Preparation and characterization of electrodeposited Ni-Ru alloys: morphological and catalytic study

Nickel-ruthenium alloys with various compositions have been deposited by electrodeposition for the first time. Cyclic voltammetry and linear stripping voltammetry measurements show that codeposition of nickel with ruthenium is possible below the potential value of nickel reduction. High-quality alloys containing nickel and ruthenium can be plated at cathodic potentials ranging from − 0.5 to − 1.0 V vs SCE. Deposited coatings were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The diffractograms obtained show that an increase of nickel concentration in alloy will lead to a change in the phase composition and formation of NiRu (100) and (101) phases which is observed to be 78 mas.% Ni. SEM studies confirm the surface homogeneity and presence of small, regular grains. AFM observation allows the estimation of the real surface area of obtained alloys which increase with more negative electrodeposition potentials. Ni-Ru alloys were found to be highly electroactive in the water splitting process, which can be connected with the presence of the NiRu phase and a well-developed electroactive area.

Electrocatalytic Properties of Nickel Foam-Based Ni-Mo, Ni +Mo and Ni+Mo/Ni-Mo Electrodes for Hydrogen Evolution Reaction

Nickel foam-based Ni-Mo alloy electrodes, Ni+Mo composite electrodes and Ni+Mo/Ni-Mo composite alloy electrodes were prepared by eletrodeposition, and the electrocatalytic characteristics for hydrogen evolution reaction (HER) in 30wt% KOH solution were investigated by cathode polarization curve and electrochemical impedance spectroscopy (EIS). The experimental results show that in comparison with nickel foam electrodes, these electrodes exhibit a lower overpotential, a higher exchange current density and a larger real surface area for HER. At 30°C and current density of 200 mA/cm2, the overpotentials of foam Ni electrodes, nickel foam-based Ni-Mo alloy electrodes, Ni+Mo composite electrodes, Ni+Mo/Ni-Mo electrodes are respectively 506, 252, 336, 202 mV. The nickel foam-based Ni+Mo/Ni-Mo composite alloy electrode had the highest HER electrocatalytic activity.

Calculating real surface area of land parcels in hilly and mountainous regions

Currently, the legal area of a land parcel in cadastral map is defined as the projected area of the parcel on a map plane. However, in practice, the real surface area of parcels plays important role for land use. In plain regions, the differences between real and legal areas of parcels are negligible, but in hilly and mountainous regions, these differences are significant and must be accounted in land management. In this paper, the authors had proposed a method for calculating real surface area of land parcels using GIS and data extracted from digital elevation models. The method was verified against Vietnam’s standard on cadastral map by using a simulated land parcel that is a part of a sphere, and got positive results. The method is then applied for calculating surface area of more than 2000 land parcels in Tien Xuan Commune, Thach That District, Hanoi City. The obtained results showed that the differences between real and legal areas of land parcels can reach a value of 23% for forestry land at mountain side with slope of more than 30o. In whole Tien Xuan Commune, these differences have an average value of 2.4%.

Comparison of Electrochemical Properties of Ni+NiAl and Ni Coatings in an Alkaline Solution

The Ni+NiAl nanocomposite coatings were prepared by the electrodeposition under the galvanostatic conditions (jdep= -250 mA cm-2) from the nickel bath containing the suspension of NiAl nanopowder. For comparison, the Ni coatings were also obtained. The combined steady-state polarization and electrochemical impedance spectroscopy (EIS) investigations of hydrogen evolution reaction (HER) were carried out in 5 M KOH solution at room temperature. It was found that the Ni+NiAl nanocomposite coatings revealed higher apparent electrocataltic activity towards the HER as compared to the comparable Ni deposits due to the increase in the real surface area development and the intrinsic activity.

Development of Microtextured Photocatalytic Surface by Vibration-Assisted Scratching

It is known that the TiO2 has some photocatalytic functions, even though they are relatively weak and their further enhancements are necessary for wider practical usages. On the other hand, improving materials surface functions by introducing microtextures is of great interest in various fields. Under such circumstances, the present study is aiming at developing a high-functional photocatalytic surface by earning the real surface area and reducing the light reflection and so on with the support of microtexturing technique. In this work, a pure Ti plate surface, which was covered with numerous micro impressions and micro pile-ups formed by the vibration-assisted microscratching, was anodized in order to obtain a regularly microtextured TiO2 film on the uppermost surface of Ti plate, and its wettabilty was evaluated in order to investigate its potential as the photocatalyst. As a result, it was found that the wettability of the TiO2 film surface regularly microtextured by the vibration-assisted microscratching was superior to those of the mirror finished one under the irradiation environment by the ultraviolet rays.

Optimization of Conversion Treatment on Austenitic Stainless Steel Using Experimental Designs

Conversion coating is commonly used as treatment to improve the adherence of ceramics films. The conversion coating properties depend on the structure of alloy as well as on the treatment parameters. These conversion coatings must be characterized by strong interfacial adhesion, high roughness, and high real surface area, which were measured by an electrochemical method. The influence of all the elaboration factors (temperature, time, and bath composition: sulphuric acid, thiosulphate as accelerator, propargyl alcohol as inhibitor, and surface state) and also the interactions between these factors were evaluated, using statistical experimental design. The specific surface area and optical factor (α) correspond to the quantitative responses. The evaluation showed, by using a designed experimental procedure, that the most important factor was “surface state.” Sanded surface allows the formation of conversion coating with high real surface area. A further aim was to optimise two parameters: treatment time and temperature using Doehlert shell design and simplex method. The growth of the conversion coating is also influenced by treatment time and temperature. With such optimized conditions, the real surface area of conversion coating obtained was about 235 m2/m2.

Influence of Surface Micro Texture on Photocatalitic Function of Titanium Dioxide Film

This study aims to develop a high-functional photocatalytic film, of which surface is regularly textured by the micro machining technique in order to earn the real surface area. In this work, a regularly textured TiO2 film surface was fabricated by anodic oxidizing a pure titanium plate with regularly arrayed micro cutting grooves, and its wettabilty was evaluated. Micro cutting grooves were machined by a 3-axis NC control precision machine tool with a single point diamond cutter. Anodic oxidation experiments were conducted by using the self-developed equipment with diluted acetic acid as the electrolyte. As a result, it was found that the wettability of the TiO2 film surface regularly textured by synchronized 3-axial micro cutting was superior to those of the mirror finished or irregularly textured surfaces under the irradiation environment by the ultraviolet rays.