Preparation And Photocatalytic Properties Of Highly Efficient Photocatalysts Based On Piezoelectric Effect

With the environmental pollution and the blind consumption of fossil fuels,the ecological imbalance and energy shortage seriously threaten the sustainable development of society.As an ideal clean technology,semiconductor photocatalysis has great potential in environmental remediation and renewable energy.However,the photocatalytic activity is seriously restricted by the fast recombination of photogenerated carriers in the photocatalyst surface and bulk phase,thus the actual photocatalytic efficiency is far from the application requirements.And the previous modification strategy is not efficient,so it is imperative to explore a new efficient strategy to improve the separation efficiency of photogenerated carriers.In recent years,piezoelectric field constructed in photocatalytic reactions has been proved to be an effective method to improve photogenerated carrier separation of photocatalyst.The piezoelectric material polarizes under the external mechanical force and generates a piezoelectric field.Driven by the strong potential energy of piezoelectric field,the photogenerated carriers are separated effectively.In this thesis,the enhancement effect of inorganic piezoelectric materials and organic piezoelectric materials on photocatalytic activity was explored.The specific research works are as follows:（1）PVDF-BaTiO₃-Cd_0.9Zn_0.1S piezoelectric films were prepared and its photocatalytic hydrogen evolution activity was studied.First,Cd_0.9Zn_0.1S photocatalyst was prepared,which has a new tetrapod morphology and coexists in both hexagonal and cubic phases.The results showed that the structure of the hexagonal and cubic phases formed a homogeneous junction,which promoted the separation of photogenerated electrons and holes,and enhanced the photocatalytic performance.After that,we successfully prepared organic piezoelectric PVDF-BaTiO₃-Cd_0.9Zn_0.1S films using PVDF as the substrate and introducing Cd_0.9Zn_0.1S and BaTiO₃ as catalysts and inorganic piezoelectric phases,respectively.And this film has porous morphology and has significant piezoelectric properties.The experiments show that the film can effectively promote the separation of photogenerated electrons from holes and improve the activity of hydrogen evolution.（2）The Ag-BaTiO₃ composites material was prepared by photochemical reduction method.The composite material exhibits a wider absorption range of visible light and can absorb more visible light.Moreover,through the synergistic effect of piezoelectric effect and local surface plasmon resonance effect,photogenerated electrons and holes are effectively separated,thus improving the photocatalytic degradation performance.