Method using laser interference to induce electrochemical deposition so as to prepare periodic and patterned Fe3O4 nano particles

[0033] The present invention will be described in detail below with reference to specific embodiments.

[0034] like figure 1 As shown, the present invention adopts a simple laser interference-induced electrochemical deposition to prepare patterned Fe 3 O 4 The nanoparticle approach is as follows:

[0035] (1) Preparation of electrodes: the ITO conductive substrate coated with hydrogenated amorphous silicon (a-Si:H) thin film was used as the working electrode; the high-purity iron sheet was used as the counter electrode; and the calomel electrode was used as the reference electrode. The surface area of ​​the ITO conductive substrate is 1 cm 2 , the square resistance is 4Ω, the thickness of the ITO film is 500nm, and the transmittance is 84%; the hydrogenated amorphous silicon (a-Si:H) film is deposited on the surface of ITO by PECVD method, the thickness is 500nm, and the dark state conductivity is 5E- 10S/cm, the photoconductivity under AM1.5G illumination is about 7E-5S/cm. Among them, the ITO with a width of 2 mm left on the edge of the ITO does not deposit a hydrogenated amorphous silicon (a-Si:H) film, which is used as a lower conductive electrode.

[0036] (2) Preparation of electrolyte: use ferric chloride hexahydrate as the ferric iron source, prepare 12mM FeCl 3 50ml of deionized water solution, using ferric chloride tetrahydrate as the divalent iron source to prepare 8mM FeCl 2 50ml of deionized aqueous solution; ultrasonically dissolve the two solutions respectively, and ultrasonically dissolve again after mixing to obtain an electrolyte solution, FeCl 3 with FeCl 2 The molar ratio is 3:2.

[0037] (3) Set up an electrochemical deposition system: place 100 ml of the electrolyte prepared in (2) in a square quartz beaker with a capacity of 150 ml, soak the three-phase electrode prepared in step (1) in the electrolyte, and place the ITO electrode in the electrolyte. On the outermost side, the uncoated side faces the beaker wall, and the hydrogenated amorphous silicon (a-Si:H) thin film is plated towards the inside of the beaker. like figure 2 As shown, the system of the present invention includes an electrochemical workstation 1, a computer 2, a laser light source 3, an interference system 4, an ITO electrode 5 coated with a hydrogenated amorphous silicon (a-Si:H) thin film, a calomel electrode 6, a high-purity iron Sheet 7, FeCl 3 and FeCl 2 Solution 8. The electrochemical workstation 1 is connected with the computer 2, the laser light source 3 is incident on the interference system 4, and the ITO electrode 5, the calomel electrode 6, and the high-purity iron sheet 7 coated with the hydrogenated amorphous silicon (a-Si:H) film are placed. In FeCl3 and FeCl2 solution 8, the negative electrode of electrochemical workstation 1 is connected with ITO electrode 5 coated with hydrogenated amorphous silicon (a-Si:H) film, the reference electrode is connected with calomel electrode 6, and the positive electrode is connected with high-purity iron Slice 7 is connected.

[0038] (4) Build a laser interference system and introduce an induced light source: Select a 457nm wavelength laser as the interference light source, build a 5μm periodic wire grid laser interference system, obtain a 5μm periodic wire grid induced light source, and introduce the light source to the ITO working electrode to adjust the optical path The interference light source was projected onto the hydrogenated amorphous silicon (a-Si:H) thin film through the beaker, the solution and the ITO substrate. The photoelectric effect generated when the induced light source is projected on the backside of the hydrogenated amorphous silicon (a-Si:H) thin film makes the exposed part of the hydrogenated amorphous silicon (a-Si:H) thin film generate a large number of photogenerated carriers and reduces the impedance, thereby reducing the impedance. A wire grid dummy electrode with a period of 5 μm was generated.

[0039] like image 3 As shown in the left figure of the present invention, the interference of two beams realizes Fe 3 O 4 Schematic diagram of the laser interferometry system fabricated by the nanoparticle array. The laser interference system used is composed of a high-reflection mirror and a beam splitter. A laser beam emitted by the laser is divided into two beams of coherent beams by a beam splitter, and the two beams of coherent beams are made spatially symmetrical by the reflection system, and they are simultaneously irradiated to the hydrogenated amorphous silicon (a-Si:H) film at a certain incident angle , forming a 5μm wire grid induced light source, such as image 3 Shown on the right.

[0040] (5) Set the electrochemical workstation parameters for electrochemical deposition: at room temperature, use CHI660D electrochemical workstation to control the cathode current density of 2 mA/cm 2 In condition 1) deposition time 50s and laser power density 2mW/cm 2;2) Deposition time 100s and laser power density 5mW/cm 2;3) Deposition time 200s and laser power density 10mW/cm 2; Electrochemical deposition was performed. After the operation, the power was turned off to take out the working electrode, rinsed with deionized water three times, and air-dried at room temperature to obtain samples 1, 2 and 3.

[0041] (6) Test the sample piece 1 with a scanning electron microscope SEM, that is, to obtain a nanoparticle wire grid with a period of 5 μm attached to the hydrogenated amorphous silicon thin film. like Figure 4 shown, the wire grid pattern Fe prepared for the two-beam interference 3 O 4 The SEM image of the nanoparticle array, the left image is the distribution map of the large-area periodic wire grid, and the right image is the enlarged image of the multi-periodic wire grid. The deposited periodic wire grid pattern Fe can be seen 3 O 4 The nanoparticle array period is 5 μm with image 3 The 5μm wire grid fringes formed by the double-beam laser interference system induce the same light source.

[0042] (7) The nanoparticles in the samples 1, 2 and 3 were tested with a scanning electron microscope SEM, and the results were as follows: Figure 5 shown, Fe with different particle size and morphology 3 O 4 SEM image of nanoparticles, in which the left pattern sheet 1 is hexahedral and triangular pyramid; the middle pattern sheet 2 is snowflake shape; the right pattern sheet 3 is scaly layered, with the deposition time from 50s-200s, laser power density from 2mW/cm 2 -10mW/cm 2 Variation, Fe as prepared 3 O 4 The particle size becomes larger and the shape changes.

[0043] (8) Test sample 1 with an X-ray diffractometer, such as Image 6 Shown is the X-ray diffraction pattern of the deposited sample, the abscissa 9 is the 2θ angle (degrees), and the ordinate 10 is the intensity. Among them, the four main peaks and Fe 3 O 4 The standard spectrum is consistent, and the main component of the nanoparticles is determined to be Fe 3 O 4.