Papers by Keyword: Electrochemical

Abstract: A novel hybrid ternary polymer nanocomposite, Reduced Graphene Oxide/Poly-N-Methyl Pyrrole@Manganese Selenide (RGO/P-NMPy@MnSe), was synthesized through a chemical oxidative in situ polymerization route and evaluated as an efficient electrocatalyst for the methanol oxidation reaction (MOR) in alkaline media. Structural and morphological characterizations using FTIR, UV–Vis spectroscopy, XRD, FESEM-EDAX, and TEM confirmed the homogeneous incorporation of MnSe nanoparticles within the conductive RGO/P-NMPy framework. Electrochemical analysis via cyclic voltammetry revealed a high electrochemically active surface area (ECSA) of 68.7 m² g^⁻¹ and a superior peak current density of 36.25 µA at pH 9.0. Chronoamperometric studies demonstrated remarkable durability with a sustained steady-state current density (798.31–93.89 µA) for over 900 s, confirming excellent catalytic stability. The synergistic effects of RGO conductivity, MnSe catalytic activity, and the polymer’s structural integrity enhance electron transfer and tolerance toward poisoning intermediates. These findings highlight RGO/P-NMPy@MnSe as a low-cost, durable, and efficient electrocatalyst for direct methanol fuel cells (DMFCs) and related electrochemical energy conversion applications.

Abstract: Developing materials for electrodes with engineered interfaces is important for improving supercapacitor performance. Combining metal oxides and two-dimensional (2D) transition-metal dichalcogenides (TMDs) is a promising approach to develop enhanced supercapacitor electrodes. To the best of our knowledge, the electrochemical activity and energy storage of the Fe₃O₄/ReS₂ heterostructure-based electrodes have not been reported in the literature. Therefore, this study employed a two-step hydrothermal method to synthesize a Fe₃O₄/ReS₂ heterostructure and investigated its electrochemical performance. The developed material exhibited exceptional specific capacitance, capacity retention, and high energy and power densities. Moreover, various characterization techniques, including SEM, TEM combined with EDX, and XRD, were employed to examine the surface and structural properties of the produced heterostructures. Electrochemical measurements for supercapacitor application were conducted in 2 M KOH electrolytes for all the developed electrodes. The Fe₃O₄/ReS₂ electrode displayed an excellent energy density of 49.31 Wh/Kg, a power density of 550 W/Kg, a specific capacitance of 322.7 F/g, at a current density of 1A/g, and attained 118 % capacitance retention after 2000 cycles at 10 A/g. A specific capacitance of 789.65 F/g was obtained at 5 mV/s. This work uncovers the potential of Fe₃O₄/ReS₂ heterostructures as promising electrode materials for high-performance energy storage applications.

Abstract: LiFe(P,Si)O₄ is a material that belong to parent compound of LiFePO₄ widely known as cathode material for lithium-ion battery (LIB). Previous study reports that electrochemical performance of LiFePO₄ can be improved by silicon (Si) substitution to the phosphorus (P) site. The sample was obtained via a solid-state synthesis route with the amount of Si doping to the P site is ∼3%. The electrochemical performance of silicon substituted LiFePO₄ has been widely studied in other report whilst the magnetic properties is still less explored. Here we investigate the magnetic properties of LiFe(P,Si)O₄ using superconducting quantum interference device (SQUID) and muon spin relaxation (µSR). The two measurements display a good agreement result showing two anomalies at the temperature of ∼27 K and ∼52 K that represent the Neel Temperature (Τ_N) of Li₂FeSiO₄ and LiFePO₄, respectively. The presence of Li₂FeSiO₄ that is also a candidate of cathode of LIB has been confirmed by X-ray Diffraction (XRD). Based on the current study, there is no alteration of Τ_N on LiFePO₄ phase due to Si doping.

Abstract: The development of non-enzymatic glucose biosensor has been the concern of many researchers mainly because enzymes based sensor despite having excellent sensitivity and selectivity, has the limitations such as poor stability, complicated enzyme immobilization, critical operating conditions such as optimum temperature and reproducibility. This study developed a cheap biocompatible non-enzymatic glucose biosensor based on silver nanoparticle (AgNPs) stabilized with sodium tripolyphosphate (NaTPP) cross-linked chitosan. Direct electron transfer and electro-catalytic activity of the AgNPs modified glassy carbon electrode (AgNPGCE) was investigated using potentiometric and amperometric techniques. AgNPs was prepared and characterized by Fourier transform Infra-red spectroscopy (FTIR), X-ray diffractometry (XRD) and Scanning electron microscopy (SEM). The crystalline size of the AgNPs was revealed with XRD. However, the SEM micrograph of AgNPs revealed the spherical shape with a non-uniform granular shape attributed to bio-mediated ionic gelation process. The FTIR spectra of AgNPs shown peaks at 1054 – 1645 cm^-1 suggesting the presence of phosphonate linkages between ammonium, -NH₃⁺ of chitosan and -PO₃^2- moieties of NaTPP during cross linking process. Electro-catalytic oxidation of glucose at the AgNPGCE surface and the mechanism involved in glucose oxidation was revealed via cyclic voltammetry. The AgNPGCE showed a better electrochemical response towards glucose. This glucose sensor showed high sensitivity at +0.54 V. A low detection limit of 1.22 µM (the confident level κ = 3), and wide linear range of 2 to 24 µM with a correlation coefficient of 0.9987 were obtained. The calculated parameters revealed that AgNPGCE had shown better overall electrochemical performance and response than enzymatic biosensor.

Abstract: Extracting oil and gas results in a significant byproduct called produced water, which contains a mix of oil, water, and various chemicals. Removing the oil from this wastewater is essential to minimize its environmental and health impacts. Traditional methods like chemical treatments and gravity separation are time-consuming and require a lot of space, so it's important to explore alternative approaches. The oil removal efficiency, measured as the percentage of the amount of oil removed from produced water after electrochemical treatment, is used as a benchmark. Initially, the oil removal efficiency increases rapidly with treatment time but eventually levels off at around 15 minutes. Aluminum electrodes outperform iron electrodes, reaching a maximum oil removal efficiency of about 88%. Moreover, when the electrochemical method was used directly on produced water from drilling sites, it achieved an impressive oil removal efficiency of over 95%.

Abstract: The implementation of water-chitosan slurry is needed to achieve better battery, in terms of enviromentally friendly and cheapest cost. In this research, sodium-ion cathode batteries based on sodium iron phosphate and the water-chitosan slurry were successfully synthesized with the sol-gel method. The result of the X-Ray Diffraction (XRD) test confirmed the two phases of sodium iron phosphate, which are Na₃Fe₂(PO₄)₃ and Na₃Fe₃(PO₄)₄, with the percentage weight of the phases of 31.19% and 68.81%, respectively. Then, this sample was examined using Scanning Electron Microscope-Energy Dispersive X-ray (SEM-EDX) test, it is known that the morphology of particles look like agglomerate thin sponges and no other elements besides Na, Fe, P, and O were found in the sample. Cyclic Voltammetry (CV) dan Electrical Impedance Spectroscopy (EIS) tests were also carried out to determine the electrochemical performance of the cathode material. The CV test was carried out to determine the specific capacity value of each sample. From the test results, it is known that sodium iron phosphate cathode with PVDF binder had a higher specific capacity value than cathode with chitosan binder, which was 44.13 mAh/g and 26.78 mAh/g, respectively. From the EIS results, it was found that sodium iron phosphate cathode with chitosan binder had better electrical conductivity and Na⁺ ion diffusion, with values of 7.44×10^-3 S.cm^-1 and 1.48×10^-11 cm² s^-1 respectively.

Abstract: In modern electrochemical coating technology, it is common practice to create uniform layers. However, this study focuses on the deposition of non-uniform layers achieved through a deliberate arrangement of micro structured electrodes on the anode side. The "dog bone effect” was employed as the primary approach [1]. When electroplating on an otherwise uniform surface, this effect selectively processes an area influenced by the geometric edge effect (figure 1 left). The coating within this area is intended to be (i) unevenly distributed and (ii) non-reproducible. Process data was obtained through electrochemical simulations and subsequently applied to a specially designed micro-galvanic setup. This enabled the production of suitable micro structured anodes, validation of coating parameters, and the deposition of visually imperceptible structured areas with inhomogeneous properties using "adhesive gold" on appropriate substrates such as silver and nickel. The layers and their local topography were characterized and analyzed using confocal laser microscopy, X-Ray fluorescence analysis (XRF), as well as a self-designed and constructed laser interference device. As a result, this specific galvanic process technology successfully produced metallic layers that (i) cannot be visually confirmed by the naked eye, (ii) exhibit varied microstructural anode geometries, (iii) display unique differences in layer thickness, (iv) possess non-reproducible and chaotic topographies, and (v) can be detected and identified using conventional analysis techniques or a simple interference setup.

Abstract: Tungsten (W) and Cerium (Ce) doped nanoTitanium oxide (TiO₂) nanophotocatalyst were prepared by the sol-gel method and their photodegradation effect against atrazine herbicide were investigated. The doping of the nanocatalyst took place at 50 °C within a time interval of 120 minutes. The prepared gel was dried and calcined in the oven at 350 °C for 75 minutes. The XRD result revealed that the synthesized nanocatalyst was 16.7 nm in size with a mostly monoclinic structure. With FTIR spectra, characteristic peaks of TiO₂ were found at 516 cm^-1, Ti-O-Ce at 1104 cm^-1, and W-O with a single bond at 1609 cm^-1. Scanning electron microscope analysis revealed the surface morphology of synthesized nanophotocatalyst. The photocatalytic activity of synthesized nanocatalyst was tested on the degradation of atrazine herbicide (ATZ) under visible and UV light in a batch reactor. The efficiency of nanocatalyst was compared for effective utilization. About 46.5 % of photocatalytic activity was observed without UV light irradiation within 120 minutes. The photocatalytic activity of W-Ce co-doped TiO₂ to degrade atrazine further increased up to 99.1 % when the solution was irradiated under UV light. Factors like pH, time, and concentration of nanocatalyst were optimized to check the photocatalytic activity of nanocatalyst on ATZ. It was concluded that nanocatalyst showed an efficient photocatalytic degradation at pH 6 within 120 mins time interval after exposure to UV light.

Abstract: Microstructure-tailored TiO₂ nanoarrays with adjustive wall-hole morphology have been designed to improve electrochemical properties. Tubular, porous and flow-through TiO₂ nanoarrays are fabricated by one-stepped, two-stepped and three-stepped anodization process under the controlled reaction condition. Tubular nanoarray with the opened-mouth and closed-bottom has a tube diameter of 120-130nm, a length of 8.12μm, and wall thickness of 15nm. Similarly, porous TiO₂ nanoarray with the opened-mouth and closed-bottom has a pore diameter of 60-70nm, a length of 8.25μm, neighboring wall distance of 70-80nm. Comparatively, flow-through TiO₂ nanoarray with the opened-mouth and opened-bottom has a pore diameter of 110-120nm, a length of 8.56μm, neighboring wall distance of 40nm. In comparison with tubular and porous TiO₂ nanoarrays, flow-through TiO₂ nanoarray indicates the deceased charge transfer resistance and diffusion-related Warburg impedance, presenting the enhanced current response at the same electrode potential. Accordingly, bottom-opened flow-through TiO₂ nanoarray achieves the specific capacitance of 6.35 mF cm^-2, which is higher than the bottom-closed tubular and porous TiO₂ nanoarrays (2.94 and 3.78 mF cm^-2). The flow-through TiO₂ nanoarray presents the improved electrochemical performance for the electrochemical energy-storage.

Abstract: Ordered carbon was prepared via nanocasting method with Santa Barbara Amorphous (SBA)-15 as the template and sucrose as the carbon precursor. The ordered carbon surface was then modified with oxygen and nitrogen species to alter its chemical and physical properties. All surface-modified ordered carbon samples were evaluated using nitrogen adsorption-desorption analyser and electrochemical impedance spectroscopy. Post modifications, the KOH electrolyte ion transportation are affected due to significant change in the ordered carbon structural properties.