CN105702756A - Photoelectrode with two-dimensional photonic crystal structure and preparation method thereof - Google Patents

Abstract

The present invention provides a photoelectrode with a two-dimensional photonic crystal structure and a preparation method thereof. The photoelectrode comprises a conductive substrate, a skeleton layer and a photoelectric conversion layer. The surface of the photoelectric conversion layer is provided with periodically and horizontally aligned circular holes. The preparation method mainly comprises the steps of forming a single-layer polystyrene spherical film on the conductive substrate; preparing the skeleton layer on the conductive substrate coated with the single-layer polystyrene spherical film; depositing a Fe film on the conductive substrate with the skeleton layer; forming a photoelectric oxide layer through the calcination process in the oxygen atmosphere; and obtaining the photoelectrode with the two-dimensional photonic crystal structure. According to the technical scheme of the invention, through introducing the two-dimensional photonic crystal structure, the photo-catalytic activity of the photoelectrode is remarkably improved. In this way, the photoelectric catalytic activity of the photoelectrode in different light irradiation directions is effectively improved. Meanwhile, the photoelectrode is simple in preparation method and low in cost. The production cost is greatly reduced.

Description

A photoelectrode with a two-dimensional photonic crystal structure and its preparation method

technical field

The invention belongs to the field of photoelectric catalysis, and relates to a photoelectrode and a preparation method thereof, in particular to a photoelectrode with a two-dimensional photonic crystal structure and a preparation method thereof.

Background technique

In the photoelectrocatalytic system, an independent photoelectrode usually consists of a transparent conductive substrate and a semiconductor catalytic material (as a photoelectric conversion layer) attached to it. Currently, commonly used conductive substrates for photoelectrodes include FTO (fluorine-doped tin oxide) and ITO (tin-doped indium oxide). The photoelectric conversion layer can be prepared on the surface of the transparent conductive substrate by methods such as hydrothermal synthesis, electrodeposition, and physical or chemical vapor deposition.

For photocatalytic reactions, the main factor restricting its energy conversion efficiency is the separation and collection efficiency of photogenerated carriers. Generally speaking, the greater the thickness of the photoelectric conversion layer, the more unfavorable the separation and collection of carriers. The thinner the photoelectric absorption layer is, although it is beneficial to the separation and collection of photogenerated carriers, the maximum light energy that can be absorbed is limited, which will also restrict the overall efficiency of the electrode. This contradiction is especially serious for _Fe2O3 .

Aiming at this problem of iron oxide materials, foreign researchers Gratzel et al. (Transparent, conductingNb: SnO ₂ for host-guest photoelectrochemistry. NanoLett. 2012, 12, 5431-5435) first reported a host-guest structure, the host is randomly stacked Nb doped SnO ₂ spherical shell, the guest (photoelectric conversion layer) was prepared by ALD method (atomic layer deposition method). However, the ALD method is slow in film formation, resulting in a long experiment cycle, and is not suitable for growing thick films of hundreds of nanometers. GeoffreyA.Ozin et al. (Enhanced hematite water electrolysis using a 3 Dantimony-dopedtinoxide electrode. ACSNano, 2013.7(5):4261-4274) prepared a disordered inverse opal structure host, and the guest was obtained by calcination of adsorbed ferric nitrate. The original intention of preparing the inverse opal host is to exploit its photonic crystal properties. It is generally believed that the existence of photonic crystal structure can enhance the effect of light and photoelectric conversion layer, thereby improving the utilization rate of light energy, but only the highly ordered inverse opal structure has the characteristics of photonic crystal. Therefore, neither of the above two structures can make full use of the characteristics of photonic crystals.

In order to take full advantage of the advantages of photonic crystals, AlexB.F.Martinson et al. (Hematite-basedPhoto-oxidationofWaterUsingTransparentDistributedCurrentCollectors.ACSAppl.Mater.Interfaces2013,5,360-367) prepared a well-periodic inverse opal host-guest structure, but in order to obtain this For the skeleton, the SiO ₂ inverse opal template must be synthesized first, but considering the conductive factor, ITO needs to be prepared between the photoelectric conversion layer and the SiO ₂ layer as a conductive layer. In this report, both the conductive layer and the photoelectric conversion layer are made of ALD method, and this synthesis process also has the problems of long preparation period and uneconomical conditions. Domestic researcher ShiheYang et al. (Athree-dimensionalhexagonalfluorine-dopedtinoxide anoconearray:asuperiorlightharvestingelectrodeforhighperformancephotoelectrochemicalwatersplitting.EnergyEnviron.Sci.,2014,7,3651-3658) reported that the electrode structure is highly ordered and the electrode performance is excellent, but the preparation of the skeleton layer and the template needs to use pressure Processes such as coating and transfer are more cumbersome.

Therefore, how to develop an electrode structure that can make full use of the characteristics of photonic crystals, achieve good light absorption and effective charge separation, and has a simple process is a problem that needs to be solved urgently.

Contents of the invention

In view of the above-mentioned problems in the prior art, the present invention provides a photoelectrode with a two-dimensional photonic crystal structure and a preparation method thereof. The surface of the photoelectric conversion layer of the photoelectrode has circular holes arranged horizontally periodically, that is, two dimensional photonic crystal structure. By introducing a two-dimensional photonic crystal structure, the photocatalytic activity of the electrode has been significantly improved, which can effectively improve the photocatalytic activity of the electrode under light irradiation in different directions; at the same time, the preparation method is simple and low in cost, which greatly reduces the production cost. cost.

For reaching this purpose, the present invention adopts following technical scheme:

In a first aspect, the present invention provides a photoelectrode with a two-dimensional photonic crystal structure, the photoelectrode includes a conductive substrate, and one side of the conductive substrate is a skeleton layer and a photoelectric conversion layer in sequence from the inside to the outside, and the surface of the photoelectric conversion layer has Periodically arranged circular holes.

In the present invention, the photoelectrode with a two-dimensional photonic crystal structure may be a photoanode or a photocathode. In the present invention, the surface of the photoelectric conversion layer has circular holes arranged horizontally periodically, which is a two-dimensional photonic crystal structure, which can effectively improve the photoelectric catalytic activity of the electrode under light irradiation in different directions; and, compared with the back-illuminated method, the two The dimensional photonic crystal structure has a more significant gain in the energy conversion efficiency under the frontal illumination mode.

The following are preferred technical solutions of the present invention, but not as limitations of the technical solutions provided by the present invention. Through the following technical solutions, the technical objectives and beneficial effects of the present invention can be better achieved and realized.

As a preferred technical solution of the present invention, the conductive substrate is a tin-doped indium oxide (ITO) substrate or a fluorine-doped tin oxide (FTO) substrate, more preferably a tin-doped indium oxide substrate. In the present invention, since the ITO surface is flatter than the FTO surface, a framework layer with a more regular structure can be obtained, so the effect of using the ITO substrate as the conductive substrate is better.

Preferably, the skeleton layer has a nano-network structure. In the present invention, the structure of the skeleton layer determines the surface topography of the photoelectric conversion layer of the photoelectrode.

Preferably, the material of the skeleton layer is any one or a combination of at least two of SnO ₂ , Fe ₂ O ₃ , ZnO or TiO ₂ , the typical but non-limiting examples of the combination are: SnO ₂ and Fe ₂ O ₃ , the combination of ZnO and TiO ₂ , the combination of SnO ₂ , Fe ₂ O ₃ and ZnO, the combination of SnO ₂ , Fe ₂ O ₃ , ZnO or TiO ₂ , etc. The choice of skeleton layer material is not limited to the above materials, Other materials that can achieve similar effects are also applicable, and SnO ₂ and/or Fe ₂ O ₃ are further preferred, and SnO ₂ and/or Fe ₂ O ₃ have the best effect.

Preferably, preferably, when the skeleton layer material is SnO ₂ , SnO ₂ is undoped SnO ₂ and/or Sb-doped SnO ₂ .

Preferably, the material of the photoelectric conversion layer is any one or a combination of at least two of Fe ₂ O ₃ , TiO ₂ or ZnO. Typical but non-limiting examples of the combination include: Fe ₂ O ₃ and TiO ₂ Combination, combination of TiO ₂ and ZnO, combination of Fe ₂ O ₃ , TiO ₂ and ZnO, etc., further preferably Fe ₂ O ₃ , the choice of photoelectric conversion layer material is not limited to the above materials, other materials that can achieve similar effects are also Applicable, but Fe ₂ O ₃ has the best effect.

Preferably, the adjustment range of the period is 200-1000nm, such as 200nm, 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm or 1000nm, etc., but not limited to the listed values, other values within the listed range are feasible. In the present invention, the "period" refers to the distance between the centers of two adjacent circular holes in the skeleton layer, and the periodicity of the photoelectric conversion layer can be adjusted according to the size of the polystyrene balls.

In a second aspect, the present invention provides a method for preparing the above photoelectrode, the method comprising the following steps:

(1) Using polystyrene spheres or SiO ₂ as a template to form a single-layer polystyrene sphere or SiO ₂ spherical film on a conductive substrate;

(2) Add a precursor solution to the conductive substrate covered with a single-layer polystyrene sphere or SiO ₂ spherical film until the precursor liquid infiltrates the single-layer polystyrene sphere or SiO ₂ spherical film, then calcine in an aerobic atmosphere, cool , to obtain the skeleton layer;

(3) Depositing a metal film on the conductive substrate on which the skeleton layer is obtained, and then performing calcination under an oxygen atmosphere to form a photoelectric oxidation layer to obtain a photoelectrode with a two-dimensional photonic crystal structure.

In the present invention, the single-layer polystyrene spheres or _SiO2 sphere films formed on the conductive substrate in step (1) are closely packed and arranged.

As a preferred technical solution of the present invention, polystyrene spheres are used as templates in step (1).

Preferably, after the conductive substrate is cleaned in step (1), a single-layer polystyrene sphere or SiO ₂ spherical film is formed on the conductive substrate.

Preferably, the cleaning treatment is: ultrasonically treating the conductive substrate in cleaning solution and water in sequence, and then blowing dry with inert gas.

Preferably, the inert gas is any one or a combination of at least two of nitrogen, helium, argon or xenon.

Preferably, the cleaning solution is any one or a combination of at least two of isopropanol, acetone or ethanol. Typical but non-limiting examples of the combination include: a combination of isopropanol and acetone, a combination of acetone and ethanol, isopropanol Combinations of propanol, acetone and ethanol, etc.

Preferably, the ultrasonic treatment time is 5 to 20 minutes, such as 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 13 minutes, 15 minutes, 17 minutes or 20 minutes, etc., but it is not limited to the listed values. Others within the listed range Any numerical value is feasible, and it is more preferably 5 minutes. In the present invention, if the ultrasonic time is too short, the pollutants cannot be completely removed; if the ultrasonic time is too long, the pollutants will be re-adsorbed on the conductive substrate.

Preferably, the length of the conductive substrate is 15-30mm, such as 15mm, 17mm, 20mm, 23mm, 25mm, 27mm or 30mm, etc., but not limited to the listed values, other values within the listed range are feasible; the width is 10-20mm, such as 10mm, 13mm, 15mm, 17mm or 20mm, etc., but not limited to the listed values, other values within the listed range are acceptable, preferably 25mm in length and 15mm in width.

As a preferred technical solution of the present invention, the diameter of the polystyrene sphere or _SiO2 sphere described in step (1) is 300-1000nm, such as 300nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm or 1000nm, etc., but not Not limited to the numerical values listed, other numerical values within the listed range are feasible, more preferably 600nm. In the present invention, the size of polystyrene spheres or SiO ₂ spheres will have a great influence on the catalytic effect of the electrode.

Preferably, in step (1), on conductive substrate, form monolayer polystyrene sphere or SiO _The method for sphere film is:

(a ₎ dissolving polystyrene spheres or SiO spheres in a solvent, and performing ultrasonic treatment to obtain polystyrene spheres or SiO sphere solutions _;

(b) carrying out hydrophilic treatment to the silicon chip;

(c) Add water and active agent solution to the petri dish, place the silicon chip after hydrophilic treatment in the petri dish, and then add the prepared polystyrene ball or SiO ₂ ball solution to make the polystyrene ball or SiO The ₂ -sphere solution diffuses along the silicon chip into the solution in the petri dish to form a single-layer polystyrene sphere or SiO ₂ spherical film;

(d) Place the conductive substrate under the single-layer polystyrene ball or _SiO2 spherical film, make the single-layer polystyrene ball or _SiO2 spherical film attached to the conductive substrate, then pick it up, dry, and obtain a single-layer Conductive substrate for polystyrene spheres or _SiO2 sphere membranes.

Wherein, in the step (c), the polystyrene spheres or the SiO ₂ spherical membranes are arranged as a single-layer polystyrene sphere or SiO ₂ spherical membranes in a self-assembled manner; in the step (d), the conductive substrate is slowly placed on the single-layer polystyrene Underneath the vinyl ball or SiO ₂ ball film, then slowly pick it up.

As a preferred technical solution of the present invention, the solvent described in step (a) is an aqueous solution of ethanol. In the present invention, if other solvents are used, the polystyrene balls or _SiO2 balls will react with part of the solvent to dissolve, and then the film cannot be formed.

Preferably, the volume concentration of the ethanol aqueous solution is 40-60%, such as 40%, 43%, 45%, 47%, 50%, 53%, 55%, 57% or 60%, but not limited to For the enumerated numerical value, other numerical values within the listed range are all feasible, more preferably 50%.

Preferably, the time of ultrasonic treatment in step (a) is 0.5-3h, such as 0.5h, 1h, 1.5h, 2h, 2.5h or 3h, etc., but it is not limited to the listed values. Others within the listed range Any numerical value is feasible, and it is more preferably 1h. In the present invention, if the ultrasonic time is too short, the dispersion of polystyrene balls or _SiO2 balls will be uneven; if the ultrasonic time is too long, the polystyrene balls or _SiO2 balls will be broken and dissolved.

Preferably, the concentration of the polystyrene sphere solution or SiO ₂ spheres prepared in step (a) is 0.03-0.08g/mL, such as 0.03g/mL, 0.04g/mL, 0.05g/mL, 0.06g/mL , 0.07g/mL or 0.08g/mL, etc., but not limited to the listed values, other values within the listed range are feasible, more preferably 0.05g/mL.

As a preferred technical solution of the present invention, the method for carrying out hydrophilic treatment to the silicon chip in step (b) is: immerse the silicon chip in the hydrophilic solution, and then keep it warm at 70-80°C for 0.5-3h; wherein, the holding time can be 70°C, 72°C, 74°C, 76°C, 78°C or 80°C, etc., but not limited to the listed values, other values within the listed range are acceptable; the holding time can be 0.5h, 1h, 1.5h, 2h, 2.5h or 3h, etc., but not limited to the listed values, and other values within the listed range are feasible.

Preferably, the method for hydrophilically treating the silicon wafer in step (b) is: immersing the silicon wafer in a hydrophilic solution, and then keeping the temperature at 75° C. for 1 hour.

Preferably, the hydrophilic solution is a mixed solution of ammonia, hydrogen peroxide and water.

Preferably, the volume ratio of ammonia, hydrogen peroxide and water is 1:1:5.

Preferably, the active agent in step (c) is sodium lauryl sulfate.

Preferably, in step (c), the polystyrene sphere or the SiO ₂ sphere solution is added dropwise, especially slowly.

As a preferred technical solution of the present invention, the precursor solution in step (2) is prepared by the following method: dissolving the metal salt and citric acid in an organic solvent and stirring until completely dissolved to obtain the precursor solution.

Preferably, the metal in the metal salt is any one or a combination of at least two of tin, iron, zinc or titanium, typical but non-limiting examples of the combination are: a combination of tin and iron, zinc and titanium The combination of tin, iron and zinc, the combination of tin, iron, zinc and titanium, etc., are more preferably tin and/or iron.

Preferably, the metal salt is a metal chloride and/or a metal nitrate.

Preferably, the metal salt is any one or a combination of at least two of tin chloride, ferric chloride, ferric nitrate, zinc nitrate or zinc chloride, the typical but non-limiting examples of the combination are: tin chloride combination with ferric chloride, combination of ferric nitrate and zinc nitrate, combination of zinc nitrate and zinc chloride, combination of tin chloride, ferric chloride and ferric nitrate, tin chloride, ferric chloride, ferric nitrate, zinc nitrate Combinations with zinc chloride, etc., are more preferably tin chloride and/or ferric chloride.

Preferably, the organic solvent is any one or a combination of at least two of ethanol, isopropanol or methanol, the typical but non-limiting examples of the combination are: the combination of ethanol and isopropanol, the combination of isopropanol and methanol Combination, combination of ethanol, isopropanol and methanol, etc.

Preferably, the concentration of the metal salt in the precursor solution is 0.03-0.1 mol/L, such as 0.03 mol/L, 0.04 mol/L, 0.05 mol/L, 0.06 mol/L, 0.07 mol/L, 0.08 mol/L , 0.09 mol/L or 0.1 mol/L, etc., but not limited to the listed values, other values within the listed range are feasible, more preferably 0.06 mol/L. In the present invention, the concentration of the metal salt in the precursor liquid directly affects the morphology of the skeleton layer. If the concentration is too low, the skeleton layer cannot cover the entire conductive substrate plane; if the concentration is too high, the skeleton layer will be obviously broken and agglomerated.

Preferably, the concentration of citric acid in the precursor solution is 0.03-0.1mol/L, such as 0.03mol/L, 0.04mol/L, 0.05mol/L, 0.06mol/L, 0.07mol/L, 0.08mol/L , 0.09 mol/L or 0.1 mol/L, etc., but not limited to the listed values, other values within the listed range are feasible, more preferably 0.06 mol/L.

Preferably, the addition method of the precursor solution in step (2) is dropwise addition.

As a preferred technical solution of the present invention, in step (2), drop a drop of precursor solution in the center of the conductive substrate covered with a single-layer polystyrene spherical membrane until the precursor solution soaks the single-layer polystyrene spherical membrane.

Preferably, the calcination in the step (2) is as follows: heat preservation at 100-130° C. for 1-4 hours, then raise the temperature to 300-500° C. and keep heat for 2-5 hours. Among them, the calcination time of the first stage can be 100°C, 105°C, 110°C, 115°C, 120°C, 125°C or 130°C, etc., but it is not limited to the listed values, and other values within the listed range are acceptable; The one-stage calcination time can be 1 h, 2 h, 3 h or 4 h, etc., but is not limited to the listed values, and other values within the listed range are all feasible. The second-stage calcination temperature can be 300°C, 330°C, 350°C, 370°C, 400°C, 430°C, 450°C, 470°C or 500°C, etc., but not limited to the listed values, other values within the listed range All are feasible; the calcination time of the second stage can be 2h, 3h, 4h or 5h, etc., but it is not limited to the listed values, and other values within the listed range are all feasible.

Preferably, the calcination in step (2) is as follows: after keeping the temperature at 110° C. for 2 hours, then raising the temperature to 400° C. and keeping the temperature for 3 hours.

As a preferred technical solution of the present invention, the method for depositing the metal film in step (3) is any one of thermal evaporation, magnetron sputtering or atomic force deposition.

Preferably, the deposition rate is For example or etc., but not limited to the listed values, and other values within the listed range are feasible. in, The angstrom is a unit of length commonly used in crystallography, atomic physics, and ultramicrostructure.

Preferably, the thickness of the metal film in step (3) is 10-150nm, such as 10nm, 30nm, 50nm, 70nm, 100nm, 130nm or 150nm, etc., but not limited to the listed values, other values within the listed range All are feasible, and more preferably 100 nm. In the present invention, if the thickness of the metal film is too thick, it will not be completely oxidized, thereby affecting its performance.

Preferably, the calcination temperature in step (3) is 400-500°C, such as 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, 460°C, 470°C, 480°C, 490°C or 500°C, etc. , but not limited to the enumerated values, other values within the listed range are feasible, more preferably 450°C.

Preferably, the calcination time in step (3) is 0.5-3h, such as 0.5h, 1h, 1.5h, 2h, 2.5h or 3h, etc., more preferably 1h.

Compared with the prior art, the present invention has the following beneficial effects:

The surface of the photoelectric conversion layer of the photoelectrode of the present invention has circular holes arranged horizontally periodically, that is, a two-dimensional photonic crystal structure. By introducing the two-dimensional photonic crystal structure, the photocatalytic activity of the electrode is significantly improved. At the same time, by introducing a two-dimensional photonic crystal structure, the present invention can effectively improve the photoelectric catalytic activity of the electrode under light irradiation in different directions. When the light is irradiated from one side of the photoelectric conversion layer, the gain of catalytic efficiency is 50-800%, and the effect is even better. Notably, this means that the separation and collection efficiency of photogenerated charges has been significantly improved (note: in the present invention, the gain calculation formula is (I ₂ -I ₁ )/I ₁ , where I ₂ refers to the Current density of a film with a 2D photonic crystal structure at a bias voltage of 0.6 V; I ₁ refers to the current density of a planar film at a bias voltage of 0.6 V).

Description of drawings

Fig. 1 is the scanning electron micrograph of skeleton layer in the photoelectrode that makes in the embodiment 1 of the present invention;

Fig. 2 is the scanning electron microscope picture of the photoelectric conversion layer in the photoelectrode that makes in the embodiment 1 of the present invention;

Fig. 3 is the ITO/Fe that makes in comparative example ₁ of the present invention O _The scanning electron microscope picture of the plane iron oxide film of electrode;

Fig. 4 is the performance test graph of the battery that the embodiment 1 of the present invention and comparative example 1 make, wherein, Fig. 4 (A) is the test graph that light is irradiated from one side of transparent conductive substrate, Fig. 4 (B) is the light from photoelectric conversion Layer (for the ITO/Fe ₂ O ₃ electrode in comparative example 1, is the planar iron oxide film side) test pattern of irradiation;

Fig. 5 is the performance test graph of the battery that the embodiment 2 of the present invention and comparative example 2 make, wherein, Fig. 5 (A) is the test graph that light is irradiated from one side of transparent conductive substrate, Fig. 5 (B) is light from photoelectric conversion Layer (for the ITO/Fe ₂ O ₃ electrode in comparative example 2, it is the plane iron oxide film side) the test figure of irradiation;

Fig. 6 is a schematic diagram of light irradiation directions in performance tests of Example 2 and Comparative Example 2 of the present invention.

detailed description

In order to better illustrate the present invention and facilitate understanding of the technical solution of the present invention, the present invention will be further described in detail below. However, the following embodiments are only simple examples of the present invention, and do not represent or limit the protection scope of the present invention, and the protection scope of the present invention shall be determined by the claims.

Example 1:

This example provides an ITO/SnO ₂ /Fe ₂ O ₃ electrode with a two-dimensional photonic crystal structure and a preparation method thereof, the method comprising the following steps:

(1) Cleaning of the conductive substrate: The conductive substrate with a size of 25 mm×15 mm was ultrasonically treated in isopropanol, acetone, ethanol and water for 5 minutes, and then dried with nitrogen.

(2) Form a single-layer polystyrene spherical membrane on a conductive substrate:

(a) Weigh 0.1 g of polystyrene (PS) spheres with a diameter of 600 nm and dissolve them in an aqueous solution of ethanol formed by 1 mL of deionized water and 1 mL of ethanol, and perform ultrasonic treatment for 1 h to obtain a polystyrene sphere solution;

(b) Perform hydrophilic treatment on the silicon wafer: immerse the silicon wafer in a mixed solution of ammonia, hydrogen peroxide and water (the volume ratio of ammonia, hydrogen peroxide and water is 1:1:5), and then keep it warm at 75°C for 1 hour;

(c) Add water and 100 μL of 2wt% sodium dodecyl sulfate solution into a petri dish with a diameter of 180 mm, place the silicon chip after hydrophilic treatment in the petri dish, and inject the silicon chip into the petri dish with a syringe Slowly add the prepared polystyrene sphere solution dropwise, so that the polystyrene sphere solution diffuses into the solution of the petri dish along the silicon chip, and the polystyrene sphere will be self-assembled on the surface of the petri dish to form a single-layer polystyrene spherical membrane;

(d) Place the cleaned conductive substrate under the single-layer polystyrene spherical film, attach the single-layer polystyrene spherical film to the conductive substrate, slowly pick it up, and dry naturally to obtain a tightly packed single-layer film. Conductive substrate for polystyrene spherical membrane.

(3) dissolving tin chloride and citric acid monohydrate in the organic solvent ethanol, stirring until fully dissolved, the obtained tin chloride concentration is 0.06mol/L, and the precursor solution whose concentration of citric acid monohydrate is 0.06mol/L;

Place the conductive substrate covered with a single-layer polystyrene spherical film horizontally, and drop the precursor solution to the center of the conductive substrate covered with a single-layer polystyrene spherical film with a syringe until the precursor solution soaks the single-layer polystyrene spherical film (i.e. Wet all PS balls), calcined at 110°C for 2 hours in an aerobic atmosphere, then raised the temperature at 0.5°C/min to 400°C for 3 hours, and cooled naturally to obtain a skeleton layer. The morphology of the prepared skeleton layer is shown in the figure 1.

(4) adopt the thermal evaporation method to prepare the conductive substrate of the skeleton layer and A 100nm Fe film was deposited at a speed of 100 nm, and then calcined at 450°C for 1 h in an aerobic atmosphere to form a photoelectric oxide layer. Its morphology is shown in Figure 2, and a photoelectrode with a two-dimensional photonic crystal structure was obtained.

Example 2:

This example provides an ITO/Fe ₂ O ₃ electrode with a two-dimensional photonic crystal structure and a preparation method thereof, the method comprising the following steps:

(1) Cleaning of the conductive substrate: The conductive substrate with a size of 25 mm×15 mm was ultrasonically treated in isopropanol, acetone, ethanol and water for 5 minutes, and then dried with nitrogen.

(2) Form a single-layer polystyrene spherical membrane on a conductive substrate:

(a) Weigh 0.1 g of polystyrene (PS) spheres with a diameter of 600 nm and dissolve them in an aqueous solution of ethanol formed by 1 mL of deionized water and 1 mL of ethanol, and perform ultrasonic treatment for 1 h to obtain a polystyrene sphere solution;

(b) Perform hydrophilic treatment on the silicon wafer: immerse the silicon wafer in a mixed solution of ammonia, hydrogen peroxide and water (the volume ratio of ammonia, hydrogen peroxide and water is 1:1:5), and then keep it warm at 75°C for 1 hour;

(c) Add water and 100 μL of 2wt% sodium dodecyl sulfate solution into a petri dish with a diameter of 180 mm, place the silicon chip after hydrophilic treatment in the petri dish, and inject the silicon chip into the petri dish with a syringe Slowly add the prepared polystyrene sphere solution dropwise, so that the polystyrene sphere solution diffuses into the solution of the petri dish along the silicon chip, and the polystyrene sphere will be self-assembled on the surface of the petri dish to form a single-layer polystyrene spherical film;

(d) Place the cleaned conductive substrate under the single-layer polystyrene spherical film, attach the single-layer polystyrene spherical film to the conductive substrate, slowly pick it up, and dry naturally to obtain a tightly packed single-layer film. Conductive substrate for polystyrene spherical membrane.

(3) Dissolve ferric chloride hexahydrate and citric acid monohydrate in ethanol, an organic solvent, and stir until completely dissolved to obtain a precursor with a concentration of ferric chloride of 0.06mol/L and a concentration of citric acid monohydrate of 0.06mol/L liquid;

Place the conductive substrate covered with a single-layer polystyrene spherical film horizontally, and drop the precursor solution to the center of the conductive substrate covered with a single-layer polystyrene spherical film with a syringe until the precursor solution soaks the single-layer polystyrene spherical film (i.e. Wet all PS balls), calcined at 110°C for 2h in an aerobic atmosphere, then raised the temperature at 0.5°C/min to 400°C for 3h, and cooled naturally to obtain an iron oxide skeleton layer.

(4) adopt the thermal evaporation method to prepare the conductive substrate of the skeleton layer and A 100nm Fe film was deposited at a high speed, and then calcined at 450°C for 1h in an oxygen atmosphere to form a photoelectric oxide layer, and a photoelectrode with a two-dimensional photonic crystal structure was obtained.

Example 3:

This example provides a kind of ITO/SnO ₂ /Fe ₂ O ₃ electrode with two-dimensional photonic crystal structure and preparation method thereof, in the described method except step (1) ultrasonic treatment 2min in the cleaning of conductive substrate; Step (2) The diameter of the polystyrene (PS) ball in (a) is 300nm, ultrasonic treatment 3h, (b) in 70 ℃ of insulation 3h, the concentration of (c) sodium lauryl sulfate solution is 1wt%; In step (3), the tin chloride concentration of the precursor solution is 0.01 mol/L, the concentration of citric acid monohydrate is 0.01 mol/L, first calcined at 100°C for 4 hours, and then heated at 0.5°C/min to 300°C for 5 hours; In step (4), the deposition thickness of the Fe film is 50 nm, and the amount of other materials used and the preparation steps are the same as those in Example 1, except that it is calcined at 400° C. for 3 hours.

Example 4:

This example provides a kind of ITO/Fe ₂ O ₃ electrodes with two-dimensional photonic crystal structure and preparation method thereof, except step (1) ultrasonic treatment 10min in the cleaning of conductive substrate in the described method; In step (2) ( The diameter of the polystyrene (PS) ball in a) is 1000nm, ultrasonic treatment 0.5h, in (b) in 80 ℃ of insulation 0.5h, the concentration of (c) sodium lauryl sulfate solution is 5wt%; Step (3) The tin chloride concentration of the precursor solution in the medium is 0.1mol/L, the concentration of citric acid monohydrate is 0.1mol/L, first calcined at 300°C for 1h, and then heated to 500°C at 0.5°C/min for 2h; step (4) The deposition thickness of the Fe film is 300nm, and it is calcined at 500° C. for 0.5 h, and the amount of other materials and preparation steps are the same as those in Example 2.

Comparative example 1:

Except that step (2) and step (3) are not included, that is, the skeleton layer is not prepared on the conductive substrate, the amount of other materials and the preparation steps are the same as in Example 1, and the ITO/Fe ₂ O with a planar iron oxide film is obtained. ₃ electrodes.

Scan the planar iron oxide film of the ITO/Fe ₂ O ₃ electrode, as shown in FIG. 3 , it can be seen that the planar iron oxide film in the electrode prepared in this comparative example does not have a two-dimensional photonic crystal structure.

Comparative example 2:

Except that step (2) and step (3) are not included, that is, the skeleton layer is not prepared on the conductive substrate, the amount of other materials and the preparation steps are the same as in Example 2, and the ITO/Fe ₂ O with a planar iron oxide film is prepared. ₃ electrodes, the thickness of the planar iron oxide film is approximately equal to the thickness of the photoelectric conversion layer prepared in Example 2.

Adopt the following method to carry out photoelectrocatalytic performance test to the electrode in embodiment and comparative example:

A three-electrode system was used in the test, with a 150W xenon lamp (model CT-XE-150) as the light source. During the test, the distance between the irradiated surface of the sample and the light source was guaranteed to be 10cm, and the test solution was a sodium hydroxide solution with a concentration of 1mol/L. , and the test results are shown in Figure 4 and Figure 5, respectively, and the schematic diagram of the light irradiation direction is shown in Figure 6.

Comparing Example 1 and Comparative Example 1, Example 2 and Comparative Example 2, it can be seen that under backlight conditions, when the applied bias voltage is 0.6V, the electrode current density with a two-dimensional photonic crystal structure is about that of a planar electrode 1.5 times; and under positive conditions, the current density of electrodes with a two-dimensional photonic crystal structure is about 9 times that of planar electrodes. It can be seen that the catalytic performance of the ITO/Fe ₂ O ₃ electrode with a photoelectric conversion layer is significantly better than that of the ITO/Fe ₂ O ₃ electrode with a planar iron oxide film in the comparative example.

From the results of comprehensive examples 1-4 and comparative examples 1-2, it can be seen that the surface of the photoelectric conversion layer of the photoelectrode of the present invention has circular holes arranged horizontally periodically, that is, a two-dimensional photonic crystal structure. By introducing two-dimensional photons The crystal structure has significantly improved the photocatalytic activity of the electrode. At the same time, by introducing a two-dimensional photonic crystal structure, the present invention can effectively improve the photoelectric catalytic activity of the electrode under light irradiation in different directions. When the light is irradiated from one side of the photoelectric conversion layer, the gain of catalytic efficiency is 50-800%, and the effect is even better. It is significant, which means that the separation and collection efficiency of photogenerated charges has been more significantly improved.

The applicant declares that the present invention illustrates the detailed process equipment and process flow of the present invention through the above-mentioned examples, but the present invention is not limited to the above-mentioned detailed process equipment and process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process equipment and process flow process can be implemented. Those skilled in the art should understand that any improvement of the present invention, the equivalent replacement of each raw material of the product of the present invention, the addition of auxiliary components, the selection of specific methods, etc., all fall within the scope of protection and disclosure of the present invention.

Claims (10)

1. A photoelectrode with a two-dimensional photonic crystal structure, characterized in that the photoelectrode includes a conductive substrate, and one side of the conductive substrate is followed by a skeleton layer and a photoelectric conversion layer from the inside to the outside, and the photoelectric conversion layer surface has a periodicity Round holes arranged horizontally. 2. The photoelectrode according to claim 1, wherein the conductive substrate is a tin-doped indium oxide substrate or a fluorine-doped tin oxide substrate, more preferably a tin-doped indium oxide substrate; Preferably, the skeleton layer has a nano-network structure; Preferably, the material of the skeleton layer is any one or a combination of at least two of SnO ₂ , Fe ₂ O ₃ , ZnO or TiO ₂ , more preferably SnO ₂ and/or Fe ₂ O ₃ ; Preferably, when the skeleton layer material is SnO ₂ , SnO ₂ is undoped SnO ₂ and/or Sb-doped SnO ₂ ; Preferably, the material of the photoelectric conversion layer is any one or a combination of at least two of Fe ₂ O ₃ , TiO ₂ or ZnO, more preferably Fe ₂ O ₃ ; Preferably, the adjustment range of the period is 200-1000 nm. 3. The preparation method of photoelectrode according to claim 1 or 2, is characterized in that, described method comprises the following steps: (1) Using polystyrene spheres or SiO ₂ spheres as a template to form a single-layer polystyrene sphere or SiO ₂ sphere film on a conductive substrate; (2) Add a precursor solution to the conductive substrate covered with a single-layer polystyrene sphere or SiO ₂ spherical film until the precursor liquid infiltrates the single-layer polystyrene sphere or SiO ₂ spherical film, then calcine in an aerobic atmosphere, cool , to obtain the skeleton layer; (3) Depositing a metal film on the conductive substrate on which the skeleton layer is obtained, and then performing calcination under an oxygen atmosphere to form a photoelectric oxidation layer to obtain a photoelectrode with a two-dimensional photonic crystal structure. 4. preparation method according to claim 3, is characterized in that, in step (1), take polystyrene sphere as template; Preferably, after the conductive substrate is cleaned in step (1), a single-layer polystyrene ball or _SiO2 spherical film is formed on the conductive substrate; Preferably, the cleaning treatment is: ultrasonically treating the conductive substrate in cleaning solution and water in sequence, and then blowing dry with an inert gas; Preferably, the inert gas is any one or a combination of at least two of nitrogen, helium, argon or xenon; Preferably, the cleaning solution is any one or a combination of at least two of isopropanol, acetone or ethanol; Preferably, the time for the ultrasonic treatment is 5 to 20 minutes, more preferably 5 minutes; Preferably, the conductive base has a length of 15-30 mm and a width of 10-20 mm, preferably 25 mm in length and 15 mm in width. 5. according to the described preparation method of claim 3 or 4, it is characterized in that, polystyrene described in step (1) or SiO _The diameter of ball is 300～1000nm, is more preferably 600nm; Preferably, in step (1), on conductive substrate, form monolayer polystyrene sphere or SiO _The method for sphere film is: (a ₎ dissolving polystyrene spheres or SiO spheres in a solvent, and performing ultrasonic treatment to obtain polystyrene spheres or SiO sphere solutions _; (b) carrying out hydrophilic treatment to the silicon chip; (c) Add water and active agent solution to the petri dish, place the silicon chip after hydrophilic treatment in the petri dish, and then add the prepared polystyrene ball or SiO ₂ ball solution to make the polystyrene ball or SiO The ₂ -sphere solution diffuses along the silicon chip into the solution in the petri dish to form a single-layer polystyrene sphere or SiO ₂ spherical film; (d) Place the conductive substrate under the single-layer polystyrene ball or _SiO2 spherical film, make the single-layer polystyrene ball or _SiO2 spherical film attached to the conductive substrate, then pick it up, dry, and obtain a single-layer Conductive substrate for polystyrene spheres or _SiO2 sphere membranes. 6. preparation method according to claim 5, is characterized in that, the solvent described in step (a) is the aqueous solution of ethanol; Preferably, the volume concentration of the ethanol aqueous solution is 40-60%, more preferably 50%; Preferably, the time for the ultrasonic treatment in step (a) is 0.5 to 3 hours, more preferably 1 hour; Preferably, the concentration of the polystyrene sphere or SiO ₂ sphere solution prepared in step (a) is 0.03-0.08 g/mL, more preferably 0.05 g/mL. 7. The preparation method according to claim 5 or 6, characterized in that, the method for carrying out hydrophilic treatment to the silicon wafer in step (b) is: immersing the silicon wafer in a hydrophilic solution, and then immersing the silicon wafer in a hydrophilic solution at 70 to 80° C. Keep warm for 0.5~3h; Preferably, the method for hydrophilically treating the silicon wafer in step (b) is: immersing the silicon wafer in a hydrophilic solution, and then keeping the temperature at 75° C. for 1 h; Preferably, the hydrophilic solution is a mixed solution of ammonia, hydrogen peroxide and water; Preferably, the volume ratio of the ammonia, hydrogen peroxide and water is 1:1:5; Preferably, the active agent described in step (c) is sodium lauryl sulfate; Preferably, in step (c), the polystyrene sphere or the SiO ₂ sphere solution is added dropwise. 8. The preparation method according to any one of claims 3-7, characterized in that the precursor solution in step (2) is prepared by the following method: dissolving the metal salt and citric acid in an organic solvent and stirring until completely dissolved , to prepare the precursor solution; Preferably, the metal in the metal salt is any one or a combination of at least two of tin, iron, zinc or titanium, more preferably tin and/or iron; Preferably, the metal salt is a metal chloride and/or a metal nitrate; Preferably, the metal salt is any one or a combination of at least two of tin chloride, ferric chloride, ferric nitrate, zinc nitrate or zinc chloride, more preferably tin chloride and/or ferric chloride; Preferably, the organic solvent is any one or a combination of at least two of ethanol, isopropanol or methanol; Preferably, the concentration of the metal salt in the precursor solution is 0.03-0.1 mol/L, more preferably 0.06 mol/L; Preferably, the concentration of citric acid in the precursor solution is 0.03-0.1 mol/L, more preferably 0.06 mol/L; Preferably, the addition method of the precursor solution in step (2) is dropwise addition. 9. according to the preparation method described in any one of claim 3-8, it is characterized in that, in the step (2), drop a drop of precursor solution to the precursor solution in the center of the conductive substrate covered with single-layer polystyrene spherical film Infiltrate a single layer of polystyrene spherical membrane; Preferably, the calcination in step (2) is as follows: heat preservation at 100-130°C for 1-4 hours, then heat up to 300-500°C for 2-5 hours; Preferably, the calcination in step (2) is as follows: after keeping the temperature at 110° C. for 2 hours, then raising the temperature to 400° C. and keeping the temperature for 3 hours. 10. The method for preparing a photoelectrode according to any one of claims 3-9, wherein the metal film in step (3) is any one or at least two of iron film, titanium film or zinc film A combination of, more preferably iron film; Preferably, the method for depositing the metal film in step (3) is any one of thermal evaporation, magnetron sputtering or atomic force deposition; Preferably, the deposition rate is Preferably, the thickness of the metal film in step (3) is 10-150 nm, more preferably 100 nm; Preferably, the calcination temperature in step (3) is 400-500°C, more preferably 450°C; Preferably, the calcination time in step (3) is 0.5-3 h, more preferably 1 h.