Solution-Phase Controlled Preparation,Growth Mechanism And Properties Investigation Of InSb Nanowires With Twinning Superlattices

Metal antimonide materials have been shown to exhibit properties that can be utilized in a wide range of applications,including high-speed optoelectronic devices,infrared detectors,thermoelectric materials,electrocatalysis and electrode materials for Li/Na ion batteries.As we known,the properties of materials are significantly influenced by their size,structure and shape.Low-dimensional materials are known to exhibit fascinating physical,optical and electrical properties that are fundamentally different from their bulk compounds,and several research groups have been focused on the controlled synthesis of metal antimonide nanomaterials with desired chemical and physical properties in recent years.Most of the metal antimonide nanomaterials have been grown by conventional synthesis techniques such as mechanical alloying,chemical alloying and catalyzed vapor-liquid-solid?VLS?growth,which may need high temperature and long reaction duration.Due to the Sb with low solubility and low surface energy,it can easily diffuse onto the surface of the material to reduce the surface energy,which makes the uniformity and morphology of the materials are difficult to control.As for producing metal antimonide nanomaterials with solvothermal/hydrothermal process,there is no effective surfactant to inhibit the agglomeration of the nanoparticles.To overcome the abovementioned obstacles,we have developed a mild solution-based route for controlled synthesis of straight indium antimonide nanowires with twinning superlattices and investigated their related properties.Meanwhile,our synthetic strategy can also be expanded to the controllable synthesis of transition metal antimonides.In this dissertation,we mainly studied the controlled synthesis of metal antimonide nanomaterials via a low-temperature solution-phase strategy and to investigate their growth mechanism and related properties.The main points were shown as follows:1.We demonstrate for the first time the preparation of high-quality InSb NWs with twinning superlattices from a cost-effective,mild solution-phase strategy from reaction of commercial triphenylantimony with tris?2,4-pentanedionato?-indium?III?at relative low temperatures,the reaction pathway can be described in two steps,melted indium nanoparticles were generated in situ by reduction of the indium precursor and subsequently catalyzed the NWs growth.Investigations reveal that the face-centered cubic?fee?zincblende phase InSb NWs are grown via a self-catalyzed solution-liquid-solid?SLS?mechanism due to the catalysis of the early formed indium droplets in the mild solution-phase reaction system.Structural characterizations reveal the InSb nanowires are high quality and have twinning structures with a common?111?plane along<111>growth direction.The influences of precursor mole ratio,reaction temperature,reaction time,and organic ligand have been explored systematically.In light of the abovemetioned growth mechanism of InSb NWs,we also present a solution synthesis of InSb twinning superlattice nanowires with same quality featuring faster nanowire yield time?60 s?.2.The growth mechanism 6f the InSb NWs with twinned superlattices is proposed.The self-catalytic growth of the InSb NWs with twinning superlattices results from an oscillating growth,triggered by the periodic fluctuation between reaction rates from the incongruous reductions of In and Sb sources as the reductant injected in the solution-based system.The pseudoperiodicity of twinned structures in segment lengths are approximately 36-42 monolayers for the as-prepared InSb NWs based on the direct observations from transmission electron microscope images,and the result is consistent with the pseudoperiodicity of 156.49 A??42 monolayers?detected by small-angle X-ray scattering?SAXS?detection.To further investigate the dynamics of photoinduced free carriers,we then performed optical-pump terahertz-probe experiments to measure the transient behavior of the as-synthesized InSb NWs,yielding a carrier lifetime of just 9.58 ps.Meanwhile,to reveal the superior transport properties of the as-obtained InSb NWs,field-effect transistors have been fabricated based on individual InSb NWs that exhibit p-type behaviors with the peak hole mobility as high as?50.71 cm2 V-1 s-1 compared to intrinsically n-type InSb crystal/nanowire,and the mechanism of n-to p-channel switching behaviors is proposed.Furthermore,the Raman spectrum confirms the anisotropic InSb NWs are in high quality,and the intensive TO scattering may also suggest that there is a high carrier concentration in the near surface region of the InSb NWs.3.Transition metal antimonide nanomaterials,such as NiSb,CoSb and Ag3Sb,were synthesized by solution-based route from the reaction of different transition metal precursors with triphenylantimony,with the injection of the strong reductant of BTB,in which oleylamine or 1-octadecene were used as the solvent.The characterizations of the X-ray diffraction confirmed that the formation of pure phase NiSb,CoSb and Ag3Sb.The electron microscopy analysis revealed the formation of transition metal antimonide nanomaterials with high crystallinity.As for NiSb,in order to improve the charge transport,a ligand-exchange strategy that long chain organic ligand was replaced by S2-to enhance interparticle coupling,the result of the ligand-exchange has been examined via ATR-FTIR.After ligand-removal,the performance of sodium ion storage and hydrogen evolution reaction?HER?catalytic of the NiSb nanocrystals have been measured,which suggested that the NiSb nanocrystals with stable cycling and good catalytic activity(Tafel slope of 115 mV dec-1 and an overpotential of 531 mV to obtain a current density of 50 mA cm^-2).