KR20210053607A - Photochemical Electrode Based on 3D Printing, And Manufacturing Methods Thereof - Google Patents

Abstract

An object of the present invention is to provide a method for manufacturing a photovoltaic electrolytic electrode having a three-dimensional structure. The present invention provides a method for manufacturing a photoelectrode, including the steps of: manufacturing a three-dimensional conductive structure through lamination; forming a metal layer on the surface of the conductive structure by electrochemical deposition; and forming an oxide semiconductor layer on the surface of the metal layer by electrochemical deposition.

Description

BACKGROUND OF THE INVENTION Photoelectrode Based on 3D Printing, And Manufacturing Methods Thereof Using 3D Printing

The present invention relates to a photoelectrode and a method of manufacturing the same, and more particularly, to a photoelectrode to which a three-dimensional printing method is applied and a method of manufacturing the same.

Due to the depletion of fossil fuels and environmental problems, a new energy source is needed. Hydrogen energy obtained through water decomposition is environmentally friendly and there is no problem of depletion. Among various water decomposition methods, the solar water-splitting method is known to be a very efficient method.

As the water electrolysis method of water, a photochemical method of producing hydrogen using sunlight as an energy source is widely known, and, for example, a photoelectrochemical method and a photocatalytic method have been proposed. The principle of the photochemical method of water electrolysis is as follows.

First, when an n-type semiconductor is supported in an aqueous solution, electron transfer occurs from the electrode to the solution, resulting in a decrease in the semiconductor carrier density near the solid-liquid interface, which results in the formation of an electrostatic layer over several hundred nm from the semiconductor surface, and conduction and valence bands. An interface gradient occurs at In such a state, when the semiconductor is irradiated with light having an energy greater than the band gap, electrons are excited from the valence band to the conduction band, but due to the band gradient, the electrons are forced to the inside and the holes to the outside. As a result, the separation of electrons and holes is efficiently performed, and electrons generated from the photoelectrode move to the counter electrode through the conducting wire to generate hydrogen at the counter electrode. In this case, in order to proceed with photolysis without applying power from the outside, the band gap of the semiconductor must be greater than the electrolytic voltage of water. Therefore, whether to apply the external power is determined according to the type of semiconductor used.

Conventionally, an electrode such as a porous structure having a large surface area has been manufactured in order to manufacture a high-efficiency solar electrolytic electrode. However, the two-dimensional electrode structure has a limitation in increasing the surface area.

Therefore, there is a need for a photoelectrode having a large surface area and a method of manufacturing the same.

(1) US 2015-36156 A

An object of the present invention is to provide a photovoltaic electrolytic electrode having a three-dimensional structure having a large surface area.

In addition, an object of the present invention is to provide a method of manufacturing a solar photovoltaic electrode having a three-dimensional structure.

In order to achieve the above technical problem, the present invention includes the steps of manufacturing a three-dimensional conductive structure by lamination; Forming a metal layer on the surface of the conductive structure by electrochemical vapor deposition; And forming an oxide semiconductor layer on the surface of the metal layer by electrochemical deposition.

In the present invention, the metal layer may include at least one metal selected from the group consisting of Au, Cu, Ag, and Ni, or an alloy of the metal.

In addition, the oxide semiconductor layer includes at least one oxide selected from the group consisting of copper oxide, zinc oxide, iron oxide, tungsten oxide, and nickel oxide.

In the present invention, it is preferable that the conductive structure includes graphene.

In the present invention, the graphene laminate manufacturing step may be performed by an ink-based injection printing method.

In the present invention, the electrochemical deposition of the metal layer forming step may include electroplating. In addition, the electrochemical deposition of the oxide semiconductor layer forming step may include electroplating.

In order to achieve the above other technical problem, the present invention is a stacked structure of graphene 3D skeleton; And a photoelectrode including a conductive metal layer and an oxide semiconductor layer on the surface of the 3D skeleton.

According to the present invention, it is possible to manufacture a photovoltaic hydrolysis electrode of a three-dimensional structure having a high specific surface area by a simple manufacturing method.

1A to 1C are procedure diagrams schematically showing a method of forming a photoelectrode according to an embodiment of the present invention.
2 is a schematic diagram for explaining an ink-based injection printing technique as an embodiment of the present invention.
3A to 3C are photographs of observing the surface of the structure of each step manufactured according to an embodiment of the present invention.
4A to 4C are electron micrographs of the front, top, and perspective views of a three-dimensional photoelectrode, respectively.
5 is a photograph of a cross-sectional structure of the 3D structure of FIG. 4.
6A to 6C are electron micrographs of a photoelectrode manufactured according to an embodiment of the present invention.
7 is a graph showing the photocurrent density measurement result of a photoelectrode manufactured according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail by describing a preferred embodiment of the present invention.

1A to 1C are procedure diagrams schematically showing a method of forming a photoelectrode according to an embodiment of the present invention.

First, referring to FIG. 1A, a conductive 3D structure is laminated and manufactured in a predetermined shape on a substrate.

In the present invention, ink-based injection printing techniques such as fused deposition modeling (FDM), selective laser sintering (SLS), selective laser sintering (SLA), or inkjet printing may be used for 3D printing.

2 is a diagram schematically illustrating an ink-based injection printing technique as an embodiment of the present invention.

Referring to FIG. 2, the ink 20 for forming a structure of the present invention is held in a printing pen 110 having a nozzle. The ink 20 may include dispersion particles 22 including conductive particles, a binder polymer, and a solvent 24. In the present invention, graphene, CNT, or metal particles may be used as the conductive particles. In addition, ethyl cellulose, polystyrene, polyethylene, propylene, etc. may be used as the binder polymer, and as the solvent, xylene, toluene, and acetone (acetone) Etc. can be used.

The printing pen 110 contacts the substrate 10, and the pen 110 presses and discharges ink from the nozzle while moving a predetermined distance from the contact point in a specific direction, for example, in a direction parallel to the substrate (Fig. 2(a)). . Any method such as pneumatic or hydraulic pressure may be used as the ink pressurization method. When the pen moves at a predetermined speed in a direction parallel to the substrate, as a result, a pattern 12 corresponding to the movement trajectory of the nozzle is printed on the substrate. Subsequently, the nozzle returns to a predetermined position on the substrate and discharges ink in the same manner to deposit a new pattern 12B on the pattern 12A. A desired three-dimensional pattern may be formed by such additive manufacturing. In the present invention, the shape of the three-dimensional pattern can be designed in various ways. Illustratively, although a pyramid-shaped structure is shown, it goes without saying that any type of three-dimensional structure that increases the surface area, such as a cylinder or a square column, may be used.

In addition, although it has been described that the nozzle moves in a horizontal direction with the substrate to form a three-dimensional structure pattern, the present invention is not limited thereto, and the nozzle moves in a vertical direction with respect to the substrate and releases ink to form a column shape or a wire shape. It is also possible to form a structure pattern.

In order to provide sufficient bonding strength between the printed pattern and the substrate (substrate) in the present invention, an appropriate amount of a binder and a coupling agent may be used. In this case, the plating ink of the present invention may exhibit a flow characteristic that converts from a liquid like behavior to a solid like behavior according to the magnitude of the stress. That is, the ink of the present invention exhibits a liquid-like behavior under the shear stress experienced while passing through the nozzle by pressure, and after passing through the nozzle and patterned on the substrate, it exhibits a solid-like behavior, thus forming a shape as a part of a three-dimensional structure. You will be able to keep it.

Referring back to FIG. 1, a conductive metal layer is formed on the surface of a conductive three-dimensional structure (b). In the present invention, the conductive metal layer may include at least one metal selected from the group consisting of Au, Cu, Ag, and Ni, or an alloy of the metal. In the present invention, since the 3D structure is a conductive material, the conductive metal layer may be formed by applying an electrochemical deposition method such as electroplating.

Next, an oxide semiconductor layer is formed on the three-dimensional structure coated with the conductive metal layer (c). The oxide semiconductor layer acts as a photovoltaic electrolysis activation layer. For example, _{an oxide semiconductor layer such as Cu 2} O, CuO, ZnO, Fe ₂ O ₃ , NiO, WO ₃ , TiO ₂ is formed on the conductive metal layer. For example, an electrochemical deposition method may be used to form the oxide semiconductor layer.

<Experimental Example 1: Preparation of graphene ink>

Graphene ink was prepared by mixing graphene powder (90-200 nm, Graphene Supermarket), Ethylene Cellulose (Sigma aldrich), Tolluene (Sigma aldrich), and Xylene (sigma aldrich). First, 0.65 g of Tolluene and 0.65 g of Xylene were mixed, 0.2 g of Ethylene cellulose and 0.5 g of graphene were added to the mixed solution, and then uniformly mixed for 5 minutes using a mixer to prepare an ink. .

<Experimental Example 2: Preparation of a three-dimensional structure pattern>

With the ink prepared in Experimental Example 1, a repeating pattern of a pyramid structure of 500 µm* 500 µm * 375 µm (L*W*H) was formed on a copper film substrate using a micronozzle having an opening diameter of 200 µm of the nozzle tip. Graphene ink was supplied through the rear end of the pipette (pen) and discharged from the front end by pneumatic pressure. The position and pulling speed of the micropipette were precisely controlled with a position precision of 100 nm with a 3-axis stepping motor.

Subsequently, the prepared structure pattern was immersed in a Cu plating solution maintained at a temperature of about 25° C. for 3 to 30 minutes to be electroplated. The plating solution was titrated to pH 2 by mixing _{0.5 M CuSO 4} ·5H ₂ O and H _{2 SO 4.} For plating, the voltage was applied at -0.1 V compared to the Ag/AgCl electrode.

_{Next, Cu 2} O was electroplated on the Cu plating surface by immersing for 30 minutes in a plating solution maintained at a temperature of about 60°C. The composition of the plating solution was titrated to pH 12 using _{0.4M CuSO 4} ·5H ₂ O, 3M NaC ₃ H ₅ O _{3 and NaOH.} The voltage was -0.4V compared to the Ag/AgCl electrode.

3(a) is after formation of a graphene structure pattern, and (b) is after deposition of a Cu metal layer. (c) is a photograph of the surface after Cu2O deposition, and (a) to (c) of FIG. 4 are electron micrographs of the front, plane, and perspective views of the three-dimensional photoelectrode, respectively.

5 is a photograph of a cross-sectional structure of the 3D structure of FIG. 4. Referring to FIG. 5, it can be seen that a _{Cu coating layer and a Cu 2} O coating layer were formed on the surface of the graphene skeleton.

<Experimental Example 3: Measurement of photocurrent density according to the surface area of a three-dimensional structure>

A photoelectrode was manufactured by making the width and length of the pyramid-shaped three-dimensional structure constant and changing the height. The photocurrent density of the prepared photoelectrode was measured. The voltage was increased by 10 mV per second from 0 to 0.6 V compared to the reference electrode Ag/AgCl, and the electrode was repeatedly exposed to light of 1 sun through a solar simulator.

6A to 6C are electron micrographs of photoelectrodes having heights of 375 µm, 500 µm, and 750 µm, respectively, and Fig. 7 is a graph showing the photocurrent density measurement results.

7B to 7D are graphs showing photocurrent density measurement results of photoelectrodes having heights of 375 µm, 500 µm, and 750 µm, respectively. For comparison, the results of measuring the photocurrent density of the photoelectrode of a two-dimensional planar structure are shown in (a).

Referring to FIG. 7, it can be seen that the photocurrent density increases as the height of the photoelectrode structure increases. This is because the surface area of the structure increases as the height of the structure increases.

In the above, the present invention has been described above through the embodiments of the present invention, but the above description is illustrative of the present invention and the present invention is not limited thereto. Anyone of ordinary skill in the field to which the present invention belongs without departing from the appended claims and the gist of the present invention should be regarded as belonging to the scope of the present invention to the extent that various modifications can be implemented.

Claims (8)

Laminating manufacturing a three-dimensional conductive structure;
Forming a metal layer on the surface of the conductive structure by electrochemical vapor deposition; And
A method of manufacturing a photoelectrode comprising the step of forming an oxide semiconductor layer on the surface of the metal layer by electrochemical deposition. The method of claim 1,
The method of manufacturing a photoelectrode, wherein the metal layer includes at least one metal selected from the group consisting of Au, Cu, Ag, and Ni, or an alloy of the metal. The method of claim 1,
The oxide semiconductor layer is a method of manufacturing a photoelectrode, characterized in that it contains at least one oxide selected from the group consisting of copper oxide, zinc oxide, iron oxide, and nickel oxide. The method of claim 1,
The method of manufacturing a photoelectrode, characterized in that the conductive structure includes graphene. The method of claim 1,
The manufacturing method of the photoelectrode, characterized in that the graphene laminate manufacturing step is performed by an ink-based injection printing method. The method of claim 1,
Electrochemical deposition of the metal layer forming step includes electroplating. The method of claim 1,
Electrochemical deposition of the oxide semiconductor layer forming step includes electroplating. Stacked graphene 3D skeleton; And
A photoelectrode comprising a conductive metal layer and an oxide semiconductor layer on the surface of the 3D skeleton.

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