Template-Directed Synthesis Of Selenium/Tellurium Based One Dimensional Nanomaterials And Their Applications

One diemensional Se/Te based nanomaterials can find applications in various fields(including optoelectronic devices,thermoelectric devices,photocatalysts and electronic devices)owing to their intriguing electrical,optical,thermal and catalytic properties.It has important practical significance and scientific value to explore general and convenient synthetic approaches for synthesis of one dimensional Se/Te based nanomaterials.Template directed method has been widely used in the synthesis of various kinds of one dimensional Se/Te based nanomaterials due to its allowance for easily proceeding,large-scale synthesis and easily controlling the structure and chemical composition.As a member of the family of template directed method,chemical transformation process represents a straightforward,versatile,and effective approach to nanomaterial synthesis.To date,chemical transformation process has been widely used for the preparation of metal selenide and telluride nanowires.However,there are few success on synthesis of alloyed/multimetal chalcogenide nanowires through the process of chemical transformation because of the lack of appropriate template.Therefore,several kinds of Se-Te alloy or hybrid nanowires with high chemical activity were prepared from Te nanowires to serve as templates for synthesis of Se/Te based one dimensional nanomaterials.The detail can be summarized as follows:1.We developed a general chemical transformation process for the synthesis of more than 45 kinds of one-dimensional alloyed/hybrid metal chalcogenide nanostructures inherited from mother template TexSey@Se core-shell nanowires with tunable compositions.Firstly,highly reactive TexSey@Se nanowires with controlled size and composition were perpared to serve as templates.Nine kinds of MSeTe alloy nanowires[that is,MSeTe(M=Ag,Hg,Cu,Bi,Pb,Cd,Sb,Ni,Co)]could be prepared through a simple chemical transformation process.Furthermore,Alloyed and hybrid nanowires integrated with any pair of the above nine kinds of MSeTe phases could also be prepared.Thus,as many as 36 kinds of bimetal chalcogenide alloy and hybrid nanowires were obtained.The compositions of MSeTe and bimetal chalcogenide nanowires were tunable within a wide range.2.We report a selective oxidation route for synthesis of SexTey nanotubes with controlled inner and outer diameters using TexSey@Se core-shell nanowires as templates.As the redox potential of TeO2/Te is lower than that of H2SeO3/Se,the elemental Te is more easily to be oxidized compared with elemental Se.Thus,the Te element in TexSey@Se nanowires can be selectively etched by an appropriate oxidant of HNO2 to form nanotubes.As the Te element in the TexSey@Se nanowire could not be completely etched,the product was SexTey nanotubes rather than Se nanotubes.The inner and outer diameters of SexTey nanotubes could be tuned by modulating the core diameters and shell thicknesses of TexSey@Se nanowires.The SexTey nanotubes could be assembled into monolayer composed of well-arranged nanotubes through the Langmuir-Blodgett technique,which could be stacked layer by layer to form films with controllable thicknesses.Based on these films,device was fabricated to study the photoconductivity of the SexTey nanotubes.The SexTey nanotubes showed good photoresponse to the whole UV-visible spectrum,revealing their potential application prospects for optoelectronic devices.3.We report a solution phase epitaxial growth of Te/Se/Te core-multishell nanowires using Te nanowires as the primary templates.It is known that the crystals of trigonal Se and trigonal Te own the same crystal symmetry.And the lattice mismatch between the(100)plane of Te and that of Se is as small as 2.1%.Obviously,the pair of Se and Te meets the requirement for epitaxial growth.Therefore,it is possible for epitaxial growth Se shells on Te nanowires or Te shells on Se nanowires.By using Te nanowires as the primary templates,we successfully obtianed a series of core-multishell nanowires,like Te/Se core-shell nanowires,Te/Se/Te core-bishell nanowires,Te/Se/Te/Se core-trishell nanowires,Te/Se/Te/Se/Te core-quadrashell nanowires and Te/Se/Te/Se/Te/Se core-pentashell nanowires.The thicknesses of the Se shells or Te shells in the core-multishell nanowires could be tuned simply by modulating the added Se or Te precursors.In addition,a series of Te nanowires with larger diameters could be prepared by directly epitaxial growth Te shells on the primary Te templates.