KR102413904B1 - Hydrogen evolution apparatus - Google Patents

Abstract

The present application includes an AC power source, a semiconductor electrode and a counter electrode connected to the AC power source, an electrolyte impregnated with the semiconductor electrode, and a light source irradiating light to the semiconductor electrode, wherein the semiconductor electrode is perpendicular to the reference electrode and the reference electrode It includes an n-type semiconductor and a p-type semiconductor grown as , and the semiconductor electrode has a three-dimensional heterojunction structure in which the n-type semiconductor and the p-type semiconductor are alternately disposed.

Description

Hydrogen generator {HYDROGEN EVOLUTION APPARATUS}

The present application relates to a hydrogen generator.

In modern times, along with the development of industrial technology, the standard of living is continuously improving, while the problems of environmental pollution and resource depletion are becoming more and more serious due to the rapid increase in energy use. In order to solve the problems of environmental pollution and resource depletion, countries are focusing on the development of clean fuels. In particular, the development of clean alternative energy using hydrogen as an energy source is attracting great attention.

Hydrogen is attracting attention as a next-generation alternative energy source as a high-density clean energy source. The conventional photoelectrochemical hydrogen generator produces hydrogen using a DC power source and platinum (Pt) as a catalyst in the single conductive semiconductor light absorption layer. However, when a voltage is continuously applied to the light absorption layer of the conventional hydrogen generator, the It is difficult to continuously produce hydrogen due to the accumulation of photocharges, which causes corrosion or limits the photocharge generation efficiency. Since the conventional hydrogen generator requires a process of directly using DC power or converting AC power to DC power, it is not possible to directly utilize AC electricity or AC energy source to produce hydrogen.

Specifically, when an electrode of a conventional hydrogen generating device is impregnated in water and light of a specific wavelength and a predetermined numerical voltage are applied to the electrode, electrons of the electrode react with H ⁺ ions in water to produce hydrogen. However, when a DC power source is used, since the number of electrons present in the electrode continues to increase, the electrode is corroded by water over time, which may decrease the efficiency of the hydrogen generating device.

Korea Patent Publication No. 10-1816839, which is the background technology of the present application, relates to a complex power circuit for a renewable energy direct link type hydrogen generator and a control method thereof. The method of generating hydrogen without conversion to DC power, only generating hydrogen after converting AC power to DC power, is not recognized.

The present application is intended to solve the problems of the prior art described above, and an object of the present application is to provide a hydrogen generator using an AC power source.

Another object of the present application is to provide a method for manufacturing a semiconductor electrode of the hydrogen generating device.

However, the technical problems to be achieved by the embodiments of the present application are not limited to the technical problems described above, and other technical problems may exist.

As a technical means for achieving the above technical problem, the first aspect of the present application is an AC power source, a semiconductor electrode and a counter electrode connected to the AC power source, an electrolyte impregnated with the semiconductor electrode, and irradiating light to the semiconductor electrode and a light source, wherein the semiconductor electrode includes a reference electrode and an n-type semiconductor and a p-type semiconductor arranged to grow vertically from the reference electrode, and the semiconductor electrode includes the n-type semiconductor and the p-type semiconductor alternately arranged It provides a hydrogen generating device that has a three-dimensional heterojunction structure.

According to one embodiment of the present application, the n-type semiconductor and the p-type semiconductor are each independently Cu-In-Se-based, Cu-In-S-based, Cu-Sb-Se-based, Cu-Sb-S-based, Zn It may include a material selected from the group consisting of -In-Se-based, Zn-In-S-based, Zn-Sb-Se-based, Zn-Sb-S-based, and combinations thereof, but is not limited thereto.

According to the exemplary embodiment of the present application, in the n-type semiconductor, Cu-In-Se has a composition ratio of 1:3:5, and in the p-type semiconductor, Cu-In-Se has a composition ratio of 1: 1:2. However, the present invention is not limited thereto.

According to the exemplary embodiment of the present application, the AC power may apply a voltage of -1.0 V to +1.5 V on the reference electrode, but is not limited thereto.

According to one embodiment of the present application, hydrogen may be generated in the electrolyte by the light irradiated from the light source and/or the voltage applied to the semiconductor electrode, but is not limited thereto.

According to one embodiment of the present application, hydrogen is generated on the surface of the p-type semiconductor by the negative voltage applied from the AC power source, and the hydrogen may be bonded to the surface of the p-type semiconductor, but is limited thereto. it is not

According to the exemplary embodiment of the present application, the hydrogen bound to the surface of the p-type semiconductor may be released by a positive voltage applied from the AC power source, but is not limited thereto.

According to one embodiment of the present application, the frequency of the AC power may be 0.01 Hz to 30 Hz, but is not limited thereto.

According to one embodiment of the present application, the reference electrode and the counter electrode are each independently Mo, Au, Pt, Ti, Ag, Ni, Zr, Ta, Zn, Nb, Cr, Co, Mn, Fe, Al, Mg , Si, W, Cu, lanthanide-based metals, nitrides thereof, oxides thereof, conductive polymers, and combinations thereof may include, but are not limited to.

According to one embodiment of the present application, the energy source of the AC power source may include one selected from the group consisting of solar cells, piezoelectric elements, thermoelectric elements, triboelectric elements, photoelectric elements, ferrofluids, and combinations thereof. However, the present invention is not limited thereto.

According to one embodiment of the present application, the wavelength of the irradiated light may be 300 nm to 900 nm, but is not limited thereto.

In addition, the second aspect of the present application, in the method for manufacturing a semiconductor electrode of the hydrogen generating device according to the first aspect, depositing a first metal on the reference electrode, a second metal on the upper end of the first metal Depositing, and heat-treating the first metal and the second metal in a selenium or sulfur atmosphere to prepare a compound semiconductor, wherein the atomic composition ratio of the first metal and the second metal is 0.3 to 1.0, A method of manufacturing a semiconductor electrode is provided.

According to the exemplary embodiment of the present application, the first metal may include Cu or Zn, and the second metal may include In or Sb, but is not limited thereto.

According to one embodiment of the present application, the compound semiconductor is Cu-In-Se-based, Cu-In-S-based, Cu-Sb-Se-based, Cu-Sb-S-based, Zn-In-Se-based, Zn-In It may include a material selected from the group consisting of -S-based, Zn-Sb-Se-based, Zn-Sb-S-based, and combinations thereof, but is not limited thereto.

According to the exemplary embodiment of the present disclosure, the compound semiconductor may include an n-type semiconductor and a p-type semiconductor alternately disposed and may have a three-dimensional heterojunction structure, but is not limited thereto.

According to one embodiment of the present application, the step of depositing the first metal or the second metal is an electrodeposition, a chemical vapor deposition, a physical vapor deposition (physical vapor deposition), atomic layer deposition ( atomic layer deposition), and may be by a process including one selected from the group consisting of combinations thereof, but is not limited thereto.

According to one embodiment of the present application, the heat treatment temperature may be 450 °C to 650 °C, but is not limited thereto.

The above-described problem solving means are merely exemplary, and should not be construed as limiting the present application. In addition to the exemplary embodiments described above, additional embodiments may exist in the drawings and detailed description.

Since the conventional hydrogen generator uses DC power, a circuit for converting AC power to DC power is additionally included. However, according to the above-described problem solving means of the present application, since the hydrogen generator according to the present application can produce hydrogen using an alternating current, it can have a simpler structure than the conventional hydrogen generator.

In addition, the voltage applied to the hydrogen generating device according to the present application is in the form of an alternating current signal, and energy band bending that changes in a short time occurs, so that the recombination process of charges can be suppressed, and the loss of photocurrent of the hydrogen generating device can be suppressed. can

When DC voltage is continuously applied to the conventional hydrogen generator. A decrease in photocurrent due to an interfacial electrochemical phenomenon occurring on the electrode surface, ie, an electric double layer, with the passage of time can be easily observed. Therefore, in the conventional hydrogen generating device, the voltage required of the photoelectrode for producing hydrogen by the electric double layer increases than the theoretical expected value, and corrosion of the photoelectrode can be promoted.

However, since the hydrogen generating device according to the present application uses an AC power source, the electric double layer phenomenon may be suppressed on the surface of the electrode of the hydrogen generating device, and the voltage required for hydrogen production may be reduced.

Specifically, since the n-type semiconductor and the p-type semiconductor are alternately arranged in the photoelectrode of the hydrogen generating device, recombination of charges is suppressed and charge transport efficiency can be improved. In addition, the electric double layer phenomenon and the corrosion phenomenon of the photoelectrode can be suppressed by suppressing a phenomenon in which charge is accumulated in the photoelectrode by rapidly generating a change in the direction of the energy band bending.

In addition, since the system for producing hydrogen by the hydrogen generating device according to the present application requires very little electric energy due to the use of solar energy, which is a renewable energy, and the effect of suppressing electric double charge, the AC power of the hydrogen generating device is The energy source may be an energy harvesting device such as solar energy, thermoelectricity, piezoelectricity, photoelectricity, and magnetic fluid, so that eco-friendly power generation is possible.

In addition, since the conventional hydrogen generator uses a DC power supply and uses a material having single conductivity and a single phase as an electrode, materials that can be used as a photoelectrode device are limited. However, since the hydrogen generating device according to the present application can use a material having a multi-phase complex structure, a wide range of materials that can be used as a photoelectrode device can be used, so that various materials can be used.

In addition, since oxygen can be produced by applying a high amount of voltage to the hydrogen generator according to the present disclosure, the hydrogen generator can be used as a device for supplying hydrogen and oxygen to a fuel cell.

However, the effects obtainable herein are not limited to the above-described effects, and other effects may exist.

1 is a schematic diagram of a hydrogen generating device according to an embodiment of the present application.
2 is a mechanism of a hydrogen generating device according to an embodiment of the present application.
3 is a mechanism of a semiconductor electrode according to an embodiment of the present application.
4 is a schematic diagram of an electric double layer generated on the electrode surface according to an embodiment of the present application.
5 is a flowchart illustrating a method of manufacturing a semiconductor electrode according to an exemplary embodiment of the present application.
6 is a schematic diagram illustrating a method of manufacturing a semiconductor electrode according to an exemplary embodiment of the present application.
7 is a TEM image and a selected area electron diffraction (SAED) image of a semiconductor electrode according to an embodiment of the present application.
8 is a graph showing the efficiency of the hydrogen generating device according to an embodiment of the present application.
9 is a graph showing the relationship between the hydrogen generation efficiency of the hydrogen generating device according to an embodiment of the present application and the frequency of the AC voltage.
10 is a graph showing the relationship between the hydrogen generation efficiency of the hydrogen generating device according to an embodiment of the present application and whether light is irradiated.
11 is a graph showing the relationship between the voltage applied on the hydrogen generating device and the hydrogen generating efficiency in an embodiment of the present application.
12 is a graph illustrating hydrogen generation according to time when an AC voltage or a DC voltage is applied to a semiconductor electrode according to an embodiment of the present application.

Hereinafter, embodiments of the present application will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art to which the present application pertains can easily carry out.

However, the present application may be implemented in several different forms and is not limited to the embodiments described herein. And in order to clearly explain the present application in the drawings, parts irrelevant to the description are omitted, and similar reference numerals are attached to similar parts throughout the specification.

Throughout this specification, when a part is "connected" to another part, this includes not only the case of being "directly connected", but also the case of being "electrically connected" with another element interposed therebetween. do.

Throughout this specification, when a member is positioned “on”, “on”, “on”, “on”, “under”, “under”, or “under” another member, this means that a member is positioned on the other member. It includes not only the case where they are in contact, but also the case where another member exists between two members.

Throughout this specification, when a part "includes" a certain component, it means that other components may be further included, rather than excluding other components, unless otherwise stated.

As used herein, the terms "about," "substantially," and the like are used in a sense at or close to the numerical value when the manufacturing and material tolerances inherent in the stated meaning are presented, and to aid in the understanding of the present application. It is used to prevent an unconscionable infringer from using the mentioned disclosure in an unreasonable way. Also, throughout this specification, "step to" or "step to" does not mean "step for".

Throughout this specification, the term "combination of these" included in the expression of the Markush form means one or more mixtures or combinations selected from the group consisting of the components described in the expression of the Markush form, and the components It is meant to include one or more selected from the group consisting of.

Throughout this specification, reference to “A and/or B” means “A or B, or A and B”.

Throughout this specification, the description of "growth vertically" includes growth such that the angle between the growth direction of the material on the substrate and the substrate is exactly 90°, as well as about 70° to about 110°.

Hereinafter, the hydrogen generating apparatus of the present application will be described in detail with reference to embodiments, examples, and drawings. However, the present application is not limited to these embodiments and examples and drawings.

As a technical means for achieving the above technical problem, the first aspect of the present application is an AC power source 200 , a semiconductor electrode 100 and a counter electrode 300 connected to the AC power source 200 , and the semiconductor electrode 100 . ) is impregnated with an electrolyte 400 , and a light source (not shown) irradiating light to the semiconductor electrode 100 , wherein the semiconductor electrode 100 is formed from the reference electrode 110 and the reference electrode 110 . It includes a p-type semiconductor 111 and an n-type semiconductor 112 that are vertically grown and arranged, and the semiconductor electrode 100 includes the p-type semiconductor 111 and the n-type semiconductor 112 are alternately disposed. It provides a hydrogen generating device (10), which has a three-dimensional heterojunction structure.

According to the exemplary embodiment of the present application, the angle at which the p-type semiconductor 111 and the n-type semiconductor 112 grow on the surface of the reference electrode 110 may be about 70° to about 110°, but is limited thereto. it is not Preferably, the p-type semiconductor 111 and the n-type semiconductor 112 may grow vertically on the surface of the reference electrode 110 , but the present invention is not limited thereto.

1 is a schematic diagram of a hydrogen generating device 10 according to an embodiment of the present application.

Modern society is supported by various fuels obtained by processing fossil fuels such as petroleum and coal. However, the fossil fuels emit various organic substances such as carbon monoxide, carbon dioxide, and methane during combustion, and the organic substances are not only toxic, but also cause global warming. Accordingly, various new and renewable energies such as solar power generation are in the spotlight, and among the new renewable energy, hydrogen is receiving a lot of attention because there is no concern about the depletion of water, a raw material.

However, there is a disadvantage that a lot of energy is required to produce hydrogen from water. In particular, since the conventional hydrogen generator uses a direct current power source and uses a photoelectrode having a single conductivity and a single phase, various problems such as low continuity and corrosion resistance, and energy loss occurring in the conversion process exist.

In the present application, the above problem can be solved by providing a hydrogen generating device 10 including the AC power source 200 and the semiconductor electrode 100 having a polyphase material, and electrons generated from the semiconductor electrode 100 and The problem caused by the recombination of holes can be solved.

Referring to FIG. 1 , the semiconductor electrode 100 and the counter electrode 300 may be impregnated in the electrolyte 400 or may exist in a state in contact with the electrolyte 400 , but is not limited thereto. When the semiconductor electrode 100 and the counter electrode 300 are impregnated in the electrolyte 400 , the AC power source 200 may exist outside the electrolyte 400 , but is not limited thereto.

According to the exemplary embodiment of the present disclosure, the semiconductor electrode 100 may have a three-dimensional heterojunction structure in which the p-type semiconductor 111 and the n-type semiconductor 112 are alternately disposed, but is not limited thereto. . In this regard, since the p-type semiconductor 111 and the n-type semiconductor 112 are grown vertically on the reference electrode 110 , the cut surface of the semiconductor electrode 100 is the p-type semiconductor 111 and The n-type semiconductors 112 may have a horizontally parallel structure in which they are alternately arranged.

According to the exemplary embodiment of the present application, the semiconductor electrode 100 includes the matrix of the p-type semiconductor 111 including the nanoparticles of the n-type semiconductor 112 , or the nanoparticles of the p-type semiconductor 111 . It may include a matrix of the n-type semiconductor 112 that includes, but is not limited thereto.

According to the exemplary embodiment of the present application, the p-type semiconductor 111 and the n-type semiconductor 112 are each independently Cu-In-Se-based, Cu-In-S-based, Cu-Sb-Se-based, Cu- It may include a material selected from the group consisting of Sb-S-based, Zn-In-Se-based, Zn-In-S-based, Zn-Sb-Se-based, Zn-Sb-S-based, and combinations thereof, However, the present invention is not limited thereto. Preferably, the p-type semiconductor 111 and the n-type semiconductor 112 may include Cu-In-Se-based materials having different compositions, but is not limited thereto.

According to the exemplary embodiment of the present application, in the n-type semiconductor 112, Cu-In-Se has a composition ratio of 1:3:5, and in the p-type semiconductor 111, Cu-In-Se is 1:1: It may have a composition ratio of 2, but is not limited thereto.

For example, when the n-type semiconductor 112 is Cu-In-Se-based, an atomic composition ratio of copper, indium, and selenium may be 1:3:5. Also, for example, when the n-type semiconductor 112 is Zn-In-Se-based, the composition ratio is 1:2:4, and in the case of Zn-In-S-based, the composition ratio is 1:2:4, and Cu-In In the case of -S system, the composition ratio is 1:1:2.

For example, when the p-type semiconductor 111 is Cu-In-Se-based, the composition ratio of atoms may be 1:1:2. Also, for example, when the p-type semiconductor 111 is Zn-In-Se-based, the composition ratio is 1:1:2, and when the p-type semiconductor 111 is Zn-In-S-based, the composition ratio is 1:2:4, and Cu The composition ratio in the case of -In-S system is 1:1:2, the composition ratio in case of Cu-Sb-Se system is 1:1:2, and the composition ratio in case of Cu-Sb-S system is 1: 1:2 can be

The Cu-In-Se-based material is referred to as a CIS material. The CIS material may be used as a light absorption layer of a thin film solar cell, and was used as a material for decomposing water in the hydrogen generating device 10 .

As will be described later, the semiconductor in which the p-type semiconductor 111 and the n-type semiconductor 112 are alternately disposed may also be referred to as compound semiconductors 111 and 112 .

Unlike the conventional semiconductor in which the p-n junction is stacked, the semiconductor electrode 100 of the present disclosure may have a horizontally parallel structure in which the p-type semiconductor 111 and the n-type semiconductor 112 are alternately disposed. Due to the horizontal parallel structure, the p-type semiconductor 111 and the n-type semiconductor 112 are always affected by the voltage applied from the AC power source 200 to generate hydrogen or oxygen, and the hydrogen or It can be seen that a significant photocurrent is generated in the semiconductor electrode 100 by the oxygen generation process.

According to the exemplary embodiment of the present application, the AC power source 200 may apply a voltage of -1.0 V to +1.5 V on the reference electrode 110 , but is not limited thereto.

For example, the voltage applied by the AC power source 200 on the reference electrode 110 is about -1.00 V to about +1.50 V, about -0.75 V to about +1.50 V, and about -0.50 V to about +1.50 V, about -0.25 V to about +1.50 V, about +0.00 V to about +1.50 V, about +0.25 V to about +1.50 V, about +0.50 V to about +1.50 V, about +0.75 V to about +1.50 V, about +1.25 V to about +1.50 V, about -1.00 V to about +1.25 V, about -1.00 V to about +1.00 V, about -1.00 V to about +0.75 V, about -1.00 V to about +0.50 V, about -1.00 V to about +0.25 V, about -1.00 V to about 0.00 V, about -1.00 V to about -0.25 V, about -1.00 V to about -0.50 V, about -1.00 V to about - 0.75 V, about -0.75 V to about +1.25 V, about -0.50 V to about +1.00 V, about -0.25 V to about +0.75 V, about 0.00 V to about +0.50 V, or about +0.25 V it is not

Theoretically, the minimum energy required to decompose water into hydrogen and oxygen is about 1.23 V. However, since the required energy increases due to the electric double layer generated on the electrode surface, energy of about 1.45 V is required to decompose water into hydrogen and oxygen. When light is irradiated to the surface of the electrode, the theoretical value of the minimum voltage for decomposing water by the photovoltage generated in the photoelectrode layer may be less than 1.23 V, and the problem caused by the electric double layer is solved by reducing the required voltage. can be

Since the hydrogen generating device 10 according to the present application includes the AC power source 200, the problem caused by the electric double layer can be further solved, and thus the problem of energy loss occurring during the hydrogen generating process can be minimized. .

According to one embodiment of the present application, the frequency of the AC power source 200 may be 0.01 Hz to 30 Hz, but is not limited thereto.

According to the exemplary embodiment of the present application, hydrogen may be generated in the electrolyte 400 by the light irradiated from the light source and/or the voltage applied to the semiconductor electrode 100 , but is not limited thereto.

The electrolyte according to the present disclosure is for producing hydrogen by receiving electrical energy or light energy, and may include a material that can contain H ⁺ ions and OH ⁻ ions at the same time, for example, water.

Specifically, when a voltage is applied to the semiconductor electrode 100 , the energy band of the p-type semiconductor 111 or the n-type semiconductor 112 is bent. In this case, when light is irradiated to the semiconductor electrode 100 , electrons of the p-type semiconductor 111 or holes of the n-type semiconductor 112 may be excited by the light to have energy. The energized charges may react with H ⁺ ions or OH ⁻ ions distributed in the electrolyte 400 , for example, water to generate hydrogen or oxygen.

As will be described later, in the p-type semiconductor 111 and the n-type semiconductor 112 , the energy band bending direction due to an AC voltage is periodically changed in the photoelectrons and the holes, so that recombination due to charge accumulation can be suppressed.

According to the exemplary embodiment of the present application, hydrogen is generated on the surface of the p-type semiconductor 111 by the negative voltage applied from the AC power source 200 , and the hydrogen is applied to the surface of the p-type semiconductor 111 . It may be combined, but is not limited thereto.

According to the exemplary embodiment of the present application, the hydrogen bound to the surface of the p-type semiconductor 111 may be released by the positive voltage applied from the AC power source 200 , but is not limited thereto.

According to the exemplary embodiment of the present application, the hydrogen generator 10 may simultaneously produce hydrogen and oxygen, but is not limited thereto.

As will be described later, when the positive voltage applied from the AC power source 200 increases, the hydrogen generator 10 may also produce oxygen. The oxygen production process of the hydrogen generator 10 is a process of generating oxygen on the surface of the n-type semiconductor 112 by a positive voltage applied from the AC power source 200 and applying from the AC power source 200 . It may include a process in which the oxygen bound to the surface of the n-type semiconductor 112 is released by the applied negative voltage.

In relation to this, hydrogen generated on the surface of the p-type semiconductor 111 and oxygen generated on the surface of the n-type semiconductor 112 are generated in the p-type semiconductor 111 or the n-type semiconductor as long as the direction of the voltage is not changed. It may be present in combination with the surface of (112).

2 is a mechanism of a hydrogen generating device 10 according to an embodiment of the present application, FIG. 3 is a mechanism of a semiconductor electrode 100 according to an embodiment of the present application, and FIG. 4 is a semiconductor according to an embodiment of the present application. It is a schematic diagram of an electric double layer generated on the surface of the electrode 100 .

In this regard, although FIG. 4 discloses only the reference electrode 110 of the semiconductor electrode 100 of the hydrogen generator 10, the AC power source 200, the counter electrode 300, and the n-type The semiconductor 112 and the p-type semiconductor 111 are also present.

2 to 4 , when a negative voltage is applied while irradiating light to the semiconductor electrode 100 , photoelectrons excited by light exist on the p-type semiconductor 111 . H ⁺ ions present in the electrolyte 400 impregnated and contacted with the p-type semiconductor 111 of the semiconductor electrode 100 are reduced by the photoelectrons present on the p-type semiconductor 111 to generate hydrogen. may be, and the hydrogen may be present by being bonded to the p-type semiconductor 111 .

Hydrogen bound on the p-type semiconductor 111 may be released from the surface of the p-type semiconductor 111 by a positive voltage applied to the semiconductor electrode 100 .

In addition, when a positive voltage is applied to the semiconductor electrode 100 , holes excited by light exist in the n-type semiconductor 112 , and OH ⁻ ions present on the electrolyte 400 are It may be oxidized by the n-type semiconductor 112 to form O ₂ and H ⁺ ions.

Oxygen present in the n-type semiconductor 112 may be released from the n-type semiconductor 112 by a negative voltage applied to the semiconductor electrode 100 .

According to the exemplary embodiment of the present application, the recombination process of electrons and holes may not occur in the semiconductor electrode 100 , but is not limited thereto.

Referring to FIG. 2 , when light of a certain intensity or higher is irradiated to the semiconductor electrode 100 , a depletion area is formed on the p-type semiconductor 111 or the n-type semiconductor 112 . In this regard, the depletion region refers to a region in which holes (h ⁺ ) or electrons (e ⁻ ), which are majority carriers, do not exist on the semiconductor electrode 100 .

When the depletion region on the p-type semiconductor 111 or the n-type semiconductor 112 is adjacent to the n-type semiconductor 112 or the p-type semiconductor 111, a photoelectric effect causes the n-type semiconductor 112 to ) or electrons generated in the p-type semiconductor 111 move to the depletion region, so that a ratio of electrons and holes in the p-type semiconductor 111 and the n-type semiconductor 112 to be combined may decrease.

According to one embodiment of the present application, the energy source of the AC power source 200 is selected from the group consisting of solar cells, piezoelectric elements, thermoelectric elements, triboelectrics, photoelectric elements, ferrofluids, and combinations thereof. It may include, but is not limited to.

As described above, since the voltage difference required for the hydrogen generating device 10 according to the present invention to produce hydrogen is as low as less than about 1.23 V, electrical energy obtained by the energy harvesting method is sufficient.

Energy harvesting according to the present application refers to a technology for generating electricity by collecting surplus energy generated in the energy conversion process in modern society, such as vibration or sound energy. The energy harvesting includes a piezoelectric element that converts pressure or vibration into electrical energy, a thermoelectric element that converts heat such as body temperature into electrical energy, triboelectric that accumulates surplus electricity such as static electricity, and a photoelectric element that converts light into electrical energy , and a magnetic fluid that obtains electrical energy through a change in a magnetic field generated by vibrating after mixing a fluid and magnetic particles, etc. can be used to produce energy.

According to one embodiment of the present application, the energy source of the AC power source 200 may include electric energy transmitted from a general power plant, but is not limited thereto.

Since the conventional hydrogen generator produces hydrogen through a DC power source, various problems such as corrosion of the electrode and reduction of photocurrent density occur due to electric charges accumulated in the electrode over time. However, since the hydrogen generating device 10 according to the present application uses the AC power source 200, no charge is accumulated on the semiconductor electrode 100, and there are problems such as corrosion or reduction in photocurrent density due to the DC power source. There are advantages that can be addressed.

In addition, since the energy source of the DC power of the conventional hydrogen generator is AC power supplied from a power plant, etc., a circuit for converting AC power to DC power is required, but the hydrogen generator 10 according to the present application is an AC current can be used directly, so it can have a simpler structure than a conventional hydrogen generator.

According to one embodiment of the present application, the reference electrode 110 and the counter electrode 300 are each independently Mo, Au, Pt, Ti, Ag, Ni, Zr, Ta, Zn, Nb, Cr, Co, Mn , Fe, Al, Mg, Si, W, Cu, lanthanide metals, nitrides thereof, oxides thereof, conductive polymers, and combinations thereof may include, but are not limited to.

According to one embodiment of the present application, the wavelength of the irradiated light may be 300 nm to 900 nm, but is not limited thereto.

The light irradiated onto the semiconductor electrode 100 supplies energy to electrons on the p-type semiconductor 111 or the n-type semiconductor 112 to excite them, thereby forming electric charges for decomposing water.

A second aspect of the present application is the method for manufacturing the semiconductor electrode 100 of the hydrogen generating device 10 according to the first aspect, the method comprising depositing a first metal on the reference electrode 110, the first metal depositing a second metal on the upper end of The atomic composition ratio of the second metal is 0.3 to 1.0, and provides a method of manufacturing the semiconductor electrode 100 .

With respect to the method of manufacturing the semiconductor electrode 100 according to the second aspect of the present application, detailed descriptions of parts overlapping with the first aspect of the present application are omitted, but even if the description is omitted, the contents described in the first aspect of the present application are The same can be applied to the second aspect of the present application

In the hydrogen generating device 10 according to the first aspect of the present application, a portion in which hydrogen is generated is the semiconductor electrode 100 , specifically, the p-type semiconductor 111 of the semiconductor electrode 100 , but as described above, the semiconductor By changing the voltage applied to the electrode 100 , the n-type semiconductor 112 of the semiconductor electrode 100 may also produce oxygen.

5 is a flowchart of a method of manufacturing the semiconductor electrode 100 according to an exemplary embodiment of the present application.

In order to manufacture the semiconductor electrode 100 according to the present disclosure, a first metal is deposited on the reference electrode 110 ( S100 ).

According to the exemplary embodiment of the present application, the semiconductor electrode 100 may further include a substrate (not shown), and the reference electrode 110 may be formed on the substrate, but is not limited thereto.

Next, the second metal is deposited on the upper portion of the first metal (S200).

According to the exemplary embodiment of the present application, the first metal may include Cu or Zn, and the second metal may include In or Sb, but is not limited thereto. For example, the first metal may be Cu and the second metal may be In, but is not limited thereto.

According to one embodiment of the present application, the step of depositing the first metal or the second metal is an electrodeposition, a chemical vapor deposition, a physical vapor deposition (physical vapor deposition), atomic layer deposition ( atomic layer deposition), and may be by a process including one selected from the group consisting of combinations thereof, but is not limited thereto. For example, the depositing may be performed by an electric vapor deposition, but is not limited thereto.

According to one embodiment of the present application, the first metal and the second metal may have a thickness gradient, but is not limited thereto.

6 is a schematic diagram illustrating a method of manufacturing a semiconductor electrode according to an exemplary embodiment of the present application.

Referring to FIG. 6 , the first metal Cu formed on the reference electrode 110 (Mo) may have a thin central portion and a thicker bowl shape as it approaches the edge. In addition, the second metal In formed on the first metal may have a thicker central portion as opposed to the first metal, and may have a thinner shape as it approaches an edge.

When the first metal and the second metal are deposited on the reference electrode 110 by electro-deposition, the first metal and the second metal are positioned at a location due to the current concentration effect of the reference electrode 110 . Depending on the thickness, it may have a different thickness, that is, a thickness gradient.

As will be described later, the compound semiconductors 111 and 112 may be formed by alternately disposing the p-type semiconductor 111 and the n-type semiconductor 112 due to the thickness gradient of the first metal and the second metal. .

According to the exemplary embodiment of the present application, the atomic composition ratio of the first metal and the second metal may be 0.3 to 1.0, but is not limited thereto.

For example, when the first metal is Cu, the second metal is In, and the atomic composition ratio of Cu and In is less than 0.3, the CIS-based compound forming the n-type semiconductor 112 is CuIn ₅ Se ₈ and CuIn ₅ Se ₈ has lower efficiency than CuIn ₃ Se ₅ . In addition, when the atomic composition ratio of Cu and In exceeds 1.0, a semiconductor matrix of Cu ₂ Se may be formed instead of the n-type semiconductor 112 , and the Cu ₂ Se is the n-type semiconductor 112 . unable to perform its function as

Then, the compound semiconductors 111 and 112 are manufactured by heat-treating the first metal and the second metal under a selenium or sulfur atmosphere (S300).

The selenium or sulfur atmosphere according to the present application is a selenium or sulfur layer deposited on the first metal and the second metal, or an atmosphere in which selenium or sulfur gas is supplied on the first metal and the second metal means

According to one embodiment of the present application, selenium or sulfur may not be additionally supplied during the heat treatment, but is not limited thereto.

According to the exemplary embodiment of the present application, the compound semiconductors 111 and 112 are Cu-In-Se-based, Cu-In-S-based, Cu-Sb-Se-based, Cu-Sb-S-based, Zn-In-Se-based It may include a material selected from the group consisting of, Zn-In-S-based, Zn-Sb-Se-based, Zn-Sb-S-based, and combinations thereof, but is not limited thereto.

According to the exemplary embodiment of the present application, the compound semiconductors 111 and 112 may include the p-type semiconductor 111 and the n-type semiconductor 112 arranged alternately, and may have a three-dimensional heterojunction structure, However, the present invention is not limited thereto.

According to one embodiment of the present application, the heat treatment temperature may be 450 °C to 650 °C, but is not limited thereto.

In order to form a conventional compound semiconductor, when two different metals or one metal are heated in multiple steps, the conventional compound semiconductor is uniformly crystallized in the entire region, and the phase is unified so that the conventional compound semiconductor can have a single phase. have. As described above, the conventional compound semiconductor having a single phase has a problem in that it can be easily corroded by the electric double layer.

In order to form the semiconductor electrode 100 according to the present application, when the first metal and the second metal are subjected to a rapid heat treatment with selenium or sulfur, the uniformity of crystallization is reduced, unlike the conventional method of forming a compound semiconductor, Since the unification effect is suppressed, the compound semiconductors 111 and 112 do not have a single phase. Therefore, the compound semiconductors 111 and 112 may simultaneously include the p-type semiconductor 111 and the n-type semiconductor 112, which are heterogeneous phases present on the thermodynamic phase diagram, and the thickness gradient is the compound semiconductor ( 111 and 112) may induce an improvement in entropy to have a polyphase.

The present invention will be described in more detail through the following examples, but the following examples are for illustrative purposes only and are not intended to limit the scope of the present application.

[Example]

Mo electrodes were formed on a glass substrate, and Cu was deposited through an electrodeposition process. Then, after vertically depositing In on the Cu, Se was vacuum-deposited on the Cu—In pillars at room temperature.

Then, after raising the temperature at a rate of 27° C./min with the supply of additional Se, selenization and recrystallization of the Cu—In column at 550° C. without the supply of Se, a Cu-In-Se-based compound of an n-type semiconductor and A semiconductor electrode in which a Cu-In-Se-based compound of a p-type semiconductor is alternately disposed was manufactured.

Then, the semiconductor electrode was connected to an AC power source and then immersed in water to create a hydrogen generating atmosphere.

7 is a TEM image and a selected area electron diffraction (SAED) image of the semiconductor electrode according to the embodiment.

Referring to FIG. 7 , it can be seen that the semiconductor electrode simultaneously contains p-type CuInSe ₂ and n-type CuIn ₃ Se ₅ , and the two materials exist separately.

8 is a graph showing the efficiency of the hydrogen generator according to the embodiment.

Referring to FIG. 8 , the voltages applied to the hydrogen generating device are -0.57 V and +0.3 V, and the photocurrent density is maintained constant over time, so that the hydrogen generating device continuously produces hydrogen can be checked

[Experimental Example 1]

9 is a graph showing the relationship between the hydrogen generation efficiency of the hydrogen generating device according to the embodiment and the frequency of the AC voltage.

In this regard, in FIG. 9 , the current density when the frequency of the applied voltage is 10 Hz is about 10 mA/cm ² , and the current density when the frequency of the applied voltage is 0.5 Hz is about 15 mA/cm ² , and , when the frequency of the applied voltage is 1/30 Hz, the current density is about 30 mA/cm ² .

Referring to Figure 9, the less the change in the voltage applied to the hydrogen generating device, that is, the lower the frequency of the voltage, the time for which the charge is maintained on the electrode increases, so that the current density on the electrode can be improved, , an increase in the current density may lead to an improvement in hydrogen production efficiency.

[Experimental Example 2]

10 is a graph showing the relationship between the hydrogen generation efficiency of the hydrogen generating device according to the embodiment and whether or not light is irradiated.

Referring to FIG. 10 , it can be confirmed that higher hydrogen generation efficiency appears when light is irradiated to the hydrogen generating device.

[Experimental Example 3]

11 is a graph showing the relationship between the voltage applied on the hydrogen generating device according to the embodiment and the hydrogen generating efficiency.

Referring to FIG. 11 , the voltage for generating hydrogen, -0.5 V, is fixed, and as the range of the opposite voltage increases, the current density for hydrogen generation increases, and hydrogen can be generated even when the range of the alternating voltage is 1.23 V or less. It can be confirmed that the larger the range of the AC voltage, the higher the hydrogen generation efficiency can be.

Summarizing the conclusions of Experimental Examples 1 to 3, it can be confirmed that hydrogen is actively generated when a voltage having a large voltage range and a low frequency is applied to the hydrogen generating device according to the present application in an environment where light is irradiated.

[Experimental Example 4]

12 is a graph illustrating hydrogen generation according to time when an AC voltage or a DC voltage is applied to the semiconductor electrode according to the embodiment.

Referring to FIG. 12 , hydrogen can be produced when a DC voltage or an AC voltage is applied to the semiconductor electrode. However, it can be confirmed that more hydrogen can be obtained when an AC voltage is applied than when a DC voltage is applied to the semiconductor electrode as in the conventional hydrogen generator.

The above description of the present application is for illustration, and those of ordinary skill in the art to which the present application pertains will understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present application. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a dispersed form, and likewise components described as distributed may also be implemented in a combined form.

The scope of the present application is indicated by the following claims rather than the above detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present application.

10: hydrogen generator
100: semiconductor electrode
110: reference electrode
111: p-type semiconductor
112: n-type semiconductor
200: AC power
300: counter electrode
400: electrolyte

Claims (15)

AC power;
a semiconductor electrode and a counter electrode connected to the AC power supply;
an electrolyte impregnated with the semiconductor electrode; and
a light source irradiating light to the semiconductor electrode;
including,
The semiconductor electrode includes a reference electrode and an n-type semiconductor and a p-type semiconductor arranged to grow vertically from the reference electrode,
The semiconductor electrode has a three-dimensional heterojunction structure in which the n-type semiconductor and the p-type semiconductor are alternately disposed,
In the semiconductor electrode, the recombination process of electrons and holes does not occur,
In the hydrogen generating device,
In the hydrogen generator, an electric double layer phenomenon is suppressed on the surface of the semiconductor electrode of the hydrogen generator by AC power,
Hydrogen is generated on the surface of the p-type semiconductor by the light irradiated from the light source and the negative voltage applied from the AC power source, and the hydrogen is coupled to the surface of the p-type semiconductor,
The hydrogen bound on the surface of the p-type semiconductor is released by the light irradiated from the light source and the positive voltage applied from the AC power source,
The n-type semiconductor is CuIn ₃ Se ₅ , the p-type semiconductor is CuInSe ₂ ,
The electrons and the holes periodically change the energy band bending direction due to an alternating voltage in the p-type semiconductor and the n-type semiconductor,
The frequency of the AC power is 0.01 Hz to 30 Hz,
The AC power applies a voltage of -1.0 V to +1.5 V on the reference electrode,
A depletion region is formed on the p-type semiconductor or the n-type semiconductor by the light irradiated to the region irradiated to the semiconductor electrode,
Electrons generated in the n-type semiconductor or the p-type semiconductor by the photoelectric effect move to the depletion region,
The cut surface of the semiconductor electrode is a horizontally parallel structure in which the p-type semiconductor and the n-type semiconductor are alternately arranged,
The wavelength of the irradiated light is 300 nm to 900 nm,
hydrogen generator.
delete delete delete delete delete The method of claim 1,
The reference electrode and the counter electrode are each independently Mo, Au, Pt, Ti, Ag, Ni, Zr, Ta, Zn, Nb, Cr, Co, Mn, Fe, Al, Mg, Si, W, Cu, lanthanum A hydrogen generating device comprising one selected from the group consisting of metal-based metals, nitrides thereof, oxides thereof, conductive polymers, and combinations thereof.
The method of claim 1,
The energy source of the AC power is a solar cell, a piezoelectric element, a thermoelectric element, a triboelectric element, a photoelectric element, a ferrofluid, and a hydrogen generating device comprising one selected from the group consisting of combinations thereof.
delete The method for manufacturing a semiconductor electrode of a hydrogen generating device according to any one of claims 1, 7, and 8,
depositing a first metal on the reference electrode;
depositing a second metal on top of the first metal; and
Comprising the step of heat-treating the first metal and the second metal under a selenium or sulfur atmosphere to prepare a compound semiconductor,
The atomic composition ratio of the first metal and the second metal is 0.3 to 1.0,
The compound semiconductor includes an n-type semiconductor and a p-type semiconductor alternately arranged, and has a three-dimensional heterojunction structure,
The n-type semiconductor is CuIn ₃ Se ₅ , the p-type semiconductor is CuInSe ₂ ,
When light is irradiated to the region irradiated to the semiconductor electrode, a depletion region is formed on the p-type semiconductor or the n-type semiconductor,
A method for manufacturing a semiconductor electrode.
delete delete delete 11. The method of claim 10,
The step of depositing the first metal or the second metal may include an electrodeposition, a chemical vapor deposition, a physical vapor deposition, an atomic layer deposition, and a method thereof. A method of manufacturing a semiconductor electrode by a process comprising one selected from the group consisting of combinations.
11. The method of claim 10,
The heat treatment temperature is 450 ℃ to 650 ℃, a method of manufacturing a semiconductor electrode.

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