State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization

Kunming, China

State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization

Kunming, China

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Xu C.,Kunming University of Science and Technology | Liu Y.,Kunming University of Science and Technology | Hua Y.,Kunming University of Science and Technology | Hua Y.,State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization | And 4 more authors.
Materials Transactions | Year: 2017

The electrochemical and chemical behaviors of titanium were examined in aluminum chloride-1-butyl-3-methylimidazolium chloride (AlCl3-BMIC) ionic liquid. The reduction of Ti(IV) in AlCl3-BMIC occurs in three consecutive steps: Ti(IV) → Ti(III) → Ti(II)→ Ti, and Ti(III) ion can quickly react with Cl- anion to form sparingly soluble TiCl3. However, No elemental titanium can be obtained in either acidic or basic AlCl3-BMIC melt. Metal titanium can be oxidized to Ti(II) by Ti(IV) in AlCl3-BMIC melt. In addition, the anodic oxidation rate of titanium obviously increases in the presence of Ti(IV) and Ti(III) ions, suggesting that the anodic dissolution of titanium involves chemical dissolution. These results indicate that it is difficult to nucleate or stabilize pure titanium in ionic liquid, which makes pure titanium deposition quite difficult. © 2017 The Japan Institute of Metals and Materials.


Yang Y.,Kunming University of Science and Technology | Xu C.,Kunming University of Science and Technology | Xu C.,State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization | Hua Y.,Kunming University of Science and Technology | And 3 more authors.
Ionics | Year: 2017

The electrodeposition behavior of Ni-La alloys was investigated in 1-ethyl-3-methylimidazolium chloride-ethylene glycol (EMIC-EG; 1:2-M ratio) eutectic-based ionic liquid containing 0.1 M NiCl2 and 0.2 M LaCl3. Cyclic voltammograms revealed that La could be co-deposited with Ni under the inducement of Ni(II) species in this solvent. The analysis of the chronoamperometric transients showed that, as with deposition of metal Ni, the co-deposition of Ni-La alloy on a glassy carbon electrode followed an instantaneous nucleation and three-dimensional growth controlled by diffusion. Galvanostatically deposited Ni-La alloys with different composition and morphology were characterized by inductively coupled plasma–atomic emission spectrometry (ICP-AES), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). The current density and temperature were found to play an important role in controlling the composition and surface morphology of the resultant Ni-La alloys. The structure of these deposits depended on the La content. Alloys containing less than 4 at.% La could be indexed to a disordered face-centered cubic structure similar to pure Ni, whereas alloys containing about 9 at.% Ni were completely amorphous (metallic glass). © 2017 Springer-Verlag Berlin Heidelberg


Zhu X.,State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization | Zhu X.,Kunming University of Science and Technology | Sun L.,State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization | Sun L.,Kunming University of Science and Technology | And 8 more authors.
International Journal of Hydrogen Energy | Year: 2014

The chemical hydrogen storage (hydrogen reduction) and production (water splitting) behaviour of Ce-modified Fe2O3 mixed oxides were investigated. Fe1-xCexO2-δ (x = 0, 0.05, 0.1, 0.2, 0.3, 0.4 and 1) oxides prepared by chemical precipitation were characterized by XRD (X-ray diffraction), H2-TPR (hydrogen temperature-programmed reduction) and H2O-TPO (steam temperature-programmed oxidation) tests. XRD results showed that two kinds of Fe-Ce-O solid solutions (Ce-based and Fe-based) coexisted in Fe-Ce mixed oxides. H2-TPR experiment suggested that Ce addition could reduce hydrogen reduction temperature while H2O-TPO experiments over reduced oxides showed that Fe-Ce mixed oxides could split water to produce hydrogen at a lower temperature and complete in a shorter time. Both redox reactions (hydrogen reduction and water splitting) were sensitive to the temperature and active at a high temperature. The successive redox cycles were carried out over the Fe 0.7Ce0.3O2-δ mixed oxide at 750 °C. It kept a stable production of hydrogen in the successive redox process at the condition of serious agglomeration of the materials. The highest hydrogen storage amount was up to 1.51 wt% for the Fe-Ce sample with a 30% substitution of Ce for Fe. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.


Li F.Y.,Kunming University of Science and Technology | Xu C.Y.,Kunming University of Science and Technology | Xu C.Y.,State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization | Yang Y.Y.,Kunming University of Science and Technology | And 4 more authors.
Advanced Materials Research | Year: 2014

Carbon-coated nickel nanoparticles were synthesized by solvothermal method in l-buty-3-methylimidazolium tetrafluoraborate ionic liquid. The obtained products are characterized by X-ray powder diffraction (XRD), Raman spectroscopy, infrared spectroscopy and transmission electron microscopy (TEM). The magnetic properties of carbon-coated nickel nanoparticles have been investigated by vibrating sample magnetometry (VSM). It was found that the carbon-coated nickel nanoparticles showed excellent magnetic properties. The present route may give researchers more choices for preparing other carbon-coated transition metal nanoparticles. © (2014) Trans Tech Publications, Switzerland.


He S.,State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization | He S.,Kunming University of Science and Technology | Xu R.,State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization | Xu R.,Kunming University of Science and Technology | And 4 more authors.
Electrochemistry | Year: 2015

An α-PbO2 layer were synthesized on the Pb-0.3%(mass proportion)Ag alloy substrates by constant current electrosynthesis from an alkaline solution, and Pb-0.3%Ag/α-PbO 2 composite inert anode materials were obtained. An electrochemical investigation of α-PbO2 deposition process on the Pb-0.3%Ag alloy substrates, using anodic polarization technique, galvanostatic polarization technique and steady state polarization technique, has been carried out. The phase composition and surface microstructures of α-PbO2 layersindifferent synthesizing times were tested by means of XRD and SEM, respectively. The experimental data have shown that the process of α-PbO2 formationon Pb-0.3%Ag alloy substrates have several stages. The optimized conditions canbeeffectively improving the formation rate of α-PbO2 and avoid the occurrence of oxygen evolution reaction. The α-PbO2 deposition layer obtained in alkaline solution possesses compact structure, and it is composed of well developed spherical grains. © The Electrochemical Society of Japan, All rights reserved.


He S.,State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization | He S.,Kunming University of Science and Technology | Xu R.,State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization | Xu R.,Kunming University of Science and Technology | And 4 more authors.
RSC Advances | Year: 2016

An α-PbO2-WC(Co3O4) composite layer was successfully prepared on a lead-coated aluminum substrate by an anodic co-deposition method. The influence of particle concentration and stirring rate was investigated by an anodic polarization technique in the process of α-PbO2 electrodeposition. The major physical and electrochemical properties of the prepared electrode were investigated. The surface morphology and crystal structure of the composite deposition layers were analyzed by X-ray diffraction (XRD), scanning electronic microscopy (SEM) and X-ray spectroscopy (EDS). The experimental data showed that the co-deposition of WC or Co3O4 particles can reduce the α-PbO2 electrodeposition rate; however, the mechanism of α-PbO2 electrodeposition is not changed. The oxygen evolution electrocatalytic activity of the composite anodes can be improved by doping WC or Co3O4 particles into the α-PbO2 layer, and the corrosion resistance of the anode can be improved by the doped WC particles. The WC particles have the ability to refine the grains and prevent the agglomeration of Co3O4 particles, while the Co3O4 particles can change the preferred orientation of α-PbO2. © The Royal Society of Chemistry.


Yang Y.,Kunming University of Science and Technology | Xu C.,Kunming University of Science and Technology | Xu C.,State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization | Hua Y.,Kunming University of Science and Technology | And 5 more authors.
International Journal of Electrochemical Science | Year: 2015

The electrochemistry of Ni(II) was studied with voltammetry and chronoamperometry at glass carbon (GC), mild steel (MS) and Pt electrodes in 1-ethyl-3-methylimidazolium (EMIC) ionic liquid with ethylene glycol. Cyclic voltammetry results shows that Ni(II) could be reduced to nickel metal via a single-step electron transfer process. However, the anodic dissolution of the nickel deposits was sluggish. In addition, the initial reduction potential of Ni(II) shifted positively as the temperature or concentration of Ni(II) increased. The diffusion coefficient of Ni(II) was estimated to be 4.6×10-7 cm2 s-1. The average activation energy for diffusion coefficient is about 21.75 kJ/mol. The electrodeposition of nickel proceeds via three-dimensional instantaneous nucleation with diffusion-controlled growth on both glassy carbon and Pt substrates. Smooth and dense Ni deposits can be obtained from EMIC ionic liquid with glycol. © 2015 The Authors.


He S.,Kunming University of Science and Technology | He S.,State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization | Xu R.,Kunming University of Science and Technology | Xu R.,State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization | And 3 more authors.
International Journal of Electrochemical Science | Year: 2016

An electrochemical investigation focused on electrosynthesis of lead dioxide in alkaline solutions, using rotating disk electrode (RDE) and rotating ring disk electrode (RRDE), has been carried out. The experiments show that Pb(II) haven't modified the evolution of oxygen in alkaline solutions, and the reaction taking place at 0.6 VSCE is under the mixed control of ionic transport and charge transfer. Koutechy-Levich equation has been used to calculate the value of diffusion coefficient D and apparent heterogeneous rate constant k of Pb(II) oxidation reaction at 0.6 VSCE. The calculation results indicate that Pb(II) itself has the negative influence on the diffusion of Pb(II). In addition, Pb(II) has the positive influence on the apparent heterogeneous rate constant of PbO2 electrodeposition process. The intermediate was discovered in PbO2 electrodeposition process using RRDE. XRD and SEM were employed to investigate the phase composition and surface microstructure of the synthesized deposit. The result confirms that PbO2 synthesized in an alkaline solution consists of pure α phase, but not all characteristic peaks are present and relative intensities are not in agreement with the ICDD card. The deposit shows the preferential orientation of growth in the (200) crystallographic plane, and the deposit is compact and uniform which is composed of rounded nanocrystallites. © 2016 The Authors.


Su Z.,Kunming University of Science and Technology | Su Z.,State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization | Xu C.,Kunming University of Science and Technology | Xu C.,State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization | And 12 more authors.
International Journal of Electrochemical Science | Year: 2016

The sub-micrometer Sn-Sb alloy powders were electrochemically prepared on a titanium substrate in choline chloride-ethylene glycol (ChCl-EG, 1:2 molar ratio) deep eutectic solvent containing 0.2 M SbCl3 and 0.2 M SnCl2. The electrochemical behaviors of Sb(III) and Sn(II) were investigated using cyclic voltammetry techniques. It revealed that the reduction of Sb(III) and Sn(II), as well as co-reduction of them in ChCl-EG involved the irreversible process controlled by diffusion. The diffusion coefficients of Sb(III) and Sn(II) species were in the range of 10-7 and 10-6 cm2 s-1, respectively. Potentiostatically deposited Sn-Sb alloys were characterized by inductively coupled plasma atomic emission spectrometry (ICP-AES), scanning electron microscopic (SEM) and X-ray diffraction (XRD). The deposition potential played an important role in controlling the composition, but had little effect on surface morphology. Depending on the deposition potential, sub-micrometer Sn-Sn alloy powders containing about 2.7-67.4 at.% Sn were obtained. © 2016 The Authors. Published by ESG.


He S.,Kunming University of Science and Technology | Xu R.,Kunming University of Science and Technology | Xu R.,State Key Laboratory of Complex Nonferrous Metal Resources Cleaning Utilization | Han S.,Kunming University of Science and Technology | And 2 more authors.
Journal of the Electrochemical Society | Year: 2016

An electrochemical investigation of NaOH concentration on electrosynthesis of lead dioxide in alkaline solutions was performed using rotating disk electrodes (RDE). The results show that Pb(II) does not modify the evolution of oxygen in alkaline solutions, and the reaction taking place at 0.84 VSHE is under the mixed control of ionic transport and charge transfer. The Koutechy-Levich equation was used to calculate the value of diffusion coefficient D and apparent heterogeneous rate constant k of the PbO2 electrodeposition process at 0.84 VSHE. The results indicate that NaOH has a negative influence on the diffusion of Pb(II) within a NaOH concentration range of 2.5 ∼ 4.5 M. In addition, NaOH has a positive influence on the apparent heterogeneous rate constant of Pb(II) oxidation reactions within a NaOH concentration range of 2.5 ∼ 3 M, but a negative influence within a NaOH concentration range of 3 ∼ 4.5 M. XRD and SEM were employed to investigate the effects of NaOH concentration on phase composition and surface microstructures of deposits. The results show that PbO2 synthesized in an alkaline solution consists of pure α phase. The deposits are all composed of rounded nanocrystallites, except for the deposit synthesized in a solution of 3 M NaOH, which exhibited rod-like crystallite. © 2016 The Electrochemical Society.

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