Optical spectroscopy, optical conductivity, dielectric properties and new methods for determining the gap states of CuSe thin films

Two simplified chemical processes, a co-precipitation and a reduction method, were developed to synthesize pure Cu2Se nanoparticles. The XRD results indicate that the co-precipitation method is a better way to synthesize high-purity Cu2Se in comparison to the reduction method, where a small amount of Cu2O and Cu are found. Scanning electron microscopy reveals that Cu2Se powder synthesized by the reduction method possesses a morphology dominated by irregular hexagonal nanoplates and spherical nanoparticles; however, only nanoplates are observed in powder prepared by the co-precipitation method. The effect of the two synthetic methods on the thermoelectric properties of Cu2Se, in the temperature range of 300–1000 K, was investigated. The results indicate that the co-precipitation method subsequently combined with a hot-press process, is an effective way to improve Cu2Se thermoelectric performance compared to the reduction method together with hot-pressing. The largest figure of merit, ZT, for Cu2Se fabricated by the co-precipitation method is 1.35, which is 40% larger than that of Cu2Se fabricated by the reduction method (ZTmax = 0.97) due to its good power factor at high temperatures.

Chemical synthesis of nanostructured Cu2Se with high thermoelectric performance

Transition metal selenides and diselenides: Hydrothermal fabrication, investigation of morphology, particle size and and their applications in photocatalyst.

The removal of copper from aqueous solutions using elemental selenium nanoparticles (nanoSe0) was presented. The uptake of copper by nanoSe0 depended on reducing agents, such as ascorbic acid (Vc) which reduced Cu(II) to Cu(I). The results of scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy dispersive X-ray (EDX) indicated that nanoSe0 adsorbed copper by interacting between nanoSe0 and cuprous ions to form copper selenide (Cu2Se) on the surface of nanoSe0. The effects of the mass of nanoSe0, contact time, pH, initial Cu(II) concentration, and temperature on the removal of copper were investigated. The adsorption kinetics was well-described by the pseudosecond-order equation which suggested that the model was indicative of a chemical adsorption mechanism. The adsorption isotherm was better fitted by the Langmuir equation. The maximum adsorption capacity of nanoSe0 for copper was found to be 0.89 g·g–1 at 298.15 K. The nanoSe0 coexisting with Vc was a promising adsorbent for the remov...

Removal of Copper from Aqueous Solutions by Adsorption on Elemental Selenium Nanoparticles

Hybrid Mg2+/Li+ batteries with Cu2Se cathode based on displacement reaction

Synthesis and characterization of Cu2Se prepared by hydrothermal co-reduction

Abstract In this paper, the stability of the fog suppression effect of 20 different domestic chrome fog inhibitors and their effect on the thickness and corrosion resistance of the plated layer were studied by formulating the basic chrome plating solution with a common chrome plating solution formulation. The stability of the fog suppression effect of the 20 different chromium fog inhibitors was analysed by measuring the variation of the thickness of the chromium fog inhibitor foam layer with time. It was found that the thickness of the foam layer produced by the TDFS chromium mist inhibitor during the plating process changed least significantly at 30 min after plating, and the stability of the fog inhibiting effect was the best; compared with the thickness of the layer obtained from a common chromium plating solution without the addition of chromium mist inhibitor, it was found that the thickness of the layer obtained from the plating solution with the addition of PALDOTMV-400 chromium mist inhibitor was the thickest. The experimental results show that the chromium plating solution with the addition of WH-883 chromium mist inhibitor has the best electrochemical corrosion resistance, because its impedance value is the largest and the corrosion current is smaller.

Electrochemical performance analysis based on chromium mist inhibitors

The passivation of zinc alloy coating was achieved through the utilization of both silicate and trivalent chromium passivation systems, employing a specific process formula consisting of Co(NO3)2 at a concentration of 2.5 g/L, C76H52O46 at 3 mL/L, Na2SiO3 at 25 g/L, C6H5Na3O7 at 15 g/L, and an appropriate amount of organic accelerator. The composite passivation of silicate and tannic acid was found to be more effective than the trivalent chromium passivation film, as it successfully eliminated the dendrite structure on the coating surface and reduced surface defects. The coordination between negatively charged SiO2− or SiO2 micelles and Zn2+ results in the formation of a passivation film that exhibits lower corrosion current and higher corrosion potential compared to the trivalent chromium passivation film. Additionally, the impedance test fitting results indicate that the silicate passivation film possesses a higher resistance value. Overall, the proposed silicate passivation system presents a viable alternative to the toxic chromate passivation system, offering non-toxicity and superior protective performance relative to the trivalent chromium passivation system.

Inhibition of Surface Corrosion Behavior of Zinc-Iron Alloy by Silicate Passivation

Abstract Molybdate passivation film was prepared on the surface of Zn-Fe alloy coating by chemical passivation treatment, and compared with unpassivation and conventional tungstate passivation film. The surface leveling of molybdate passivation film is the best, and tungstate surface still has a few protrusions. Salt spray test shows that the white rust time after passivation by sodium molybdate is up to 127 h, which is much longer than the unpassivation time. After passivation, the corrosion current density of the two passivated surfaces decreased significantly, and the molybdate passivated surface was 0.815 × 10−2 μA cm−2, tungstate passivated surface was 1.653 × 10−2 μA cm−2, and the unpassivated surface was 2.187 × 10−2μA cm−2.EIS experiment showed that the corrosion current density of the two passivated surfaces decreased significantly. Molybdate passivation has the highest resistance Rp 3582.9 Ω ·cm2.

Lei Shi

Papers

Synthesis and characterization of Cu2Se prepared by hydrothermal co-reduction

Electrochemical performance analysis based on chromium mist inhibitors

Inhibition of Surface Corrosion Behavior of Zinc-Iron Alloy by Silicate Passivation

Preparation and study of a molybdate passivation film on zinc alloy