Activation Of Typical Semiconductor Oxides Photocatalysts With Solution Plasma Discharging

Oxide semiconductor photocatalysts have attracted much attention due to their important applications in the fields of environment and energy.However,due to the limitation of charge separation efficiency and surface reaction rate,the photocatalytic activity of semiconductor photocatalysts is always insufficient.How to activate oxide semiconductor photocatalyst and improve the efficiency of photocatalytic reaction is the key to realize its practical application in the field of environment and energy.In this paper,the advanced solution plasma discharge technology is used to introduce defects on the surface of two typical semiconductor photocatalysts（TiO₂ and BiVO₄）to explore an effective method to improve the activity of oxide photocatalyst through surface defect engineering,and to provide a feasible strategy for the design and preparation of efficient photocatalyst.The main research contents are as follows:（1）Activation of decahedral bismuth vanadate photocatalyst by solution plasma.Decahedral bismuth vanadate was prepared by hydrothermal method with reductive{010}crystal facets as enriched electron and oxidizing{110}crystal facets as enriched hole,and then decahedral bismuth vanadate was treated by solution plasma.The theoretical calculation and ESR,XPS spectroscopy show that the solution plasma discharge can introduce vanadium defects on the surface of bismuth vanadate,and the introduced vanadium defects are more likely to form on the{110}crystal facets.Transient photovoltage（TPV）test and crystal facets selectivity verification show that the introduction of surface vanadium defects can enhance hole enrichment at{110}crystal facets,inhibit the photogenerated carrier recombination,and promote the directional transmission of photogenerated electron-hole pairs to reductive crystal surface and oxidizing crystal facets,so as to improve the selectivity of decahedral bismuth vanadate crystal facets.The experiment of photocatalytic oxygen production showed that under the presence of Ag⁺sacrificial agent,the oxygen production activity of 8h-Plasma samples could be increased by 1.5 times.（2）Preparation of blue titanium dioxide with hydrogen doped by solution plasma.Blue titanium dioxide doped with hydrogen was prepared by Degussa P25 and other commercial titanium dioxide powders.TEM,ESR and solid NMR spectroscopy showed that TiO₂ powders treated by solution plasma had less oxygen defects and formed disordered hydrogen-doped titanium dioxide layer on the surface.The photocatalytic activity of Degussa P25 powder treated by solution plasma for 1 hour and 3 hours was 48 and 18 times of that of the original samples.RDB-PAS spectroscopy showed that the solution plasma treatment could introduce hydrogen doped shallow defect level on the surface of TiO2 and heal the electron trapped by the oxygen defect deep level,thus reducing the electron-hole recombination,improving the photocatalytic reaction efficiency on the surface and enhancing the photocatalytic hydrogen production activity.The above research indicates that solution plasma discharge is an effective method to activate Bi VO4 and TiO2 typical oxide photocatalyst.This method is simple and fast,and is expected to have important applications in the field of photocatalysis.