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Solid polymer electrolytes containing methylcellulose:dextran (MC-DEX), ammonium hexafluorophosphate (NH4PF6), and glycerol have been prepared via the solution cast method. Various techniques have been used to characterize the prepared electrolyte samples. Fourier transform infrared spectroscopy (FTIR) analysis revealed the interaction between polymers and electrolyte components. According to the electrical impedance spectroscopy (EIS), the highest conducting plasticized system achieves a conductivity of 6.71 × 10-4 S cm−1 at ambient temperature. The mobility, number density, and diffusion coefficient of ions were measured using both FTIR and EIS methods, and it was found that their values rise as the amount of glycerol increases. Polarization due to ion migration is responsible for the high value of dielectric parameters. According to transference number measurement (TNM), the transport ion (tion) is 0.92, verifying that the ions are the primary charge carriers. The electrochemical stability window of the maximum conducting plasticized system is 1.58 V, based on linear sweep voltammetry (LSV) analysis. The electrical double-layer capacitor (EDLC) device is fabricated using the highest conducting plasticized system. The cyclic voltammetry (CV) curve is roughly rectangular in shape and with no presence of Faradaic peaks with its specific capacitance of 32.69F/g at 10 mV/s.

A facile and mild route to synthesize C-coated SiC nanosheets (SiC/C NSs) via wet-chemical etching in hydrofluoric acid (HF) at 60 °C for 48 h using carbon aluminum silicate (Al4SiC4) as raw materials is reported for the first time. HF molecule leads to the breaking of C-Al bonds in Al4SiC4, which eventually results in the formation of two-dimensional SiC nanosheets. A carbon layer with a thickness of approximately 1.5 nm is formed on the surface of SiC nanosheets due to the excess carbon. The prepared SiC/C NSs possess a smooth and rectangular sheet with a mean 150 nm in width, 500 nm in length and 10 nm in thickness, respectively. The crystallographic characterization indicates that 3C-SiC and 2H-SiC coexist and the parallel plane relationship of 3C/2H-SiC heterojunction is (111)3C-SiC//(001)2H-SiC. Due to the formed 3C-SiC/2H-SiC heterojunction and graphitic carbon, the fabricated electrode based on SiC/C NSs exhibits prolonged cycling stability and high specific areal capacitance as a promising supercapacitor candidate. It remains 91.2% retention even after 20000 cycles and 734 μF/cm2 at a scan rate of 10 mV/s.

The pure and Zn doped CdS nanoparticles were synthesized using a simple method of co-precipitation. The structural, functional group and morphological analysis were carried through XRD, FTIR and SEM analysis. For supercapacitor applications, cyclic voltammetry analysis was studied for pure and Zn doped CdS nanostructures. From the XRD analysis all the samples were formed as a hexagonal crystal structure. SEM images show that the prepared Zn doped CdS formed like form as the flaks. The supercapacitor characterization (CV analysis) suggest that CdS and CdS-Zn electrodes are exhibit pseudocapacitive nature and it delivered the specific capacitance of 302 and 277 Fg−1 at a scan rate of 10 mV s−1.

Herein, a fully integrated thread/textile-based electrochemical sensing device has been demonstrated. A hydrophilic conductive carbon thread, chemically modified with gold nanoparticles through an electrodeposition process, was used as a working electrode (WE). The hydrophilic thread coated with Ag/AgCl and an unmodified bare hydrophilic thread were used as reference electrode (RE) and counter electrode (CE) respectively. The device was fabricated with hydrophilic conductive carbon threads supported by capillary tubes and these integrated electrodes were placed in a 2 mL glass vial. The physico-chemical characterization of the working electrode was carried out using SEM (scanning electron microscopy) and X-ray photoelectron spectroscopy (XPS). Furthermore, the fabricated sensing platform, was tested for electrochemical sensing of arsenic. The electrocatalytic oxidation activity of arsenic in the designed platform was investigated via cyclic voltammetry (CV) and square wave Voltammetry (SWV). An oxidation peak at -0.4 V corresponding to the oxidation of arsenic was obtained. Scan rate effect was performed using CV analysis and the diffusion coefficient was found to be 2.478×10-10 with a regression coefficient of R2 = 0.9647. Further, concentration effect was accomplished in the linear range 0.4 μM to 60 μM. The limit of detection was obtained as 0.416 μM. For the practical application, effect of interference from other chemicals and real sample analysis from the tap water and blood serum sample was carried out which gave remarkable recovery values.

In this work, novel rhombus-shaped cerium oxide sheets (RCOS) were prepared using a facile, soft-chemical approach that was low cost, scalable, eco-friendly, and industrially viable. The structural and surface chemical properties were studied using spectroscopic and electron microscopic techniques. The synthesized RCOSs were used for the methanol oxidation reaction and supercapacitor studies. The RCOSs showed a current density of ∼227 mA cm–2 with an onset potential of ∼0.37 V. The electrocatalyst activity retention was 92% of the initial activity after 500 CV cycles. A specific capacitance of 481 F g–1 at a scan rate of 5 mV s–1 was observed for supercapacitor application. The specific capacitance retention was ∼83% after 500 cycles. The huge specific surface area and conductivity associated with cerium oxide sheets were responsible for the enhanced electrochemical properties. This is the first report on the synthesis of rhombus-shaped cerium oxide sheets, which leads to new avenues for synthesizing novel cerium-based electrode materials.

In the present study, MnO2 nanoparticles were synthesized by simple facile hydrothermal method. The structural, morphological, and electrochemical behaviour of the synthesized nanoparticles were analyzed by XRD, SEM/EDX and CV. XRD confessed that the tetragonal structure of bare MnO2. The crystallite size of MnO2 nanoparticles obtained at MnCl2: KMnO4 (0.5: 0.4 M) was found to be 9.2 nm. The nanorod structures of the synthesised MnO2 nanoparticles were revealed by morphological studies. The electrochemical behaviour of nanorod like MnO2 nanoparticles showed a specific capacitance of 91 Fg−1 at lower scan rate of 10 mV s−1.

This project was to study analytical technique foranti_thalassemia drug of deferasirox by glassy carbon electrode (GCE).The electrochemical performance of deferasirox was studied by cyclic voltammetry technique. The determination of deferasirox wasapplicate under Optimize condition in pH 13, scan rate 50 and 500mv/s,temperature 40 0Candinterference that have been studied. where found the resultsthat calibration curve ofdeferasiroxwas linear in the concentrations 2.6 × 10-4-2.6 × 10-2 M,the detection limits were9.227 × 10-4 M at 50mv/s and1.084 × 10-4 Mat 500mv/s while LOQ were 3.075 × 10-3 M and 3.613 × 10-4 M.The active area of electrode was calculated to be 0.314 cm2 and also the diffusion coefficientswere (2.294 × 10-4cm2sec-1)in scan rate 500 mv/s and (1.452 × 10-4cm2sec-1) in scan rate 50 mv/s.where RSD% for bulk, form and serum less than 0.5% while in urine less from 1.5% and recovery close to 99.8% in bulk, form and serum while in urine is 100.1. The voltammogram for deferasirox giveirreversible process with adsorption– controlled process. Finally, this technique was appliedfor deferasirox on pharmaceutical formulations and biological samples (serum and urine).

Cyclic voltammetry (CV) is the most popular electrochemical technique for the study of electrode processes. One of the reasons for its popularity is its adjustable timescale which can vary several ...

The main objective of the research was to deposit thin films of silver on a graphite carbon paste in a phosphate buffer medium using an electrochemical method. To construct a nitrofurazone detection sensor that is highly sensitive. Different manufacturing parameters, such as electrodeposition potential, pH effect, potential scan rate effect, and number of scan cycles, were examined in this section. The parameters were optimized to improve the deposited silver layers various electrocatalytic characteristics. The Nitrofurazone reduction process is diffusion controlled, as seen by the linear variation of Epc with log(v). The constructed Ag-NPs@CPE electrod has excellent electrical characteristics a large active surface area and low background with extremely high electrical conductivity, according to structural and electrochemical characterizations such as Scanning electron microscopy, X-ray diffraction (XRD) and cyclic voltammetry. The constructed sensor has a very remarkable analytical performance for nitrofurazone molecule identification, with a very low detection limit of about 10–8 M. The detection of nitrofurazone using our Ag-NPs@CPE sensors in real samples contaminated with the antibiotic nitrofurazone, such as tap water and urine. In the selected sample, the electroanalytical findings reveal a very satisfactory recovery rate of more than 94 percent.

In recent era of modern and bendable technology, energy dearth arises as a paramount subject around the globe with a dire demand of flexible and lightweight energy storage devices. This study targets fabrication of reduced graphene oxide (rGO) and utility of abundantly available, cost effective, and environment friendly lignocelluloses (LC) fibers extracted from Carica papaya source, as a binder to bind active material (rGO) as robust and compact paper sheet. Fabricated samples were analyzed by X-ray diffraction for crystallographic analysis, Scanning electron microscopy, Transmission electron microscope for morphology, Fourier transform infrared spectroscopy for structural bonding, and Raman spectroscopy for vibrational modes. Robust and bendable rGO/LC paper electrode was tested for energy storage application by employing in different characterizations, i.e., cyclic voltammetry for capacitive behavior, galvanostatic charge–discharge for symmetric EDLC, and electrochemical impedance spectroscopy for resistive charge kinetics, respectively. rGO/LC composite sheet employed as working electrode in 3-electrode CV measurements and revealed specific capacitance of 591 F/g at a scan rate of 5 mV/s by keeping the undistorted shape of voltammograms at higher scan rates which present it as a suitable candidate for modern flexible and energy storage devices. rGO/LC-based symmetric cell revealed the highest specific capacitance of 228 F/g at applied current density of 0.1 A/g, the energy density of 6.3 Wh/kg, and power density of 129 W/kg, respectively. rGO/LC-based symmetric cell confirmed the cycling stability by revealing capacitance retention of 82% after 200 cycles. It can conclude that biomass-based rGO paper sheet can be a potential candidate as environmentally safe with remarkable electrochemical activity in energy storage applications.

In the present work, Orange CD was chosen as an intriguing modifier for the electropolymerization on the surface of CPE by the CV technique. A novel, sensitive, and cost-effective poly (Orange CD) MCPE (PoOCD/MCPE) sensor was utilized for the selective detection of paracetamol (PA) in 0.2 M phosphate buffer solution (PBS) of pH 7.4. The oxidation peak current of PA was vastly enhanced at the sensor. The scan rate study is suggested that electro-oxidation of PA was adsorption-controlled. The pH study testifies the redox pathways transport with the same quantity of electrons and protons. The detection limit of PA is found to be 2.64 µM. DPV results show that substantial peak separation between PA, folic acid (FA), and dopamine (DA) could be facilitating their individual and simultaneous determination on the sensor. The decorated sensor demonstrates high sensitivity, stability, reproducibility, repeatability and has been successfully exploited for the detection of PA in a tablet with promising results.

Rechargeable Mg ion batteries (MIBs) have aroused great interests, and using alloy-type anodes and conventional electrolytes offers an effective way to develop high energy density Mg battery systems. However, the dealloying-induced nanoporosity evolution of alloy-type anodes during the charging process has received less attention. Herein, using a magnetron-sputtered Mg3Bi2 film as an example, we investigate its electrochemical dealloying and associated structural evolution in an all-phenyl-complex electrolyte by in-situ and ex-situ characterizations. The microstructures and length scales of nanoporous Bi can be facilely regulated by changing electrochemical parameters, and there exists a good linear correlation between the surface diffusivity of Bi and the applied current density/potential scan rate on a logarithm scale. More importantly, the self-supporting nanoporous Bi electrodes deliver satisfactory Mg storage performance and alloy-type anodes show good compatibility with conventional electrolytes. Furthermore, the charging-induced dealloying in MIBs is a general strategy to fabricate nanoporous less noble metals like Sn, Pb, In, Cu, Zn and Al, which shows advantages over chemical dealloying in aqueous solutions. Our findings highlight the significance of nanoporosity evolution of alloy-type anodes during dealloying, and open opportunities for the fabrication of nanoporous reactive metals.

We are reporting here a novel antimony doped cobalt oxide based electrode material for supercapacitor application to overcome the current scenario of energy crises by offering excellent capacitive abilities. A facile hydrothermal route was employed to produce this antimony doped cobalt oxide material by varying content value of antimony in the range of 2–6 at. %. The X-ray diffraction results have successfully explored the cubic crystal structure along with phase composition of these as obtained Sb doped Co3O4 materials. The development of sub-micron sized structures-based material was explored by obtaining scanning electron microscopic images. The energy dispersive X-ray spectroscopy results have shown the highly pure nature of as obtained material. Cyclic voltammogram results have exhibited that among the SbCo-0, SbCo-2, SbCo-4 and SbCo-6 materials, SbCo-4 has exhibited higher specific capacitance value i.e 894.15 F/g than remaining, which was obtained by scanning the material at the scan rate of 5 mV/s. More significantly, Galvanostatic charge-discharge profiles obtained at different scan rates ranging from 1 to 10 A/g, for SbCo-4 material has shown even good capacitance retention i.e 75.70% at higher sweep rate, equal to 10 A/g. On the basis of electrochemical impedance spectroscopic analysis, it is concluded that this material has also shown excellent conductive properties. Furthermore, after performing 3000 galvanostatic charge-discharge cycles, it is concluded that this material can possessed an excellent cycling stability equal to 82.02%. All these excellent capacitive properties shown by this material have suggested that it can be proved as a potential applicant in the field of energy storage devices.

In the present paper, electrochemical quantification of an opioid analgesic butorphanol (BTR) at copper oxide/polyaniline nanocomposite modified glassy carbon electrode (CuO/PANI/GCE) has been discussed. The electroactive surface was produced by drop casting a suspension of CuO/PANI onto the surface of glassy carbon electrode. The nanocomposite was characterized by XRD, XPS, EDX, TEM, UV–Vis, FT-IR, Raman and FESEM techniques. Electrochemical impedance spectroscopy (EIS) technique was utilized to study the enhanced charge transfer phenomenon occurring at the surface of the modified sensor. The two electron oxidation process of BTR at CuO/PANI/GCE was found to be a function of pH (5.6) of the medium, scan rate and concentration of BTR. The optimized voltammetric response is observed in Britton-Robinson buffer, which shows an occurrence of an irreversible diffusion-controlled phenomenon where the anodic peak current is proportional to the BTR concentration within the range of 1.99 to 9.95 µg/L, with a detection limit of 1.38 µg/L (LOD) and the quantification limit of 4.18 µg/L (LOQ). The applicability of the proposed method was also studied for the determination of BTR in pharmaceutical formulation and human blood serum.

The polyaniline/hydrothermal active carbon fiber (PANI/EACF) is designed and acted as supercapacitor electrode for the electrochemical energy storage application. PANI fiber layer with porous structure is fully covered on the surface of EACF substrate to form electroactive PANI/EACF electrode. The active carbon fiber (ACF) conducts the electrochemical oxidation and reduction activation to form EACF with functional hydroxyl group. The PANI/EACF with intermolecular hydrogen bond interaction exhibits the stronger and more stable bonding interface than PANI/ACF with Van der Waals force interaction, which accordingly promotes the interfacial charge transfer and charge storage capacitance in the charge–discharge process. PANI/EACF exhibits higher response current density than PANI/EACF at the same scan rate, indicating higher conductivity and electroactivity of PANI/EACF. The specific capacitance declines from 78.1 to 36.8 F g−1 for PANI/ACF and from 133.5 to 65.3 F g−1 for PANI/EACF when current density increases from 1 to 10 A g−1, presenting the obviously improved capacity. The corresponding capacitance retention, respectively, achieves 47.1 and 48.9%, presenting the slightly increased rate capability. The capacitance retention ratio of PANI/ACF and PANI/EACF achieves 61.4 and 67.1% at 5 A g−1 after 1000 cycles, presenting the slightly increased cycling stability. PANI/EACF with superior capacitive performance in the electrochemical charge–discharge process presents the promising energy storage application.

In the present work, Copper cobaltites (CuCo2O4) were efficiently developed by the CTAB-assisted sonochemical process succeeded by calcination at 350 °C for 3 h. The differential scanning calorimetric analysis results showed that all the reactions ended at 300 °C. The Fourier transform infrared spectroscopy and X-ray diffraction results established the formation of spinel CuCo2O4/CuO. The morphological analytic results exposed that CuCo2O4 possesses both the nanorods and nanoparticles structure. Furthermore, cyclic voltammetry (CV) and chronopotentiometric (CP) methods were used to evaluate the electrochemical properties of various CuCo2O4 formed. It is observed that the freshly prepared CuCo2O4 electrodes exhibit a very high specific capacitance of 811 Fg−1 at a scan rate of 5 mV s−1 and also demonstrates superior cycling stability retaining 91% of the initial capacitance even after 3000 continuous CV cycles. Hence, typical CuCo2O4 could be considered as an important electrode material for supercapacitor applications.

The rapid growth of flexible electronic devices greatly stimulates the demand for planer and microscale energy storage devices. Flexible and planer microsupercapacitors (MSCs) with their interdigitated electrode architecture serve as a promising platform for energy and power sources for flexible microelectronics. This study reports the fabrication of in-plane interdigitated structure-based MSC device utilizing TiO2 nanofibers (NFs) as an active material via binder-free, cost-effective, and environmental-friendly electrophoretic deposition (EPD) technique. The fabricated MSC device delivers an excellent areal capacitance ( ${C} _{A}$ ) of 9.4 mF/cm2 at 10 mV/s scan rate. Furthermore, the flexible MSC device shows 80% capacitance retention after 10 000 successive GCD cycles and 73% retention after 2000 bending cycles. Moreover, the maximum areal energy density and areal power density obtained for the device are $0.64~\mu $ Wh/cm2 and $307.2~\mu \text{W}$ /cm2, respectively.

Transition metal sulfides such as MoS2 and VS2 have emerged as promising candidates for energy storage applications in recent years. Among the reported transition metal sulfides, the patronite (VS4) form of vanadium sulfide is less explored and understanding its charge storage mechanisms is unusual in the literature. Here, we report the pseudocapacitive energy storage performance of patronite (VS4) nano-bundles synthesized via template-free hydrothermal approach by fabricating a solid-state asymmetric supercapacitor device (SSAD) with MXene (Ti3C2Tx) as the negative electrode. The fabricated VS4//MXene SSAD displayed a remarkable supercapacitive behavior in an expanded working potential window of 1.3 V. The device demonstrated a record high performance with the areal capacitance of 70.9 mF/cm2 at the scan rate of 5 mV/s and demonstrated ~ 4.5 and ~ 6 times superior areal capacitance as compared to the bare VS4 nano-bundles and MXene-based symmetric devices. Further, the device displayed an excellent energy density of 5.65 mW h/cm2 with a remarkable power density of 290.9 mW/cm2 and good cyclic stability ~ 75% after 3000 cycles in neutral electrolyte. Moreover, we have performed extensive density functional theory simulations to present electronic properties of VS4 and MXene supporting pseudocapacitive behavior for VS4 through reversible Faradic redox reactions and pre-dominant electrical double-layer capacitive behavior for MXene due to intercalation/de-intercalation of ions. The diffusion energy barrier for electrolytic ions is lower in VS4 (only 0.17 eV) satisfying better and rapid transport of charge carriers generated in VS4 justifying high charge storage performance. Populated electronic states for V 3d orbital in both the valence band and conduction band justify superior redox-type behavior for VS4 supporting experimental observations. Enhanced energy storage performance of asymmetric supercapacitors based on VS4 and MXene.

In this paper, acetaminophen (AP), typically consumed as a painkiller, was sensitively detected using an electrochemical sensor through cyclic voltammetry. Therefore, special attention focused on fabricating a sensitive voltammetric sensor based on cetrimide (CA) incorporated on a poly oxalic acid modified carbon nanotube paste electrode (POAMCNTPE). The topographical features and electrochemical characterisations of unmodified and modified electrodes were compared using a variable pressure scanning electron microscope (VP-SEM) and electrochemical impedance spectroscopy (EIS). The scan rate study reveals that the redox reaction of the AP at the surface of the modified electrode was controlled by diffusion. The detection limit (DL) of 1.50 × 10−8 M and quantification limit (QL) of 5.02 × 10−8 M was gained by utilising differential pulse voltammetry (DPV). The constructed electrochemical sensor displayed acceptable repeatability, excellent stability, and adequate reproducibility. The prepared sensor exhibited an outstanding selectivity to detect the AP in the presence of dopamine (DA) and folic acid (FA). The practicability of the proposed electrode was examined to be successful towards the quantification of AP in both pharmaceutical and biological samples.

A new algorithm that describes the faradaic current for elementary redox reactions in the cyclic voltammetric responses of persistently adsorbed species on metal electrodes at any scan rate is presented. This work does not assume electrochemical reversibility and instead demonstrates a set of equations that encapsulate how the forward and back charge-transfer rate constants influence the data as a function of the experimental time scale. The method presented here is compared against other approaches that rely on either finite-difference calculations or that require numerical approximation of improper integrals (i.e., ±infinity as a bound). The method here demonstrates that the current-potential data can be described by incomplete gamma functions, whose two arguments capture the relevant kinetic variables. Following the notation for the Butler-Volmer model of charge transfer, exact solutions are presented for the cases of the charge-transfer coefficient, α, equal to 1 or 0. A related algorithm based on these results affords calculation of current-potential data for 0 < α < 1, allowing comprehensive analysis (i.e., point by point) of voltammetric data throughout the reversible, quasi-reversible, and irreversible regimes. Accordingly, this work represents an alternative to the method of Laviron, i.e., analyzing just the peak splitting values, for experimentalists to understand and interpret their voltammetric data in totality.

Cellulose nanofiber (CNF) materials have attracted increasing attention in the field of energy storage and sensing due to their flexibility, environmental protection and sustainability. However, CNF materials have poor conductivity and low utilization effciency, which limits their applications. Improving the conductivity and utilization efficiency of CNFs while retaining their advantages is of great significance for developing wide applications of biomass resources. In this work, noncarbonized CNF@graphene quantum dot (GQD) film with good flexibility was fabricated through a combination of electrolysis and liquid dispersion. The as-obtained hybrid film shows excellent electrochemical storage performance, mechanical properties and sensing characteristics. Specifically, the film presents a specific capacitance of 118 mF cm− 2 even at a ultrahigh scan rate of 1000 mV s− 1, and a high capacitance retention higher than 93% at different current densities after 5000 cycles. Additionally, the assembled supercapacitor based on the hybrid film possesses high power and energy density at the same time (782 mW cm− 2 and 596 µWh cm− 2). These results demonstrate that the hybrid film possesses excellent rate performance and cycle stability. In addition, the film is sensitive to movement of the human body.

In this work, nanofibrillated cellulose (NFC), LiFePO4 (LFP), and graphene (GR) were used as raw materials to prepare a flexible self-supporting electrode. NFC shows excellent mechanical properties and flexibility. NFC is used as the skeleton of the flexible electrode, coupling LFP and GR to form a conductive network structure. The Flexible electrodes show excellent flexibility and bendability. The mass of the flexible electrode no longer decreased significantly at temperature higher than 400 °C. The final residual rate of the flexible electrode is about 58%. The surface resistance of the flexible electrode is found to decrease by 93% with the content of LFP increasing from 25 to 45 wt%. The flexible electrode also shows higher electrochemical reaction activity and higher reversibility of Li+ extraction/intercalation with the increase of LFP and GR. At 0.1 C rate, the first discharge capacity is 121.47 mAh g−1, 146.76 mAh g−1 and 167.74 mAh g−1 for NFC/GR/LFP flexible electrode with 25 wt%, 35 wt%, and 45 wt% LFP, respectively. After 60 cycles of cycling, the capacity retention rate remains above 98%. Under 5 C rate, the first discharge capacity of these electrodes decrease to 29.87 mAh g−1, 77.41 mAh g−1, 99.84 mAh g−1, respectively, and after 770 cycles, the capacity retention rate is still above 90%. The AC impedance of the NFC/GR/LFP flexible electrodes with LFP content of 25 wt%, 35 wt%, and 45 wt% is 40 Ω, 15 Ω, and 9 Ω, respectively. The above results show that the flexible electrode exhibits excellent mechanical and electrochemical properties. The flexible electrode shows very high capacity retention rate no matter at low scan rate and or high scan rate. The cycle stability can be further enhanced by increasing the loading of active materials.

Silicon carbide nanofibers (SiCnf) that possess high electron mobility and wide bandgap have attracted tremendous research attention in the past decades, and they have been of paramount importance in promoting the application of novel energy technologies. Herein, we proposed a facile and efficient method to accelerate the in-situ growth of SiCnf on a carbon fabric with fused KCl. The carbon fabric impregnated with KCl solution can realize an efficient reaction between the active carbon atom and the silicon source at a temperature as low as 1100 °C. The as-obtained composite yields a porous structure with an enhanced graphitization degree. It is suggested that the fused KCl can promote the growth of SiCnf with much lower energy consumption, and the proposed method is facile, eco-friendly, and easy to be scaled-up. When evaluated as a supercapacitor electrode, the as-prepared material exhibits a capacitance as high as 4.36 mF⋅cm−2 at a scan rate of 0.05 V⋅s−1. Furthermore, the capacitance of the as-assembled supercapacitor exhibits an increase of 6.51% after 10000 cycles at room temperature. Therefore, the prepared SiCnf is a good candidate for supercapacitor electrodes. This work may facilitate the design of high-performing supercapacitor electrodes in the future.

In the present study, the electrochemical behavior of Folic acid (FA) on the glassy carbon electrode modified with 2D-MoS2 nanosheets has been investigated utilizing differential pulse voltammetry (DPV), cyclic voltammetry (CV), and chronoamperometric techniques at pH 6.0 Britton-Robinson buffer. The experimental conditions, including the pH, scan rate, were optimized. Under the optimized experimental conditions, to determine the selectivity and sensitivity of FA, the DPV procedure was conducted in the linear dynamic range from 0.06 to 1.16 to 1.16–24.3 µM with a detection limit of 32.0 nM. The 2D-MoS2 nanoparticle was synthesized and characterized by EDX and SEM methods. The proposed modified electrode offered an outstanding electrocatalytic activity towards the oxidation of FA. The FA detection successfully validated the analytical reliability of 2D-MoS2/GCE in the food samples with acceptable recoveries at the range of 97.1 and 103.1%. Based on the results, it can be speculated that 2D-MoS2/GCE can be used as an alternative analytical instrument to determine FA in real samples.

One-dimensional iron hydroxide@cadmium hydroxide nanostructures have been prepared by sequentially converting cadmium hydroxide into iron hydroxide via simple and cost-effective cation exchange reaction based on solubility product to design electrochemical supercapacitive electrode. Surface architecture of iron hydroxide@cadmium hydroxide nanostructures in the form of core–shell enables easy and effective electrochemical reactions which have been studied via electrochemical cyclic voltammetry and charge–discharge studies. Interestingly, iron hydroxide@cadmium hydroxide electrode exhibits specific capacitance of 368 F g−1 at current density of 0.5 A g−1 along with electrochemical impedance analysis. Capacitance retention performed at the scan rate of 50 mV s−1 for 5000 cycles results in 52% capacity of its initial.

Controlling the scan rate of frequency-scanned antennas can be useful for any bandwidth-limited application. Two techniques to control the scan rate of planar periodic leaky-wave antennas are discussed: optimizing unit cell dispersion and meandering unit cells with a desired periodicity. Each technique presents a tradeoff of limited matching bandwidth or reduced antenna gain, respectively. These techniques are used together to design a broadside-scanning Ka -band antenna. Measurements demonstrate a very high scan rate of $10.5^{\circ }/\%\text{BW}$ . The 8 $\%$ available bandwidth and $80^{\circ }$ scan range through broadside is very favorable for frequency-scanned applications.

The problem of the cyclic voltammetry investigation of the initial stages of electrochemical phase formation is considered. Analytical expressions are derived for the cyclic voltammograms and the sizes of the independent new-phase nuclei having formed on an indifferent electrode under linear potential sweep conditions for the cases of instantaneous and progressive nucleation followed by diffusion-controlled growth. The current as a function of the overpotential is found to have different dependences on the scan rate for the given limiting cases of nucleation. The results of a numerical simulation are presented. The logarithmic dependences of the maximum and minimum currents on the scan rate are shown to have a slope of –1/2 if nuclei appear in a narrow time interval long before the reverse, their number does not change when the scan rate changes, and their growth is controlled by diffusion. The slope of the dependences is –3/2 when nuclei form before and after the reverse and their number decreases with increasing scan rate. The possibility of using the proposed criteria for the interpretation of the experimental cyclic voltammograms is analyzed and confirmed for the model system (KNO3–NaNO3–AgNO3 melt/iridium substrate/silver) at low concentrations of depositing ions, which provide diffusion control of the process. Both instantaneous nucleation and progressive nucleation are shown to occur in this system, depending on other experimental conditions.

Two hydrothermal techniques under microwave irradiation were used to synthesize γ-MnO2 from 90°C to 150°C in 10−30 min. The first technique is based on reducing KMnO4 with MnSO4, and the second one involves liquid-phase oxidation between MnSO4 and (NH4)2S2O8. The structures and morphologies of the samples were analyzed using X-ray diffraction, scanning electron microscopy, and N2 physisorption measurements. The electrochemical properties were evaluated through cyclic voltammetry and electrochemical impedance spectroscopy. The γ-MnO2 materials obtained by the first technique mainly exhibited nanorods with diameters of 40–60 nm, and the samples obtained by the second technique showed flower-like microspheres with diameters of 1−2 µm; each flower was composed of nanosheets with a thickness of 10−20 nm. The processing time directly depends on the size of the nanorods. The sample synthesized by the first technique at 150°C and 10 min has the highest specific surface area of up to 59.08 m2 g−1 and mean pore diameter of 34.11 nm. Furthermore, this sample exhibits a near-rectangular cyclic voltammetry curves and high specific capacitance of 331.3 F g−1 in 0.1 M Na2SO4 solution at 5 mV s−1 scan rate. Graphic abstract

Carbon fiber via electrochemical and hydrothermal activation (EACF and HACF) treatment is designed and fabricated as supercapacitor electrode material for effective energy storage. HACF with porous surface pit structure shows higher surface area (241.2 m2 g−1) than EACF with smooth surface structure (147.6 m2 g−1), causing the enhanced electrical double layer capacitance. HACF with predominant hydroxyl group is more feasible to introduce additional Faradaic capacitance rather than EACF with predominant carbonyl group and epoxy group. HACF exhibits higher response current density (3.26 A g−1) than EACF (1.92 A g−1) at the same scan rate. The specific capacitance declines from 18.8 to 11.9 F g−1 for EACF and from 28.8 to 18.3 F g−1 for HACF when current density increases from 1 to 10 A g−1, presenting obviously improved capacitance. The corresponding capacitance retention achieves 47.1 % and 48.9 %, presenting similar rate capability. The density-functional theory calculation results indicate HACF exhibits lower band gap, lower interface energy and higher density of states at Fermi energy level than EACF, indicating higher orbital electron cloud distribution and electrical conductivity. The experimental measurement results are well consistent with the theoretical calculation results to prove higher conductivity and electroactivity of HACF. HACF with superior capacitive performance presents the promising energy storage application.

In the present study, a highly efficient electrochemical sensor for methadone measurement through the use of a glassy carbon electrode modified with two layers of graphene/Ag nanoparticles ((Gr/AgNPs)2/GCE) nanocomposite is introduced. The morphological, elemental and electrochemical properties of the as-prepared nanocomposite were evaluated by scanning electron microscopy, energy dispersive spectroscopy. The influence of different experimental parameters such as pH and scan rate on the voltammetric response of methadone was also addressed. Exhibiting a peak potential at + 0.79 V (vs. Ag/AgCl), the as-prepared electrode manifested an improvement in its catalytic activity toward methadone oxidation. Under optimal conditions, the developed sensor exhibited an excellent response toward methadone in the concentration range of 1.0–200.0 µM with a detection limit of 0.12 µM. Moreover, the proposed electrode offered superior selectivity for methadone reflecting its efficiency for the real samples such as human blood serum.

Nickel oxide is a significant candidate for the supercapacitor electrode application due to its high theoretical capacitance. This work demonstrates the synthesis of ultra-small-sized NiO nanomaterial using Polyvinyl alcohol template-assisted hydrothermal route succeeded by a significant annealing process. The crystallinity, chemical state, and bonding properties of the NiO materials are evaluated by X-ray diffraction studies, X-ray photoelectron, Raman, and Fourier transform infrared spectroscopic analyses. The morphological features are controlled by a variation of PVA template, and the high concentrations of PVA template provide ultra-small-sized NiO nanomaterial. The surface morphological features are characterized using scanning electron microscopy and high-resolution transmission electron microscopy. The pseudocapacitor behavior of NiO materials was confirmed by the electrochemical performance studies using cyclic voltammetry, EIS, and galvanocharge-discharge measurements. The ultra-small-sized NiO material possessed a specific capacitance of 534.5 Cg−1 and good rate capability at a scan rate of 5 mVs−1. The discharge curve provides the specific capacitance of 563.75 Cg−1 at a current density of 1 Ag−1 and at a scan rate of 100 mVs−1, withstands 91% of its primary capacitance after 2000 cycles. This work authenticates an efficient approach for enhancing the potential of metal oxides for energy storage applications.

Zinc (Zn(II)) is a divalent cation involved in regulating intracellular signal transduction and gene expression through transcription factor activity, and can act as a metal neurotransmitter by modulating synaptic activity and neuronal plasticity. Previous research has demonstrated spatial heterogeneity of Zn(II) in the brain, has estimated extracellular concentrations of Zn(II) across various brain regions, and has measured rapid intracellular changes in Zn(II) concentration during glutamate flux. Despite this work, quantification of rapid extracellular Zn(II) release from neurons, on a millisecond time scale, in real time has remained difficult with existing technologies. Here, we have developed an electrochemical waveform, called the "extended sawhorse waveform (ESW)," for fast-scan cyclic voltammetry detection at carbon-fiber microelectrodes which enabled rapid and stable Zn(II) monitoring over time. This waveform was developed to overcome existing challenges in monitoring metallotransmitters stably over time electrochemically by introducing a brief cleaning step to facilitate rapid cleaning of the electrode surface in between scans. The ESW scans from 0.5 V down to -1.0 V, up to 1.45 V for 3 ms (cleaning step), and back to 0.5 V at a scan rate of 400 V/s. Repeated introductions of Zn(II) at the electrode using a traditional waveform cause plating which ultimately deteriorates the sensitivity over time; however, using the ESW, significant improvements in stability were observed. Overall, we provide a unique approach to monitor and quantitate rapid Zn(II) signaling in the brain at carbon electrodes which will impact our ability to advance fundamental knowledge of Zn(II) involvement in extracellular signaling pathways in the brain.

Co3O4 nanostructures with different reaction times are synthesized using a hydrothermal method. The structural, morphological as well as electrochemical characteristics are performed for Co3O4 nanostructures. The XRD study reveals that the prepared Co3O4 exhibits the cubic structure. The Co3O4 shows microflakes-like morphology. The electrochemical study shows that the Co3O4 nanostructures synthesized with a reaction time of 18 h show better specific supercapacitance of 309 F g−1 at scan rate 5 mV s−1 with 7.46 W h kg−1 and 92.85 W kg−1 of energy and power density, respectively. Also, it shows excellent cyclic stability over 1000 cycles with a capacity retention of about 95.6%. Furthermore, the electrochemical results demonstrate that the prepared Co3O4 nanostructures with a reaction time of 18 h show better sensitivity of 0.3395 mA mM−1 cm−2 toward glucose with a detection limit of ~ 0.22 mM. This electrode also shows better selectivity toward glucose as compared to various interfering species.

The effects of potentiostat scan rate on the impedance, topography, and morphology of the Polyaniline (PANi) thin film has observed in this study. PANi has deposited on the Quartz Crystal Microbalance (QCM) surface with various scan rates, and changes in the impedance value have observed through an impedance analyzer test. Topography Measurement System (TMS) has observed the layer topography, while the layer morphology has observed using optical microscopy and Scanning Electron Microscope (SEM). The results have shown that the best sample has a scan rate of 10 mV/s, with a low impedance value indicating the layer has rigid. The variation in scan rate can affect the impedance value, but it is not significant and does not indicate a damping effect on QCM. A homogeneous layer is deposited at a low scan rate from topography and morphological observations, while a high scan rate results in an inhomogeneous layer. DOI: 10.17977/um024v6i22021p046

Design of nanostructured surface architecture is currently playing a vital role to enhance the energy storage capability of electrode materials and opening up a new era for future technologies through electrochemical supercapacitors. Present effort portrays the growth of nanostructured bismuth vanadate (BiVO4) as an active electrode for supercapacitor application by using ease and industry scalable successive ionic layer adsorption and reaction (SILAR) method. Structural analysis reveals the development of orthorhombic structured BiVO4 with spongy nano-pebbles like surface architecture. Synthesized BiVO4 electrode yields remarkable capacitance of 707 F/g @3 mV/s scan rate. Faradaic and capacitive type contributions have been evaluated for in-depth understanding along with the estimation of electrochemical active surface area. Electrochemical impedance spectroscopy (EIS) analysis of BiVO4 electrode exhibits 5.723 and 0.89 Ω cm2 values of series and charge transfer resistances, respectively. Interestingly, BiVO4 electrode delivers outstanding capacitive retention of 102% even at 3500 cycles, indicating its potential candidature for the advancement in high capability supercapacitors with excellent stability for the future technologies.

Thickness and specific surface area of the film electrode are critical parameters for supercapacitors. The relationship between the thickness and the specific surface area of the film directly affects the capacitance and electrochemical stability performance of super supercapacitors, which virtually affects the contact chance of ion in the electrolyte on the surface of electrode and the ion transport path of electrode. In this paper, the CrN thin films with a thickness of 200–3500 nm are prepared using direct current magnetron sputtering. Atomic force microscopy (AFM) technique is introduced to investigate the relationship between thickness and the specific surface area of the CrN films. The electrochemical performances of CrN electrode with the nanoporousper structure is analyzed in different electrolytes H2SO4, Na2SO4 and NaCl aquous solutions. The specific surface area of the film increases linearly with the film thickness increases. The areal capacitance is also linearly related to the specific surface area. The spurtted CrN film with a thickness of 3370 nm has a specific surface of up to 43.59 cm2 per cm2 footprint area. Its areal and volume capacitances reache to 53.92 mF cm−2 and 650 F cm−3 at 5 mV s−1, respectively. In addition, the areal capacitance of CrN film electrode with 655 nm possesses reaches to 40.53 mF cm−2 for 0.5 M H2SO4 solution, 32.69 mF cm−2 for 0.5 M Na2SO4 solution and 9.17 mF cm−2 for NaCl solution at a scan rate of 5 mV s−1. Furthermore, the CrN film electrode exhibits excellent capacitance retention of 95.3%, 93.8% and 89.9% in H2SO4, Na2SO4 and NaCl electrolytes, respectively, after 2000 cycles. Therefore, the sputtered CrN thin film is an potential electrode material for electrochemical supercapacitors.

Gold compound AuCl4 used in different medical purpose especially in different diseases such as Arthritis, the study focused on the electrochemical properties of gold compound in an electrolyte (KCl solution) using modified glassy carbon electrode with carbon nanoparticles (CNT/GCE) as a good nanosensor to determine the chemical behavior of gold compound by the oxidation – reduction current peaks as appeared in the cyclic voltammogram at 115 and 500 mV respectively. It was studied in this study the different concentrations, scan rates, pH, and the reliability (stability), also the effect of ascorbic acid on the redox current peaks of the gold compound was studied. The results were discussed to promising the gold compound as a treatment in different disease in an alkaline medium because the Au(IV) compound acts as antioxidant by disappearing current peak of the oxidation and enhanced the reduction current peak.

Determination of food toxic compounds is one of the significant strategies for investigating food quality. The presence research introduces an electrochemical approach for toxic ractopamine sensing using a gold electrode amplified with gold nanoparticles (Au-Nps/AuME). The oxidation signal of ractopamine was investigated at the surface of Au-Nps/AuME, and results showed a 2.36-fold amplification in current and reducing 100 mV in oxidation potential compare to the pristine gold electrode. The redox reaction of ractopamine shows a pH dependence behavior with two electrons and two protons. Furthermore, the scan rate and chronoamperometric investigation showed a diffusion coefficient of 1.0 × 10−6 cm2/s to the oxidation reaction of ractopamine at the surface of Au-Nps/AuME. Analytical investigation showed a linear dynamic range of 0.1–380 µM for sensing of ractopamine using square wave voltammetric technique. Also, Au-Nps/AuME could be used to measure ractopamine in food samples such as pork samples with a recovery range of 98.3–103.9% and a detection limit of 50 nM.

Critical to the applications of pseudocapacitors is the cycling performance of electrodes. Here, we present a new carbon fibre electrode enhanced by multilayer structure of vertical graphene (VG) and manganese dioxide (MnO2) to achieve a cycling performance at a very high areal capacitance (546.3 mF/cm2) that outperforms most of the reported pseudocapacitors in the literature. Particularly, this multilayer electrode is able to retain 99.3% of its initial capacitance after 10,000 cycles at scan rate of 200 mV/s. The retention ratio is significantly higher than the state-of-art value. In addition, this electrode shows excellent rate performance (75.4% capacitance retention for current density from 1 to 10 mA/cm2). This exceptionally high stability at high capacitance and rate performance originates from the multilayer electrode’s effectiveness in self-replenishing the degraded MnO2 in the outer layer. The microcracks and micro holes induced in the VG layer by electrical charge/discharge cycling enable the inner layer MnO2 to progressively participate in the redox reaction. Results from energy dispersive spectroscopy, X-ray photoelectron, and Raman spectroscopy confirm the self-replenishing mechanism responsible for the exceptionally stable performance. The new multilayer electrode designed herein provides a new route for improving the cycling performance of pseudocapacitors.

Demands for flexible electronic equipment such as wearable devices and wrap-round displays have motivated the development of flexible energy storage devices. Although cellulose paper is one of the most promising substrates for flexible devices, its intrinsic limitations, such as poor mechanical durability, hamper its practical use. In this study, we adopted the traditional Korean paper, Hanji, with superior mechanical robustness as a substrate for supercapacitor electrodes. The effective infiltration of activated carbons (ACs) as an electrode material into the dense network of Hanji cellulose fibers was performed by a simultaneous one-pot process of network formation and AC embedment. The fabricated symmetric supercapacitors based on the AC-embedded Hanji electrode exhibited a specific capacitance (Csp) of 16.0 F/g measured at a scan rate of 10 mV/s with excellent cycle stability, the Csp retention of 94.5%, over 1000 charge-discharge cycles.

The present study reports the design of the Mn3O4-Cn electrode and its use for simultaneous detection of selenium and nickel in water. The designed electrode can be used as a convenient electrochemical device for on-site testing of Se (IV) and Ni (II) levels in affected regions. The best responses are obtained with 0.1 M phosphate buffer saline (PBS) and 5 mM Fe (CN)6 as supporting electrolyte. The scan rate and the number of cyclic repetitions have a great effect on peak shape and intensity. It is seen from our study that peak intensity is directly proportional to Se (IV) and Ni (II) concentrations in the range of 5 to 250 µg/L (correlation coefficients 0.952 and 0.984) when the optimized parameters are used. The detection limit of 0.533 µg/L Se (IV) and 0.718 µg/L for Ni (VI) with a response time of 18 s for 5–250 µg/L concentration is obtained, respectively. Enhanced analytical results for different water samples establish that the proposed method is appropriate for Se (IV) and Ni (II) detection. FESEM images confirm the Mn3O4-Cn nanocomposite formation on the electrode.

In this study, poly(3-methylthiophene) modified electrode as a voltammetric sensor was developed for the detection of florfenicol (FF). Firstly, for the modification of glassy carbon electrode (GCE), 3-methylthiophene (3-MTF) was polymerized in acetonitrile (AcN) containing tetrabutylammonium tetrafluoroborate (TBATFB) by cyclic voltammetry (CV) method. Then, in order to determine the florfenicol sensor property of 3-MTF modified GCE, parameters such as electrolyte type and electrolyte pH, scan rate, film thickness, pulse amplitude, and pulse width were investigated by using differential pulse voltammetry method (DPV). When the florfenicol responses of the modified electrode were compared to the unmodified GCE responses, it was found that the florfenicol selectivity, sensitivity, and response stability of the modified electrode were significantly increased. A linear calibration plot was obtained for florfenicol in the concentration range of 0.1–1.0 mM. From the linear calibration curve, the correlation coefficient (R2 value), determination limit (LOD), and quantitation limit (LOQ) were calculated as 0.999, 0.0399 mM, and 0.1197 mM, respectively. In addition, analytical application of the developed sensor for the determination of florfenicol was carried out in red and chicken meat samples. The recovery efficiency for red and chicken meat samples was obtained from 90.07 to 111.92% by using 3-MTF modified GCE. As a result, an electrochemical sensor was developed for the florfenicol detection which is fast, simple, low cost, 98.72% reproducible, stable, sensitive, and selective.

A faradaic supercapacitor electrode capable of sensing current is presented for the first time using chitosan/poly-o-toluidine composites. The semiconducting and highly electroactive composites have an agglomerated nano granular morphology with sufficient porosity enabling efficient electrochemical reaction. A moderately high specific capacitance of 425 F g−1 was achieved for the composite at a scan rate of 5 mV s −1. The sensing abilities monitored through chronopotentiometry show that the consumed electrical energy during reactions varied as a linear function of the applied current which proves that the composites can function as a current sensing supercapacitor. The sensitivity with regard to current increases as the specific capacitance increases. The sensing ability is imparted through the electrochemical reaction of poly-o-toluidine, whose reaction rate (and potential) responds to and senses the electrical working condition (current). This finding suggests that any device based on conducting polymers driven by electrochemical reactions is capable of sensing electrical working conditions.

In this work, a cubic-like ZnMn2O4 nanostructure was prepared by a cost-effective double-hydroxide-mediated hydrothermal route. As-synthesized material was characterized by powder X-ray diffraction and Fourier-transform infrared spectroscopy studies. The cubic-like surface morphology of the material was viewed using scanning electron microscopy and high-resolution transmission electron microscopy analyses. The electrochemical properties of the ZnMn2O4 electrode were examined by cyclic voltammetry, charge-discharge, and electrochemical impedance spectroscopy analyses. The electrochemical results revealed that the ZnMn2O4 electrode had battery-type Faradic behavior with the highest capacitance of 776 F g−1 at a scan rate of 5 mV s−1 in a 2 M KOH electrolyte and showed good cyclic stability, with an efficiency of 91.7% after 5000 continuous long cycles. The synthesis method entails that the ZnM2O4 electro-active material acts as a promising high-performance supercapacitor electrode.

Self-organized porous sheet-like assemblies have attracted extensive attention for the development of flexible high-performance electrodes. This work demonstrates the facile synthesis and effects of reduction time on the electrochemical performance of porous sheet-like assemblies of reduced graphene oxide (rGO) on carbon cloth. An rGO porous assembly with a reduction time of 4 h exhibited a superior specific capacitance of 456 F/g at a scan rate of 5 mV/s and 223 F/g at a current density of 1 mA/cm2, with ~ 93.9% initial capacity retention over 2000 cycles. A solid-state symmetric supercapacitor device constructed of a rGO4//rGO4 porous assembly achieved a specific capacitance of 45.86 F/g at a scan rate of 5 mV/s and yielded an energy density of 1.27 Wh/kg and specific power of 833.3 W/kg in a PVA-H2SO4 gel polymer electrolyte. Furthermore, the flexible solid-state symmetric device provides outstanding cyclic stability with a 95.3% retention of its initial capacity over 2000 cycles. Thus, electrodes constructed of rGO porous sheets show great potential for flexible and transparent solid-state symmetric energy storage devices.

This study reports the preparation and performance of a smart material—a carbon paste electrode combined with TiO2 semiconductor (CPE/TiO2) as electrochemical sensor for detecting profenofos—a toxic organophosphates group insecticide widely used in agriculture. Such techniques as real samples tests and electrochemical tests were used to investigate the following parameters: a scan rate, an electrode response, a limit of detection (LoD), and repeatability. Based on the obtained results, the best mass composition of TiO2 combined with CPE was found to be in a ratio of 1 : 1 : 5, with an anodic peak current (Ipa) of 150 μA, an anodic peak potential (Epa) of 0.87 V, and an optimal scan rate measurement of 0.5 V s–1. The LoD based on a linearity curve with a value of 4.0 × 10–5 μM was also observed, and a repeatability test against the working electrode was performed until the 30th day, using the Horwitz ratio of 0.16. A good electrochemical performance of the working electrode tested against a real sample showed the specifically detected profenofos with Ipa value of 7.0 × 10–5 μM.

We report the double perovskite electrode material La2NiMnO6 for energy storage application prepared by facile wet chemical sol–gel method. The double perovskite La2NiMnO6 exhibits monoclinic crystal structure with P21/n symmetry. The La2NiMnO6 electrode has shown pseudocapacitive behavior, yielded specific capacitance of 478.2 F / g at scan rate of 2 m V / s , via cyclicvoltammetric technique.

MXene is a generic name for a large family of two-dimensional transition metal carbides or nitrides, which show great promise in the field of transparent supercapacitors. However, the manufacturing of supercapacitor electrodes with a high charge storage capacity and desirable transmittance is a challenging task. Herein, a low-cost, large-scale, and rapid preparation of flexible and transparent MXene films via inkjet printing is reported. The MXene films realized the sheet resistance (Rs) of 1.66 ± 0.16 MΩ sq-1 to 1.47 ± 0.1 kΩ sq-1 at the transmissivity of 87-24% (λ = 550 nm), respectively, corresponding to the figure of merit (the ratio of electronic to optical conductivity, σDC/σOP) of ∼0.0012 to 0.13. Furthermore, the potential of inkjet-printed transparent MXene films in transparent supercapacitors was assessed by electrochemical characterization. The MXene film, with a transmittance of 24%, exhibited a superior areal capacitance of 887.5 μF cm-2 and retained 85% of the initial capacitance after 10,000 charge/discharge cycles at the scan rate of 10 mV s-1. Interestingly, the areal capacitance (192 μF cm-2) of an assembled symmetric MXene transparent supercapacitor, with a high transmittance of 73%, still surpasses the performance of previously reported graphene and single-walled carbon nanotube (SWCNT)-based transparent electrodes. The convenient manufacturing and superior electrochemical performance of inkjet-printed flexible and transparent MXene films widen the application horizon of this strategy for flexible energy storage devices.

Use of co-doped metal oxide-based materials for supercapacitor application is a novel approach to attain significantly enhanced capacitive properties. In this context, we are reporting here, the synthesis of Cr and Sn co-doped Co3O4 polygon-based material and its application in supercapacitor. The co-doped Co3O4 material was synthesized by varying the doping ratios of Cr and Sn as 3:7, 5:5 and 7:3 at.% respectively through hydrothermal synthesis route. Material and capacitive properties were studied for pristine and co-doped Co3O4 material. The crystalline structure, morphology and chemical composition were investigated by using XRD, SEM and EDX techniques, respectively. The XRD results revealed the formation of single cubic phase Co3O4 nanostructures with average crystallite size 40 nm. The SEM results explored the development of polygon-based nanostructures having sizes in the range of 40–50 nm. The EDX results exhibited the presence of only Co, Cr, Sn and O elements in the material thus proved the highly pure nature of this material. The electrochemical measurements were done with the help of CV, GCD and EIS techniques performed in a 3 M KOH electrolyte solution. The CV test revealed that, among the samples with doping ratios 3:7, 5:5 and 7:3 at.% of Cr and Sn in Co3O4 crystal lattice labeled as CrSnCo-1, CrSnCo-2 and CrSnCo-3, respectively, the CrSnCo-2 sample exhibited highest specific capacitance, i.e. 1413.56 Fg−1 at 5 mVs−1 and also showed excellent capacitance retention, i.e. 89.41% after 3000 CV cycles performed at a scan rate 5 mVs−1. The GCD test showed the pseudocapacitive nature of the material with good stability, i.e. 77.38% (capacitance retention) at higher scan rate, i.e. 10 Ag−1. Moreover, the EIS spectroscopy revealed the excellent conductive nature of CrSnCo-2 material. These results suggest its potential application in energy storage devices like supercapacitors.

Graphene nanoribbon (GNR) is a potential sensor material owing to its high surface area, high aspect ratio, variable band gap, and high density of reactive edges. Herein, for the first time, we propose a binder-free and non-enzymatic sensor for the detection and electro-analysis of rutin using GNRs. GNRs were first synthesized from multi-walled carbon nanotubes (MWCNTs) by chemical unzipping in an oxidative environment and later casted onto graphite (Gr) electrode to get Gr/GNRs sensor. The developed sensor exhibited excellent electrocatalytic activity towards oxidation of rutin in phosphate-buffered solution (PBS) with a pair of well-defined redox peaks for rutin. Cyclic voltammetry (CV) studies showed linear dependence of sensor response on the scan rate (R2 = 0.992) and the electrode reaction occurred via diffusion-controlled charge transfer mechanism. Differential pulse voltammetry (DPV) measurements showed the existence of linear correlation between sensor response and the concentration of rutin with a detection limit of (LOD) 7.862 nM and sensitivity of 917.23 μA μM−1 cm−2. Further, the sensor showed good stability and selectivity which are attributed to synergic effects of GNRs as a sensing material. The proposed sensor was tested for its practical applicability by successfully analyzing rutin content in pharmaceutical rutin tablets which suggest that the proposed sensor can find application in the analysis of rutin in food, drug tablets, and neutraceutical samples.