Research On Semiconductor Nanowire Arrays-based Triphase Interface Photocatalysis

Photocatalysis technology has great potential in environmental water pollutants degradation.Dye-sensitized visible light catalysis can effectively utilize visible light to degrade organic matter,and thus has attracted widespread attention.During this process,organic dye adsorbed on the semiconductor surface absorbs visible light and injects the photoinduced electrons into the conduction band of the semiconductor.The electrons react with O2 at the interface between the semiconductor and the aqueous solution,and generate reactive oxygen species for degradation of organic molecules.Therefore,the accessibility of oxygen to the photocatalyst and the adsorption of organic compounds are two critical factors to the photocatalytic reaction kinetics.However,dye-sensitized visible light catalytic reactions usually occur at a semiconductor-aqueous solution diphase interface.Such a photocatalytic system is unfavorable for efficient contact between organic molecules and photocatalysts because they are generally surrounded by a hydration film that hampers organics adsorption.Furthermore,the low concentration and slow diffusion rate of reactant O2 in water restrict its accessibility to the photocatalyst and the subsequent generation of reactive oxygen species.In view of the above problems,this paper starts with the design and control of the interface microenvironment,and constructs a gas-liquid-solid thriphase interface photocatalytic reaction system(triphase system)based on the use of superhydrophobic semiconductor nanowire arrays.On one hand,the system uses hydrophobic force to increase the adsorption capacity of the organic dye on the semiconductor surface,and on the other hand,oxygen can directly transport to the reaction interface through gas phase,thereby enhancement the interface oxygen concentration and reactive oxygen species generation.The design and construction of the thriphase interface microenvironment makes the photocatalytic reaction kinetic constant more than 30 times higher than of normal solid-liquid diphase interface photocatalytic system.In addition,this photocatalytic system is stable via repeated cycling.The results of this paper show that in addition to the photocatalytic material itself,the microenvironment of the reaction interface also plays a crucial role in the performance of the photocatalytic reaction.The research content of this paper is divided into the following two parts:Part ?.Construction of a semiconductor nanowire arrays-based triphase interface photocatalytic reactions system.In this chapter,we prepared a series of superhydrophobic semiconductor nanowire arrays using different methods and contructed triphase interface photocatalytic reaction system.We studied the gas-liquid-solid triphase interface microenvironment by employing a laser scanning confocal microscope.Part ?.Study of dye-sensitization visible light catalytic kinetics using the triphase interface.In this chapter,on the basis of the reaction principle of dye-sensitized visible light catalysis,we studied the influence of hydrophobic force on the adsorption ability between organic dye compounds and superhydrophobic semiconductor nanowire arrays,and its impact on the photocatalytic reaction kinetics.We respectively studied the influence of oxygen concentration in gas phase and liquid phase of the triphase interface microenvironment on the photocatalytic reaction kinetics.We further studied the stability and university of the triphase photocatalytic system.