Research And Application Of Enhanced Photocatalytic Degradation Of VOCs By Built-in Electric Field Regulation

Volatile organic compounds(VOC)are the main pollutants in indoor air,which have been proved to have a variety of adverse effects on health.VOCs are not only harmful to themselves,but also produce harmful by-products through reaction.Photocatalysis is one of the most promising and sustainable solutions in VOCs treatment technology.However,how to reasonably design and construct high-performance photocatalysts has always been the main challenge of environmental photocatalysis.Under most conditions,electron hole pairs will rapidly compound,thus reducing the efficiency of the photocatalytic process.By coupling piezoelectric material with photocatalyst,the energy band of piezoelectric material can be bent through piezoelectric field,so as to enhance the transmission ability of photogenerated electrons.At the same time,the built-in electric field of piezoelectric materials can promote the separation of electron hole pairs.In the first part of the work,we selected Pb Ti O₃ and photocatalyst Ti O₂ to couple,and designed a simple preparation method Pb Ti O₃@Ti O₂ Core shell structure catalyst.The composite is composed of Pb Ti O₃ single crystal nano sheet and mesoporous Ti O₂coating,which is hydrothermal method and then annealed at 400°C.Finally,the material was polarized under high pressure,and a catalyst that continuously enhanced the rate of photocatalytic degradation of VOCs was obtained in this way.After many experiments,the optimum roasting temperature was obtained.At the same time,comparative experiments were carried out to verify the promoting effect of ferroelectric materials on the photocatalytic process.Finally,through high-voltage polarization,it is further improved Pb Ti O₃@Ti O₂ Degradation activity of.In the second part,the polymer piezoelectric material PVDF is selected as the substrate.It has natural flexibility,durability and easy processing.Moreover,PVDF also has the highest dielectric constant and electroactive response(including piezoelectric,thermoelectric and ferroelectric effects).Therefore,it has a very wide range of applications.PVDF-P25 ferroelectric thin films were prepared by electrospinning with PVDF doped with P25 photocatalyst.The effects of different electrospinning parameters on the micro morphology and phase structure of nanofibers were studied.The spinning voltage,needle model and solution propulsion speed had a great influence on PVDF electrospun fibers,and the best synthesis parameters were obtained.Powder PVDF is polarized by the high-voltage electric field applied in the electrospinning process.The prepared film is flexible and has good ductility,and has a wide range of applications.The photocatalytic activity is excellent,and the degradation rate of toluene is 2-3 times that of pure P25.The reasons for the improvement of material properties were revealed by means of X-ray diffractometer,transient fluorescence spectrometer and Fourier infrared spectroscopy.The piezoelectric properties of the material were proved by piezoelectric microscope.Finally,combined with in-situ infrared,the oxidation removal path of simulated pollutants is described.