Preparation And Electrocatalytic Oxidation Properties Of Magnèli Titanium Suboxide

Water quality problems caused by various harmful species and pollutants have become a major hidden danger to global water safety.Electrocatalytic oxidation technology is considered to be one of the advantageous technologies for decentralized water purification in the future because of its high efficiency,cleanliness and simple operation.Oxidation and purification of water based on the in-situ generation of active oxygen in the electrode places extremely high requirements on the activity,practicability and stability of the electrode itself,which is also the main challenge for electrocatalytic oxidation to remove pollutants in water.Given the high catalytic activity,high electrical conductivity,and chemical stability of Magnèli-phase titania(Ti_nO_2n-1)materials,it becomes a promising anode material for electrocatalytic oxidation.In this paper,in view of the harsh synthesis conditions of Magnèli phase titanium oxide and the large differences in product properties,the technical parameters of four preparation methods of Ti_nO_2n-1 were firstly explored,using aluminum powder,hydrogen,commercial carbon materials,and hydrothermal carbon layers respectively.As a reducing agent,anatase Ti O₂ was reduced,and the phase characterization,morphology and structure analysis,electrochemical test and four-probe test of the reduced product were combined to demonstrate the best synthesis process.In order to further verify the potential application performance of Magnèli phase titania,a Tin O2n-1 porous membrane electrode was fabricated in this paper,and the Ti4O7 with the highest conductivity in the Ti_nO_2n-1 series was used as the electrocatalytic oxidation anode to degrade five kinds of dyes.The over-flow sterilization experiment of bacterial water.Among various reduction methods,1)the aluminothermic reduction method has the highest reduction degree and the shortest reduction time.Ti₃O₅and Ti₂O₃ phases can be obtained by reducing at 850°C for 30 min.Al₂O₃formed during the reduction process.2)In the hydrogen reduction method,single-phase Ti₄O₇ was formed at 1100°C,with a high oxygen evolution potential of 2.89 V vs.SCE,the specific surface area of the BET test was 1.513m2/g,and the resistivity was 7.24?cm.3)In the ball milling-carbon black reduction method,the commercial carbon black material is uniformly mixed with Ti O2 by the ball milling method and then reduced at high temperature.The research results show that the content of 3.6%acetylene black is beneficial to the formation of highly conductive and catalytically active Ti_nO_2n-1,of which Ti₆O₁₁ is formed at 1300℃.4)The hydrothermal-carbothermal reduction method is a new method for preparing Ti O₂ proposed in this paper.The glucose is converted into a carbon layer uniformly coated on the surface of Ti O₂ by the hydrothermal method to obtain the Ti O₂@C precursor,the hydrothermal-carbon The thermal reduction method has a faster carbothermic reduction reaction rate than the ball milling-carbothermic reduction method.The optimal hydrothermal conditions obtained were that 1.6 g glucose and 2 g Ti O₂ were hydrothermally heated at 180°C for 4 hours,and Ti O₂@C was thermally treated at 1200°C to form a mixed phase of Ti₄O₇ and Ti₅O₉,and the oxygen evolution potential was2.73 V vs.SCE,the resistivity is 48.2?cm.In the overcurrent mode,the Ti₄O₇ membrane electrode was used as the anode for dye degradation.The reaction rate constant of the Ti₄O₇ membrane electrode to azo fluorescent pink was 0.05759 min^-1,which was 8 times higher than that of other electrodes（sprayed Ti₄O₇ mesh,titanium tin antimony mesh,and titanium dioxide film）.By 15 times,the degradation rate reached 97.77%,much higher than the other three electrodes（23.37%-33.41%）.The degradation rate and reaction rate constant increase with the increase of current density and electrolyte concentration.The membrane electrode has a good degradation effect on various types of dyes,and the degradation rate is above 92%-Rhodamine B（94.57%）,methyl Orange（98.60%）,Methylene Blue（92.67%）,Malachite Green（99.99%）.At the same time,the Ti₄O₇ film also has an excellent sterilization effect.The sterilization rate increases with the increase of voltage.When the voltage increases from 2 V to 4 V,the sterilization rate increases from 70.0%to 97.2%.The sterilization rate of 10⁴ CFU/m L bacterial solution at 10 V can reach 100%.Exploring the effect of time on the sterilization effect found that the sterilization rate of 10⁵ CFU/m L bacterial solution reached 82.69%in 8 minutes,and the sterilization rate reached 98.36%in 40 minutes.