Doping Modification Of TiO-nano Tube Array-TiO₂ Ekectrode And Its Eletroreduction Activity For L-cystine

L-cysteine is widely used in many fields,and often is produced by electrocatalytic reduction of L-cystine.Currently,Pb or supported Pb electrodes uesd widely in industry are prone to heavy metal pollution in acid electrolyte.Ti electrode can electro-reduce the L-cystine but it is not effective.Develop new electrode materials with environentally friendly,stable performance,high catalytic reduction activity is a research hotspot.But most of the studies are about the photocatalysis of TiO2.Considering that TiO2 electrode possesses many advantages such as high,the oxygen vacancies and transitional Ti3+ in anatase TiO2,is also deemed to a potential materials for electrocatalytic reduction.In this work,the TiO2 nanotube array electrode was prepared by anodizing method.A series of modified TiO2 nanotube array tube electrodes were prepared by chemical immersion to dope Ag,,In,graphene,Zr and by electrochemical polarization to induce Ti3+self-doping.By a heat treatment process,the crystal form of TiO2 in the above electrodes can transform into anatase crystal form.X-ray diffraction(XRD),scanning electron microscope(SEM),X-ray diffraction(XPS)and other methods were used to characterize the surface morphology and crystal structure of the nano-TiO2 electrode,the electrochemical performance of the prepared electrode was tested and characterized and by cyclic voltammetry(CV)and linear scanning voltammetry(LSV).The main results obtained are as follows:(1)The hydrogen evolution acticity of the modified nano-TiO2 array tube electrode depends on the doping element itself.Because the hydrogen evolution overpotential of In is higher than that of Ti,doping In will slightly suppress the hydrogen evolution of the electrode,which is helpful to reduce the side reaction of hydrogen evolution during the electrocatalytic reduction and improve the energy utilization efficiency of the electrode.(2)In the anatase crystal form,self-doping of Ti3+ on the TiO2 electrode will occur at a potential of-1.01V.The excessive valence state Ti3+ of Ti metal plays a good catalytic role in the electrocatalytic reduction of L-cystine.The study found that both Ag and Zr can increase the density of Ti3+ at-1.01V on the TiO2 electrode,which is beneficial to enhance the catalytic reduction activity of the electrode for L-cystine.However,Ag doping improves the electrode's hydrogen evolution ability,which is not.conducive to electrocatalytic reduction of L-cystine.(3)XPS,XRD,SEM and other characterization analysis of the electrocatalytic reduction mechanism of Zr-doped anatase TiO2 electrode.The results show that Zr4+was successfully doped on the TiO2 nanoarray tube.Because Zr4+is mixed into the TiO2 crystal form,it replaces part of Ti4+to form more oxygen holes and Ti3+,so that the catalytic activity of Zr/TiO2 nanoarray electrode electrocatalytic reduction of L-cystine is significantly improved.