Semiconductor Nanocomposites:Preparation And Photocatalytic Properties

As the energy crisis and the increasing pollution of environment,it seriously restricts the sustainable development of human society.How to resolve these two difficult problems are the human challenges in recent years.So semiconductor photocatalytic nano-materials technology is a historical background to be caused human extensive attention.Due to traditional semiconductor nanomaterial,such as TiO2,ZnO with a wide band gap,which the visible light utilization is low,photo generated electron migration efficiency is low and light-generated electron-hole recombination rate is high.The above factors limit their practical application.In recent years,there have been lots of reports about the conventional semiconductor nanomaterial improvement of photocatalysis.However,there are still many composites with poor catalytic performance,repeated stable recycle low,morphology structure and catalytic properties were not further detail discussion.In this,the main tasks of this paper are as follows:1.A special Cu?NO₃?₂ thin solution layer was built on highly hydrophilic mica surfaces and subjected to rapid evaporation.Controlling the evaporation time can intentionally manipulate the supersaturation.Morphology-selective synthesis of nameplateor microsphere-like Cu?NO3?2·2.5H2O micro/nanostructures has been succeeded by alternatively boosting either the heterogeneous nucleation at the substrate–solution interface at a low supersaturation level or the homogeneous nucleation in the bulk solution phase at a high supersaturation level.As a demonstration,Cu?NO3?2·2.5H2O micro/nanostructures were converted into hierarchical porous CuO with well-preserved starting morphologies.2.On the basis of synthetic mica substrate supported CuO semiconductor nanomaterial.The Ag/CuO heterostructure semiconducting nanocomposites were prepared by photochemical method loading Ag nanoparticle onto CuO surfaces without any additive.Both CuO and Ag/CuO micro/nanostructures photocatalytic activity towards visible-light degradation of methylene blue?MB?was evaluated.The results show that the activity of the composite Ag/CuO photocatalyst is much higher than that of the single CuO.At the same time,the two different semiconductor catalysts mechanism of visible-light degradation of MB were also given explanation.3.The commercial zinc oxide?ZnO?was fixed on the clean silicon wafer by a simple hydrothermal method and finally obtains two different morphologies of ZnO substrate.On the two different substrates,we synthesized two different Ag2O/ZnO heterostructures semiconductor nanocomposites via photochemical method.After a series of characterizations,the sample composition and structure were verified and further studied the effect of substrate on synthesized Ag2O nanorods.Both ZnO and Ag2O/ZnO nanocomposites photocatalytic activity towards ultraviolet and visible light degradation of methylene blue?MB?was evaluated.The results show that the activity of the composite Ag2O/ZnO photocatalyst is much higher than that of the single ZnO.The stability of the semiconductor composite photocatalyst is far higher than single ZnO catalyst and it's also improved the response range of the photocatalyst.4.The selective synthesis of different silver-based semiconductor nanocomposites via different percentages of ethanol in AgNO₃ solution.We used the photochemical method selective synthesis Ag/ZnO,Ag2O/ZnO and Ag/Ag2O/ZnO silver-based semiconductor nanocomposites.The samples were characterized by SEM,TEM,XRD,DRS,BET and its also explored the different heterostructures formed process.The three different catalytic activities were further compared and the possible mechanisms degradation proposed under visible light irradiation.The experimental results show that selectively synthesized photocatalytic activity of different silver-based semiconductor composite catalysts under visible light irradiation is as follows: Ag/Ag2O/ZnO>Ag2O/ZnO>Ag/ZnO.