Papers by Keyword: Current Density

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: Nickel-Phosphorous/diamond coatings were electrodeposited onto steel substrates using a pulse-stirring method. The electrodeposition process involved a solution containing nickel sulphate, phosphorus acid, and diamond particles, resulting in the co-electrodeposition of 4-8 µm of diamond particles into a Ni-P matrix. To investigate the effects of electrodeposition current density on the properties of the Ni-P/diamond composite coating, scanning electron microscopy (SEM), hardness testing, and electrochemical testing were employed. The research findings revealed that higher current density (0.03 A/cm²) led to a denser diamond particle coating with diamond contents of up to 32.70 vol%. Additionally, the Ni-P/diamond coatings achieved a maximum hardness of 2819 ± 12.55 HV_0.1 when fabricated using the current density of 0.03 A/cm². The "pulse-stirring fabrication" method yields a coating with significantly enhanced wear resistance due to incorporating densely packed diamond particles. The intermittent pulses during the fabrication process are crucial for achieving the desired dispersion and adhesion of the diamond particles, leading to a practical and durable wear-resistant coating.

Abstract: Stress Corrosion Cracking (SCC) is a phenomenon in which cracks develop in certain materials due to a combination of stress and corrosion. This process is commonly observed in low-alloy steels with a ferritic-pearlitic structure, such as X70, which are often used in buried pipeline applications within the oil and gas industry. These materials are particularly susceptible to SCC failure in dilute solutions. To simulate SCC conditions, the Near-neutral simulated soil solution (NS4) has been established as a widely accepted industry standard for conducting crack growth experiments in many laboratories. This paper aims to investigate the role of electrochemistry in SCC under near-neutral soil solution conditions by presenting a numerical study using COMSOL on the effects of applied potential on corrosion rate in near-neutral soil solutions. According to the findings, the electrode thickness, current density, and corrosion rates were mostly affected by an applied potential of -1.2 V. This implies that slight modifications in the applied voltage can greatly influence the corrosion rate of the electrode. This outcome aligns with prior research on the influence of potential on electrode performance and emphasizes the crucial role of precise control of the applied potential in electrochemical systems.

Abstract: The Proton Exchange Membrane Fuel Cells (PEMFCs) performance is improved by flow field channel design. The flow field reactant distribution geometry on PEMFCs is primarily influenced by the perceived effect of pressure and transmission characteristics of reactant flow fields on the efficiency of fuel cells. Nutrients distributed in the biological branching structures systems found their optimum arrangement have more efficiently in each part. The flow fields design channels in polymer electrolyte membrane (PEM) fuel cells serve the same roles as nutrient transport systems in plants and animals, so bio-inspired flow fields design with a similar could maximize reactant transport efficiency and improve fuel cell performance. In this analysis, the lung channel design of a humane lung and a tree leaf bio-inspired flow field design is used for the flow fields of the anode and cathode bipolar plates. SOLIDWORKS produces a 3-D numerical CFD design for four new flow field pattern designs: leaf design, lung design, single-serpentine, and triple-serpentine. The model is simulated using ANSYS FLUENT-15.0 software to obtain pressure distributions in the flow field, concentration profiles of hydrogen on anode and oxygen on cathode channel, current flux density on the membrane, water concentration on the membrane, water generating in a cathode channel, the polarization curve and the power curve. It is observed that bio-inspired leaf and lung design performs better than serpentine flow field channels. So, leaf and lung design can be used in mopeds and automobiles to enhance electrical efficiency and at the same time reduce fuel consumption.

Abstract: The PEM fuel cell was examined using numerical simulation in varied circumstances. To restore the fuel cell performance, a 3D-based PEMFC model was designed employing COMSOL Multiphysics 5.1. The analysis validity was confirmed using the V-I curves derived from data analysis in varied operational circumstances. The continuity, momentum, species transport and charge equations were used to represent the cell transport phenomenon. The flow of permeable medium in the gas diffusion layer was defined by employing Brinkman equations. V-I curves were obtained using the Butler-Volmer equations. According to findings, the current supply in the cathode catalyst layer achieves an optimum one, functioning as mass transport, ionic and charge transport resistances. It indicates optimum current supply in the cell holds a feature of highest oxygen deprivation on the channel's output side.

Abstract: This paper presents an analysis of the current density distribution in the zinc plating process, using a two-dimension approach. The simulation presents a model based on COMSOL Multi-physics software. The simulation neglected the effect of mass transfer and production of gaseous species, in order to simplify the resolution. Additionally, a validation from the simulation through a comparison with the experimental data at similar conditions was performed. The results presented a good agreement between the experimental and simulated data. The graphics from both approaches showed a decreasing trend in the current density along the cathode length. This trend arises from the electrons movement in the electrodes; electrons flow through the least resistive path. Given the fact that zinc electroplating incurs an important industrial application, simulation is becoming a promising way to optimization and improvement.

Abstract: A white light, i.e., Fabry-Perot, interferometry was unprecedently applied to determine the rate change of the current density (J) of aluminum samples during the anodization processes of the samples in aqueous solutions. The current density(J) values were obtained by Fabry-Perot interferometry rather than the direct current (DC) or alternating current (AC), methods. Therefore, the abrupt rate change of the J was called electrochemical-emission spectroscopy. The anodization of the aluminum samples was conducted by an external DC source in 0.0,2,4,6,8,10% sulfuric acid (H₂SO₄) solutions at room temperature. In the meantime, the Fabry-Perot interferometry was used to determine the difference between the J of two subsequent values, dJ, as a function of the elapsed time of the DC experiment for the aluminum samples in 0.0,2,4,6,8,10% H₂SO₄ solutions. The Fabry-Perot interferometry was based on a fiber-optic sensor in order to make real time-white light interferometry possible at the aluminum surfaces in the sulfuric acid solutions. As a result, a new spectrometer was developed based on the combination of the Fabry-Perot, i.e., white light, interferometry and DC method for studying in situ the electrochemical behavior of metals in aqueous solutions.

Abstract: Composite of two phases with crystal grains of titanium nitride (TiN) and amorphous of silicon nitride (Si3N4) had shown an improvement of mechanical properties as shown by composite layer of nickel (Ni) and TiN. In this study, Ni-TiN/Si3N4 composite layer on tungsten carbide bar have been prepared by using electrodeposition to study the effect of current density on the microstructure and mechanical properties of the layer. The optimum properties of composite coating with no crack morphology and maximum hardness was shown by the sample electrodeposited at current density of about 2.5 mA/cm2. The high hardness was attributed to the nickel crystallite size refinement

Abstract: The fabrication of porous GaN (PGaN) by UV-assisted electrochemical etching with a variations of current densities (40, 60, and 80 mA/cm²) for 60 min in electrolytes consisting of 4% KOH are reported. Field Emission Scanning Electron Microscopy (FESEM), Energy Dispersive X-Ray (EDX), Atomic Force Microscopy (AFM) and X-ray Diffraction (XRD) were used to characterize the morphological and structural characteristics of the PGaN. All PGaN sample prepared by electrochemical etching technique produced a hexagonal-like pore shape. FESEM images demonstrated that the pore uniformity and porosity are affected significantly by the current density. The PGaN sample fabricated with 80 mA/cm² produces a uniform and high porosity structure compared to other PGaN sample. This shows that the morphology and structural characteristic of PGaN are increase with the increase of current density. The EDX result revealed significant Ga and N atom presence in all samples. However, the O atom only presence in sample etched with 80 mA/cm² implying that the etching process is occur vigorously in this sample. The AFM verified that the surface roughness and the pore depth are increased as current density increased. There were relatively large variations of the peak intensities for 2Theta-scan patterns as exposed by XRD. The peak shift for PGaN sample relative to as-grown was inconsistent and the changed was relatively small. Raman intensity found to be enhanced with the increase in current density and among the PGaN sample, the E₂(high) peak for sample prepared with 60mA/cm² and 80mA/cm² was observed to be slightly shifted to lower frequency. The PL spectra displayed that the porosity has high impact on the PL peak intensity. . Overall, this proved that with the usage of low power UV light, the pore structure still can be produced as good as pore structure fabricated with high power UV light.

Abstract: This research presents how to use high current density (2.85A/dm²) to do 6061 aluminum alloy hard anodization. There are five steps during the process including mechanical polishing, anodization, acid spitting, sealing and surface cleaning. By using electrochemical molds which we designed and controlling the electrolyte temperature at-2°C, then we could obtain ordering anodization film with 20nm pore size and 33.3μm thickness. However, there are some situations should be overcome such as raising the success rate of sealing and reducing the defects on the AAO surface by means of adjusting the parameters such as the current density, final voltage, electrolyte temperature, etc.