The influences of sodium silicate on manganese electrodeposition in sulfate solution were investigated. Manganese electrodeposition experiments indicate that a certain amount of sodium silicate can improve cathode cur...The influences of sodium silicate on manganese electrodeposition in sulfate solution were investigated. Manganese electrodeposition experiments indicate that a certain amount of sodium silicate can improve cathode current efficiency and initial pH 7.0?8.0 is the optimized pH for high cathode current efficiency. The analyses of scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicate the compact morphology and nanocrystalline structure of electrodeposits. X-ray photoelectron spectrometry (XPS) analysis shows that the elements of Mn, Si and O exist in the deposit. The solution chemistry calculations of sulfate electrolyte and sodium silicate solution indicate that species of Mn2+, MnSO4, Mn(SO4)2?2 , Mn2+, MnSiO3, Mn(NH3)2+, SiO32?and HSiO3? are the main active species during the process of manganese electrodeposition. The reaction trend between Mn2+ and Si-containing ions is confirmed by the thermodynamic analysis. In addition, polarization curve tests confirm that sodium silicate can increase the overpotential of hydrogen evolution reaction, and then indirectly improve the cathode current efficiency.展开更多
A mechanism study on MoO2 electrodeposition from ammonium molybdate solution was presented via linear sweep voltammetry,species distribution diagram,Raman spectra,Fourier transform infrared spectrometry and X-ray diff...A mechanism study on MoO2 electrodeposition from ammonium molybdate solution was presented via linear sweep voltammetry,species distribution diagram,Raman spectra,Fourier transform infrared spectrometry and X-ray diffractometry.The results show that there exist two reducible species in ammonium molybdate aqueous solution,i.e.Mo7 O24^6- and molybdenum ammonium complex.In weak acid medium without NH4^+,an obvious reduction peak denoting the reduction of Mo7 O24^6- to molybdenum(Ⅳ)oxides emerges at around-0.7 V(vs SCE).While in neutral and basic solutions without NH4^+,the dominant species changes to MoO4^2-,and accordingly,no reduction peak appears except hydrogen evolution.NH4^+ plays an important role in MoO2 electrodeposition.A new current peak appears at-1.25 V(vs SCE)in both acid and basic solutions,which is attributed to the reduction of molybdenum complex.The effects of solution composition and the electrodeposition conditions on the current efficiency were discussed systematically.By optimizing the electrodeposition conditions,the current efficiency can reach up to51.9%.展开更多
ZrO2 films on NaCl(100) substrate produced by oxygen ion bombardment and argon ion sputtering of Zr are analysed using TEM, XRD and XPS. The result of TEM shows that only cubic phase exists for the ZrO2 film produced ...ZrO2 films on NaCl(100) substrate produced by oxygen ion bombardment and argon ion sputtering of Zr are analysed using TEM, XRD and XPS. The result of TEM shows that only cubic phase exists for the ZrO2 film produced by oxygen ion bombardment with 30μA/cm2 and 200eV, while the XRD result shows that there seems to exhibit a small quanitity of monoclinic phase apart from cubic one under the production condition of oxygen ion of 25μA/cm2, 100eV.展开更多
Corrosion behavior of AZ91 magnesium alloy under NaCl particle deposition condition was investigated by gravimetric method and surface analysis technique.It was found that the mass gain increased rapidly at the beginn...Corrosion behavior of AZ91 magnesium alloy under NaCl particle deposition condition was investigated by gravimetric method and surface analysis technique.It was found that the mass gain increased rapidly at the beginning of exposure and then slowly with time.The corrosion morphologies were observed and the results showed that NaCl deposition resulted in the occurrence of localized corrosion.The composition of corrosion product was analyzed using X-ray photo electron spectroscopy.It was suggested that the corrosion product was a mixture of oxide and hydroxide of magnesium and aluminum.展开更多
基金Project(2015BAB17B01)supported by the National Science and Technology Support Program of ChinaProject(21376273)supported by the National Natural Science Foundation of China
文摘The influences of sodium silicate on manganese electrodeposition in sulfate solution were investigated. Manganese electrodeposition experiments indicate that a certain amount of sodium silicate can improve cathode current efficiency and initial pH 7.0?8.0 is the optimized pH for high cathode current efficiency. The analyses of scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicate the compact morphology and nanocrystalline structure of electrodeposits. X-ray photoelectron spectrometry (XPS) analysis shows that the elements of Mn, Si and O exist in the deposit. The solution chemistry calculations of sulfate electrolyte and sodium silicate solution indicate that species of Mn2+, MnSO4, Mn(SO4)2?2 , Mn2+, MnSiO3, Mn(NH3)2+, SiO32?and HSiO3? are the main active species during the process of manganese electrodeposition. The reaction trend between Mn2+ and Si-containing ions is confirmed by the thermodynamic analysis. In addition, polarization curve tests confirm that sodium silicate can increase the overpotential of hydrogen evolution reaction, and then indirectly improve the cathode current efficiency.
基金Project(51374185) supported by the National Natural Science Foundation of China
文摘A mechanism study on MoO2 electrodeposition from ammonium molybdate solution was presented via linear sweep voltammetry,species distribution diagram,Raman spectra,Fourier transform infrared spectrometry and X-ray diffractometry.The results show that there exist two reducible species in ammonium molybdate aqueous solution,i.e.Mo7 O24^6- and molybdenum ammonium complex.In weak acid medium without NH4^+,an obvious reduction peak denoting the reduction of Mo7 O24^6- to molybdenum(Ⅳ)oxides emerges at around-0.7 V(vs SCE).While in neutral and basic solutions without NH4^+,the dominant species changes to MoO4^2-,and accordingly,no reduction peak appears except hydrogen evolution.NH4^+ plays an important role in MoO2 electrodeposition.A new current peak appears at-1.25 V(vs SCE)in both acid and basic solutions,which is attributed to the reduction of molybdenum complex.The effects of solution composition and the electrodeposition conditions on the current efficiency were discussed systematically.By optimizing the electrodeposition conditions,the current efficiency can reach up to51.9%.
文摘ZrO2 films on NaCl(100) substrate produced by oxygen ion bombardment and argon ion sputtering of Zr are analysed using TEM, XRD and XPS. The result of TEM shows that only cubic phase exists for the ZrO2 film produced by oxygen ion bombardment with 30μA/cm2 and 200eV, while the XRD result shows that there seems to exhibit a small quanitity of monoclinic phase apart from cubic one under the production condition of oxygen ion of 25μA/cm2, 100eV.
基金Projects(50671005,50971093)supported by the National Natural Science Foundation of ChinaProject(2007CB613705)supported by the National Basic Research Program of China
文摘Corrosion behavior of AZ91 magnesium alloy under NaCl particle deposition condition was investigated by gravimetric method and surface analysis technique.It was found that the mass gain increased rapidly at the beginning of exposure and then slowly with time.The corrosion morphologies were observed and the results showed that NaCl deposition resulted in the occurrence of localized corrosion.The composition of corrosion product was analyzed using X-ray photo electron spectroscopy.It was suggested that the corrosion product was a mixture of oxide and hydroxide of magnesium and aluminum.
