Influence of a magnetic field on the electrodeposition of nickel–iron alloys

MXene/Ferrite Magnetic Nanocomposites for Electrochemical Supercapacitor Applications

MXene has been identified as a new emerging material for various applications including energy storage, electronics, and bio-related due to its wider physicochemical characteristics. Further the formation of hybrid composites of MXene with other materials makes them interesting to utilize in multifunctional applications. The selection of magnetic nanomaterials for the formation of nanocomposite with MXene would be interesting for the utilization of magnetic characteristics along with MXene. However, the selection of the magnetic nanomaterials is important, as the magnetic characteristics of the ferrites vary with the stoichiometric composition of metal ions, particle shape and size. The selection of the electrolyte is also important for electrochemical energy storage applications, as the electrolyte could influence the electrochemical performance. Further, the external magnetic field also could influence the electrochemical performance. This review briefly discusses the synthesis method of MXene, and ferrite magnetic nanoparticles and their composite formation. We also discussed the recent progress made on the MXene/ferrite nanocomposite for potential applications in electrochemical supercapacitor applications. The possibility of magnetic field-assisted supercapacitor applications with electrolyte and electrode materials are discussed.

Magnetic Field Effect on the Handedness of Electrodeposited Heusler Alloy

Magneto-electrochemistry (MEC) experiments were carried out in the electrodeposition of a ferromagnetic Heusler alloy. The electrodeposition was carried out in the absence (as a reference) and in the presence of a magnetic field that was applied perpendicularly to the electrode–solution interface. The obtained metallic deposit was characterized by SEM-EDS, XRF, and XRD techniques. The ferromagnetic properties are assessed on the basis of SQUID measurements. The experimental results indicate that the influence of the presence of the magnetic field induces differences in the electrochemical measurements and a macroscopic handedness (chirality) in the deposit, which is a function of magnet orientation. Eventually, the coercivity of the Heusler alloy that was obtained in the presence of the magnetic field was larger compared to that of the deposit that was obtained without a magnetic field.

The Influence of the Substrate and External Magnetic Field Orientation on FeNi Film Growth

The magnetic field-assisted electrodeposition of iron–nickel thin films on different substrates (aluminum, silver, and brass) was investigated. The process was performed galvanostatically in a sulfate solution. The same chemical and electrical conditions were applied for each sample growth, but the time restrictions and the external magnetic field orientation were changeable. The obtained results show a variation of surface morphology and composition dependence on the selected surfaces as a consequence of the presence and orientation of the external magnetic field. We discussed that the FeNi crystal structure depends on the film thickness. The results show the reduction of the film thickness after the external magnetic field application—a decrease of deposition rate.The FeNi alloy’s morphology, composition, and magnetic properties were investigated by scanning electron microscopy (SEM), X-ray diffraction, energy dispersive X-ray spectroscopy (EDX), and Mössbauer spectroscopy (MS).

Chiral Magneto-Electrochemistry

Magneto-electrochemistry (MEC) is a unique paradigm in science, where electrochemical experiments are carried out as a function of an applied magnetic field, creating a new horizon of potential scientific interest and technological applications. Over time, detailed understanding of this research domain was developed to identify and rationalize the possible effects exerted by a magnetic field on the various microscopic processes occurring in an electrochemical system. Notably, until a few years ago, the role of spin was not taken into account in the field of magneto-electrochemistry. Remarkably, recent experimental studies reveal that electron transmission through chiral molecules is spin selective and this effect has been referred to as the chiral-induced spin selectivity (CISS) effect. Spin-dependent electrochemistry originates from the implementation of the CISS effect in electrochemistry, where the magnetic field is used to obtain spin-polarized currents (using ferromagnetic electrodes) or, conversely, a magnetic field is obtained as the result of spin accumulation.

Nickel recovery from electronic waste II electrodeposition of Ni and Ni-Fe alloys from diluted sulfate solutions

This study focuses on the electrodeposition of Ni and Ni-Fe alloys from synthetic solutions similar to those obtained by the dissolution of electron gun (an electrical component of cathode ray tubes) waste. The influence of various parameters (pH, electrolyte composition, Ni(2+)/Fe(2+) ratio, current density) on the electrodeposition process was investigated. Scanning electron microscopy (SEM) and X-ray fluorescence analysis (XRFA) were used to provide information about the obtained deposits' thickness, morphology, and elemental composition. By controlling the experimental parameters, the composition of the Ni-Fe alloys can be tailored towards specific applications. Complementarily, the differences in the nucleation mechanisms for Ni, Fe and Ni-Fe deposition from sulfate solutions have been evaluated and discussed using cyclic voltammetry and potential step chronoamperometry. The obtained results suggest a progressive nucleation mechanism for Ni, while for Fe and Ni-Fe, the obtained data points are best fitted to an instantaneous nucleation model.

AN INVESTIGATION ON THE EFFECT OF ELECTROCHEMICAL ADSORBATES ON PROPERTIES OF ELECTRODEPOSITED NANOCRYSTALLINE Fe–Ni ALLOYS

Iron–Nickel nanocrystalline alloys were electrodeposited from a simple chloride bath using different current densities. The composition and grain size of deposited alloys were in the range of 29–42% Ni and 8–11 nm, respectively. The alloy deposited at lower current density showed higher microhardness, which is most probably due to its higher Fe content and lower grain size. EIS measurements showed that the iron hydroxide species can be formed and adsorbed onto the cathode surface during the deposition. Such species showed an inhibitive effect not only on Ni ion reduction but also on grain growth. By increasing the deposition current density, the adsorption tendency of iron hydroxide was reduced which caused an increase in grain size and Ni percentage of the alloy produced.

Magnetic field effects on electrochemical metal depositions

This paper discusses recent experimental and numerical results from the authors' labs on the effects of moderate magnetic (B) fields in electrochemical reactions. The probably best understood effect of B fields during electrochemical reactions is the magnetohydrodynamic (MHD) effect. In the majority of cases it manifests itself in increased mass transport rates which are a direct consequence of Lorentz forces in the bulk of the electrolyte. This enhanced mass transport can directly affect the electrocrystallization. The partial currents for the nucleation of nickel in magnetic fields were determined using an in situ micro-gravimetric technique and are discussed on the basis of the nucleation model of Heerman and Tarallo. Another focus of the paper is the numerical simulation of MHD effects on electrochemical metal depositions. A careful analysis of the governing equations shows that many MHD problems must be treated in a 3D geometry. In most cases there is a complex interplay of natural and magnetically driven convection.