Two‐Step Synthesis of Large‐Area 2D Bi2S3 Nanosheets Featuring High In‐Plane Anisotropy (original) (raw)

Synthesis of Bi 2S3 Nanostructures : Solvothermal Approach

2014

Recently young researchers are concentrating on the morphology controlled synthesis of Bi 2S3 for their widespread application in the fields of semic onductors, photo diode, thermoelectric devices, sup er capacitors, etc. In this work nanostructured Bi 2S3 has been synthesized by solvothermal method using bismuth nitrate, formaldehyde and sodium thiosulfate as sta rting materials. The effect of calcinations and pre cursor concentration on the properties of Bi 2S3nanoparticles have been explored and reported. The phase and structure of the bismuth sulphide has been identified using X -ray powder diffraction. The crystallites were foun d to have orthorhombic structure. The surface properties and morphology has been investigated using a scanning electron microscopy (SEM) technique. The properties of the synthesized nanostructures have been investigated an d reported.

Surface Morphology and Optical Studies of Non-aqueous Bi2S3 Thin Films

A high purity, amorphous Bi2S3 thin film composed of loosely packed nanometer-sized spherical grains has been successfully deposited onto ITO substrate at room temperature from non-aqueous bismuth nitrate and sodium thiosulphate solution using a simple, inexpensive, reproducible, and environmentally friendly chemical route method. Film was characterized for structural, surface morphological, optical properties by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis spectrometer, respectively. In last section, Bi2S3 film on ITO substrate was utilized in photo- electrochemical (PEC) solar cell as a working and platinum as a reference electrode in presence of 80 mW/cm2 light intensity in lithium iodide as an electrolyte. Film of non-aqueous Bi2S3 exhibits two separate direct band transitions. Existence of two separate direct transitions was firstly noted in Bi2S3 thin films and explained its possible causes. PEC analysis confirms n-type conductivity.

Substrate-independent catalyst-free synthesis of high-purity Bi2Se3 nanostructures

Applied Physics Letters, 2013

We describe a catalyst-free vapor-solid synthesis of bismuth selenide (Bi 2 Se 3) nanostructures at ambient pressure with H 2 as carrier gas. The nanostructures were synthesized on glass, silicon and mica substrates and the method yields a variety of nanostructures: nanowires, nanoribbons, nanoplatelets and nanoflakes. The materials analysis shows high chemical purity in all cases, without sacrificing the crystalline structure of Bi 2 Se 3. Lowtemperature measurements of the nanostructures indicate contributions from the surface states with a tunable carrier density. Samples synthesized on flexible mica substrates show no significant change in resistance upon bending, indicating robustness of as-grown Bi 2 Se 3 nanostructures and their suitability for device applications.

Oriented Attachment of 2D Nanosheets: The Case of Few-Layer Bi2Se3

Chemistry of Materials

Developing growth schemes for functional two-dimensional (2D) nanomaterials is of much interest, especially because synthetic conditions are often correlated with physical properties such as optical absorbance. Bi 2 Se 3 is an interesting material because of its transition from a narrow gap semiconductor, for the thinnest structures, to a topological insulator, when the structures are at least six quintuple molecular layers (QLs), and its appealing photothermal, thermoelectric, and optical properties. Here, we developed a controlled colloidal synthesis based on oriented attachment to produce Bi 2 Se 3 nanoplatelets with varying thicknesses. The synthesis scheme also enables the facile doping of the structures without noticeable intercalation. The variation in optical properties confirmed the higher concentration of charge carriers at the edge of the structures, which is due in this system to Se deficiency and low crystallinity. This research opens a way to tune the composition and thickness of nanostructured 2D Bi 2 Se 3 , an important functional material.

Preparation of uniform Bi2S3 nanoribbons at a low temperature

Materials Letters, 2008

Bismuth sulfide (Bi 2 S 3 ) nanoribbons with uniform size have been prepared by the reaction of bismuth nitrate (Bi (NO 3 ) 3 ) and sodium O-isopropyldithiocarbonate (xanthate, C 3 H 7 OCSSNa in N,N-dimethylformamide (DMF) at 80°C for 24 h. The powder X-ray diffraction (XRD) pattern shows the Bi 2 S 3 crystals belong to the orthorhombic phase with calculated lattice constants a = 1.1244, b = 1.0520 and c = 0.3372 nm. The energy dispersive spectroscopy (EDS) analysis gives an atomic ratio of 2.1: 3.0 for Bi: S. The scanning electron microscopy (SEM) and transmission electron microscopic (TEM) studies reveal the appearance of as-prepared Bi 2 S 3 crystals is ribbon-like with the typical lengths in the range of 2-5 μm and the average diameter of ca. 40 nm. Finally the influences of the reaction conditions are discussed and a possible mechanism for the formation of Bi 2 S 3 nanoribbons is proposed.

Morphology Manipulation and Related Properties of High Crystalline Bi2S3 Nanorods by Reflux Approach

Volume 4,Issue 5,2018, 2018

One dimensional Bi2S3 nanorods have been successfully synthesized by a very simple reflux method with different precursor concentration for 2 hours at 180 �C. The as-synthesized Bi2S3 powders were characterized by X-ray diffraction (XRD), high resolution scanning electron microscope (HRSEM), high resolution transmission microscope (HRTEM), UV-Vis spectrometer, Fourier transform infrared (FTIR) spectrometer. X-ray diffraction (XRD) results show that the resulting nanocrystals have an orthorhombic structure. X-ray diffraction patterns indicate a polycrystalline nature and the crystallite sizes seem increase with increase in the concentration. The HRSEM and HRTEM images reveal that the diameter of the nanorods increase with increasing concentration of the precursor. Morphological analysis reveals that the as-prepared Bi2S3 nanorods can be tuned to morphology by varying precursor concentration from 0.01 M to 0.001 M. The bismuth nitrate, which is known to be a linear polymer, plays a cr...

Studies on chemically deposited nanocrystalline Bi2S3 thin films

Materials Research Bulletin, 2000

Nanocrystalline thin films of Bi 2 S 3 of different thicknesses were deposited from solutions containing bismuth nitrate, ethylenediamine tetraacetic acid (EDTA), and thioacetamide maintained at a bath temperature of 6°C. These films were prepared for different deposition time periods. Uniform thin films having thicknesses up to 437 nm were obtained on the glass substrates. Characterization of the films was carried out using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), optical absorption, electrical resistivity, and thermoemf techniques. These studies reveal that Bi 2 S 3 films consist of nanocrystalline grains. Average grain size was calculated using Scherrer's formula. With an increase in grain size of Bi 2 S 3 crystallites from 6.85 to 33.86 nm, a shift of 0.46 eV in the optical bandgap energy E g , and a decrease in electrical resistivity from 2.4043 ϫ 10 6 to 0.7250 ϫ 10 6 ohm-cm were observed. The n-type electrical conductivity of the Bi 2 S 3 films was observed from thermoemf studies.

Synthesis and characterization of high-purity, single phase hexagonal Bi2Te3 nanostructures

RSC Advances, 2015

In order to synthesize defect free, highly crystalline single phase nanostructured bismuth chalcogenide, we have performed and analyzed the effects of several reaction conditions including, solvents, temperatures, reaction time, and reducing agents. A small variation in the reaction method resulted in Bi 2 Te 3 with different morphologies, ranging from nanosize particles, rods, platelets, and tubes to nanosheets. The materials were characterized by powder X-ray crystallography, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray analysis, Raman spectroscopy, and four-probe current (I)-Voltage (V) analysis. An optimized reaction condition allowed the synthesis of single-phase, impurity-free hexagonal nanoplates with size varying between 50 nm and 500 nm and thickness varying between 45 nm and 55 nm in a reproducible manner. The Raman spectra of the optimized hexagonal plates and sheets showed infra red (IR)-active modes around 116 cm-1 resulting from symmetry breaking, a characteristic feature of nanostructured Bi 2 Te 3. Additional peaks at 94 cm-1 in the nanosheets, resulting from the surface phonon mode further confirmed the ultrathin Bi 2 Te 3 structures. The I-V measurements on the optimized surface showed an n-type semiconducting behavior. The surface current measured as a function of applied voltage is two orders of magnitude higher than that across the stacked pellet in ambient conditions and much higher compared to previously published data on few quintuplet-thick Bi 2 Te 3 nanofilms. The highlights of this study are the optimal solvothermic reaction conditions and their impact on obtaining defect free, highly crystalline single phase bismuth chalcogenides.