微波法制备金属钴纳米晶棒及其表征

微波法制备金属钴纳米晶棒及其表征;微波法;钴;纳米晶棒;表面活性剂;表面修饰     

金纳米棒的生长及与FeCl_3的作用

采用三氯化铁选择性刻蚀法获得了预定长径比的金纳米棒.相比于晶种生长法,三氯化铁选择性刻蚀法可以更加简便快捷地调控金纳米棒形貌.以三氯化铁为刻蚀剂的刻蚀反应优先发生在金纳米棒尖端,这是因为金纳米棒尖端反应活性更高且表面活性剂钝化作用更弱.通过控制刻蚀反应时间及刻蚀剂浓度,可以精确调控金纳米棒的长径比.实验结果表明,增加刻蚀剂浓度、卤素离子浓度以及升高反应温度可以加快刻蚀反应速率.进一步讨论了金属离子的刻蚀作用机理.     

Alloyed ZnS–CuInS2 Semiconductor Nanorods and Their Nanoscale Heterostructures for Visible‐Light‐Driven Photocatalytic Hydrogen Generation

A promising photocatalytic system in the form of heterostructured nanocrystals (HNCs) is presented wherein alloyed ZnS–CuInS₂ (ZCIS) semiconductor nanorods are decorated with Pt and Pd₄S nanoparticles. This is apparently the first report on the colloidal preparation and photocatalytic behavior of ZCIS–Pt and ZCIS–Pd₄S nanoscale heterostructures. Incorporation of Pt and Pd₄S cocatalysts leads to considerable enhancement of the photocatalytic activity of ZCIS for visible‐light‐driven hydrogen production.     

End‐to‐End Self‐Assembly of Semiconductor Nanorods in Water by Using an Amphiphilic Surface Design

One‐dimensional (1D) self‐assemblies of nanocrystals are of interest because of their vectorial and polymer‐like dynamic properties. Herein, we report a simple method to prepare elongated assemblies of semiconductor nanorods (NRs) through end‐to‐end self‐assembly. Short‐chained water‐soluble thiols were employed as surface ligands for CdSe NRs having a wurtzite crystal structure. The site‐specific capping of NRs with these ligands rendered the surface of the NRs amphiphilic. The amphiphilic CdSe NRs self‐assembled to form elongated wires by end‐to‐end attachment driven by the hydrophobic effect operating between uncapped NR ends. The end‐to‐end assembly technique was further applied to CdS NRs and CdSe tetrapods (TPs) with a wurtzite structure.     

Magnetic Nanohybrids Loaded with Bimetal Core–Shell–Shell Nanorods for Bacteria Capture,Separation, and Near‐Infrared Photothermal Treatment

A novel antimicrobial nanohybrid based on near‐infrared (NIR) photothermal conversion is designed for bacteria capture, separation, and sterilization (killing). Positively charged magnetic reduced graphene oxide with modification by polyethylenimine (rGO–Fe₃O₄–PEI) is prepared and then loaded with core–shell–shell Au–Ag–Au nanorods to construct the nanohybrid rGO–Fe₃O₄–Au–Ag–Au. NIR laser irradiation melts the outer Au shell and exposes the inner Ag shell, which facilitates controlled release of the silver shell. The nanohybrids combine physical photothermal sterilization as a result of the outer Au shell with the antibacterial effect of the inner Ag shell. In addition, the nanohybrid exhibits high heat conductivity because of the rGO and rapid magnetic‐separation capability that is attributable to Fe₃O₄. The nanohybrid provides a significant improvement of bactericidal efficiency with respect to bare Au–Ag–Au nanorods and facilitates the isolation of bacteria from sample matrixes. A concentration of 25 μg mL^?1 of nanohybrid causes 100 % capture and separation of Escherichia coli O157:H7 (1×10⁸ cfu mL^?1) from an aqueous medium in 10 min. In addition, it causes a 22 °C temperature rise for the surrounding solution under NIR irradiation (785 nm, 50 mW cm^?2) for 10 min. With magnetic separation, 30 μg mL^?1 of nanohybrid results in a 100 % killing rate for E. coli O157:H7 cells. The facile bacteria separation and photothermal sterilization is potentially feasible for environmental and/or clinical treatment.     

金纳米棒的制备、生长机理及纯化

金纳米棒由于其独特物理性质而在众多的各向异性金纳米颗粒中赢得了关注。目前,金纳米棒在纳米电子学、光学、生物医药等研究领域均具有良好的应用前景。对金纳米棒合成的有效调控直接决定着其形状、尺寸和长径比,而这些又进一步影响着金纳米棒的物理性质。本文梳理了金纳米棒制备方法的发展脉络,以模板法、电化学方法、种子生长法以及近年来出现的无种子生长法为主线,系统综述了金纳米棒制备过程实验参数调控对产物结构、物理性质的影响,详细阐述了关于单晶以及孪晶金纳米棒的生长机理,并介绍了提高产物纯度的分离纯化手段。     

Alloyed (ZnS)x(CuInS2)1−x Semiconductor Nanorods: Synthesis,Bandgap Tuning and Photocatalytic Properties

Rod-like nanocrystals of the semiconductor alloy (ZnS)_x(CuInS₂)_1−x (ZCIS) have been colloidally prepared by using a one-pot non-injection-based synthetic strategy. The ZCIS nanorods crystallize in the hexagonal wurtzite structure and display preferential growth in the direction of the c axis. The bandgap of these quarternary alloyed nanorods can be conveniently tuned by varying the ratio of ZnS to CuInS₂. A non-linear relationship between the bandgap and the alloy composition is observed. The ZCIS nanorods are found to exhibit promising photocatalytic behaviour in visible-light-driven degradation of Rhodamine B.     

金纳米球和金纳米棒的制备及其光热催化性能

以氯金酸(HAuCl_4)为原料,硼氢化钠(NaBH_4)为还原剂,聚乙烯吡咯烷酮K30(PVP)为稳定剂制备了尺寸5 nm的金纳米球;以阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)为模板剂和油酸钠(NaOL)稳定剂,用种子生长法制备了不同长径比(R=2.5~4)的金纳米棒。在2 W·cm~(-2)的808 nm激光照射10 min条件下,C(0.4 mg·mL~(-1))浓度金纳米球溶液升温10.2℃,该溶液可催化血液中亚硝基硫醇释放NO,最大释放量可达1.42 nmol·L~(-1);相同光热及催化条件下,C(0.4 mg·mL~(-1))浓度金纳米棒(R=3.01)溶液升温41.3℃,该溶液催化血液中亚硝基硫醇释放NO最大释放量可达1.89 nmol·L~(-1)。金纳米球和金纳米棒的光热及催化性能随着浓度增加而增强,金纳米棒的光热及催化性能要优于金纳米球。