Preparation method of nitride photoelectrode with photoelectrocatalytic performance and application thereof

Abstract

This disclosure proposes a method for preparing a nitride photoelectrode with photoelectrocatalytic properties, comprising etching a nitride material with an irregular surface using an alkaline solution to obtain a nitride material with an irregular surface; and depositing a co-catalyst onto the nitride material with the irregular surface to obtain a nitride photoelectrode loaded with the co-catalyst.

Description

Technical Field

[0001] This disclosure pertains to the field of semiconductor materials, specifically relating to a method for preparing a nitride photoelectrode with photoelectrocatalytic properties and its application. Background Technology

[0002] In semiconductor material research, nitride semiconductor materials, such as gallium nitride, aluminum nitride, and indium nitride, are considered as novel semiconductor materials with superior performance, based on comprehensive evaluation of factors such as chemical stability, band structure, and material system. Nitride semiconductor materials have significant application prospects in energy conversion and optoelectronics. Theoretically, their high specific surface area, superior electron transport performance, and photocatalytic potential make them highly active and efficient photocatalytic materials. Their photogenerated electrons and holes possess strong oxidation and reduction capabilities, thus enabling their application in various catalytic scenarios.

[0003] In related technologies, the main challenges faced by nitrides in photoelectrocatalysis include the efficiency of their surface charge separation and the optimization of cocatalyst loading. Nitride semiconductor materials are often used in conjunction with other cocatalysts, a common method being the uniform loading of the cocatalyst onto nitride nanopillars. However, this loading method results in a limited number of catalytically active sites and low interaction efficiency between the cocatalyst and the nitride nanopillars, leading to limited catalytic efficiency. Furthermore, in this loading method, the bonding between the cocatalyst and the nitride nanopillars is not tight, lacking directional control over the cocatalyst, making it prone to detachment and reducing stability. Summary of the Invention

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

[0005] The surface of the nitride material is etched using an alkaline solution to obtain a nitride material with an irregular surface.

[0006] A cocatalyst is deposited onto a nitride material with an irregular surface to obtain a nitride photoelectrode loaded with the cocatalyst.

[0007] According to embodiments of this disclosure, an irregular surface is a surface after treatment that exhibits one or more crystal planes different from the crystal planes before treatment. According to embodiments of this disclosure, the nitride material includes GaN and 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, where 0≤x≤1, 0≤y≤1; the polarity of the nitride material is metallic polarity or nitrogen polarity.

[0008] According to embodiments of this disclosure, the shape of the nitride material includes any one of nanopillars, planar structures, triangular pyramids, and arbitrary irregular structures, wherein the shape of the nanopillars is polygonal or arbitrary irregular; the length of the nitride nanopillars is 1 nm to 10 μm, and the width of the nitride nanopillars is 1 nm to 10 μm. According to embodiments of this disclosure, the semiconductor structure type of the nitride material includes one of the following: pn junction, np junction, pin junction, and corresponding tunnel junction structures formed by n-type doping or p-type doping of nitride.

[0009] According to embodiments of this 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 to obtain a nitride material with an irregular surface.

[0010] According to embodiments of this disclosure, the deposition method includes one of photoelectrodeposition, photodeposition, electrodeposition, plasma sputtering, and magnetron sputtering.

[0011] According to embodiments of this disclosure, the photoelectrodeposition operation includes: preparing a precursor aqueous solution, immersing a nitride material with an irregular surface as a working electrode in the precursor aqueous solution, and irradiating it with light to obtain a nitride photoelectrode loaded with a cocatalyst; wherein the precursor aqueous solution is an electrolyte conductive solution containing the cocatalyst.

[0012] According to embodiments of this disclosure, the co-catalyst includes one or more of noble metal nanoparticles, transition metal nanoparticles, hydroxide nanoparticles, sulfide nanoparticles, and phosphide nanoparticles.

[0013] In another aspect of this disclosure, an application of a nitride photoelectrode with photoelectrocatalytic properties obtained by the above preparation method in photoelectrochemical reactions is proposed, including photoelectrocatalytic water splitting, carbon dioxide reduction, nitrogen reduction, organic matter decomposition, or seawater chlorination.

[0014] According to embodiments of this disclosure, etching the surface of nitride materials with an alkaline solution alters the original crystal planes, creating other crystal planes. This changes the surface crystal structure and energy level distribution of the nitride nanopillars, improving their surface reactivity, exposing more active sites, which is beneficial for the directional loading of co-catalysts and for improving the photoelectrocatalytic performance of the nitride materials and co-catalysts. Attached Figure Description

[0015] Figure 1 This is an X-ray photoelectron spectroscopy valence band spectrum of gallium nitride nanopillars before and after etching in an embodiment of this disclosure;

[0016] Figure 2 This is a graph showing the contact potential difference of gallium nitride nanopillars before and after etching, measured by Kelvin probe force microscopy in an embodiment of this disclosure.

[0017] Figure 3 This is a flowchart of the preparation method of nitride nanopillars with photoelectrocatalytic properties disclosed herein;

[0018] Figure 4 This is a scanning electron microscope image of gallium nitride nanopillars before etching in an embodiment of this disclosure;

[0019] Figure 5 This is a projection electron microscope image of gallium nitride nanopillars before etching in an embodiment of this disclosure;

[0020] Figure 6 This is a scanning electron microscope image of gallium nitride nanopillars after etching in an embodiment of this disclosure;

[0021] Figure 7 This is a projection electron microscope image of gallium nitride nanopillars after etching in an embodiment of this disclosure;

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

[0023] Figure 9 This is a schematic diagram of the structure of gallium nitride nanopillars after etching in an embodiment of this disclosure;

[0024] Figure 10 The gallium nitride nanopillars etched in the embodiments of this disclosure Schematic diagram of the crystal plane structure;

[0025] Figure 11 This is a comparison of linear scan voltammetric curves before and after etching of gallium nitride nanopillars in the embodiments of this disclosure; and

[0026] Figure 12 This is a comparison of linear scanning voltammetric curves of gallium nitride nanopillars loaded with gold nanoparticles before and after etching in the embodiments of this disclosure.

[0027] [Attached image labels]

[0028] 1. Substrate; 2. Nitride nanopillars. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and 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 such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this disclosure.

[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

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

[0033] Surface treatment of nitride materials is an effective way to improve loading effect and loading efficiency. However, conventional chemical modification or functionalization treatment can alter the surface properties of nitride materials and cannot guarantee that the modification direction will effectively improve the photoelectrocatalytic performance of nitride materials. After loading, the co-catalyst is prone to detachment, resulting in a decrease in catalyst stability. Therefore, this disclosure uses a surface etching method to treat the surface of nitride materials, preferably nitride nanopillars, thereby changing the surface structure and energy level distribution of the nitride materials and directionally loading the co-catalyst for photoelectrode applications. This disclosure uses gallium nitride semiconductor material as an example, and performs energy level tests before and after etching to verify the feasibility of the method proposed in this disclosure.

[0034] In this disclosure, the technical term "catalytically active site" refers to a specific location or region that plays a crucial role in a catalytic reaction, typically an atomic or molecular location on the surface of a catalyst. These sites possess special properties that enable them to adsorb, activate, and promote interactions between reactants, thereby lowering the activation energy of the reaction, accelerating the reaction rate, and facilitating the smooth progress of the chemical reaction.

[0035] Figure 1 The images shown are X-ray photoelectron spectroscopy valence band spectra of gallium nitride nanopillars before and after etching, as described in the embodiments of this disclosure.

[0036] Figure 2 This is a graph showing the contact potential difference of gallium nitride nanopillars before and after etching, measured by Kelvin probe force microscopy in an embodiment of this disclosure.

[0037] like Figure 1 , Figure 2 As shown, the binding energy of the gallium nitride nanopillars before etching was 2.74 eV, and the binding energy after etching was 2.47 eV. The contact potential difference of the gallium nitride nanopillars after etching was also significantly lower than that before etching. It can be seen that after the etching operation, different crystal planes appeared, which reduced the surface binding energy of the gallium nitride nanopillars, making it more conducive to loading co-catalysts and ensuring the stability of the loading.

[0038] Figure 3 This is a flowchart of the preparation method of nitride materials with photoelectrocatalytic properties disclosed herein.

[0039] This disclosure proposes a method for preparing a nitride photoelectrode with photoelectrocatalytic properties, such as... Figure 3 As shown, it includes the following steps S1 and S2:

[0040] Step S1: Use an alkaline solution to etch the surface of the nitride material to obtain a nitride material with an irregular surface;

[0041] Step S2: Deposit the cocatalyst onto a nitride material with an irregular surface to obtain a nitride photoelectrode loaded with the cocatalyst.

[0042] According to embodiments of this disclosure, etching the surface of nitride materials with an alkaline solution alters the original crystal planes, creating other crystal planes. This changes the surface crystal structure and energy level distribution of the nitride nanopillars, improving their surface reactivity, exposing more active sites, which is beneficial for the directional loading of co-catalysts and for improving the photoelectrocatalytic performance of the nitride materials and co-catalysts.

[0043] Figure 4 , 6 These are scanning electron microscope images of gallium nitride nanopillars before and after etching in the embodiments of this disclosure.

[0044] Figure 5 , 7 These are projection electron microscope images of gallium nitride nanopillars before and after etching, respectively, in embodiments of this disclosure.

[0045] Figure 8 , 9 These are schematic diagrams of the gallium nitride nanopillars before and after etching in the embodiments of this disclosure.

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

[0047] According to embodiments of this disclosure, an irregular surface is a surface after treatment that exhibits one or more crystal planes different from those before treatment. In some specific embodiments, the etching process alters the crystal planes of the nitride material surface; preferably, for nitrides... The crystal plane is etched to obtain More preferably, for nitride materials, to terminate irregular surfaces of crystal planes. Obtained by etching the crystal plane Crystal facets.

[0048] According to embodiments of this disclosure, the nitride materials include GaN and 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, where 0≤x≤1, 0≤y≤1; the polarity of the nitride material is metallic polarity or nitrogen polarity.

[0049] According to embodiments of this disclosure, the nitride material can be shaped as a nanopillar, a planar structure, a triangular pyramid, or any irregular structure, wherein the nanopillar is polygonal or any irregular shape. The length of the nitride nanopillar is 1 nm to 10 μm, for example, 1 nm, 1 nm, 1 nm, 10 μm, 10 μm, 10 μm, etc., and the width is 1 nm to 10 μm, for example, 1 nm, 1 nm, 1 nm, 10 μm, 10 μm, 10 μm, etc. According to embodiments of this disclosure, the semiconductor structure type of the nitride material includes one of the following: pn junction, np junction, pin junction, and corresponding tunnel junction structure formed by n-type or p-type doping of the nitride.

[0050] According to embodiments of this disclosure, nitride materials include those epitaxially grown on silicon substrates, metal substrates, sapphire substrates, and organic flexible substrates, as well as nitride single crystals.

[0051] According to embodiments of this disclosure, the growth method of nitride materials includes epitaxial growth using a molecular beam epitaxy device and preparation by top-down processing of a nitride wafer substrate.

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

[0053] According to embodiments of this disclosure, the etching process includes: cleaning the nitride material and then immersing it in an alkaline solution, etching at room temperature for 1 second to 10 hours, cleaning and drying to obtain a nitride material with an irregular surface. The etching time can be selected from 10 seconds, 30 seconds, 60 seconds, 10 minutes, 30 minutes, 1 hour, 5 hours, 10 hours, etc.

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

[0055] Figure 10 The gallium nitride nanopillars etched in the embodiments of this disclosure A schematic diagram of the crystal plane structure.

[0056] In some specific embodiments of this disclosure, a 3.5 mol / L NaOH solution is used to etch the gallium nitride nanopillars during the etching process. The GaN nanopillars, cleaned with ultrapure water, are placed in the sodium hydroxide solution, left to stand at room temperature for 20 seconds, then removed, cleaned with ultrapure water, and dried. Figure 10 As shown, gallium nitride The crystal surface has more active sites and catalytic activity, and this etching process enhances the interaction between the nitride and the cocatalyst.

[0057] According to embodiments of this disclosure, the deposition method includes one of photoelectrodeposition, photodeposition, electrodeposition, plasma sputtering, and magnetron sputtering, wherein photoelectrodeposition under operating conditions is preferred.

[0058] According to embodiments of this disclosure, the photoelectrodeposition operation includes: preparing a precursor aqueous solution, immersing a nitride material with an irregular surface as a working electrode in the precursor aqueous solution, and irradiating it with light to obtain a nitride photoelectrode loaded with a cocatalyst; wherein the precursor aqueous solution contains an electrolyte conductive solution containing the cocatalyst.

[0059] In some specific embodiments, the photoelectrodeposition operation includes: in a mixed solution of Na2SO4 and a cocatalyst precursor, using a three-electrode structure with nitride nanopillars as the working electrode, running in current-time (it) mode for 10 minutes under light source irradiation to obtain nitride nanopillars loaded with cocatalyst.

[0060] According to embodiments of this disclosure, the co-catalyst includes one or more of noble metal nanoparticles, transition metal nanoparticles, hydroxide nanoparticles, sulfide nanoparticles, and phosphide nanoparticles.

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

[0062] In some specific embodiments, gold nanoparticles are loaded onto gallium nitride nanopillars using photoelectrode deposition. A three-electrode structure is used, and the target co-catalyst precursor solution is added to a 0.5 M Na₂SO₄ solution. Taking the loading of gold nanoparticles as an example, 10-20 μl of 0.2 M HAuCl₄ solution is added. The co-catalyst loading is completed by operating in it mode with a bias voltage of 0.4 V relative to the standard hydrogen potential for 10 minutes under LED light (255-400 nm) or xenon lamp illumination.

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

[0064] In another aspect of this disclosure, an application of a nitride photoelectrode with photoelectrocatalytic properties obtained by the above preparation method in photoelectrochemical reactions is proposed, including photoelectrocatalytic water splitting, carbon dioxide reduction, nitrogen reduction, organic matter decomposition, or seawater chlorination.

[0065] In some specific embodiments, the photoelectric properties of the etched gallium nitride nanopillars were tested.

[0066] In photoelectric performance testing, a photoelectrochemical device is used, mainly consisting of a photocathode, a counter electrode, a reference electrode, an electrolyte solution (such as sulfuric acid or sodium chloride solution), and an electrochemical workstation (which can be understood as a power source, providing electrical energy and accurately measuring the electrical signal passing through the circuit). The photocathode, solution, counter electrode, and electrochemical workstation form a closed loop (the reference electrode is not considered for simplicity as it does not participate in the chemical reaction). Its specific working principle is as follows: the photocathode, when illuminated with light matching its band gap, generates photogenerated electron-hole pairs. Due to the contact between the photocathode and the solution, the energy band bends, causing holes to leave the photocathode and travel through a wire to the electrochemical workstation to the counter electrode. Electrons diffuse to the contact point between the photocathode and the solution, where a reduction reaction occurs, while holes undergo an oxidation reaction at the counter electrode. During this process, relevant ions in the solution undergo directional movement, forming a current in the entire loop. The electrochemical workstation records the current flowing through the closed loop, converting it into an electrical signal for computer analysis (this current directly corresponds to the number of electrons and holes involved in the chemical reaction and is closely related to the redox reaction rate and diffusion process in the solution).

[0067] Figure 11 This is a comparison of linear scanning voltammetric curves before and after etching of gallium nitride nanopillars in the embodiments of this disclosure.

[0068] like Figure 11 As shown, the light intensity was 100 mW / cm² when tested under AM1.5G. 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 illuminated conditions; and the solid line represents the linear sweep voltammetry curve of GaN / Si after etching under illuminated conditions.

[0069] Figure 12 This is a comparison of linear scanning voltammetric curves of gallium nitride nanopillars loaded with gold nanoparticles before and after etching in the embodiments of this disclosure.

[0070] like Figure 12 As shown, the light intensity was 100 mW / cm² when tested under AM1.5G. 2 The dashed line represents the linear sweep voltammetry curve of Au / GaN / Si under dark conditions before etching; the dotted line represents the linear sweep voltammetry curve of Au / GaN / Si under illumination conditions before etching; and the solid line represents the linear sweep voltammetry curve of Au / GaN / Si under illumination conditions after etching.

[0071] The photoelectrochemical water splitting performance of GaN nanopillars was significantly improved after alkaline etching. This enhancement became even more pronounced after loading gold nanoparticles; the etched GaN nanopillars with gold nanoparticles exhibited excellent photoelectrochemical water splitting performance, with a maximum saturation photocurrent density reaching 40.5 mA / cm². 2 Therefore, it can be determined that the improved GaN nanopillars generate higher current and higher catalytic efficiency in the photoelectrocatalytic reaction, and their photoelectrocatalytic hydrogen evolution performance is the best among currently known catalysts.

[0072] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A method for preparing a nitride photoelectrode with photoelectrocatalytic properties, comprising: Nitride nanopillars with irregular surfaces are obtained by etching the surface of a nitride material using an alkaline solution; wherein the irregular surface refers to the appearance of one or more crystal planes on the treated surface that are different from the crystal planes before treatment; the nitride material includes GaN and 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, where 0≤x≤1, 0≤y≤1, and the polarity of the nitride material is nitrogen polarity; A cocatalyst is deposited onto the nitride nanopillars with irregular surfaces to obtain a nitride photoelectrode loaded with the cocatalyst.

2. The preparation method according to claim 1, wherein, The nitride nanopillars are polygonal in shape; the length of the nitride nanopillars is 1 nm to 10 μm, and the width of the nitride nanopillars is 1 nm to 10 μm.

3. The preparation method according to claim 2, wherein, The semiconductor structure types of the nitride material include one of the following: pn junction, np junction, pin junction, and corresponding tunnel junction structures formed by n-type or p-type doping of nitride.

4. The preparation method according to claim 1, wherein, The etching process includes: After cleaning, the nitride material is immersed in an alkaline solution and etched at room temperature for 1 second to 10 hours. After cleaning and drying, the nitride material with an irregular surface is obtained.

5. The preparation method according to claim 1, wherein, The deposition method includes one of photoelectrodeposition, photodeposition, electrodeposition, plasma sputtering, and magnetron sputtering.

6. The preparation method according to claim 5, wherein, The photoelectrode deposition operation includes: A precursor aqueous solution is prepared, and the nitride material with an irregular surface is used as the working electrode and immersed in the precursor aqueous solution for light irradiation to obtain the nitride photoelectrode loaded with the co-catalyst; wherein, the precursor aqueous solution is an electrolyte conductive solution containing the co-catalyst.

7. The preparation method according to claim 6, wherein, The co-catalyst includes one or more of noble metal nanoparticles, transition metal nanoparticles, hydroxide nanoparticles, sulfide nanoparticles, and phosphide nanoparticles.

8. The application of a nitride photoelectrode with photocatalytic properties obtained by the preparation method according to any one of claims 1 to 7 in photoelectrochemical reactions, wherein, The applications include photoelectrocatalytic water splitting, carbon dioxide reduction, nitrogen reduction, organic matter decomposition, or seawater chlorination.

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