Controlled Synthesis And Properties Of Copper Chalcogenide Nanomaterials

Copper chalcogenide nanomaterials are an important class of semiconductor materials with a variety of stoichiometric ratios and crystal phases.They possess excellent optoelectronic properties,good biocompatibility,and low cost that make them attractive for potential applications in the fields of catalysis,solar cells,biological therapy and so on.Moreover,they can also be used as templates for cation exchange reaction to synthesize other metal chalcogenide nanomaterials with various crystal structures and morphologies.Till now,there are lots of methods have been applied to synthesize copper chalcogenide nanomaterials.However,it is still a hot issue and a difficult point to develop a facile and effective approach to synthesize copper chalcogenide nanomaterials with defined crystal structures and morphologies and investigate the dependence of these factors on their properties.In this thesis,hot-injection method was used to controllably synthesize copper chalcogenide nanomaterials by using Cu SCN and CuSeCN as precusors.The influence of reaction conditions on the final morphology and crystal structure of the products was studied.Furthermore,their properties and potential applications were explored.The main contents are listed as follows:1.Monodispersed Cu₇S₄nanoplates with different lateral dimensions and thicknesses were synthesized by hot-injection method through two manners.The fist one is injecting a single precursor Cu SCN,and the other one is injecting NH₄SCN into the solution with Cu Cl₂·2H₂O as the copper source.The produced Cu₇S₄nanoplates by first approach have a thickness of about 10 nm and lateral dimension of60-83 nm,which is tuned by the reaction temperature.The thickness of Cu₇S₄nanoplates by second method was decreased to about 5 nm and the lateral dimension can be adjusted from 28 to 44 nm.Moreover,Cd S nanoplates were fabricated via cation exchange by using the first type Cu₇S₄nanoplates as templates.Furthermore,three kinds of semiconductor/metal heterostructures including Cd S/Ag,Cd S/Pt and Cd S/Au were constructed by growth of metal nanoparticles on the Cd S nanoplates.2.Monodispersed copper selenide nanocubes with size ranging from 24 to 42nm were synthesized via hot-injection method by using CuSeCN as the single precursor.The influence of reaction temperature,solvent,the amount of precursor and ligand on the morphology and crystal structure of the final products was explored.The optical and electrical properties of the synthesized copper selenide nanocubes were studied,and it is found that they have obvious LSPR absorption property and exhibit good electrical conductivity.Moreover,the copper selenide nanocubes show electrocatalytic activity for CO₂reduction,and it is found that the Faraday efficiency of formic acid formation could reach 64.6%when the applied voltage reached at-0.5V vs.RHE.Copper selenide nanocubes can transform into Cu Se nanoplates by the treatment of dibenzyl diselenide based on their intrinsic metastable feature.Furthermore,the Au-Cu-Se ternary hollow nanocubes with amorphous structure could be fabricated by the reduction reaction of copper selenide nanocubes with gold precursors.It is found that the final morphology and crystal structure of the ternary nanomaterials are highly dependent on the amount of the gold precursor.Finally,the rhombic CdSe and Cd-Au-Cu-Se quaternary hollow nanocubes were synthesized by the exchange reaction of Cd²⁺with copper selenide nanocubes and Au-Cu-Se ternary hollow nanocubes as templates,respectively.