During the past decade, one-dimensional (1D) nanostructures such as wires, rods, belts, and tubes have been explored extensively in nanotechnology due to their excellent properties, which may lead to unique applications in various nanoscale device. It is known that nanowires with high aspect ratios can provide a low-scattering transport path of the carriers and the electron and hole energy states become discrete due to the spatial confinement, which are highly beneficial for achieving high-performance electrical or optical properties.

Antimony tri-sulfide (Sb₂S₃) is a low-toxic and earth-abundant semiconductor and important binary chalcogenide, that with an energy band gap varying between 1.78 and 2.2 eV has attracted particular attention and . Owing to its good photovoltaic properties, high thermoelectric power, suitable valence band position, and broad spectrum the response. Sb₂S₃ used in technological applications such as photo-catalysis, photovoltaics, and thermoelectric devices^[1-2] . It has a direct band gap with large absorption coefficient (>10⁴ cm⁻¹) in the visible region. Especially, it has wide application in optical property because of wide band gap and the other point is the thermoelectric property of Sb₂S₃. The Sb₂S₃ of NWs show excellent light-to-heat performance. In this work, Sb₂S₃ nanowires (NWs) were fabricated by a vacuum hydraulic pressure injection process using anodic aluminum oxide (AAO) as templates. The AAO quality depends on the purity of Al substrate. The higher Al purity, such as 99.999% (5N), the better quality of AAO with uniform pore diameter can be obtained. The AAO templates with, 70 nm, and 100 nm diameters are manufactured by anodizing a pure aluminum (Al) substrate (99.999%) in acid solutions of oxalic acid (COOH)₂. It will help us to easily get a large quantity and uniform Sb₂S₃ NWs. The nanomaterials arrayed photoelectric devices have great potential to obtain high sensitivity, fast response, and low energy consumption. The highly ordered array nanostructure can be achieved with high-aspect-ratio template. Porous anodic aluminium oxide played a significant role for the fabrication of Sb₂S₃, which controlled the diameter of NWs. Compare to the other synthesis, vacuum hydraulic pressure injection process is easy way to fabricate heterogeneous structure. First, antimony tri-sulfide powder was prepared by Sb/S=2/3 in a vacuum quartz tube and make the powder homogeneous mixing. Then, it was melted at 650 ^oC for 20 min and homogenized at 520 ^oC for 1 day. Then, the Sb₂S₃ of ingot was slowly cooling to room temperature. After Sb₂S₃ ingot was obtained, mechanical polishing was conducted to remove surface oxide. Second, the ingot of Sb₂S₃ was placed between the two plates of AAO template. Next, the entire chamber was vacuumed and heated to 600 ^oC again, holding the temperature for 5 min, load 50 kgf / cm² for 1 min to press. Then, the melting Sb₂S₃ is pressed into the AAO template to form Sb₂S₃ nanowire array. Finally, the entire chamber was cooled down under air atmosphere and etch the AAO of Sb₂S₃. It will obtain the nanowires. Moreover, we will observe the different condition of NWs by controlling the time of etching. The time of etching decides the cleanness of NWs. As the time is longer the mass of bundles will decrease. Also, the difference of acid solutions is one of the important condition of etching the NWs, such as phosphoric acid (H₃PO₄), chromic acid (H₂CrO₄). In this work, we use chromic acid to etching the AAO to obtain the NWs. The temperature of the acid solution also affect the rate of etching speed. The temperature of etching is kept at around 60 ^oC. Combination of above conditions, the diameter of NWs is around 70 nm, the length of NWs is about 6 µm. Furthermore, The morphologies and crystal structures of Sb₂S₃ NWs were characterized by using optical microscopy (OM), field-emission scanning electron microscope (FE-SEM), X-Ray diffraction (XRD), UV-Vis spectrophotometry, Raman spectroscopy and transmission electron microscopy (TEM). The composition was analyzed with energy dispersive x-ray spectroscopy (EDS) attached the SEM. In the future, we can fabricate the heterogeneous structure of Sb system and Sb₂S₃ NWs to increase the diversity of the research on electrical and optical applications.

Ref.

[1] Kai Zhang, Tao Luo, Haoran Chen, Zheng Lou and Guozhen Shen, Au-nanoparticles-decorated Sb₂S₃ nanowirebased flexible ultraviolet/visible photodetectors.. J. Mater. Chem. C, 2017, 5, 3330-3335.

[2] Godël, K. C.; Choi, Y. C.; Roose, B.; Sadhanala, A.; Snaith, H. J.; Seok, S. I.; Steiner, U.; Pathak, S , K.Efficient Room Temperature Aqueous Sb₂S₃ Synthesis for Inorganic-Organic Sensitized Solar Cells with 5.1% Efficiencies. Chem. Commun, 2015, 51, 8640– 8643.