Ultra‐Thin Trigonal Selenium Nanoribbons Developed from Series‐Wound Beads

Abstract

[15] provides encouragement that the solution-phase methods of SLS and SFLS will eventually reach their potential as a general strategy for nanowire synthesis of any desired material. Experimental SectionPrecursor Preparation: The precursors (tBu) 3 Ga and As(SiMe 3 ) 3 were prepared by literature methods [16,17]. GaCl 3 was purchased and used as received from STREM. A stock solution of 50 mM (tBu) 3 Ga and As(SiMe 3 ) 3 was prepared in hexane under a nitrogen atmosphere. Dodecanethiol-coated gold nanocrystals 7 nm in diameter were prepared by arrested precipitation as described in the literature [18]. The gold nanocrystals were weighed and dispersed in hexane such that the molar concentration of gold was in a 100:1 precursor/gold ratio in the precursor solution.Nanowire Synthesis: A 1 mL reaction cell was loaded with a Si/SiO 2 deposition substrate then heated to 500 C and pressurized to 7 MPa. The experimental apparatus was similar to that in Hanrath and Korgel modified to include two 200 lL 6-way high-performance liquid chromatography (HPLC) injection loops in series [9]. The loop nearest the reactor was loaded with the gold nanocrystal solution, and the other with the precursor solution. Both solutions were sequentially injected into the reactor at 4.00 mL min ±1 as the pressure was ramped to 37 MPa. The reaction proceeded for 8 min before cooling under air flow and depressurizing back to room temperature and ambient pressure. The nanowire product on the substrate forms a yellow film up to several micrometers thick consisting of a mat of tangled GaAs nanowires.Characterization: The GaAs nanowire product was collected on the Si/SiO 2 substrate and characterized by a field-emission scanning electron microscope (SEM) (LEO 1530) operating between 3 and 8 kV using an in-lens detector. HRTEM and EDS analysis (JEOL 2010F, operating voltage 200 kV, with attached Oxford INCA EDS) were performed on nanowires re-dispersed in hexane and drop cast onto lacey carbon-coated copper grids. XRD of nanowires deposited on quartz slides was obtained using a Phillips vertical scanning diffractometer. XPS (Phi ESCA 5700, with monochromatic Al anode operating at 11.75 eV pass energy) data was obtained from wires drop cast on a gold substrate.Device Fabrication: GaAs nanowire devices were fabricated by orienting the nanowires onto a substrate patterned with gold leads and subsequently making electrical contact with Pt electrodes deposited using a focused ion beam technique. A Raith 50 Electron Beam Lithography Tool in combination with a Standard XL Scanning Microscope was used to pattern a PMMA resist layer on a silicon oxide chip. This pattern was metallized by evaporating 3 nm Cr and 30 nm Au in a Denton DV502 Vacuum Chamber. After the chip was cleaned, the wires were deposited using a method similar to literature but without an applied electric field [19]. Nanowires were suspended in a toluene solution by sonication. A drop of the solution was placed onto a chip that had two leads grounded. The drop was removed by blowing over th...

Polychloro‐alkanes used as templates in solvothermal synthesis of selenium microrods

“…Element selenium, especially for the trigonal structure, has an anisotropic special crystal structure. Selenium atoms in infinite spiral chains parallel to the c-axis in the trigonal phase are bound with covalent bonds, whereas the chains are packed into a hexagonal lattice through van der Waals' interactions [3]. Owing to the stronger interaction between selenium atoms in a chain than that between the two neighboring chains, one-dimensional (1 D) selenium (Se) readily forms from the view of dynamics and crystal structure [4].…”

Inorganic and organic templates‐assisted solvothermal synthesis of trigonal selenium microrods

“…Thus, the synthesis of 1D Se nanostructures has aroused considerable interest. Recently, many methods reported in literature were used to obtain diverse nano-or microstructures of Se, such as laser ablation using selenium powders [4], sonochemical assistance approach [5], solution-mediated transformation [6][7][8][9], hydrothermal method [10], chemical vapor deposit (CVD) [11][12][13], and photoinduced method [11,15]. Especially, some chemical methods, because of their low cost and low toxicity, are desirable to be explored to synthesize 1D Se nano-and microstructures.…”

Controlled synthesis of selenium of different morphologies at room temperature

“…In addition, selenium also holds a high reactivity toward large quantities exploited to convert selenium into other functional materials, such as CdSe, ZnSe, Ag 2 Se, RuSe 2 , Pd17Se15, Pt etc [5][6][7][8][9][10][11]. Recently, many methods reported in literature were used to obtain diverse nano-or microstructures of Se, such as laser ablation using selenium powders [12], sonochemical assistance approach [13], solution-mediated transformation [14][15][16][17], hydrothermal method [18], chemical vapor deposit (CVD) [19][20][21], and photoinduced method [22,23]. However, in order to obtain polydispersed nano-or microstructures, these reactions have to be assisted by special conditions such as high temperature and/or pressures, sonochemical process or invert gas surrounding.…”