WO2023082586A1 - Photoelectrode, water photoelectrolysis apparatus and energy system using same, and water photoelectrolysis method - Google Patents

Abstract

The present disclosure relates to a photoelectrode, a water photoelectrolysis apparatus and an energy system using same, and a water photoelectrolysis method. The photoelectrode comprises a catalyst layer, an adjustment layer and an electron transport layer, which are sequentially stacked in a stacking direction and are in contact with each other, wherein the catalyst layer contains a reducing catalyst; and the material of the adjustment layer has the following features of surface work functions: denoting the surface work function when the material contained in the adjustment layer is present independently as φ8, denoting the surface work function when the reducing catalyst is present independently as φ3, and denoting the surface work function when the material contained in the electron transport layer is present independently as φ2n, and φ8 ≤ φ2n < φ3. The photoelectrode of the present disclosure can effectively reduce transport resistance to photo-generated charges from an electron transport layer to a catalyst, and prevent the formation of a transport barrier, thereby improving the transmission efficiency of charges from a light absorbing layer to the catalyst and the overall energy conversion efficiency of the photoelectrode.

Description

Photoelectrode, photoelectric water splitting device, energy system using the same, and method for photoelectric water splitting

This application claims the priority of the Chinese patent application submitted to the China Patent Office on November 15, 2021, with the application number 202111350675.5, and the title of the invention is "photoelectrode, photoelectric water splitting device, energy system using the same, and photoelectric water splitting method" rights, the entire contents of which are incorporated in this application by reference.

technical field

The disclosure relates to the field of new energy, and in particular, to a photoelectrode, a photoelectric water splitting device, an energy system using the same, and a photoelectric water splitting method.

Background technique

With the continuous consumption of fossil energy such as coal and oil, the world's energy crisis and environmental pollution are becoming increasingly severe. Vigorously developing clean energy is the only way to achieve sustainable human development. Hydrogen is an important clean energy, and the energy production, storage and utilization system centered on hydrogen energy is considered to be an ideal way to replace the current energy system based on fossil fuels. Hydrogen production by electrolysis of water has attracted extensive research and application attention due to its simple principle, high purity of hydrogen, and clean and pollution-free production process. The photoelectric water electrolysis hydrogen production technology can use light energy to reduce the energy consumption of electrolysis water hydrogen production, and can directly convert light energy into hydrogen chemical energy without consuming additional electric energy. The photoelectric water splitting device generally includes one or two photoelectrodes, and the photoelectrode undertakes two core functions: one is to absorb sunlight to generate photogenerated charges (including photogenerated electrons and holes); the other is to use the generated photogenerated electrons and holes to catalyze Carry out reduction and oxidation reactions. Therefore, photoelectrodes usually contain photoresponsive components and reaction catalytic components. The light absorption efficiency (η _abs ), the separation and transmission efficiency of photogenerated carriers (η _charge ), and the electrocatalytic efficiency (i.e. Faraday efficiency, η _F ) jointly determine the energy conversion efficiency of the photoelectrode (solar-to-hydrogen efficiency, η _STH )(η _STH =η _abs ×η _charge ×η _F ), and the effective utilization of photogenerated carriers is the key factor limiting the energy conversion efficiency of current photoelectrodes.

In the prior art and research, the energy conversion efficiency of photoelectrodes composed of photovoltaic structures combined with electrocatalytic materials is relatively high (currently the highest efficiency is 19%), but in the existing photoelectrodes of this type, due to the work function between photovoltaic structures and catalysts The mismatch problem leads to the formation of a certain charge transport barrier, resulting in the loss of transmission voltage, making the overall energy conversion efficiency of the photoelectrode lower than its theoretical value.

overview

The purpose of the present disclosure is to provide a photoelectrode, a photoelectric water splitting device, an energy system using the same, and a photoelectric water splitting method. The photoelectrode can reduce the transfer resistance of photogenerated charges to the catalyst, improve the transfer and utilization efficiency of photogenerated charges and the overall photoelectrode energy conversion efficiency.

In order to achieve the above object, the first aspect of the present disclosure provides a photoelectrode, which includes a catalyst layer, an adjustment layer, and an electron transport layer that are sequentially stacked and contacted according to the stacking direction; wherein, the catalyst layer contains a reducing catalyst , the material of the adjustment layer has the following surface work function characteristics: the surface work function when the material contained in the adjustment layer exists independently is recorded as

The surface work function when the reducing catalyst exists independently is denoted as

The surface work function when the material contained in the electron transport layer exists independently is recorded as

in,

Optionally, the adjustment layer includes 1-2 adjustment sublayers, each of which has a thickness of 0.2-10 nm, and the total thickness of the adjustment layers is 0.2-12 nm.

Optionally, the electron transport layer includes 1-3 electron transport sublayers, and the surface work function of the material contained in the electron transport sublayer on the side of the electron transport layer close to the adjustment layer exists independently

satisfy

Optionally, the adjustment layer is a continuous layer or a discontinuous layer; on a plane perpendicular to the stacking direction, the projected area of the adjustment layer accounts for more than 80% of the projected area of the electron transport layer.

Optionally, the photoelectrode further includes a first passivation layer, the first passivation layer is disposed between the adjustment layer and the catalyst layer, the thickness of the first passivation layer is 0.1-3 nm, the The material of the first passivation layer is selected from one or more of silicon nitride, silicon oxide and titanium oxide.

Optionally, the material of the adjustment layer is selected from an insulating material whose surface work function is less than 2eV when it exists independently, a metal material whose surface work function is 2.1-4.3eV when it exists independently, and a surface work function when it exists independently. The surface work function is 1.9-4.1eV at least one of the semiconducting materials;

Preferably, the insulating material is alkali metal fluoride and/or alkaline earth metal fluoride, more preferably one or more of LiF, NaF, CsF, _MgF2 and _CaF2 ;

Preferably, the metal material is selected from one or more of alkali metals, alkaline earth metals and transition metals, more preferably one of Li, Na, K, Cs, Ca, Mg, Zn, Al, Ag and Nb species or several;

Preferably, the semiconductor material is selected from inorganic low work function semiconductor materials and/or organic n-type semiconductor materials, more preferably ErSi _0.2 , ErSi _0.85 , ErSi _1.7 , YbSi ₂ , TbSi _1.7 , SmSi _1.7 , DPPT2-TT, PDBTAZ , TCTA, NPB, m-MTDATA, BDB and one or more of Al-doped ZnO.

Optionally, the reducing catalyst has an overpotential of less than _50mV at a current density of 10mA/ ^cm2 in 0.5M _H2SO4 or 1M KOH, and

Greater than 4.5eV;

Preferably, the reducing catalyst is selected from Pt, Pd, Ru, Rh, Ni, Co, Pt-Pd alloy, Pt-Fe alloy, Pt-Ni alloy, Pt-Co alloy, Ni-Mo alloy, Ni-Zn alloy, Pt-Ru alloy, Co-Fe-Pt alloy, metal phase molybdenum sulfide and metal phase molybdenum selenide.

Optionally, the electron transport layer contains an n-type semiconductor material, preferably TiO _x , TiO ₂ , ZnO, SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , CdS, fullerene and its derivatives, polyethylene One or more of imine, polyethoxyethyleneimine and graphene.

Optionally, the photoelectrode further includes a light absorption layer, a hole transport layer, and an electrode that are sequentially stacked and contacted according to the stacking direction, and the light absorption layer is in contact with the side of the electron transport layer away from the adjustment layer ;

The material of the light absorbing layer is selected from Group III-Group V semiconductors and heterojunctions, Group IIB-Group VIA semiconductors and heterojunctions, copper indium gallium selenide thin films, perovskite, silicon, PCDTBT:PC One or more of ₇₀ BM and polyethylene;

The material of the hole transport layer is selected from p-type semiconductor and/or n-type semiconductor materials, preferably nickel oxide, copper thiocyanide, cuprous iodide, cuprous oxide, 2,2',7,7'- Tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene and its derivatives, poly[bis(4-phenyl)(2,4,6-trimethyl phenyl)amine], poly(3,4-ethylenedioxythiophene), poly(3-hexylthiophene), poly(3-hexyloxythiophene), poly(3-dodecyloxythiophene), poly(3-dodecyloxythiophene), poly (3,4-ethylenedioxythiophene): one or more of polystyrene sulfonate, molybdenum oxide, vanadium oxide and tungsten oxide;

The electrode material is selected from one or more of Ti, Au, Pd, Al, Ag, Pt, Cu, Ni, graphite, fluorine-doped tin oxide, indium tin oxide and indium zinc oxide.

The second aspect of the present disclosure provides a photoelectric water splitting device, which includes the photoelectrode provided by the first aspect of the present disclosure.

The third aspect of the present disclosure provides an energy system, the energy system is provided with the photoelectric water splitting device provided in the second aspect of the present disclosure; the hydrogen generated by the photoelectric water splitting device; and the fuel cell, which is connected to the hydrogen storage device through a second pipe, and converts the hydrogen stored in the hydrogen storage device into electrical energy.

The fourth aspect of the present disclosure provides a method for producing hydrogen by photoelectric water splitting, the method has the following steps: (a) providing the photoelectric water splitting device described in the second aspect of the present disclosure; (b) irradiating the photoelectrode light, the process of generating hydrogen on the photoelectrode.

Through the above technical scheme, the photoelectrode of the present disclosure is provided with an adjustment layer of a specific material, which can effectively reduce the transfer resistance of photogenerated charges from the electron transfer layer to the catalyst, prevent the formation of a transfer barrier, and thereby improve the absorption of charges from light. Layer-to-catalyst transfer efficiency and overall energy conversion efficiency of the photoelectrode.

Other features and advantages of the present disclosure will be described in detail in the detailed description that follows.

Brief description of the drawings

The accompanying drawings are used to provide a further understanding of the present disclosure, and constitute a part of the description, together with the following specific embodiments, are used to explain the present disclosure, but do not constitute a limitation to the present disclosure. In the attached picture:

FIG. 1 is a schematic structural view of a specific embodiment of a photoelectrode of the present disclosure;

Fig. 2 is a schematic structural view of another specific embodiment of the photoelectrode of the present disclosure;

3 shows a schematic diagram of the transmission energy level before and after the contact between the electron transport layer 2 and the catalyst layer 3 in the case of Example 1 of the present disclosure without the adjustment layer 8;

4 shows a schematic diagram of the transmission energy level before and after the contact between the electron transport layer 2 and the catalyst layer 3 in the case of Example 1 of the present disclosure containing the adjustment layer 8;

5 shows a schematic diagram of the transmission energy level before and after the contact between the electron transport layer 2 and the catalyst layer 3 in the case of Example 2 of the present disclosure without the adjustment layer 8;

Fig. 6 shows a schematic diagram of the transport energy level before and after the contact between the electron transport layer 2 and the catalyst layer 3 in the case of Example 2 of the present disclosure containing the regulating layer 8;

Figure 7 shows that the conditioning layer 8 of the present disclosure has a discontinuous layered structure containing holes;

FIG. 8 shows that the adjustment layer 8 of the present disclosure has a discontinuous layered structure composed of multiple bulk materials;

FIG. 9 shows the catalyst morphology contained in the catalyst layer of the present disclosure.

Explanation of reference signs

1. Light absorption layer 2. Electron transport layer 3. Catalyst layer

4. Hole transport layer 5. Electrode 6. Wire

7. Counter electrode 8. Adjustment layer

A detailed description

Specific embodiments of the present disclosure will be described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described here are only used to illustrate and explain the present disclosure, and are not used to limit the present disclosure.

The first aspect of the present disclosure provides a photoelectrode, which includes a catalyst layer 3, an adjustment layer 8, and an electron transport layer 2 that are sequentially stacked and contacted according to the stacking direction; wherein, the catalyst layer 3 contains a reducing catalyst, The material of the adjustment layer 8 has the following surface work function characteristics: the surface work function when the material contained in the adjustment layer 8 exists independently is denoted as

The surface work function when the reducing catalyst exists independently is denoted as

The surface work function when the material contained in the electron transport layer 2 exists independently is denoted as

in,

In the present disclosure, "the material exists independently" means that the material does not contact with the substance, and "the catalyst exists independently" means that the catalyst does not contact with the substance. In the traditional photoelectrode structure, in order to adjust the work function mismatch between the light absorbing layer and the catalyst layer, a multi-layer transition layer material is usually arranged between the light absorbing layer and the catalyst layer, and the surface work function of the transition layer material It is usually between the work functions of the adjacent layer materials on both sides. Although this method can alleviate the above-mentioned work function mismatch problem to a certain extent in theory, it will actually increase the interfacial transmission resistance due to the setting of multi-layer transition layers, and may even cause Transmission voltage loss increases. However, the photoelectrode of the present disclosure is provided with an adjustment layer of a specific material, and the surface work function of the adjustment layer satisfies

The function of the adjustment layer can effectively reduce the transmission resistance and transmission voltage loss of the photogenerated charge from the electron transport layer to the catalyst, prevent the formation of the transport barrier, thereby improving the transport efficiency of the charge from the light absorption layer to the catalyst and the overall energy of the photoelectrode Conversion efficiency.

According to the present disclosure, the adjustment layer 8 may include a plurality of adjustment sublayers, and the surface work function of the material of each adjustment sublayer when it exists independently

Satisfied

In a specific embodiment of the present disclosure, the adjustment layer 8 includes 1-2 adjustment sublayers, preferably 1 layer, and the thickness of each adjustment sublayer is 0.2-10 nm, preferably 0.3-3 nm, The total thickness of the adjustment layer 8 is 0.2-12 nm, preferably 0.3-5 nm. In the present disclosure, sub-layers are divided according to the consistency of material types. The present disclosure does not limit the specific shape of the adjustment layer 8. The adjustment layer 8 can be a continuous layer or a discontinuous layer. The continuous layer means that the adjustment layer is a continuous and flat layered structure. A discontinuous layered structure or a discontinuous layered structure composed of multiple bulk materials, the schematic diagrams are shown in Figure 7 and Figure 8, the black in Figure 7 and Figure 8 represents the material in the adjustment layer 8, Figure 7 shows In order to show that the adjustment layer 8 has a discontinuous layered structure containing holes, FIG. 8 shows that the adjustment layer 8 is composed of a discontinuous layered structure composed of multiple bulk materials.

According to the present disclosure, the electron transport layer 2 may include a plurality of electron transport sublayers. In a specific embodiment of the present disclosure, the electron transport layer 2 includes 1-3 electron transport sublayers, and the electron transport layer 2 is close to all electron transport sublayers. The surface work function when the material contained in the electron transport sublayer on one side of the adjustment layer 8 exists independently

satisfy

Wherein, the thickness of each electron transport sublayer is 10-50 nm, and the total thickness of the electron transport layer 2 is 10-100 nm.

According to the present disclosure, the photoelectrode further includes a first passivation layer, the first passivation layer is arranged between the adjustment layer 8 and the catalyst layer 3, so as to prevent the adjustment layer 8 from being slightly soluble in water, acid , Alkali, or materials with very active chemical properties, contact with the solution to cause damage to the structure of the photoelectrode. The thickness of the first passivation layer is 0.1-3 nm, and the material of the first passivation layer is selected from one or more of silicon nitride, silicon oxide and titanium oxide. In addition, the surface of the adjustment layer 8 is fully covered by the catalyst to form a continuous catalyst layer, which can also protect the adjustment layer 8 .

According to the present disclosure, the material of the adjustment layer 8 is selected from insulating materials whose surface work function is less than 2eV when they exist independently, metal materials whose surface work function is 2.1-4.3eV when they exist independently, and metal materials whose surface work function is 1.9-4.1 when they exist independently. At least one of the semiconductor materials of eV.

In a specific embodiment of the present disclosure, the insulating material whose surface work function is less than 2eV when it exists independently is an alkali metal fluoride and/or an alkaline earth metal fluoride, wherein the alkali metal may include Li, Na, K, One or more of Rb and Cs, and the alkaline earth metal may include one or more of Mg, Ca, Be, Sr and Ba. Preferably, the insulating material whose surface work function is less than 2eV when present independently may include but not limited to one or more of LiF, NaF, CsF, MgF ₂ and CaF ₂ . In this embodiment where the material contained in the regulating layer 8 is an insulating material with a surface work function of less than 2eV when it exists alone, the total thickness of the regulating layer 8 is preferably less than 3 mm to ensure that electrons can tunnel through. When the above-mentioned insulating material is used as the adjustment layer 8, the surface work function of the catalyst layer 3 will be reduced, and an ohmic contact will be formed with the electron transport layer 2, so that the transmission voltage loss can be ignored.

In a specific embodiment of the present disclosure, the metal material with a surface work function of 2.1-4.3eV when present independently is selected from one or more of alkali metals, alkaline earth metals and transition metals, for example, it may include but not Limited to one or more of Li, Na, K, Cs, Ca, Mg, Zn, Al, Ag and Nb. When the above-mentioned metal material is used as the adjustment layer 8, an ohmic contact is formed between the electron transport layer 2 and the adjustment layer 8, and the transmission voltage loss is negligible, while the adjustment layer 8 and the catalyst layer 3 are in metal-metal contact, and the transmission resistance can also be neglect. The surface work function of some metal materials when they exist independently is shown in the table below:

Material	Work function (eV)
Li	2.9
Na	2.28
K	2.3
Cs	2.14
Ca	2.9
Mg	3.68
Al	4.28
Ag	4.26
Nb	4.3
Zn	4.3

In a specific embodiment of the present disclosure, the semiconductor material with a surface work function of 1.9-4.1 eV when independently existing is selected from inorganic low work function semiconductor materials and/or organic n-type semiconductor materials, wherein the inorganic low work function Semiconductor materials may include, but are not limited to, ErSi _0.2 (3.28Ev), ErSi _0.85 (3.58eV), ErSi _1.7 (3.85eV), YbSi ₂ (3.68eV), TbSi _1.7 (3.79Ev), SmSi _1.7 (3.72eV) and One or more of Al-doped ZnO (3.92eV), organic n-type semiconductor materials may include but not limited to DPPT2-TT (~4.07eV), PDBTAZ (~4.2eV), TCTA (~2.3eV), One or more of NPB (~2.4eV), m-MTDATA (~2.0eV) and BDB (~1.9eV). Among them, the numbers in parentheses represent the surface work functions of the corresponding materials when they exist independently. In one embodiment, among the above-mentioned materials, a material with a surface work function of less than 4.0 eV when present independently is preferred. When the above-mentioned semiconductor material is used as the adjustment layer 8, the surface work function of the catalyst layer 3 will be reduced, and the adjustment layer 8 will form an ohmic contact with the electron transport layer 2, so that the transmission voltage loss can be ignored.

In a specific embodiment of the present disclosure, the catalyst layer 3 is a continuous layer or a discontinuous layer. The present disclosure does not specifically limit the form of the catalyst contained in the catalyst layer. For example, it can be a granular catalyst or a layered catalyst. The schematic diagram is shown in FIG. catalysts, layered catalysts are shown in Figure 9c and Figure 9d. On a plane perpendicular to the stacking direction, the projected area of the catalyst layer 3 accounts for 80-100%, preferably 95-100%, of the projected area of the regulating layer 8 .

According to the present disclosure, the catalyst layer 3 contains a reducing catalyst, which is selected from metals and/or compounds with metalloid properties that have a higher work function and better catalytic performance for hydrogen production, and have better electrocatalytic performance. In a specific embodiment of the present disclosure, the reducing catalyst has an overpotential of less than 50 mV at a current density of 10 mA/cm ² in 0.5 M H ₂ SO ₄ or 1 M KOH, and

Greater than 4.5eV. Preferably, the reducing catalyst may include but not limited to Pt, Pd, Ru, Rh, Ni, Co, Pt-Pd alloy, Pt-Fe alloy, Pt-Ni alloy, Pt-Co alloy, Ni-Mo alloy, Ni-Zn alloy, Pt-Ru alloy, Co-Fe-Pt alloy, metal phase molybdenum sulfide (1T phase MoS ₂ or 1T' phase MoS ₂ ) and metal phase molybdenum selenide (1T phase MoSe ₂ or 1T' phase MoSe ₂ ) in one or more. The surface work function of the partially reducing catalyst is shown in the following table:

Material	Work function (eV)
Pt	5.65
PD	5.0-5.12
Ru	4.71
Re	4.96
Rh	4.98
Ni	5.15
Ni-Mo	4.8～5.1
Ni-Zn	4.8～5.1
co	5
1T/1T'MoS 2	5.6～5.8
1T/1T'MoSe 2	5.2

In a specific embodiment of the present disclosure, the electron transport layer 2 contains n-type semiconductor materials, which may include but not limited to TiO _x , titanium oxide (TiO ₂ ), zinc oxide (ZnO), tin oxide (SnO ₂ ) , niobium oxide (Nb ₂ O ₅ ), tantalum oxide (Ta ₂ O ₅ ), cadmium sulfide (CdS), polyethyleneimine (PEI), polyethoxyethyleneimine (PEIE), fullerene and its derivatives One or more of PCBM, graphene and C ₆₀ , wherein fullerene and its derivatives are, for example, [6,6]-phenyl-C61-butyric acid isomethyl ester (PC61BM), [6 ,6]-Phenyl-C71-butyric acid isomethyl ester (PC71BM), C ₆₀ . In a specific embodiment, the electron transport layer comprises two sublayers, one of which contains polyethoxyethyleneimine (PEIE), which is in contact with the catalyst layer, and PEIE can reduce the work function at the interface of the electron transport functional layer. For part of the light-absorbing layer, the material obtained by n-type doping of the electron-transporting end can be selected as the material of the electron-transporting layer 2. For example, the light-absorbing layer of crystalline silicon uses n-type doped amorphous silicon as the electron-transporting layer. . The surface work function of some n-type semiconductor materials when they exist independently is shown in the table below:

Material	Work function (eV)
TiO 2	4～4.5
ZnO	3.6～4.2
SnO2	4.5
Nb 2 O 5	4.5
Ta 2 O 5	4.0
CdS	3.5
PEI	4.05
PCBM	4.37
Graphene	~4.6eV
C 60	4.69-5.02

As shown in FIG. 1 , in a specific embodiment of the present disclosure, the photoelectrode further includes a light absorbing layer 1 , a hole transport layer 4 and an electrode 5 that are sequentially stacked and contacted according to the stacking direction. Layer 1 is in contact with the side of the electron-transport layer 2 remote from the regulating layer 8 .

According to the present disclosure, the open voltage at both ends of the light absorbing layer 1 may be greater than 1.3 eV, preferably greater than 1.5 eV. The material contained in the light-absorbing layer 1 can be selected from group III-group V semiconductors and heterojunctions, IIB-VIA group semiconductors and heterojunctions, copper indium gallium selenide (CIGS) thin films, perovskite, silicon, PCDTBT: one or more of PC ₇₀ BM and polyethylene, wherein, III-V semiconductors and heterojunctions may include but not limited to GaAs, GaInAs-GaInP heterojunctions, etc., IIB-VIA semiconductors may include but Not limited to cadmium sulfide, cadmium telluride, etc., silicon may include but not limited to single crystal silicon, polycrystalline silicon, n-type silicon, p-type silicon, silicon pn junction, etc.

According to the present disclosure, the material of the hole transport layer 4 is selected from p-type semiconductor and/or n-type semiconductor materials. In a specific embodiment, the p-type semiconductor may include but not limited to nickel oxide, copper thiocyanide, cuprous iodide, cuprous oxide, 2,2',7,7'-tetra[N,N-di (4-methoxyphenyl)amino]-9,9'-spirobifluorene (Spiro-MeOTAD) and its derivatives, poly[bis(4-phenyl)(2,4,6-trimethylbenzene Base) amine] (PTAA) and one or more of polythiophene derivatives, wherein the polythiophene derivatives may include, for example, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(3-hexylthiophene )(P3HT), poly(3-hexyloxythiophene) (P3OHT), poly(3-dodecyloxythiophene) (P3ODDT), poly(3,4-ethylenedioxythiophene): polystyrenesulfonic acid One or more of salts (PEDOT:PSS), n-type semiconductor materials can include one or more of molybdenum oxide (MoO ₃ ), vanadium oxide (V ₂ O ₅ ) and tungsten oxide (WO ₃ ), for example . In one embodiment, for the light-absorbing layer, the material obtained after doping the hole-transporting end of the light-absorbing layer may be selected as the material of the hole-transporting layer 4, such as p-doped silicon, Al-doped Ge wait. In one embodiment, the hole transport functional layer 4 can also have the functions of anti-reflection layer and passivation layer in addition to the function of hole transport; for III-V semiconductor solar cells, this layer may include heterojunction base layer for epitaxial growth.

In a specific embodiment of the present disclosure, the photoelectrode further includes a second passivation layer, and the second passivation layer is disposed between the electron transport layer 2 and the light absorption layer 1 . The second passivation layer can be multilayer, preferably 1 layer, and the total thickness of the second passivation layer can be no more than 3nm, preferably 1-2nm, to ensure that electrons can tunnel through this layer without generating additional transmission resistance; the material of the second passivation layer is selected from one or more of silicon oxide, silicon nitride, titanium oxide, and zinc oxide.

As shown in Figure 2, in a specific embodiment of the present disclosure, the electrode 5 is used as a conductive electrode to connect the counter electrode 7 containing the catalytic component through a wire 6; in another embodiment, the electrode 5 is directly used as a catalytic anode . The material of the electrode 5 is well known to those skilled in the art, for example, it can be selected from Ti, Au, Pd, Al, Ag, Pt, Cu, Ni, graphite, fluorine-doped tin oxide (FTO), indium tin oxide One or more of (ITO) and indium zinc oxide (IZO). The specific structure of the electrode 5 is conventionally used by those skilled in the art, for example, it can be an opaque or transparent conductive layer containing one or more materials, a single layer or multiple layers, which can be dense, grid-like or grid-like. lattice etc.

According to the present disclosure, the present disclosure does not limit the preparation method of the photoelectrode, which can be conventionally used by those skilled in the art. In one embodiment, in order to make the adjustment layer 8 form a good contact with the electron transport layer 2 and the catalyst layer 3, the method of vacuum sputtering, atomic layer deposition or chemical deposition is first used to make the adjustment layer 8 support or grow on the electron transport layer. On the layer 2, the catalyst layer 3 is supported or grown on the adjustment layer 8 by means of atomic layer deposition, chemical deposition or electrodeposition.

The second aspect of the present disclosure provides a photoelectric water splitting device, which includes the photoelectrode provided by the first aspect of the present disclosure.

In a specific embodiment, the photoelectric water splitting device includes a photoanode known in the prior art, and the photoelectrode provided in the first aspect of the present disclosure as a photocathode.

The third aspect of the present disclosure provides an energy system, the energy system is provided with the photoelectric water splitting device provided in the second aspect of the present disclosure; the hydrogen generated by the photoelectric water splitting device; and the fuel cell, which is connected to the hydrogen storage device through a second pipe, and converts the hydrogen stored in the hydrogen storage device into electrical energy.

The fourth aspect of the present disclosure provides a method for producing hydrogen by photoelectric water splitting, the method has the following steps: (a) providing the photoelectric water splitting device provided by the second aspect of the present disclosure; (b) irradiating light to the photoelectrode , the process of generating hydrogen on the photoelectrode.

The present disclosure is further illustrated by the following examples, but the present disclosure is not limited thereby. The raw materials used in the following examples and comparative examples were obtained commercially unless otherwise specified.

Example 1

The present embodiment is a group III-group V semiconductor light-absorbing photoelectrode in series with a noble metal as the catalyst layer 3), as shown in Figure 1, the photoelectrode includes:

The light absorbing layer 1 is made of typical GaAs-based stacked photovoltaic materials, with a total output voltage of 2.8-2.9V, which successively includes a 1500nm p-type progressively doped GaInAs transition layer, a 3500nm GaInAs layer, and a 30nm GaInAs-GaInP stack A transition layer, a GaInP layer of about 2000nm, a 20nm AlInP window layer, and a 10nm AlInPO _x passivation layer; wherein, GaInAs is the hole transport end connected to the hole transport layer 4, and GaInP is the electron transport end connected to the electron transport layer;

The light absorbing layer 1 is grown on a 350 μm GaAs substrate (constituting the hole transport layer 4);

The electrode 5 is an opaque metal electrode, and the method is to sequentially deposit 70nm Pd, 70nm Ti and 200nm Au on the surface of the hole transport layer 4 by electron beam evaporation method, and then quickly calcinate at 400°C for 60s in a nitrogen atmosphere; before metal deposition, It is necessary to remove the surface oxide layer on the back of the GaAs substrate, that is, rinse with acetone, isopropanol, 10% NH ₄ OH and deoxygenated water in sequence;

The electron transport layer 2 contains TiO ₂ with a thickness of 30nm, which is synthesized by atomic deposition. The surface work function (~4.5eV) of the TiO ₂ when it exists independently is very close to the work function of the AlInP-AlInPO _x layer, and TiO ₂ can absorb light The layer plays the role of anti-corrosion and anti-reflection;

The material of the adjustment layer 8 is LiF with a thickness of 0.6nm, and it is deposited on the surface of _{the TiO} layer by vacuum sputtering. 98% of projected area;

The catalyst layer 3 is made of Pt-Ru alloy nanoparticles. The surface work function of the Pt-Ru alloy when it exists independently is 5.2eV, and the particle size is 2-5nm. It is loaded on the surface of the adjustment layer 8 by vacuum rapid sputtering or chemical deposition. The deposited amount density is 60-70mg/m ² , which is approximately equivalent to a metal layer with a thickness of 0.3nm;

The light incident end of the photoelectrode is the end where the catalyst 3 is located;

Fig. 3 and 4 have provided the transmission energy level schematic diagram before and after the contact between electron transport layer 2 and catalyst layer 3 based on this example not containing and containing regulating layer 8 situation respectively, as can be seen from the figure, when regulating layer 8 does not exist, A certain transmission barrier (Schottky barrier) will be formed between the electron transport layer 2 and the catalyst layer 3, resulting in a certain transmission voltage loss; and when the regulating layer 8 exists, the potential barrier disappears, and the transmission voltage loss can be ignored Excluding.

Example 2

This embodiment is a group III-V semiconductor series light-absorbing photoelectrode in which the non-noble metal is the catalyst layer 3. The structure of the photoelectrode is similar to that of the photoelectrode in Example 1, wherein the open circuit voltage of the light-absorbing layer 1 is 2.74 ~2.83V, composed of GaInP ₂ , GaAs and Ge three-segment photovoltaic structures in series, GaInP ₂ is the electron output terminal, connected to the electron transport layer 2; the electron transport layer 2 is TiO _x , and the surface work function of TiO _x when it exists independently is 4.5 eV; the adjustment layer 8 is alkali metal Na, and the projected area of the adjustment layer 8 accounts for 83% of the projected area of the electron transport layer 2, and the thickness is about 2nm; the catalyst layer 3 is Ni-Mo alloy particles, and when the Ni-Mo alloy exists independently The surface work function is 4.9eV, and the thickness is about 10nm; the electrode 5 is a thin film layer of Al and Au; the hole transport layer 4 is an Al-doped Ge layer formed when p-type Ge contacts the Al electrode; the catalyst layer 3 side is light incident side.

The method for depositing the adjustment layer 8 includes firstly depositing a discontinuous Na layer on TiO _x by vacuum sputtering, and then sputtering a layer of Ni-Mo alloy metal layer, the molar ratio of Ni:Mo being 1:1. Figures 5 and 6 show schematic diagrams of the transport energy levels before and after contact between the electron transport layer 2 and the catalyst layer 3 based on the example without and with the adjustment layer 8, respectively.

Example 3

The structure of the photoelectrode in this embodiment is basically the same as that in Example 2, except that the catalyst contained in the catalyst layer 3 is Ni-Mo alloy particles, and the surface work function of the Ni-Mo alloy when it exists independently is 4.85. eV, and add a passivation layer between the regulation layer 8 and the catalyst layer 3 for protecting the regulation layer 8, the passivation layer is a silicon nitride layer with a thickness of 1.5nm.

First, a discontinuous Na layer is deposited on the _TiOx of the electron transport layer 2 as the adjustment layer 8 by vacuum sputtering, and then a layer of silicon nitride is sputtered on its surface, and then a Ni-Mo alloy with a thickness of about 5 nm is deposited by chemical vapor phase Catalyst layer 2 composed of particles.

Example 4

This embodiment is a perovskite-crystalline silicon stacked light-absorbing photoelectrode in which the noble metal is the catalyst layer 3. The structure of the photoelectrode is shown in Figure 1. The overall output voltage is 2.5-2.7V. The light-absorbing layer 1 contains the first CsFAPbIBr perovskite layer, NiO, IZO, SnO ₂ , C ₆₀ , LiF, second CsFAPbIBr perovskite layer, 2,2',7,7'-tetrakis(di-p-tolylamino)spiro-9,9'- Difluorene (Spiro-TTB), microcrystalline silicon (nc-Si:H), amorphous silicon (a-Si:H) and single crystal silicon layer; the side of the single crystal silicon layer is connected to the hole transport layer 4, the hole transport Layer 4 (direction from hole transport layer 4 to electrode 5) sequentially includes amorphous doped silicon (a-Si:H) and ITO passivation anti-reflection layer; electrode 5 is ITO glass and hole transport layer 4 shares ITO layer; the side of the first CsFAPbIBr perovskite layer is connected to the electron transport layer 2, and the electron transport layer 2 (direction from the light absorbing layer 1 to the electron transport layer 2) contains C ₆₀ sublayer, SiO ₂ sublayer and IZO sublayer in sequence, and IZO The sub-layer side is sequentially connected with the adjustment layer 8 and the catalyst layer 3; the catalyst of the catalyst layer 3 is metal Rh nanoparticles with a particle size of 3-6nm, and the thickness of the catalyst layer 3 is about 10nm; the material of the adjustment layer 8 is MgF ₂ , the thickness About 1.1 nm; the catalyst layer 3 side is the light incident side.

The method of depositing the adjusting layer 8 is: depositing the MgF ₂ layer by wet chemical method, and then supporting Rh nanoparticles by photochemical deposition method.

Example 5

This embodiment is a crystalline silicon-crystalline silicon laminated light-absorbing photoelectrode, the overall output voltage of the photoelectrode is 1.56-1.61V, and the side of the electrode 5 is used as the light incident side; the electrode 5 is ITO glass; the hole transport layer 4 is SiO _x Tunneling passivation layer (a-SiO _x ); from the electrode 5 side to the catalyst layer 3 side, the light absorbing layer 1 contains p-type amorphous silicon (a-Si:H p-layer), amorphous silicon transition layer ( a-Si:H buffer layer), amorphous silicon germanium absorber layer (i-SiGe), n-type amorphous silicon transition layer (a-Si:H n-layer), n-type microcrystalline silicon layer (nc-Si: H n-layer), p-type microcrystalline silicon layer (nc-Si:H p-layer), intrinsic amorphous silicon layer (a-Si:H i-layer), n-type crystalline silicon base layer (n-type Si); the electron transport layer 2 is a layer of intrinsic amorphous silicon layer (a-Si:H i-layer) superimposed with a layer of n-type amorphous silicon layer (a-Si:H n-layer); electron transport layer 2 The n-type amorphous silicon layer side of the n-type amorphous silicon layer is successively connected with the adjustment layer 8 and the catalyst layer 3, the adjustment layer 8 is selected from the alkali metal Mg, and the projected area of the adjustment layer 8 accounts for 85% of the projected area of the electron transport layer 2, and the thickness is 3nm; the catalyst layer 3 is metal Ni, and the thickness of the catalyst layer 3 is 15nm.

The method for depositing the adjusting layer 8 is: first vacuum sputtering the Mg particle layer, and then vacuum sputtering the Ni layer thereon.

Example 6

The photoelectrode structure of this embodiment is basically the same as the photoelectrode structure of Embodiment 1. The only difference is that the material of the adjustment layer 8 is a low work function semiconductor ErSi _0.85 with a thickness of about 2nm. 90% of the projected area of layer 2.

Comparative example 1

The structure of the photoelectrode in this embodiment is basically the same as the structure of the photoelectrode in Embodiment 1, except that the adjustment layer 8 is not included.

Comparative example 2

The structure of the photoelectrode in this embodiment is basically the same as the structure of the photoelectrode in Embodiment 2, except that the adjustment layer 8 is not included.

test case 1

In this test example, a two-electrode system was used to test the performance of the photoelectrodes of Examples 1, 4, 6 and Comparative Example 1 on Chenhua CHE760E.

The specific operation steps are as follows: the photoelectrode (as photocathode) prepared by embodiment 1 or embodiment 4 or embodiment 6 or comparative example 1 is connected to the Ti sheet (as photoanode) deposited with _RuO2 by copper wire, respectively placed Into the cathode tank and anode tank of the electrolytic cell, there is a layer of Nafion diaphragm between the cathode tank and the anode tank; except for the light-transmitting quartz glass on the photocathode side, the rest of the electrolytic cell is black to prevent the influence of light on other parts; The cathodically illuminated area is about 0.3 cm ² . 1M HClO ₄ was selected as the acidic electrolyte and 0.5M KH ₂ PO ₄ /K ₂ HPO ₄ phosphate buffer solution was used as the neutral electrolyte for performance testing; the electrolyte was purged with nitrogen for 1 hour before use to reduce the effect on the subsequent reaction of solution oxygen; to prevent mixing of the gases produced. During the reaction, a 500W xenon lamp was used to simulate AM1.5G sunlight to irradiate the photoelectrode, and the light intensity on the photoelectrode was kept at 100mW/cm ² . The test results are shown in Table 1.

Table 1

As can be seen from the data in Table 1, no matter in acidic or neutral electrolyte, when the additional voltage is -0.4VvsRuO , the electrochemical reaction current density of the photoelectrodes of Examples 1 _, 4, and 6 is greater than that of Comparative Example 1, which shows that the photoelectrode of the present disclosure can reduce the transfer resistance of the photogenerated charge to the catalyst, improve the transfer and utilization efficiency of the photogenerated charge and the overall energy conversion efficiency of the photoelectrode.

test case 2

In this test example, a two-electrode system was used to test the performance of the photoelectrodes of Examples 2, 3, 5 and Comparative Example 2 on Chenhua CHE760E. The test conditions are basically the same as in Test Example 1, except that the electrolyte used is 1M KOH alkaline electrolyte and the additional voltage is -0.5VvsRuO ₂ . The test results are shown in Table 2,

Table 2

the	Current density at -0.5VvsRuO 2 in mA/cm 2
Example 2	-17.7
Example 3	-18.8
Example 5	-18.2
Comparative example 2	-15.2

As can be seen from the data in Table 1, in the alkaline electrolyte, when the additional voltage is-0.5VvsRuO , the electrochemical reaction current density of the photoelectrode adopting Examples ₂ , 3, and 5 is all greater than that of the photoelectrode adopting Comparative Example 2 This shows that the photoelectrode of the present disclosure can reduce the transfer resistance of the photogenerated charge to the catalyst, improve the transfer utilization efficiency of the photogenerated charge and the overall energy conversion efficiency of the photoelectrode.

The preferred embodiments of the present disclosure have been described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure. These simple modifications all belong to the protection scope of the present disclosure.

In addition, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way if there is no contradiction. The combination method will not be described separately.

In addition, various implementations of the present disclosure can be combined arbitrarily, as long as they do not violate the idea of the present disclosure, they should also be regarded as the content disclosed in the present disclosure.

Claims (12)

1. A photoelectrode, comprising a catalyst layer (3), an adjustment layer (8) and an electron transport layer (2) that are sequentially stacked and contacted according to a stacking direction;

   Wherein, the catalyst layer (3) contains a reducing catalyst, and the material of the adjustment layer (8) has the following surface work function characteristics:

   The surface work function when the material contained in the adjustment layer (8) exists independently is denoted as

   

   The surface work function when the reducing catalyst exists independently is denoted as

   

   The surface work function when the material contained in the electron transport layer (2) exists independently is denoted as

   

   in,

   
2. The photoelectrode according to claim 1, wherein the adjustment layer (8) comprises 1-2 adjustment sublayers, each of which has a thickness of 0.2-10 nm, and the total of the adjustment layer (8) The thickness is 0.2-12nm.
3. The photoelectrode according to claim 1 or 2, wherein the electron transport layer (2) comprises 1-3 electron transport sublayers, and the electron transport layer (2) is close to the adjustment layer (8) side The surface work function of the materials contained in the electron-transporting sublayer of

   

   satisfy

   
4. The photoelectrode according to claim 1, wherein the adjustment layer (8) is a continuous layer or a discontinuous layer; on a plane perpendicular to the stacking direction, the projected area of the adjustment layer (8) accounts for the electron More than 80% of the projected area of the transmission layer (2).
5. The photoelectrode according to claim 1, wherein the photoelectrode further comprises a first passivation layer, and the first passivation layer is arranged between the adjustment layer (8) and the catalyst layer (3), so The thickness of the first passivation layer is 0.1-3nm, and the material of the first passivation layer is selected from one or more of silicon nitride, silicon oxide and titanium oxide.
6. The photoelectrode according to claim 1, wherein the material of the adjustment layer (8) is selected from an insulating material whose surface work function is less than 2eV when it exists independently, a metal material whose surface work function is 2.1-4.3eV when it exists independently, and at least one semiconductor material having a surface work function of 1.9-4.1 eV on its own;

   Preferably, the insulating material is alkali metal fluoride and/or alkaline earth metal fluoride, more preferably one or more of LiF, NaF, CsF, _MgF2 and _CaF2 ;

   Preferably, the metal material is selected from one or more of alkali metals, alkaline earth metals and transition metals, more preferably one of Li, Na, K, Cs, Ca, Mg, Zn, Al, Ag and Nb species or several;

   Preferably, the semiconductor material is selected from inorganic low work function semiconductor materials and/or organic n-type semiconductor materials, more preferably ErSi _0.2 , ErSi _0.85 , ErSi _1.7 , YbSi ₂ , TbSi _1.7 , SmSi _1.7 , DPPT2-TT, PDBTAZ , TCTA, NPB, m-MTDATA, BDB and one or more of Al-doped ZnO.
7. The photoelectrode according to claim 1, wherein the reducing catalyst has an overpotential of less than _50mV at a current density of 10mA/ ^cm in 0.5M _H2SO4 or 1M KOH, and

   

   Greater than 4.5eV;

   Preferably, the reducing catalyst is selected from Pt, Pd, Ru, Rh, Ni, Co, Pt-Pd alloy, Pt-Fe alloy, Pt-Ni alloy, Pt-Co alloy, Ni-Mo alloy, Ni-Zn alloy, Pt-Ru alloy, Co-Fe-Pt alloy, metal phase molybdenum sulfide and metal phase molybdenum selenide.
8. The photoelectrode according to claim 1, wherein the electron transport layer (2) contains an n-type semiconductor material, preferably TiO _x , TiO ₂ , ZnO, SnO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , CdS One or more of , fullerene and its derivatives, polyethyleneimine, polyethoxyethyleneimine and graphene.
9. The photoelectrode according to claim 1, wherein the photoelectrode further comprises a light absorbing layer (1), a hole transport layer (4) and an electrode (5) which are sequentially stacked and contacted according to the lamination direction, the photoelectrode The absorption layer (1) is in contact with the side of the electron transport layer (2) away from the adjustment layer (8);

   The material of the light absorbing layer (1) is selected from group III-group V semiconductors and heterojunctions, group IIB-VIA semiconductors and heterojunctions, copper indium gallium selenide thin films, perovskite, silicon, PCDTBT: one or more of PC ₇₀ BM and polyethylene;

   The material of the hole transport layer (4) is selected from p-type semiconductor and/or n-type semiconductor materials, preferably nickel oxide, copper thiocyanide, cuprous iodide, cuprous oxide, 2,2',7, 7'-Tetrakis[N,N-bis(4-methoxyphenyl)amino]-9,9'-spirobifluorene and its derivatives, poly[bis(4-phenyl)(2,4,6 -trimethylphenyl)amine], poly(3,4-ethylenedioxythiophene), poly(3-hexylthiophene), poly(3-hexyloxythiophene), poly(3-dodecyloxythiophene ), poly(3,4-ethylenedioxythiophene): one or more of polystyrene sulfonate, molybdenum oxide, vanadium oxide and tungsten oxide;

   The material of the electrode (5) is selected from one or more of Ti, Au, Pd, Al, Ag, Pt, Cu, Ni, graphite, fluorine-doped tin oxide, indium tin oxide and indium zinc oxide.
10. A photoelectric water splitting device comprising the photoelectrode according to any one of claims 1-9.
11. An energy system, said energy system is equipped with the photoelectric water splitting device of claim 10;

    a hydrogen storage device, which is connected to the photoelectric water splitting device through a first pipe, and stores hydrogen generated by the photoelectric water splitting device; and

    A fuel cell is connected to the hydrogen storage device through a second pipe, and converts the hydrogen stored in the hydrogen storage device into electric energy.
12. A method for preparing hydrogen by electrolysis of water, the method has the following steps:

    (a) providing the operation of the photoelectric water splitting device described in claim 10;

    (b) A step of irradiating light to the photoelectrode to generate hydrogen on the photoelectrode.

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