 135 F g-1 demonstrating the feasibility of this composite and the techniques involved in near future's State-of-Art supercapacitors.