Preparation and Capacitance of Ni Metal Organic Framework/Reduced Graphene Oxide Composites for Supercapacitors as Nanoarchitectonics

We obtained nickel metal organic framework/reduced graphene oxide (Ni-MOF/rGO) composites in the presence of graphene oxide solution using hydrothermal method. The electrochemical performance of the composite was measured by voltammetry and charge–discharge tests. As a result of morphological and structural analysis, Ni-MOF/rGO composite was found to be a composite of cubic structure with good crystallinity and large specific surface area. The Ni-MOF/rGO composite used as the electrode material of the supercapacitor exhibited a high specific capacitance (1154.4 F/g) of 1 A/g in the 6 M KOH and 53.4% at the current density range of 0.66 to 3 A/g. A retention of capacitance of 90% after 3000 cycles was confirmed. This means that Ni-MOF/rGO composites are proper electrode materials for electrochemical energy storage systems.

EFFECT OF ANODIC AND CATHODIC CURRENT DENSITIES ON THE CAVITATION DAMAGE CHARACTERISTICS OF ALUMINUM ALLOY IN SEAWATER

In this study, the influences of electrolytic gas generation on the surface of aluminum as a cushioning media against cavitation bubbles were experimentally investigated. The electrolytic gas evolution was controlled by applying electric current to the metal with different polarity and current densities. The surface of the metal specimen was either polarized anodically or cathodically while simultaneously being subject to vibratory cavitation. It was revealed that the surface damage behavior was mainly dependent on the current densities applied to the metal. It was apparent that a moderate current density range of between [Formula: see text] and [Formula: see text] A/cm2 applied cathodically can produce electrolytic gas evolution to cushion the cavitation bubbles sufficiently. However, application of a too a high current density (greater than [Formula: see text] A/cm[Formula: see text] may lead to cathodic corrosion of Al alloys.

Graphene anchored on Cu foam as a lithiophilic 3D current collector for a stable and dendrite-free lithium metal anode

GN@Cu foam serves as a lithiophilic host material for Li anode, showing dendrite-free morphology and stable performance over a wide current density range.

A broad parameter range for selective methane production with bicarbonate solution in electrochemical CO2 reduction

Selective methane production was achieved over a broad current density range with 0.5 M KHCO3 solution and bulk, polycrystalline Cu.

Electrodeposited Cu2O|ZnO Heterostructures With High Built-In Voltages For Photovoltaic Applications

ABSTRACTMethods of improving low-cost Cu2O|ZnO heterojunction diodes fabricated through galvanostatic deposition of Cu2O are presented. Improved processing parameters responsible for maximizing built-in voltage (Vbi) are determined. The relationship between pH, deposition current, temperature, and diode quality is analyzed and a process window for optimal Cu2O deposition on ZnO is obtained with a pH range between 12.0 and 12.1 and a current density range which is determined by the effect of both pH and deposition current (Jdep) on grain size. The pH window is found to be narrower than previously reported1 and much narrower than the processing window for the deposition of Cu2O films. A two-step approach deposition based on the use of different Jdep is presented for the first time. A Vbi of 0.6 V is achieved, which is the highest reported for cells produced using low temperature processing routes involving electrodeposition and reactive sputtering.

Effects of bath composition and current density on the electrodeposition of Fe-Ni alloy on copper substrate and the property of deposited alloy

One simple and six complex baths are used to electrodeposit Fe-Ni alloy coating on copper substrate. All baths contain the same 1.04 Ni/Fe ratio. In addition to NiSO4.7H2O, FeSO4.7H2O, H3BO3 used in simple bath, the complex baths contain Ascorbic acid, Saccharin and Citric acid in different ratios. Electrodepositions have been carried out in the bath pH and constant current density range of 1 - 2.6 and 20 - 140 mA/cm2, respectively. Anomalous nature of Fe-Ni alloy electrodeposition is suppressed in the complex baths. Microhardness as well as corrosion resistance of coating increased with increasing %Ni content in the deposit. The morphology of the Fe-Ni films obtained from simple baths is characterized by coarse-grained, non-smooth surface with presence of microcracks onto it. Coatings from complex baths are finegrained with smooth surfaces. Bangladesh J. Sci. Ind. Res. 47(4), 379-386, 2012 DOI: http://dx.doi.org/10.3329/bjsir.v47i4.8699

Effect of Deposition Parameters & Molybdenum Percentage on Nickel-Molybdenum Alloy Coatings

The use of Potassium-phosphate baths for the alloy deposition of Nickel–Molybdenum is recently proved equally good as Sodium-citrate baths. The coatings so obtained from Potassium-phosphate baths were examined for atomic weight percentage of Molybdenum. The variation in weight percentage of Molybdenum was obtained by varying different plating parameters like - molar ratio, current density range, and potential range. The observed co-deposited Molybdenum Atomic percentage variation in alloy was investigated for grain size, porosity in structure and surface roughness. The results revel that Molybdenum Atomic percentage in the Nickel–Molybdenum alloy has effect on porosity and surface roughness. It was also found that root mean square value of surface roughness was not only affected by the Molybdenum Atomic percentage but also by potential at relaxation time (TOFF) potential.

Positive Temperature Coefficient SiC PiN Diodes

Integration of patterned ballast resistance into the anode of SiC PiNs is a solution to the dilemma of negative dVf /dT for such diodes. In fabricated 4H-SiC PiN diodes, we demonstrate a cross-over from negative to positive temperature coefficient for current densities as low as 80 A/cm2. Adjusting the percentage of the patterned anode area, the positive or neutral dVf /dT can be achieved over a wide current-density range without substantial penalty in the forward voltage drop. This characteristic is crucial for high-power SiC packages with ganged-parallel rectifier arrays.

Electrodeposition of Polyhedral Copper Crystals on Porous Silicon

Electrochemical deposition of copper from copper chloride aqueous electrolyte on porous silicon (PS) substrate was investigated in the current density range of 5 mA/cm2to 35 mA/cm2. Scanning electron microscopy (SEM) was utilized to characterize the surface morphology of as-electrodeposited PS. SEM images illustrate that the applied current density has a profound influence on the shape of copper crystal electrodeposited on the top surface of PS films. When the applied current density was fixed at 5mA/cm2, most of the copper crystals are in the shape of cube along with a small number of cuboid-shape. With the increasing current density, cuboid-shaped copper crystals gradually vanished. When the current density is up to the 35mA/cm2, we surprisingly observe that the cube shape predominates simultaneously with the emergence of truncated tetrahedron. A tentative explanation for the growth mechanism of copper crystal having various shapes is explored.