Researches On Electrodeposition Of Metal Titanium From Ionic Liquids

Titanium is praised as "space metal",due to its excellent corrosion resistance,high strength,light weight and good biocompatibility and other characteristics,it is widely used in aerospace,petrochemical,energy,transportation,biomedical and other fields.The present method to obtain Ti metal is through the Kroll method,a complex and expensive method,with long process,great energy consumption,pollut the environment and other serious problems.The molten salt electrolysis method for preparing metal Ti need high temperature,so it has the characteristics of large energy consumption,serious equipment corrosion,low current efficiency,pollute the environment and other issues,and it is difficult to achieve industrialization.Due to their unique features such as neglible vapor pressure,wide electrochemical window,being liquids at room temperature and outstanding designability characteristic,ionic liquids are considered as promising media for the electrodeposition of Ti.At present,most of the ionic liquids used for electrodeposition of metallic titanium are imidazolium ionic liquids.However,the electrochemical window of imidazolium ionic liquids is narrow,and so it is not applied to the deposition of metallic titanium.In this paper,two ionic liquids suitable for the deposition of metal titanium were selected,and the electrodeposition of metal titanium in ionic liquid was systematically studied.There was a paucity of systematic study on the electrodeposition of Ti from ionic liquids.The major research contents and innovative results of this dissertation are listed as follows:?1?[BisoMPyrr]NTf₂ and [N1,2,2,4]NTf₂ were designed and synthesized by 1H NMR,13 C NMR and mass spectrometry,which physical and electrochemical properties are investigated,and proved to be the target ionic liquids.Through the detection of impurities,the purity of ionic liquids was high,and it can meet the requirements of electrochemical experiments.?2?The conductivity of two ionic liquids was measured,with the temperature increasing,the conductivity increased.The conductivity almost linearly increases withTemperature duing 293.15 K and 333.15 K,which is in accordance with the Arrhenius equation.The conductivity of two ionic liquids decreased with the addition of TiCl₄.?3?The use of [BisoMPyrr] NTf₂-TiCl₄ for electrodeposition of metal titanium,cyclic voltammetry test showed that the reduction of titanium on the cathode at least two steps:?1?Ti???? Ti???or Ti????2?Ti???? Ti???or Ti???? Ti?0?.The results of XRD and XPS showed that it wass mainly TiCl₃ and TiO₂ in the coating.TiCl₃ attached to the surface of electrode,and prevented further reduction.The small amount of Ti was oxidized to TiO₂ in the air.UV absorption results showed that Ti???and Ti???had not been detected after deposition,whith indicated that the titanium species were mainly on the substrate.?4?Study on the electrodeposition of titanium in [N1,2,2,4]NTf₂-TiCl₄.Cyclic voltammetry showed that the reduction step of titanium was Ti???? Ti???? Ti????Ti?0?.Scanning electron microscope indicated that the coating of Ti was not homogeneous,and the basic shape of the crystal was irregular and independent particles.X ray electron probe showed the component of titanium was only 3.82%,because of the thin coating,most of the element was silver.XRD results showed that there are TiO₂ and Ti in the coating.From the UV absorption results,Ti???has not been detected after deposition,the same as Ti???,so it indicated that the titanium species were mainly on the substrate.