Preparation method and application of nitride photoelectrode with photoelectrocatalysis performance

Abstract

The invention provides a preparation method of a nitride photoelectrode with photoelectrocatalysis performance, which comprises the following steps: etching a nitride material by using alkali liquor to obtain a nitride material with an irregular surface; a promoter is deposited on a nitride material with an irregular surface, and the nitride photoelectrode loaded with the promoter is obtained.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor materials, and specifically relates to a preparation method of a nitride photoelectrode with photoelectrocatalytic performance and its application. Background Art

[0002] In the research of semiconductor materials, nitride semiconductor materials, such as gallium nitride, aluminum nitride, indium nitride, etc., are a new type of semiconductor material with superior performance after comprehensive evaluation from various aspects such as chemical stability, energy band structure, and material system. Nitride semiconductor materials have important application prospects in the fields of energy conversion and optoelectronics. In theory, their high specific surface area, superior electron transport performance, and photoelectric catalytic potential make them photocatalytic materials with high catalytic activity and high catalytic efficiency. Their photogenerated electrons and holes have strong oxidation and reduction capabilities, and can be used in a variety of catalytic scenarios.

[0003] In the related art, the main problems faced by nitrides in photoelectrocatalysis include the optimization of their surface charge separation efficiency and co-catalyst loading. Nitride semiconductor materials are often used in conjunction with other co-catalysts, and a common method is to uniformly load the co-catalyst on the nitride nanocolumns. However, this loading method has few catalytic active sites, and the interaction efficiency between the co-catalyst and the nitride nanocolumns is low, which limits the catalytic efficiency. At the same time, in this loading method, the co-catalyst is not tightly bound to the nitride nanocolumns, lacks directional control over the co-catalyst, and is easy to fall off, resulting in reduced stability. Summary of the invention

[0004] In view of this, in order to solve at least one technical problem in the related art and other aspects, the present disclosure proposes a method for preparing a nitride photoelectrode with photoelectrocatalytic performance, comprising:

[0005] Using an alkali solution to etch the surface of the nitride material to obtain a nitride material with an irregular surface;

[0006] The co-catalyst is deposited onto the nitride material with an irregular surface to obtain a nitride photoelectrode loaded with the co-catalyst.

[0007] According to an embodiment of the present disclosure, the irregular surface is a surface after treatment where one or more crystal planes different from the crystal planes before treatment appear. According to an embodiment of the present disclosure, the nitride material includes GaN, Al x Ga 1-x N、In x Ga 1-x N,In y Al x Ga 1-x- y N.B x Al y Ga1-x-y N.B x In y Ga 1-x-y One of N, wherein 0≤x≤1, 0≤y≤1; the polarity of the nitride material is metal polarity or nitrogen polarity.

[0008] According to an embodiment of the present disclosure, the shape of the nitride material includes any one of a nanocolumn, a planar structure, a triangular pyramid, and any irregular structure, wherein the shape of the nanocolumn is a polygon or any irregular shape; the length of the nitride nanocolumn is 1nm to 10μm, and the width of the nitride nanocolumn is 1nm to 10μm. According to an embodiment of the present disclosure, the semiconductor structure type of the nitride material includes one of a pn junction, an np junction, a pin junction, and a corresponding tunneling junction structure formed by n-type doping or p-type doping of nitride.

[0009] According to an embodiment of the present disclosure, the etching process includes: cleaning the nitride material and immersing it in an alkaline solution, etching it at room temperature for 1 second to 10 hours, cleaning and drying it, and obtaining a nitride material with an irregular surface.

[0010] According to an embodiment of the present disclosure, the deposition method includes one of photoelectric deposition, optical deposition, electrodeposition, plasma sputtering, and magnetron sputtering.

[0011] According to an embodiment of the present disclosure, the operation of photoelectric deposition includes: preparing a precursor aqueous solution, using a nitride material with an irregular surface as a working electrode, immersing it in the precursor aqueous solution, and irradiating it with light to obtain a nitride photoelectrode loaded with a co-catalyst; wherein the precursor aqueous solution is an electrolyte conductive solution containing a co-catalyst.

[0012] According to an embodiment of the present disclosure, the promoter includes one or more of noble metal nanoparticles, transition metal nanoparticles, hydroxide nanoparticles, sulfide nanoparticles, and phosphide nanoparticles.

[0013] In another aspect of the present disclosure, a nitride photoelectrode with photoelectrocatalytic performance obtained by the above-mentioned preparation method is used in photoelectrocatalytic reactions, including photoelectrocatalytic water decomposition, carbon dioxide reduction, nitrogen reduction, organic matter decomposition or seawater chlorine absorption.

[0014] According to the embodiments of the present disclosure, the surface of the nitride material is etched by alkaline solution to reveal other crystal planes on the original surface, thereby changing the surface crystal plane structure and energy level distribution of the nitride nanocolumn, improving its surface reaction activity, exposing more active sites, and facilitating the directional loading of co-catalysts, thereby improving the photoelectrocatalytic performance of the nitride material and the co-catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a valence band spectrum of the X-ray photoelectron spectrum of the gallium nitride nanorods before and after etching in the embodiment of the present disclosure;

[0016] Figure 2 is a diagram showing the relationship between the contact potential difference of the gallium nitride nanorods before and after etching measured by a Kelvin probe force microscope in an embodiment of the present disclosure;

[0017] Figure 3 is a flow chart of a method for preparing nitride nanorods with photoelectrocatalytic performance in the present disclosure;

[0018] Figure 4 is a scanning electron microscope image of a gallium nitride nanorod before etching in an embodiment of the present disclosure;

[0019] Figure 5 is a projection electron microscope image of a gallium nitride nanorod before etching in an embodiment of the present disclosure;

[0020] Figure 6 is a scanning electron microscope image of a gallium nitride nanorod after etching in an embodiment of the present disclosure;

[0021] Figure 7 is a projection electron microscope image of a gallium nitride nanorod after etching in an embodiment of the present disclosure;

[0022] Figure 8 is a schematic diagram of the structure of a gallium nitride nanorod before etching in an embodiment of the present disclosure;

[0023] Fig. 9 is a schematic diagram of the structure of the gallium nitride nanorod after etching in an embodiment of the present disclosure;

[0024] Fig.10 The gallium nitride nanorod after etching in the embodiment of the present disclosure Schematic diagram of the structure of the crystal plane;

[0025] Fig.11 is a comparison curve of the linear sweep voltammetric curves before and after etching of the gallium nitride nanorods in the embodiment of the present disclosure; and

[0026] Fig.12 It is a comparison graph of the linear sweep voltammetric curves of the gallium nitride nanocolumns loaded with gold nanoparticles before and after etching in the embodiments of the present disclosure.

[0027] [Reference Signs]

[0028] 1. Substrate; 2. Nitride nanorods. DETAILED DESCRIPTION

[0029] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0030] The endpoints and any values ​​of the ranges disclosed in this disclosure are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this disclosure.

[0031] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0032] All terms (including technical and scientific terms) used herein have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification, and should not be interpreted in an idealized or overly rigid manner.

[0033] Surface treatment of nitride materials is an effective way to improve the loading effect and loading efficiency, but conventional chemical modification or functionalization treatment will change the surface properties of nitride materials, and it cannot be guaranteed that the modification direction can effectively improve the photoelectrocatalytic performance of nitride materials. After loading, the co-catalyst is easy to fall off, resulting in a decrease in the stability of the catalyst. Therefore, the surface etching method is used in the present disclosure to treat the surface of the nitride material, preferably nitride nanocolumns, thereby changing the surface structure and energy level distribution of the nitride material, and directionally loading the co-catalyst for use as a photoelectrode. In the present disclosure, gallium nitride semiconductor materials are taken as an example, and energy level tests before and after etching are carried out to verify the feasibility of the method proposed in the present disclosure.

[0034] The technical term "catalytically active site" used in this disclosure means a specific location or region that plays a key role in a catalytic reaction, usually some atomic or molecular locations on the catalyst surface. These sites have special properties that can adsorb, activate and promote the interaction between reactants, thereby reducing the activation energy of the reaction, accelerating the reaction rate, and promoting the smooth progress of the chemical reaction.

[0035] Figure 1 It is a valence band spectrum of the X-ray photoelectron spectrum of the gallium nitride nanorods before and after etching in the embodiment of the present disclosure.

[0036] Figure 2 3 is a diagram showing the relationship between the contact potential difference of the gallium nitride nanorods before and after etching measured by a Kelvin probe force microscope in an embodiment of the present disclosure.

[0037] like Figure 1 , Figure 2 As shown in the figure, the binding energy of the GaN nanopillars before etching is 2.74eV, and the binding energy of the GaN nanopillars after etching is 2.47eV. The contact potential difference of the GaN nanopillars after etching is also significantly lower than that before etching. It can be seen that after the etching operation, a crystal plane different from that before etching appears, thereby reducing the surface binding energy of the GaN nanopillars, which is more conducive to loading the catalyst and ensuring the stability of the loading.

[0038] Figure 3 It is a flow chart of the method for preparing the nitride material with photoelectrocatalytic performance disclosed in the present invention.

[0039] The present disclosure proposes a method for preparing a nitride photoelectrode with photoelectrocatalytic performance, such as Figure 3 As shown, the steps include the following steps S1 and S2:

[0040] Step S1: etching the surface of the nitride material using an alkali solution to obtain a nitride material with an irregular surface;

[0041] Step S2: depositing the co-catalyst onto the nitride material with an irregular surface to obtain a nitride photoelectrode loaded with the co-catalyst.

[0042] According to the embodiments of the present disclosure, the surface of the nitride material is etched by alkaline solution to reveal other crystal planes on the original surface, thereby changing the surface crystal plane structure and energy level distribution of the nitride nanocolumn, improving its surface reaction activity, exposing more active sites, and facilitating the directional loading of co-catalysts, thereby improving the photoelectrocatalytic performance of the nitride material and the co-catalyst.

[0043] Figure 4 , 6 The following are scanning electron microscope images of the gallium nitride nanorods before and after etching in the embodiments of the present disclosure.

[0044] Figure 5 , 7 The following are transmission electron microscope images of the gallium nitride nanorods before and after etching in the embodiments of the present disclosure.

[0045] Figure 8 , 9 They are schematic diagrams of the structures of gallium nitride nanorods before and after etching in the embodiments of the present disclosure.

[0046] like Figures 4 to 9 As shown, after etching, the gallium nitride nanorod 1 with a flat surface is transformed into a gallium nitride nanorod with an irregular undulating surface, and its crystal plane changes.

[0047] According to an embodiment of the present disclosure, the irregular surface is a surface after treatment in which one or more crystal planes different from the crystal planes before treatment appear. In some specific embodiments, the etching process causes the crystal planes on the surface of the nitride material to change. The crystal surface is etched to obtain To terminate the irregular surface of the crystal plane, more preferably, the nitride material The crystal surface is etched to obtain Crystal face.

[0048] According to an embodiment of the present disclosure, the nitride material includes GaN, Al x Ga 1-x N、In x Ga 1-x N,In y Al x Ga 1-x-y N.B x Al y Ga 1-x-y N.B x In y Ga 1-x-y One of N, wherein 0≤x≤1, 0≤y≤1; the polarity of the nitride material is metal polarity or nitrogen polarity.

[0049] According to an embodiment of the present disclosure, the shape of the nitride material includes any one of a nanocolumn, a planar structure, a triangular pyramid, and any irregular structure, wherein the shape of the nanocolumn is a polygon or any irregular shape. The length of the nitride nanocolumn is 1nm to 10μm, for example, it can be selected as 1nm, 1nm, 1nm, 1nm, 10μm, 10μm, 10μm, etc., and the width is 1nm to 10μm, for example, it can be selected as 1nm, 1nm, 1nm, 1nm, 10μm, 10μm, 10μm, etc. According to an embodiment of the present disclosure, the semiconductor structure type of the nitride material includes a pn junction, an np junction, a pin junction, and a corresponding tunneling junction structure formed by n-type doping or p-type doping of the nitride.

[0050] According to an embodiment of the present disclosure, the nitride material includes epitaxial material on a silicon substrate, a metal substrate, a sapphire substrate, an organic flexible substrate, and the like, as well as a nitride single crystal.

[0051] According to an embodiment of the present disclosure, the growth method of the nitride material includes epitaxial growth using a molecular beam epitaxy device and top-down processing of the nitride wafer substrate.

[0052] In some specific embodiments, the nitride material is preferably gallium nitride nanorods.

[0053] According to the embodiment of the present disclosure, the etching process includes: cleaning the nitride material and immersing it in an alkaline solution, etching it at room temperature for 1s to 10h, cleaning and drying it, and obtaining a nitride material with an irregular surface. The etching time can be selected from 10s, 30s, 60s, 10min, 30min, 1h, 5h, 10h, etc.

[0054] According to the embodiments of the present disclosure, different etching times will produce different etching effects and different crystal planes, and the etching time can be adjusted according to the target effect.

[0055] Fig.10 The gallium nitride nanorod after etching in the embodiment of the present disclosure Schematic diagram of the structure of the crystal plane.

[0056] In some specific embodiments of the present disclosure, a 3.5 mol / L NaOH solution is used to etch the GaN nanorods during the etching process. The GaN nanorods cleaned with ultrapure water are placed in a sodium hydroxide solution, left to stand at room temperature for 20 seconds, and then taken out, and the nanorods are cleaned with ultrapure water and blown dry. Fig.10 As shown, GaN The crystal surface has more active sites and catalytic activity, and this etching process enhances the interaction between nitride and co-catalyst.

[0057] According to an embodiment of the present disclosure, the deposition method includes one of photoelectric deposition, optical deposition, electrodeposition, plasma sputtering, and magnetron sputtering, among which photoelectric deposition under working conditions is preferred.

[0058] According to an embodiment of the present disclosure, the operation of photoelectric deposition includes: preparing a precursor aqueous solution, using a nitride material with an irregular surface as a working electrode, immersing it in the precursor aqueous solution, and irradiating it with light to obtain a nitride photoelectrode loaded with a co-catalyst; wherein the precursor aqueous solution contains an electrolyte conductive solution of the co-catalyst.

[0059] In some specific embodiments, the operation of photoelectric deposition includes: using a three-electrode structure in a mixed solution of Na2SO4 and a co-catalyst precursor, with nitride nanocolumns as working electrodes, and operating in a current-time (it) mode for 10 minutes under irradiation of a light source to obtain nitride nanocolumns loaded with co-catalysts.

[0060] According to an embodiment of the present disclosure, the promoter includes one or more of noble metal nanoparticles, transition metal nanoparticles, hydroxide nanoparticles, sulfide nanoparticles, and phosphide nanoparticles.

[0061] According to the embodiments of the present disclosure, the co-catalyst may provide catalytic active sites, promote the separation of photogenerated electrons and holes and the corresponding catalytic reactions.

[0062] In some specific embodiments, the method of photoelectrodeposition is used to load gold nanoparticles as co-catalysts on gallium nitride nanorods. Using a three-electrode structure, a target co-catalyst precursor solution is added to a 0.5M Na2SO4 solution. Taking the loading of gold nanoparticles as an example, 10-20μl of 0.2M HAuCl4 solution is added thereto. Under the irradiation of an LED light source (255-400nm) or a xenon light source, the co-catalyst is loaded for 10 minutes in an it mode with a bias voltage of 0.4V relative to the standard hydrogen potential.

[0063] According to the embodiments of the present disclosure, this directional loading method can optimize the location and distribution of active sites in the catalyst, thereby improving the utilization efficiency of the catalyst. The key parameters in the loading process include the concentration of the catalyst, the carrier material, and the temperature and time of the loading process.

[0064] In another aspect of the present disclosure, a nitride photoelectrode with photoelectrocatalytic performance obtained by the above-mentioned preparation method is used in photoelectrocatalytic reactions, including photoelectrocatalytic water decomposition, carbon dioxide reduction, nitrogen reduction, organic matter decomposition or seawater chlorine absorption.

[0065] In some specific embodiments, the photoelectric performance of the loaded GaN nanorods after etching is tested.

[0066] In the photoelectric performance test, a photoelectrochemical device is used, which is mainly composed of a photocathode, a counter electrode, a reference electrode, an electrolyte solution (such as sulfuric acid, sodium chloride, etc.), and an electrochemical workstation (which can be understood as a power source, which can accurately measure the electrical signal passing through the circuit in addition to providing electrical energy). The photocathode, solution, counter electrode, and electrochemical workstation form a closed loop (because the reference electrode does not participate in the chemical reaction, it is not considered for the convenience of understanding). Its specific working principle is: the photocathode generates photogenerated electron-hole pairs when illuminated by light that matches its band gap. The energy band is bent due to the contact between the photocathode and the solution, causing the holes to leave the photocathode and reach the counter electrode through the wire and the electrochemical workstation. The electrons diffuse to the contact point between the photocathode and the solution, and a reduction reaction occurs, while the holes undergo an oxidation reaction at the counter electrode. In this process, the relevant ions in the solution move in a directional manner, and the entire circuit forms a current. The electrochemical workstation records the current flowing through the closed loop and converts it into an electrical signal to the computer for analysis (the current directly corresponds to the number of electrons and holes that undergo chemical reactions. It is closely related to the redox reaction rate and diffusion process in the solution).

[0067] Fig.11 It is a comparison curve diagram of the linear sweep voltammetric curves before and after etching of the gallium nitride nanocolumns in the embodiment of the present disclosure.

[0068] like Fig.11 As shown, the test was conducted under AM1.5G, with a light intensity of 100mW / cm 2 The dashed line represents the linear sweep voltammetry curve of GaN / Si before etching under dark conditions; the dotted line represents the linear sweep voltammetry curve of GaN / Si before etching under light conditions; and the solid line represents the linear sweep voltammetry curve of GaN / Si after etching under light conditions.

[0069] Fig.12 It is a comparison graph of the linear sweep voltammetric curves of the gallium nitride nanocolumns loaded with gold nanoparticles before and after etching in the embodiments of the present disclosure.

[0070] like Fig.12 As shown, the test was conducted under AM1.5G, with a light intensity of 100mW / cm 2 The dashed line represents the linear sweep voltammetry curve of Au / GaN / Si before etching under dark conditions; the dotted line represents the linear sweep voltammetry curve of Au / GaN / Si before etching under light conditions; the solid line represents the linear sweep voltammetry curve of Au / GaN / Si after etching under light conditions.

[0071] After the GaN nanopillars were etched with alkaline solution, their photoelectrocatalytic water splitting performance was significantly improved. After loading with gold nanoparticles, this improvement effect became more obvious. After etching, the GaN nanopillars loaded with gold nanoparticles showed very good photoelectrocatalytic water splitting performance, and its saturated photocurrent density could reach up to 40.5mA / cm 2 Therefore, it can be determined that the improved GaN nanorods produce higher current and higher catalytic efficiency in the photoelectrocatalytic reaction, and their photoelectrocatalytic hydrogen evolution performance is the best among the currently known catalysts.

[0072] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A method for preparing a nitride photoelectrode having photoelectrocatalytic performance, comprising: Using an alkali solution to etch the surface of the nitride material to obtain a nitride nanocolumn with an irregular surface; The co-catalyst is deposited on the nitride nanorod with irregular surface to obtain a nitride photoelectrode loaded with the co-catalyst.

2. The preparation method according to claim 1, wherein The irregular surface refers to a surface after treatment in which one or more crystal planes different from the crystal planes before treatment appear.

3. The preparation method according to claim 1, wherein The nitride material includes GaN, Al x Ga 1-x N、In x Ga 1- x N,In y Al x Ga 1-x-y N.B x Al y Ga 1-x-y N.B x In y Ga 1-x-y N, wherein 0≤x≤1, 0≤y≤1, and the polarity of the nitride material is metal polarity or nitrogen polarity.

4. The preparation method according to claim 3, wherein The shape of the nitride material includes any one of a nanocolumn, a planar structure, a triangular pyramid and any irregular structure, wherein the shape of the nanocolumn is a polygon or any irregular shape; the length of the nitride nanocolumn is 1nm to 10μm, and the width of the nitride nanocolumn is 1nm to 10μm.

5. The preparation method according to claim 4, wherein: The semiconductor structure type of the nitride material includes one of a pn junction, an np junction, a pin junction and a corresponding tunnel junction structure formed by n-type doping or p-type doping of the nitride.

6. The preparation method according to claim 1, wherein The etching process comprises: The nitride material is cleaned and immersed in an alkaline solution, and then etched at room temperature for 1 second to 10 hours, and then cleaned and blown dry to obtain the nitride material with an irregular surface.

7. The preparation method according to claim 1, wherein The deposition method includes one of photoelectric deposition, optical deposition, electrodeposition, plasma sputtering, and magnetron sputtering.

8. The preparation method according to claim 7, wherein: The photoelectric deposition operation includes: A precursor aqueous solution is prepared, and the nitride material with an irregular surface is used as a working electrode, immersed in the precursor aqueous solution, and irradiated with light to obtain the nitride photoelectrode loaded with the co-catalyst; wherein the precursor aqueous solution is an electrolyte conductive solution containing the co-catalyst.

9. The preparation method according to claim 8, wherein: The promoter includes one or more of noble metal nanoparticles, transition metal nanoparticles, hydroxide nanoparticles, sulfide nanoparticles, and phosphide nanoparticles.

10. Use of a nitride photoelectrode having photoelectrocatalytic performance obtained by the preparation method according to any one of claims 1 to 9 in a photoelectric reaction, wherein: The applications include photoelectrocatalytic water splitting, carbon dioxide reduction, nitrogen reduction, organic matter decomposition or chlorine absorption from seawater.

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