JP2018016842A - Semiconductor electrode, light energy conversion device and method for producing semiconductor electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cause a photo-electrochemical hydrogen generation reaction.SOLUTION: A semiconductor electrode has: a p-type semiconductor layer 3 containing Cr as a structure element; and a surface layer 4 that contacts the p-type semiconductor layer and is composed of crystalline metal oxide semiconductors or amorphous metal oxide semiconductors. The surface layer 4 is put on the p-type semiconductor layer 3. Suitably, the surface layer 4 carries a promoter 5 on it.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a semiconductor electrode containing a p-type Cr-based oxide semiconductor.

As one of the methods for effective use of light energy, development of a photoelectrode for driving water splitting has been actively made, and literature on it has been issued. However, there are few examples of p-type semiconductors that can be used for water-splitting hydrogen (H ₂ ) production reaction, and most of them contain rare metals such as InP and GaP. For this reason, it is desired to develop a p-type semiconductor that is rich in resources and inexpensive.

Cr-based oxide semiconductors are a promising material because they are relatively abundant in resources and many exhibit p-type semiconductor characteristics. However, there are few studies using Cr-based oxides as photoelectrodes. For example, Cr ₂ O ₃ is known as a p-type semiconductor material, and its lower end potential of the conduction band is located on the negative side of the water splitting hydrogen generation potential, but there is no report of utilizing it as a light absorber of a photoelectrode.

CuCrO ₂ and Fe _0.84 Cr _1.0 Al _0.16 O ₃ are used for photoelectrochemical reactions in aqueous electrolytes, but they are generated by water decomposition only by observing unstable photocurrents. It has not yet been possible to actually detect H ₂ (Non-Patent Documents 1-3).

  Moreover, although there is a report on a semiconductor electrode including a p-type Fe-based oxide semiconductor, there is no mention of using a p-type Cr-based semiconductor (Patent Document 1).

JP 2016-50327 A

Ana Koriana Diaz-Garcia et al. J. Mater. Chem. A, 2015, 3, 19683-19687 Ya-Hui Chuai et al. J Mater Sci, 2016, 51, 3592-3599 Ilina Kondofersky et al. J. Am. Chem. Soc., 2016, 138, 1860-1867 Barbra Zydorczak et al. Ind. Eng. Chem. Res. 2012, 51, 16537-16543

In the prior art Cr ₂ O ₃ , CuCrO ₂ , and Fe _0.84 Cr _1.0 Al _0.16 O ₃ , the photocathode current in which electrons flow from the photoelectrode to the electrolyte solution is observed. current will be attenuated, not yet been measured in H _2. Among these papers on Cr oxides, there are papers that claim that the water-splitting hydrogen generation reaction has progressed based on the observation of the photocathode current in an aqueous solution in the absence of O ₂ . However, in this case, electrons generated by the semiconductor light excitation, without being provided to H ^+, such as the reduction of the semiconductor itself, there is a possibility that is being consumed in side reactions, not actually measured of H ₂ these In the prior art, it cannot be said that the photoelectrochemical hydrogen production reaction was successful. Actually, as will be described later, in the Cr ₂ O ₃ photoelectrode, only the attenuation of the photocurrent was observed, and the amount of hydrogen generation was very small.

  There are two possible reasons why the Cr-based p-type semiconductor cannot be applied to the photoelectrochemical hydrogen production reaction. One is that the Cr oxide is unstable in an aqueous solution. For example, it is known that in an alkaline solution, it becomes a Cr (III) hydroxide species and dissolves (Non-Patent Document 4). Another reason is that reaction sites that catalyze hydrogen generation cannot be formed on the surface of the Cr-based p-type semiconductor. In general, in a semiconductor photocatalyst, a photocatalytic reaction proceeds by supporting a promoter metal that becomes a reaction site by accepting electrons on the surface of a semiconductor that absorbs light. However, as will be described later, the photocatalytic activity was hardly improved even when Pt was supported on a Cr-based p-type semiconductor. This is thought to be because electrons are trapped by surface defects of the Cr-based semiconductor and the electron transfer to the promoter is difficult to proceed.

  The semiconductor electrode according to the present invention includes a conductive substrate, a p-type Cr-based oxide semiconductor layer made of a p-type oxide semiconductor stacked on the conductive substrate and containing Cr as a constituent element, and the p-type Cr-based semiconductor layer. A surface layer made of a metal oxide crystal having an n-type semiconductor property or an amorphous form of the metal oxide, and a promoter supported on the surface layer and promoting a chemical reaction; ,including.

The p-type Cr-based oxide semiconductor layer is at least one Cr oxide of Cr ₂ O ₃ , CuCrO ₂ , Fe _1-x CrAl _x O ₃ , ACrO ₂ , and ACr ₂ O ₄ , A is a Cr oxide which is any one of Ca, Sr, Cu, Mg, Ni, Zn, Ba, and Ag, or Ca, Sc, Ti, V, Mn, and Fe, which are different elements from these Cr oxides. , Co, Ni, Cu, Zn At least one of the semiconductors doped with at least one of them may be included.

The surface layer may include any one of TiO ₂ , ZnO, Ta ₂ O ₅ , SrTiO ₃ , and ZrO ₂ .

  The promoter may be a compound containing any one metal of Pt, Rh, Au, Co, Cu, Ru, Ni, Pd, and Ag.

The light energy conversion device according to the present invention causes a hydrogen generation reaction or a CO ₂ reduction photocatalytic reaction by irradiating the above-described semiconductor electrode with light.

  In the present invention, a p-type Cr-based oxide semiconductor layer made of a p-type oxide semiconductor containing Cr as a constituent element is formed on the transparent electrode film, and on the p-type Cr-based oxide semiconductor layer, A method for producing a semiconductor electrode comprising laminating a surface layer made of a metal oxide crystal having an n-type semiconductor characteristic or an amorphous form of the metal oxide, and carrying a promoter for promoting a chemical reaction on the surface layer. Then, the p-type Cr-based oxidized portion rain semiconductor layer and the surface layer are formed by any one of an RF magnetron sputtering method, an electrodeposition method, a spin coating method, a coating method, or a squeegee method.

  According to a semiconductor electrode in which an n-type metal oxide semiconductor is laminated on the surface of a p-type Cr-based oxide semiconductor, a hydrogen generation reaction occurs using excited electrons generated by light irradiation on the p-type Cr-based oxide semiconductor. can do.

It is a figure which shows the structural example of a semiconductor electrode. It is a schematic diagram which shows the structure of a photoelectrochemical cell. It is a figure which shows a photocurrent-potential curve. It is a figure which shows the time-dependent change of the photocurrent of each electrode. It is a figure which shows the hydrogen generation amount of each electrode. It is a figure which shows a time-dependent change of a photocurrent. It is a figure which shows a time-dependent change of a photocurrent.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments described herein.

<Configuration of semiconductor electrode>
First, a configuration example of the semiconductor electrode according to the present embodiment is shown in FIG. Thus, the conductor layer 2 is provided on the glass substrate 1, and the electroconductive board | substrate is comprised. As the glass substrate 1 having such a conductor layer 2, for example, a commercially available transparent conductive film laminated glass substrate can be used. For example, Geomatic Co., Ltd.'s highly durable transparent conductive film can be used.

  Instead of the glass substrate 1, an insulating substrate that does not transmit light may be employed, and various conductors that do not transmit light to the conductor layer 2 may be employed. In this case, no light is incident from the substrate side.

A p-type Cr-based oxide semiconductor layer 3 is formed on the conductor layer 2. Examples of the p-type Cr-based oxide semiconductor layer 3 include Cr oxides represented by Cr ₂ O ₃ , CuCrO ₂ , Fe _1-x CrAl _x O ₃ , ACrO ₂ , and ACr ₂ O ₄ , or these Cr oxides. In addition, a semiconductor containing at least one of Cr oxides doped with at least one of Ca, Sc, Ti, V, Mn, Fe, Co, Ni, Cu, and Zn, which are different elements, is used. Here, A may be one of Ca, Sr, Cu, Mg, Ni, Zn, Ba, and Ag.

Then, on the surface of the p-type Cr-based oxide semiconductor layer 3, a surface layer 4 made of an n-type metal oxide semiconductor (a metal oxide crystal having an n-type semiconductor characteristic or its amorphous) is formed. As the n-type metal oxide semiconductor, for example, an n-type metal oxide semiconductor containing any one of TiO ₂ , ZnO, Ta ₂ O ₅ , SrTiO ₃ , and ZrO ₂ can be used. Moreover, the film thickness can be 10 nm or more and 120 nm or less.

  A cocatalyst 5 made of a metal such as Pt or a metal oxide is supported on the surface of the surface layer 4. The cocatalyst 5 is a fine particle having a thickness of 1 nm.

  Thus, in the semiconductor electrode according to the present embodiment, the surface layer 4 made of an n-type metal oxide semiconductor was formed on the surface of the p-type Cr-based oxide semiconductor layer 3. Therefore, the surface of the p-type Cr-based oxide semiconductor layer 3 can be prevented from coming into contact with the solution (acidic solution), thereby preventing the p-type Cr-based oxide semiconductor layer 3 from being dissolved. Since the surface layer 4 is an n-type metal oxide and is relatively stable in an acidic solution, it hardly dissolves.

  In addition, since the surface layer 4 is an n-type metal oxide semiconductor, electrons generated in the p-type Cr-based oxide semiconductor layer 3 easily move to the surface layer 4 through the pn junction, thereby increasing the photocurrent. be able to.

  A promoter is supported on the surface of the surface layer 4. When the co-catalyst is directly supported on the p-type Cr-based oxide semiconductor layer 3, it is difficult to form an excellent contact interface between the two, so that electron transfer is unlikely to occur, but the interface that contacts the catalyst has changed to the surface layer 4, Electron transfer to the cocatalyst 5 is promoted, and a reduction reaction can occur via the cocatalyst 5. As a result, a stable and large photocurrent and an accompanying improvement in hydrogen production efficiency can be realized.

<Photoelectrochemical cell>
In FIG. 2, the structure of the photoelectrochemical cell using the semiconductor electrode which concerns on embodiment is shown. A semiconductor electrode 6 shown in FIG. 2, a reference electrode 7 made of Ag / AgCl, and a counter electrode 8 made of a Pt (platinum) wire or the like are immersed in an electrolyte solution 9 such as K ₂ SO ₄ to form a sealed container 10. Housed inside. For example, argon (Ar) gas is sealed in the container 10.

  The container 10 is made of, for example, Pyrex (registered trademark) glass, and transmits light from the outside. The conductor layer 2, the reference electrode 7, and the counter electrode 8 of the semiconductor electrode 6 are connected to a potentiostat 11.

  With such a photoelectrochemical cell, the potential of the semiconductor electrode 6 with respect to the reference electrode 7 is adjusted by the potentiostat 11. Thereby, the electric potential at the time of reaction with the electrolyte in the semiconductor electrode 6 can be determined.

  In the present embodiment, a semiconductor electrode 6 is used in which the surface layer 4 is formed on the p-type Cr-based oxide semiconductor layer 3 shown in FIG. 1 and the promoter 5 is disposed on the surface thereof. Therefore, the reaction of the electrolyte solution 9 with the electrolyte occurs when electrons generated in the p-type Cr-based oxide semiconductor layer 3 by light irradiation move to the surface layer 4. The generated photocurrent flows from the semiconductor electrode 6 toward the counter electrode 8.

<Production of semiconductor electrode>
“Formation of Cr-based oxide semiconductor layer 3”
By RF magnetron sputtering, on the conductor layer 2 of the glass substrate 1 on which the conductor layer 2 is formed in Ar plasma, on the conductor layer 2 in Ar / O ₂ (45: 5 v / v) mixed plasma. A Cr ₂ O ₃ film was deposited to 60 nm by sputtering Cr. _Then, N 2 / mixed under a stream of _{O 2 (4: 1 v /} v), was crystallized by heat treatment at 550 ° C.. As a result, the Cr-based oxide semiconductor layer 3 made of Cr ₂ O ₃ crystals is formed on the conductor layer 2.

“Lamination of surface layer 4”
Next, the surface layer 4 of 10 to 120 nm was laminated on the Cr-based oxide semiconductor layer 3 by sputtering TiO ₂ in Ar / O ₂ (4: 1 v / v) mixed plasma. The post heat treatment was performed at 475 ° C. under a mixed air stream of N ₂ and O ₂ (4: 1 v / v). As a result, the surface layer 4 made of TiO ₂ crystals is formed.

"Supporting promoter 5"
Of TiO ₂ TiO ₂ on the semiconductor electrode formed by laminating a surface layer 4 in an Ar plasma, by sputtering Pt as cocatalyst 5 was laminated thickness 1nm equivalent Pt particles (cocatalyst 5).

Thus, a conductor layer 2, a Cr-based oxide semiconductor layer 3 of Cr ₂ O ₃ and a surface layer 4 of TiO ₂ are formed on a glass substrate 1, and a semiconductor in which a Pt promoter 5 is supported on the surface layer. Electrode 6 (Cr ₂ O ₃ electrode) is produced.

<Specific example>
Examples 1 to 5 and Comparative Examples 1 to 3 were prepared for the semiconductor electrode 6 and examined for a photoelectrochemical cell using the same. This will be described below.

○ Example 1
An electrode in which 10 nm of TiO ₂ is stacked on a Cr ₂ O ₃ electrode and 1 nm of Pt is supported.

Example 2
An electrode in which 30 nm of TiO ₂ is stacked on a Cr ₂ O ₃ electrode and 1 nm of Pt is supported

Example 3
An electrode in which 60 nm of TiO ₂ is stacked on a Cr ₂ O ₃ electrode and 1 nm of Pt is supported.

Example 4
An electrode in which 80 nm of TiO ₂ is stacked on a Cr ₂ O ₃ electrode and 1 nm of Pt is supported.

Example 5
Cr ₂ O ₃ and TiO ₂ was 120nm laminated on the electrode electrodes 1nm loading Pt

○ Comparative Example 1
Cr ₂ O ₃ electrode

○ Comparative Example 2
Electrode carrying 1 nm of Pt directly on the Cr ₂ O ₃ electrode

○ Comparative Example 3
An electrode in which 60 nm of TiO ₂ is laminated on a Cr ₂ O ₃ electrode

<Evaluation of photoelectrochemical properties>
In a sealed cell containing an Ar-substituted 0.5 M Na ₂ CO ₃ -NaHCO ₃ (1: 1; pH 9.8) mixed solution, any one of Examples 1 to 5 and Comparative Examples 1 to 3 was used as a working electrode. An evaluation experiment was conducted using a tripolar photoelectrochemical cell (FIG. 2) using a Pt wire as a counter electrode and an Ag / AgCl electrode as a reference electrode. A bipotentiostat was used for the measurement.

The current-potential characteristic was measured by sweeping the potential of the working electrode with respect to the reference electrode while intermittently irradiating the light of pseudo sunlight (AM1.5, 100 mWcm ⁻² ). Photoelectrolysis is performed at −0.5 V vs. while irradiating light of pseudo-sunlight (AM1.5, 100 mWcm ⁻² ). This was performed by applying a potential of Ag / AgCl (+0.1 V vs reversible hydrogen electrode potential (reference electrode)) for 1 hour.

<Improvement of photoelectrochemical properties by introduction of surface layer>
The photocurrent-potential curves of Comparative Examples 1 to 3 and Example 3 are shown in FIG.

In the case of the Cr ₂ O ₃ electrode without the surface layer 4 and the promoter 5 (Comparative Example 1), a negative photocurrent, that is, a photocathode current was observed when irradiated with light, but + 0.1V to +0. A dark current peak was observed in the vicinity of 8 V vs Ag / AgCl. In the Cr ₂ O ₃ electrode (Comparative Example 2) in which the surface oxide layer 4 was not provided and Pt was supported as the promoter 5 on the Cr-based oxide semiconductor layer 3, the photocurrent disappeared and the dark current increased. In the case of the Cr ₂ O ₃ electrode laminated with TiO ₂ (Comparative Example 3), the photocurrent increased compared to Comparative Example 1, and the dark current decreased.

On the other hand, _Cr 2 the surface layer 4 of TiO ₂ laminated on _{O 3} and Cr-based semiconductor layer 3, _Cr 2 _{O 3} electrode carrying Pt as a promoter 5 on the surface layer 4, i.e. Pt supported TiO ₂ laminated Cr _{In 2} O ₃ (Example 3), a larger photocurrent was seen than in Comparative Examples 1 to 3, and dark current was hardly seen. That is, by sweeping the potential in the negative direction, the difference in current between when the light is turned on and off becomes significant, and the negative current when the light is turned on increases. From this, it can be seen that the photocurrent was effectively generated in Example 3.

<Stabilization of photocurrent by introduction of surface layer>
In Comparative Examples 1 to 3 and Example 3, -0.5 V vs. FIG. 4 shows changes with time in photocurrent when simulated sunlight is irradiated for 60 minutes while applying a potential of Ag / AgCl (+0.1 V vs. reversible hydrogen electrode potential).

In the case of the Cr ₂ O ₃ electrode (Comparative Example 1), a dark current of about ² μA · cm ⁻² was observed before the start of light irradiation. When irradiated with light, a photocurrent of about 12 μA · cm ⁻² was observed, but attenuated and became 1 μA · cm ⁻² after 60 minutes. In the Cr ₂ O ₃ electrode carrying Pt (Comparative Example 2), only dark current was observed, and no photocurrent was observed. In the Cr ₂ O ₃ electrode laminated with TiO ₂ (Comparative Example 3), no dark current was observed, but only a photocurrent of about 1 μA · cm ⁻² was generated.

On the other hand, the Pt-supported TiO ₂ multilayer _Cr 2 _{O 3} (Example 3), immediately after the start of light irradiation to the observed 40 .mu.A · ^{cm -2} order of photocurrent, also in the light irradiation 1 h after, 30 .mu.A · ^{cm -2} order Maintained.

The amount of H ₂ produced in each reaction vessel after these photoelectrochemical measurements is shown in FIG. In Comparative Examples 1 to 3, almost no H ₂ was produced, and only Example 3 produced H ₂ . From this, it can be seen that the photocurrent by water electrolysis is effectively generated in Example 3.

<Depends on film thickness of TiO ₂ layer>
A Pt-supported TiO ₂ laminated Cr ₂ O ₃ electrode (Examples 1 to 5) having different thicknesses of TiO ₂ was applied at −0.5 V vs. FIG. 6 shows the change in photocurrent with time when irradiated with simulated sunlight for 3 minutes while applying a potential of Ag / AgCl (+0.1 V vs. reversible hydrogen electrode potential).

The electrode having the TiO ₂ layer of 10 nm (Example 1) has a relatively large dark current and attenuation of the photocurrent with the passage of time. However, in the electrode having a thickness of 30 nm or more, the dark current is small and the photocurrent is reduced. The attenuation of was also suppressed. Although the photocurrent decreased at 80 nm or more, a stable photocurrent was observed. From these results, it can be seen that by laminating TiO ₂ on the Cr ₂ O ₃ electrode, the effect of suppressing dark current and increasing photocurrent is exhibited. The film thickness of TiO ₂ is 10 nm or more, the desirable film thickness is 30 nm or more and 120 nm or less, and the optimum film thickness is 30 nm or more and 60 nm or less.

<Effect of TiO ₂ laminated>
As described above, in Comparative Examples 1 to 3, almost no photocurrent was generated, or even when generated, the photocurrent was attenuated and the water splitting hydrogen generation reaction did not proceed. In the Cr ₂ O ₃ electrode (Comparative Example 1), it is considered that the photoexcited electrons were consumed in the self-reduction of Cr ₂ O ₃ itself, not in the water splitting reaction.

In the Cr ₂ O ₃ electrode (Comparative Example 2) supporting Pt as a hydrogen generation co-catalyst, the dark current increased from that in Comparative Example 1 and the photocurrent decreased. Therefore, the surface of Cr ₂ O ₃ and Pt It is presumed that there is an interaction between them, and electrons flow into the generated level, thereby inhibiting the water splitting reaction.

In the case of Cr ₂ O ₃ (Comparative Example 3) in which TiO ₂ is laminated, the dark current is suppressed, but the reaction does not proceed because there is no site for catalyzing the hydrogen generation reaction on the TiO ₂ surface.

On the other hand, in Pt-supported TiO ₂ laminated Cr ₂ O ₃ (Example 1-5), dark current due to Pt support did not occur, photocurrent increased, and stable water decomposition proceeded. This is considered to be due to the effect of protecting the surface of the TiO ₂ layer, the effect of shielding unfavorable interactions, and the effect of promoting electron transfer. It is considered that the self-reduction reaction of Cr ₂ O ₃ was suppressed because the contact between the Cr ₂ O ₃ and the electrolyte solution was blocked by the protective effect of the TiO ₂ layer. Moreover, since the contact between Cr ₂ O ₃ and Pt was interrupted by inserting TiO ₂ , there was no interaction between the Cr ₂ O ₃ surface and Pt causing dark current, and Pt generated hydrogen. It is presumed that it has become a reaction site. Further, due to the effect of promoting electron transfer due to band bending accompanying the formation of a pn junction between p-type Cr ₂ O ₃ and n-type TiO ₂ , electrons are not easily accumulated in Cr ₂ O ₃ , and easily flow into Pt. It is thought that it became. As a result of these, it is considered that water-resolved hydrogen generation using a Cr-based semiconductor electrode has become possible.

<Hydrogen generation process of Pt-supported TiO ₂ laminated Cr ₂ O ₃ >
Based on the above results, the photoelectrochemical hydrogen generation process will be further described. FIG. 7 shows an energy diagram of Pt-supported TiO ₂ laminated Cr ₂ O ₃ using Cr ₂ O ₃ for the p-type Cr-based oxide semiconductor layer 3, TiO _{2 for the} surface layer 4, and Pt for the co-catalyst 5.

Here, the light transmitted through the TiO ₂ is absorbed in the p-type Cr-based oxide semiconductor _{Cr 2 O 3, Cr 2 O} 3 is excited.

Accordingly, holes (h ⁺ ) are generated in the valence band of Cr ₂ O ₃ and electrons (e ⁻ ) are generated in the conduction band. The hole (h ⁺ ) moves to the back conductor layer 2 (transparent electrode) and flows to the counter electrode 8. On the other hand, the electrons (e ⁻ ) move to TiO ₂ due to the band gradient formed by the pn junction. Electron transfer to Pt is unlikely to occur when directly contacting Cr ₂ O ₃ , but is likely to occur when contacting TiO ₂ , so that electron transfer from TiO ₂ to Pt proceeds, and H ₂ on Pt Generation proceeds.

When the surface layer 4 is formed by stacking n-type semiconductor layers such as ZnO, Ta ₂ O ₅ , SrTiO ₃ , and ZrO ₂ instead of TiO ₂ , and as the co-catalyst 5, Rh, Au, When a metal or metal oxide that catalyzes hydrogen generation such as Co, Cu, Ru, Ni, Pd, or Ag is introduced, it is considered that H ₂ generation proceeds by the same mechanism.

  1 glass substrate, 2 conductor layer, 3 p-type Cr-based oxide semiconductor layer, 4 surface layer, 5 promoter, 6 semiconductor electrode, 7 reference electrode, 8 counter electrode, 9 electrolyte solution, 10 container, 11 potentiostat.

Claims (6)

A conductive substrate;
A p-type Cr-based oxide semiconductor layer made of a p-type oxide semiconductor stacked on the conductive substrate and containing Cr as a constituent element;
A surface layer made of a metal oxide crystal or an amorphous metal oxide layered on the p-type Cr-based oxide semiconductor layer and having n-type semiconductor properties;
A promoter supported on the surface layer and promoting a chemical reaction;
including,
Semiconductor electrode. The semiconductor electrode according to claim 1,
The p-type Cr-based oxide semiconductor layer is at least one Cr oxide of Cr ₂ O ₃ , CuCrO ₂ , Fe _1-x CrAl _x O ₃ , ACrO ₂ , and ACr ₂ O ₄ , wherein A is Cr oxide which is any one of Ca, Sr, Cu, Mg, Ni, Zn, Ba and Ag, or Ca, Sc, Ti, V, Mn, Fe and Co which are different elements from these Cr oxides , Including at least one of semiconductors doped with at least one of Ni, Cu, and Zn,
Semiconductor electrode. The semiconductor electrode according to claim 1 or 2,
The surface layer includes any one of TiO ₂ , ZnO, Ta ₂ O ₅ , SrTiO ₃ , and ZrO ₂ ;
Semiconductor electrode. The semiconductor electrode according to any one of claims 1 to 3,
The promoter is a compound containing any one metal of Pt, Rh, Au, Co, Cu, Ru, Ni, Pd, and Ag.
Semiconductor electrode. Including the semiconductor electrode according to any one of claims 1 to 4,
By irradiating the semiconductor electrode with light, a hydrogen generation reaction or a CO ₂ reduction photocatalytic reaction occurs.
Light energy conversion device. Forming a p-type Cr-based oxide semiconductor layer made of a p-type oxide semiconductor containing Cr as a constituent element on the transparent electrode film;
On the p-type Cr-based oxide semiconductor layer, a surface layer made of a metal oxide crystal having n-type semiconductor characteristics or an amorphous form of the metal oxide is laminated,
On the surface layer, a promoter for promoting a chemical reaction is supported.
A method for manufacturing a semiconductor electrode, comprising:
The p-type Cr-based oxidized portion rain semiconductor layer and the surface layer are formed by any one of an RF magnetron sputtering method, an electrodeposition method, a spin coating method, a coating method, or a squeegee method.
A method for manufacturing a semiconductor electrode.