Rgo-modified ingan nanorod photoelectrode material, and preparation method therefor and use thereof

Abstract

An rGO-modified InGaN nanorod photoelectrode material, and a preparation method therefor and the use thereof, which belong to the technical field of photoelectrodes. The photoelectrode material comprises an Si substrate, an InGaN nanorod layer arranged on the Si substrate, and an rGO layer arranged on the surface of the InGaN nanorod, wherein the rGO layer is made of a two-dimensional nanosheet material. The electrode material is used for preparing a photoanode, which serves as a photoanode for hydrogen production by means of photoelectrochemical water decomposition. The use of rGO not only broadens the absorption spectrum range of the photoelectrode material and effectively passivates the surface state of the nanorod, but also forms a heterostructure with the InGaN nanorod, which effectively reduces the initial potential, promotes the dissociation and transport of charge carriers and the oxidation reaction of the charge carriers on the electrode / electrolyte interface, and greatly improves the photoelectric conversion efficiency, thereby providing an effective strategy for achieving efficient PEC water decomposition hydrogen production.

Description

An rGO-modified InGaN nanocolumn photoelectrode material and its preparation method and application Technical Field

[0001] The present invention belongs to the technical field of photoelectrodes, and specifically relates to an rGO-modified InGaN nanocolumn photoelectrode material, a preparation method thereof, and applications thereof. Background Art

[0002] Solar photoelectrochemical (PEC) water splitting hydrogen production technology can convert solar energy into clean and renewable hydrogen, which is a promising way to solve the problems of energy shortage and environmental pollution. InGaN nanopillars not only have an adjustable direct band gap (E g 0.65 eV to 3.4 eV) and high carrier mobility, along with suitable band edge potentials and a large reactive area, make InGaN photoelectrodes ideal for efficient hydrogen production. Research has shown that when the In content in InGaN alloys reaches ~50%, their band edge potentials can simultaneously cross the redox potential of water splitting, promising the potential for photocatalytic hydrogen production from water splitting within the visible spectrum, with a theoretical solar-to-hydrogen (STH) efficiency of 27%. However, the performance of InGaN nanopillars for photocatalytic hydrogen splitting is often limited by the rapid recombination of surface charges and slow oxidation reaction kinetics. Therefore, developing catalysts for surface modification of InGaN nanopillar photoelectrodes is of great research significance for achieving high-performance PEC water splitting.

[0003] Existing literature discloses an application example of a Z-type heterostructure photoelectrode material formed by InGaN and Cu2O in PEC water splitting (Lin J, Zhang Z, Chai J, et al. Highly Efficient InGaN Nanorods Photoelectrode by Constructing Z-scheme Charge Transfer System for Unbiased Water Splitting[J]. Small, 2021, 17(3): 2006666.). In this work, Cu2O nanoparticles were prepared by electrochemical deposition on InGaN nanorods. Although efficient PEC water splitting can be achieved under unbiased conditions, due to the poor stability of Cu2O, efficient, continuous and stable hydrogen and oxygen production cannot be achieved. The rGO proposed in this invention is a promising strategy for low-cost, high-efficiency and stable water splitting systems, and it can be used as an efficient metal-free electrocatalyst for sustainable water splitting applications.

[0004] The present invention utilizes rGO to further improve the PEC performance of InGaN nanocolumn photoanode, effectively reduce the starting potential, promote the dissociation and transmission of charge carriers and their oxidation reaction at the electrode / electrolyte interface, greatly improve the photoelectric conversion efficiency, and thus provide an effective strategy for achieving efficient PEC water decomposition to produce hydrogen. Technical issues

[0005] The present invention aims to address the limitations of rapid surface charge recombination in InGaN nanopillars by providing an rGO-modified InGaN nanopillar photoelectrode material, its preparation method, and its application. The use of rGO not only broadens the absorption spectrum but also facilitates the dissociation and transport of photogenerated carriers, significantly improving the photoelectric performance of the nanopillars and enabling efficient photoelectrochemical water splitting for hydrogen production. Technical Solutions

[0006] The purpose of the present invention is achieved through the following technical solutions.

[0007] An rGO-modified InGaN nanocolumn photoelectrode material comprises a Si substrate, an InGaN nanocolumn is arranged on the Si substrate, and an rGO layer is arranged on the surface of the InGaN nanocolumn; the rGO layer is a two-dimensional nanosheet material.

[0008] Preferably, the atomic ratio of In atoms in the InGaN nanocolumns is 5% to 30% of the metal atoms, and the metal atoms include In and Ga; the height of the nanocolumns is 100 to 400 nm, the diameter is 30 to 100 nm, and the density is 100 to 300 mm -2 .

[0009] Preferably, the Si substrate is ultra-low-resistance silicon with a resistivity of less than 1 Ω·cm.

[0010] The preparation method of the rGO-modified InGaN nanocolumn photoelectrode material comprises the following steps:

[0011] (1) InGaN nanorods were grown on Si substrates using molecular beam epitaxy.

[0012] (2) Two-dimensional nanosheets of GO were deposited on the InGaN nanopillars by electrochemical deposition using cyclic voltammetry and then thermally reduced; wherein the deposition conditions were as follows: the concentration of the GO solution was 0.05-0.2 mg / mL, the potential was -1.5-0.6 V, the number of deposition cycles was 3-9, the thermal reduction temperature was 200-400°C, and the thermal reduction time was 1-3 hours.

[0013] Preferably, the deposition conditions are: the concentration of the GO aqueous solution is 0.08-0.15 mg / mL, the potential is -1.5-0.6 V, the number of deposition cycles is 6-8, the thermal reduction temperature is 240-260° C., and the thermal reduction time is 1.5-2.5 hours.

[0014] Preferably, the growing of InGaN nanorods on a Si substrate comprises the following steps:

[0015] The molecular beam epitaxial growth process was used, and the temperature of the Si substrate was controlled at 450~980℃, the rotation speed of the Si substrate was 5~10 r / min, and the Ga beam equivalent pressure was 1.0×10 -8 ~1.5×10 -7 Torr, the equivalent pressure of In beam is 1.0×10 -8 ~5×10 -7 Torr, nitrogen flow rate of 1~5 sccm, plasma source power of 200~400 W, growth time of 1~3 h, and growth of InGaN nanorods on Si substrates.

[0016] Preferably, the Si substrate is a Si (111) crystal plane (conductivity <0.005 Ω), which needs to undergo cleaning and annealing treatments; the cleaning treatment is to first remove organic pollutants on the surface of the Si substrate with an organic solvent, then treat the Si substrate with an HF solution to treat the surface oxide layer, and finally blow dry with high-purity dry nitrogen; the annealing treatment is to place the Si substrate obtained after the cleaning treatment into a reaction chamber, and anneal the Si substrate at 900-980°C for 10-30 minutes to obtain a reconstructed surface.

[0017] Preferably, the organic contaminants on the surface of the Si substrate are removed by using an organic solvent, and the substrate is cleaned in acetone and anhydrous ethanol in sequence, and then rinsed with water; the mass concentration of the HF solution is 5-20%.

[0018] The application of the rGO-modified InGaN nanocolumn photoelectrode material in the preparation of a photoelectrode, wherein the photoelectrode is a photoanode, which is a heterostructure electrode.

[0019] Preferably, the photoelectrode is formed by connecting a wire to the back side of the Si substrate of the rGO-modified InGaN nanocolumn photoelectrode material using a Ti-Au alloy.

[0020] The photoelectrode is used in a photoelectrochemical water splitting hydrogen production system, which includes a photoanode, a photocathode, an electrolyte, a light source and an electrolytic cell; the photoanode and photocathode are respectively placed in the electrolyte, and the photoelectrode produces hydrogen under sunlight.

[0021] Preferably, the pH of the electrolyte is 6-10, preferably 8-10; and the sunlight irradiation method for the photoelectrode is parallel light irradiation.

[0022] Reduced graphene oxide (rGO) is a flexible material derived from graphene oxide (GO) by reducing functional groups such as hydroxyl, epoxy, carbonyl, and carboxyl groups. It exhibits excellent electrical conductivity and optical bandgap tunability. Due to the presence of delocalized electrons in its carbon network, it can effectively collect electrons from the photoelectrode and quickly transfer them to the counter electrode.

[0023] The surface groups of the rGO-modified InGaN nanopillar photoelectrode material of the present invention can provide anchoring points for In clusters on the surface of the nanopillars, avoiding or reducing the use of precious metals and saving costs to a certain extent; on the other hand, it can reduce the surface state of the nanopillars and further enhance the photoelectric conversion efficiency. Beneficial effects

[0024] (1) The present invention uses rGO to modify InGaN nanopillars. This system broadens the absorption spectrum range of the photoelectrode material, effectively passivates the surface state of the nanopillars, increases the photocurrent density to a certain extent, and greatly improves the photoelectric conversion efficiency, thereby improving the performance of PEC water decomposition to produce hydrogen.

[0025] (2) The present invention uses rGO and InGaN nanopillars to form a heterostructure, which can form a good Schottky barrier between the InGaN nanopillars and effectively transfer the holes in the InGaN nanopillars to the two-dimensional nanosheet rGO, thereby promoting the oxidation reaction at the electrode / electrolyte interface.

[0026] (3) The present invention uses rGO to modify InGaN nanopillars, which can prevent the underlying nanopillars from being subjected to photoelectric corrosion in the electrolyte and can be used as an efficient metal-free electrocatalyst for sustainable water splitting applications, further enhancing the stability of the photoelectrode and thus improving the photoelectric performance of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG1 is a schematic structural diagram of an rGO-modified InGaN nanorod photoelectrode in Examples 1-4;

[0028] FIG2 is a SEM image of the surface of the rGO-modified InGaN nanocolumn anode electrode of Examples 1-4;

[0029] FIG3 is a current-voltage relationship diagram of a rGO-modified InGaN nanorod photoelectrode material in Examples 1-4 and Comparative Example 1 in a photoelectrochemical hydrogen production system under a certain bias voltage;

[0030] FIG4 is a graph showing the bias photoelectric conversion efficiency of an rGO-modified InGaN nanorod photoelectrode material in Examples 1-4 and Comparative Example 1 in a photoelectrochemical hydrogen production system under a certain bias voltage. Best Mode for Carrying Out the Invention

[0031] The present invention will be further described in detail below with reference to the examples, but the embodiments of the present invention are not limited thereto. Modes for Carrying Out the Invention

[0032] Example 1

[0033] The preparation of an rGO-modified InGaN nanorod photoelectrode material and its application in a photoelectrochemical hydrogen production system under no bias comprises the following steps:

[0034] (1) Substrate selection: n-type Si (conductivity < 0.005 Ω) is used as the substrate.

[0035] (2) Photoanode preparation: Molecular beam epitaxial growth process was used, with the substrate temperature controlled at 900 °C, the substrate rotation speed at 10 r / min, and the Ga beam equivalent pressure at 1×10 -7 Torr, the equivalent pressure of In beam is 2.0×10 -7 Torr, nitrogen flow rate of 2 sccm, plasma source power of 400 W, growth time of 3 h, InGaN nanocolumns were grown on Si substrates; In atoms accounted for 20% of the InGaN nanocolumns, the height of the nanocolumns was 100~400 nm, the diameter was 60~90 nm, and the density was 100~300 mm -2 Two-dimensional GO nanosheets were then deposited on the InGaN nanopillars and thermally reduced to rGO. The deposition conditions were: a GO aqueous solution concentration of 0.1 mg / mL, a potential between -1.5 and 0.6 V, and three deposition cycles. The thermal reduction conditions were: a temperature of 250°C and a time of 2 hours. Finally, a wire was connected to the back of the Si substrate using a Ti-Au alloy to create a photoanode.

[0036] (3) Construction of photoelectrochemical cell: The prepared photoanode was connected in series with the Pt electrode, the light source was parallel light, and the electrolyte was 0.2 M Na2HPO4 electrolyte (pH = 9).

[0037] As shown in FIG1 , a schematic diagram of the photoanode structure of an rGO-modified InGaN nanorod photoelectrode material in a photoelectrochemical hydrogen production system under a certain bias voltage is shown in FIG1 .

[0038] An rGO-modified InGaN nanorod photoelectrode material of this embodiment was used in a photoelectrochemical hydrogen production system under a certain bias voltage for solar hydrogen production, and the maximum bias photoelectric conversion efficiency obtained was 0.166%. Example 2

[0039] The preparation of an rGO-modified InGaN nanorod photoelectrode material and its application in a photoelectrochemical hydrogen production system under no bias comprises the following steps:

[0040] (1) Substrate selection: n-type Si (conductivity < 0.005 Ω) is used as the substrate.

[0041] (2) Photoanode preparation: Then, the molecular beam epitaxial growth process was adopted, with the substrate temperature controlled at 900 °C, the substrate rotation speed at 10 r / min, and the Ga beam equivalent pressure at 1×10 -7 Torr, the equivalent pressure of In beam is 2.0×10 -7 Torr, nitrogen flow rate of 2 sccm, plasma source power of 400 W, growth time of 3 h, InGaN nanocolumns were grown on Si substrates; In atoms accounted for 20% of the InGaN nanocolumns, the height of the nanocolumns was 100~400 nm, the diameter was 60~90 nm, and the density was 100~300 mm -2 Two-dimensional GO nanosheets were deposited on InGaN nanopillars and then thermally reduced to rGO. The deposition conditions were: a GO aqueous solution concentration of 0.1 mg / mL, a potential between -1.5 and 0.6 V, and five deposition cycles. The thermal reduction conditions were a temperature of 250°C and a time of 2 hours. Finally, a Ti-Au alloy wire was connected to the back of the Si substrate to form a photoanode.

[0042] (3) Construction of photoelectrochemical cell: The prepared photoanode was connected in series with the Pt electrode, the light source was parallel light, and the electrolyte was 0.2 M Na2HPO4 electrolyte (pH = 9).

[0043] As shown in FIG1 , a schematic diagram of the photoanode structure of an rGO-modified InGaN nanorod photoelectrode material in a photoelectrochemical hydrogen production system under a certain bias voltage is shown in FIG1 .

[0044] An rGO-modified InGaN nanorod photoelectrode material of this embodiment was used in a photoelectrochemical hydrogen production system under a certain bias voltage for solar hydrogen production, and the maximum bias photoelectric conversion efficiency obtained was 0.167%. Example 3

[0045] The preparation of an rGO-modified InGaN nanorod photoelectrode material and its application in a photoelectrochemical hydrogen production system under no bias comprises the following steps:

[0046] (1) Substrate selection: n-type Si (conductivity < 0.005 Ω) is used as the substrate.

[0047] (2) Photoanode preparation: Then, the molecular beam epitaxial growth process was adopted, with the substrate temperature controlled at 900 °C, the substrate rotation speed at 10 r / min, and the Ga beam equivalent pressure at 1×10 -7 Torr, the equivalent pressure of In beam is 2.0×10 -7 Torr, nitrogen flow rate of 2 sccm, plasma source power of 400 W, growth time of 3 h, InGaN nanocolumns were grown on Si substrates; In atoms accounted for 20% of the InGaN nanocolumns, the height of the nanocolumns was 100~400 nm, the diameter was 60~90 nm, and the density was 100~300 mm -2 Two-dimensional GO nanosheets were deposited on InGaN nanopillars and then thermally reduced to rGO. The deposition conditions were: a GO solution concentration of 0.1 mg / mL, a potential between -1.5 and 0.6 V, and seven deposition cycles. The thermal reduction conditions were: a temperature of 250°C and a time of 2 hours. Finally, a wire was connected to the back of the Si substrate using a Ti-Au alloy to form a photoanode.

[0048] (3) Construction of photoelectrochemical cell: The prepared photoanode was connected in series with the Pt electrode, the light source was parallel light, and the electrolyte was 0.2 M Na2HPO4 electrolyte (pH = 9).

[0049] As shown in FIG1 , a schematic diagram of the photoanode structure of an rGO-modified InGaN nanorod photoelectrode material in a photoelectrochemical hydrogen production system under a certain bias voltage is shown in FIG1 .

[0050] The rGO-modified InGaN nanorod photoelectrode material of this embodiment was used in a photoelectrochemical hydrogen production system under a certain bias voltage for solar hydrogen production, and the maximum bias photoelectric conversion efficiency obtained was 0.280%. Example 4

[0051] An rGO-modified InGaN nanorod photoelectrode material, its preparation, and application in a photoelectrochemical hydrogen production system under no bias, comprising the following steps:

[0052] (1) Substrate selection: n-type Si (conductivity < 0.005 Ω) is used as the substrate.

[0053] (2) Photoanode preparation: Then, the molecular beam epitaxial growth process was adopted, with the substrate temperature controlled at 900 °C, the substrate rotation speed at 10 r / min, and the Ga beam equivalent pressure at 1×10 -7 Torr, the equivalent pressure of In beam is 2.0×10 -7Torr, nitrogen flow rate of 2 sccm, plasma source power of 400 W, growth time of 3 h, InGaN nanocolumns were grown on Si substrates; In atoms accounted for 20% of the InGaN nanocolumns, the height of the nanocolumns was 100~400 nm, the diameter was 60~90 nm, and the density was 100~300 mm -2 Two-dimensional GO nanosheets were deposited on InGaN nanopillars and then thermally reduced to rGO. The deposition conditions were: a GO solution concentration of 0.1 mg / mL, a potential between -1.5 and 0.6 V, and nine deposition cycles. The thermal reduction conditions were: a temperature of 250°C and a time of 2 hours. Finally, a wire was connected to the back of the Si substrate using a Ti-Au alloy to create a photoanode.

[0054] (3) Construction of photoelectrochemical cell: The prepared photoanode was connected in series with the Pt electrode, the light source was parallel light, and the electrolyte was 0.2 M Na2HPO4 electrolyte (pH = 9).

[0055] As shown in FIG1 , a schematic diagram of the photoanode structure of an rGO-modified InGaN nanorod photoelectrode material in a photoelectrochemical hydrogen production system under a certain bias voltage is shown in FIG1 .

[0056] The rGO-modified InGaN nanorod photoelectrode material of this embodiment was used in a photoelectrochemical hydrogen production system under a certain bias voltage for solar hydrogen production, and the maximum bias photoelectric conversion efficiency obtained was 0.261%. Industrial Applicability

[0057] The application of InGaN nanorod photoelectrode materials in a photoelectrochemical hydrogen production system includes the following steps:

[0058] (1) Substrate selection: n-type Si (conductivity < 0.005 Ω) is used as the substrate.

[0059] (2) Photoanode preparation: Then, the molecular beam epitaxial growth process was adopted, with the substrate temperature controlled at 900 °C, the substrate rotation speed at 10 r / min, and the Ga beam equivalent pressure at 1×10 -7 Torr, the equivalent pressure of In beam is 2.0×10 -7 Torr, nitrogen flow rate of 2 sccm, plasma source power of 400 W, growth time of 3 h, InGaN nanocolumns were grown on Si substrates; In atoms accounted for 20% of the InGaN nanocolumns, the height of the nanocolumns was 100~400 nm, the diameter was 60~90 nm, and the density was 100~300 mm -2 Finally, a wire was connected to the back side of the Si substrate using Ti-Au alloy to fabricate a photoanode.

[0060] (3) Construction of photoelectrochemical cell: The prepared photoanode was connected in series with the Pt electrode, the light source was parallel light, and the electrolyte was 0.2 M Na2HPO4 electrolyte (pH = 9).

[0061] As shown in FIG4 , the InGaN nanorod photoelectrode material in this comparative example is used in a photoelectrochemical hydrogen production system under a certain bias voltage to produce hydrogen from solar energy, and the maximum bias photoelectric conversion efficiency obtained is 0.134%.

[0062] FIG2 is a SEM image of the surface of the rGO-modified InGaN nanocolumn anode electrode of Examples 1-4;

[0063] FIG3 is a current-voltage relationship diagram of a rGO-modified InGaN nanorod photoelectrode material in Examples 1-4 and Comparative Example 1 in a photoelectrochemical hydrogen production system under a certain bias voltage;

[0064] FIG4 is a graph showing the bias photoelectric conversion efficiency of an rGO-modified InGaN nanorod photoelectrode material in Examples 1-4 and Comparative Example 1 in a photoelectrochemical hydrogen production system under a certain bias voltage.

[0065] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. An rGO-modified InGaN nanorod photoelectrode material, characterized in that: It comprises a Si substrate, an InGaN nanocolumn layer is arranged on the Si substrate, and an rGO layer is arranged on the surface of the InGaN nanocolumn; the rGO layer is a two-dimensional nanosheet material reduced graphene oxide.

2. The rGO-modified InGaN nanorod photoelectrode material according to claim 1, characterized in that: The atomic ratio of In atoms in the InGaN nanocolumns is 5% to 30% of the metal atoms, and the metal atoms include In and Ga. The height of the nanocolumns is 100 to 400 nm, the diameter is 30 to 100 nm, and the density is 100 to 300 mm -2 .

3. The rGO-modified InGaN nanorod photoelectrode material according to claim 1, characterized in that: The Si substrate is ultra-low-resistance silicon with a resistivity of less than 1Ω·cm.

4. The method for preparing the rGO-modified InGaN nanorod photoelectrode material according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) InGaN nanorods were grown on Si substrates using molecular beam epitaxy. (2) Depositing two-dimensional nanosheets of GO on the InGaN nanorods of step (1) by cyclic voltammetry through electrochemical deposition, and then thermally reducing them to rGO; wherein the deposition conditions are: the concentration of the GO solution is 0.05-0.2 mg / mL, the potential is -1.5-0.6 V, and the number of deposition cycles is 3-9 cycles; the conditions for thermal reduction are: the thermal reduction temperature is 200-400°C, and the thermal reduction time is 1-3 hours.

5. The method for preparing the rGO-modified InGaN nanorod photoelectrode material according to claim 4, characterized in that: The deposition conditions are as follows: the concentration of the GO solution is 0.08-0.15 mg / mL, the potential is -1.5-0.6 V, and the deposition times are 6-8 cycles; the thermal reduction conditions are as follows: the thermal reduction temperature is 240-260° C., and the thermal reduction time is 1.5-2.5 hours.

6. The method for preparing the rGO-modified InGaN nanorod photoelectrode material according to claim 4, characterized in that: The InGaN nanorods grown on the Si substrate are prepared by a molecular beam epitaxial growth process, and the process conditions are: The molecular beam epitaxial growth process was used to control the temperature of the Si substrate to 450-980°C, the rotation speed of the Si substrate to 5-10 r / min, and the Ga beam equivalent pressure to 1.0×10 -8 ~1.5×10 -7 Torr, the equivalent pressure of In beam is 1.0×10 -8 ~5×10 -7 Torr, nitrogen flow rate of 1-5 sccm, plasma source power of 200-400 W, growth time of 1-3 h, InGaN nanorods were grown on Si substrates.

7. The use of the rGO-modified InGaN nanorod photoelectrode material in the preparation of a photoelectrode according to any one of claims 1 to 3, characterized in that: The photoelectrode is a photoanode.

8. The use according to claim 7, characterized in that: The photoanode is formed by connecting a wire with the back side of the Si substrate of the rGO-modified InGaN nanocolumn photoelectrode material using a Ti-Au alloy.

9. Use of the photoelectrode according to claim 7 or 8 in photoelectrochemical water decomposition to produce hydrogen, characterized in that: The system for photoelectrochemical water decomposition to produce hydrogen comprises a photoanode, a photocathode, an electrolyte, a light source and an electrolytic cell; the photoanode and the photocathode are respectively placed in the electrolyte, and under the irradiation of sunlight, the photoelectrode prepares hydrogen; the photoanode is defined as in claim 7 or 8.

10. The use according to claim 9, characterized in that: The pH of the electrolyte is 8-10.

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