CN112795937B - Composite material for photoelectrochemical water decomposition, preparation method and application thereof, and electrode - Google Patents

Abstract

The invention is applicable to the field of photoelectric technology, and provides a composite material for photoelectrochemical water decomposition, a preparation method, application and an electrode thereof, wherein the composite material comprises Ti₃C₂-MXene nanoplatelets and in situ growth in said Ti₃C₂Gold nanorods on MXene nanoplates. The invention is realized by two-dimensional Ti₃C₂The gold nanorods grow in situ to form the composite material with Schottky junction, which not only can improve Ti₃C₂The carrier mobility can also expand the absorption spectrum and realize the wide absorption spectrum of ultraviolet-visible-near infrared; the photoelectrochemical water splitting electrode prepared by the composite material can realize full-band photoelectric response, has good photoelectric conversion efficiency and hydrogen production rate, is simple in manufacturing method, has good working stability and shows wide application prospect.

Description

Composite material for photoelectrochemical water decomposition, preparation method and application thereof, and electrode

Technical Field

The invention belongs to the technical field of photoelectricity, and particularly relates to a composite material for photoelectrochemical water decomposition, a preparation method and application thereof, and an electrode.

Background

With the development of economy, the search for clean, sustainable energy has been an important strategic demand to reduce the excessive consumption of fossil fuels and to alleviate environmental problems. Solar energy is regarded as the most valuable energy to be developed and utilized as an inexhaustible renewable energy source to provide power for all lives on the earth. Since 1972, scientists have seen direct use of photo-electrochemical (PEC) and photocatalytic water splitting to convert solar energy into hydrogen and oxygen, both of which have been considered to be the most promising approaches in renewable energy research. Most electrodes currently used for photoelectrochemical conversion are semiconductors whose band gaps are generally matched to the Ultraviolet (UV) and visible (Vis) radiation of solar energy. However, 50% of the solar spectrum is in the Near Infrared (NIR) region and is difficult to absorb, resulting in inefficient use of solar energy. Therefore, there is a need for an effective material with broad band photoelectrochemical conversion to achieve efficient water splitting reactions.

In recent years, MXenes is a novel graphene-like two-dimensional (2D) material composed of a transition metal and C and/or N elements, and has attracted much attention in the fields of photonics, photovoltaics, and flexible electronics. Wherein, Ti₃C₂Has broadband absorption in the range from ultraviolet to near infrared, and also has large specific surface area and abundant surface hydrophilic functional groups (-OH and-O), so that the nano-composite material is easy to be compounded with other nano-materials. Second, the exposed terminal Ti atoms have strong redox properties and can also shorten the distance of PEC surface charge transfer. Third, the abundant chemical and surface properties make Ti₃C₂Has adjustable work function and good conductivity. Finally, Ti₃C₂Has very small free energy (| Δ G) for hydrogen adsorption_H*I = 0.00283 eV) so that it has a significant photocatalytic hydrogen production activity. However, despite Ti₃C₂The absorption range of nanoparticles can be extended to the NIR region, but is based on Ti₃C₂The device of (1) can only be excited by Ultraviolet (UV) or visible light of sunlight. And, Ti₃C₂The total light absorption intensity of (2) is still low, which limits the Ti-based light absorption₃C₂The quantum efficiency of the high activity catalyst of (2).

Disclosure of Invention

An object of an embodiment of the present invention is to provide a composite material for photoelectrochemical water splitting, which aims to solve the problems set forth in the background art.

The embodiment of the invention is realized by the composite material for photoelectrochemical water splitting, which comprises Ti₃C₂-MXene nanoplatelets and in situ growth in said Ti₃C₂Gold nanorods on MXene nanoplates.

Wherein, the surface plasma resonance position of the gold nanorod is continuously adjustable along with the length-diameter ratio of 650 nm to 1100 nm, and the two-dimensional Ti₃C₂-MXene nanoplatelets are a monolayer structure; in addition, gold nanorods are in two dimensionsTi₃C₂The concentration of growth on MXene nanosheets was tunable.

Another object of the embodiments of the present invention is to provide a method for preparing the above composite material for photoelectrochemical water splitting, which comprises the following steps:

cetyl trimethyl ammonium bromide and HAuCl₄And Ti₃C₂Preparing a solution from the (MXene) nanosheets, and adding NaBH₄Mixing and stirring to obtain a seed solution;

cetyl trimethyl ammonium bromide and HAuCl₄Preparing into solution, and adding AgNO₃Mixing with HCl, and adding ascorbic acid for mixing to obtain a mixed solution;

and adding the seed solution into the mixed solution, mixing and stirring, and then adding deionized water for centrifugal treatment to obtain the composite material.

As a preferable scheme of the embodiment of the invention, the concentration of cetyl trimethyl ammonium bromide in the seed solution is 0.05-0.15 mol/L, and HAuCl₄The concentration of (B) is 0.5 to 1.5 mmol/L.

As another preferable embodiment of the present invention, in the seed solution, Ti₃C₂The concentration of the-MXene nano-sheet is 0.5-1.5 mg/mL, and NaBH₄The concentration of (b) is 5 to 15 mmol/L.

As another preferable mode of the embodiment of the present invention, AgNO is added to the mixed solution₃The concentration of (b) is 5-15 mmol/L, the concentration of HCl is 1-3 mol/L, and the concentration of ascorbic acid is 0.05-0.15 mol/L.

As another preferable scheme of the embodiment of the invention, in the mixed solution, the concentration of hexadecyl trimethyl ammonium bromide is 0.05-0.15 mol/L, and HAuCl₄The concentration of (B) is 0.5 to 1.5 mmol/L.

The embodiment of the invention also aims to provide the composite material for photoelectrochemical water splitting prepared by the preparation method.

Another object of the embodiments of the present invention is to provide an application of the above composite material in photoelectrochemical water splitting.

Another object of an embodiment of the present invention is to provide an electrode for photoelectrochemical water splitting, which includes a conductive substrate, and the composite material is disposed on the conductive substrate.

As another preferable aspect of the embodiment of the present invention, the method for manufacturing the electrode includes the steps of:

and dispersing the composite material in water, mixing the composite material with a perfluorinated sulfonic acid solution, and then spin-coating the mixture on a conductive substrate to obtain the electrode.

Gold nanorods (Au NRs) have been widely used as visible-near infrared antennas for water splitting of many semiconductor PECs due to specific lateral and longitudinal resonance modes. Heterostructures composed of metal and semiconductor nanoparticles produce direct metal-semiconductor interface charge transfer transitions that can be directly excited to facilitate electron entry from the metal into the semiconductor conduction band, facilitating charge separation. NIR light can enhance light collection and photoelectric activity through efficient charge separation and plasma thermionic transfer if an efficient electron acceptor is introduced to capture the thermal electrons rapidly excited in Surface Plasmon Resonance (SPR) states from Au NRs. Therefore, the wide absorption spectrum from ultraviolet, visible and near infrared can be realized, and the photoelectrochemistry water splitting electrode can realize the photoelectricity response of the full spectral band and the high-efficiency water splitting capability.

The composite material for photoelectrochemical water decomposition provided by the embodiment of the invention is prepared by two-dimensional Ti₃C₂The gold nanorods grow in situ to form the composite material with Schottky junction, which not only can improve Ti₃C₂The carrier mobility can also expand the absorption spectrum and realize the wide absorption spectrum of ultraviolet-visible-near infrared; the photoelectrochemical water splitting electrode prepared by the composite material can realize full-band photoelectric response, has good photoelectric conversion efficiency and hydrogen production rate, is simple in manufacturing method, has good working stability and shows wide application prospect.

Drawings

FIG. 1 is a topographical view of the composite material prepared in example 1.

FIG. 2 is an X-ray diffraction pattern of the composite material obtained in example 1.

FIG. 3 is an X-ray photoelectron (XPS) spectrum of the composite material prepared in example 1.

FIG. 4 is an absorption spectrum chart of the composite material obtained in example 1.

FIG. 5 is an electrochemical impedance spectrum of the composite material obtained in example 1.

FIG. 6 is a linear sweep voltammogram of the composite material prepared in example 1.

FIG. 7 is a graph of I-t characteristics for different wavelength excitations for electrodes made in example 1.

FIG. 8 is a graph of the hydrogen production rate per hour for different wavelength excitations for the electrodes prepared in example 1.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The embodiment provides a composite material for photoelectrochemical water splitting, and the preparation method comprises the following steps:

s1, mixing Cetyl Trimethyl Ammonium Bromide (CTAB) and HAuCl₄And Ti₃C₂Preparing a solution from the (MXene) nanosheets, and adding NaBH₄Mixing and stirring for 2h at the temperature of 30 ℃ to obtain a seed solution for later use; wherein, the concentration of hexadecyl trimethyl ammonium bromide in the seed solution is 0.1mol/L, and HAuCl₄Has a concentration of 1mmol/L, Ti₃C₂Concentration of-MXene nanosheet is 1mg/mL, NaBH₄The concentration of (2) is 10 mmol/L.

S2, mixing cetyl trimethyl ammonium bromide and HAuCl₄Preparing into solution, and adding AgNO₃Mixing with HCl, and adding ascorbic acid for mixing to obtain a mixed solution; wherein, in the mixed solution, AgNO₃Has a concentration of 10mmol/L, a concentration of HCl of 2mol/L, a concentration of ascorbic acid of 0.1mol/L, a concentration of cetyltrimethylammonium bromide of 0.1mol/L, HAuCl₄The concentration of (2) was 1 mmol/L.

S3, adding 120 mu L of the seed solution into the mixed solution with the same volume to start the growth of gold NRs, placing the mixture at 30 ℃ to continue stirring for 5 hours to ensure the complete growth of gold rods, and then adding deionized water to carry out centrifugal treatment to remove redundant CTAB, thus obtaining the composite material.

In addition, the composite material is dispersed in 50mL of water, mixed with 0.1 mL of 5 wt% perfluorosulfonic acid (Nafion) solution, ultrasonically treated for 10min, and then spin-coated on a cleaned FTO conductive substrate, so that the electrode for photoelectrochemical water splitting can be prepared.

Example 2

The embodiment provides a composite material for photoelectrochemical water splitting, and the preparation method comprises the following steps:

s1, mixing Cetyl Trimethyl Ammonium Bromide (CTAB) and HAuCl₄And Ti₃C₂Preparing a solution from the (MXene) nanosheets, and adding NaBH₄Mixing and stirring the mixture for 2 hours at the temperature of 25 ℃ to obtain a seed solution for later use; wherein, the concentration of hexadecyl trimethyl ammonium bromide in the seed solution is 0.05mol/L, and HAuCl₄Has a concentration of 0.5mmol/L, Ti₃C₂Concentration of-MXene nanosheet is 0.5mg/mL, NaBH₄The concentration of (2) was 5 mmol/L.

S2, mixing cetyl trimethyl ammonium bromide and HAuCl₄Preparing into solution, and adding AgNO₃Mixing with HCl, and adding ascorbic acid for mixing to obtain a mixed solution; wherein, in the mixed solution, AgNO₃Has a concentration of 5mmol/L, HCl 1mol/L, ascorbic acid 0.05mol/L, cetyltrimethylammonium bromide 0.05mol/L, HAuCl₄The concentration of (B) was 0.5 mmol/L.

S3, adding 120 mu L of the seed solution into the mixed solution with the same volume to start the growth of gold NRs, placing the mixture at 25 ℃ to continue stirring for 5 hours to ensure the complete growth of gold rods, and then adding deionized water to carry out centrifugal treatment to remove redundant CTAB, thus obtaining the composite material.

In addition, the composite material is dispersed in 50mL of water, mixed with 0.1 mL of 3 wt% perfluorosulfonic acid (Nafion) solution, ultrasonically treated for 10min, and then spin-coated on a cleaned FTO conductive substrate, so that the electrode for photoelectrochemical water splitting can be prepared.

Example 3

The embodiment provides a composite material for photoelectrochemical water splitting, and the preparation method comprises the following steps:

s1, mixing Cetyl Trimethyl Ammonium Bromide (CTAB) and HAuCl₄And Ti₃C₂Preparing a solution from the (MXene) nanosheets, and adding NaBH₄Mixing and stirring the mixture for 2 hours at the temperature of 35 ℃ to obtain a seed solution for later use; wherein, the concentration of hexadecyl trimethyl ammonium bromide in the seed solution is 0.15mol/L, and HAuCl₄Has a concentration of 1.5mmol/L, Ti₃C₂Concentration of-MXene nanosheet is 1.5mg/mL, NaBH₄The concentration of (2) was 15 mmol/L.

S2, mixing cetyl trimethyl ammonium bromide and HAuCl₄Preparing into solution, and adding AgNO₃Mixing with HCl, and adding ascorbic acid for mixing to obtain a mixed solution; wherein, in the mixed solution, AgNO₃Has a concentration of 15mmol/L, a concentration of HCl of 3mol/L, a concentration of ascorbic acid of 0.15mol/L, a concentration of cetyltrimethylammonium bromide of 0.15mol/L, HAuCl₄The concentration of (B) was 1.5 mmol/L.

S3, adding 120 mu L of the seed solution into the mixed solution with the same volume to start the growth of gold NRs, placing the mixture at 35 ℃ to continue stirring for 5 hours to ensure the complete growth of gold rods, and then adding deionized water to carry out centrifugal treatment to remove redundant CTAB, thus obtaining the composite material.

In addition, the composite material is dispersed in 50mL of water, mixed with 0.1 mL of 8 wt% perfluorosulfonic acid (Nafion) solution, ultrasonically treated for 10min, and then spin-coated on a cleaned FTO conductive substrate, so that the electrode for photoelectrochemical water splitting can be prepared.

Example 4

The embodiment provides a composite material for photoelectrochemical water splitting, and the preparation method comprises the following steps:

s1, mixing Cetyl Trimethyl Ammonium Bromide (CTAB) and HAuCl₄And Ti₃C₂Preparing a solution from the (MXene) nanosheets, and adding NaBH₄Mixing and stirring for 2h at the temperature of 30 ℃ to obtain a seed solution for later use; wherein, the concentration of hexadecyl trimethyl ammonium bromide in the seed solution is 0.08mol/L, and HAuCl₄Has a concentration of 1.2mmol/L, Ti₃C₂Concentration of-MXene nanosheet is 0.8mg/mL, NaBH₄The concentration of (2) was 12 mmol/L.

S2, mixing cetyl trimethyl ammonium bromide and HAuCl₄Preparing into solution, and adding AgNO₃Mixing with HCl, and adding ascorbic acid for mixing to obtain a mixed solution; wherein, in the mixed solution, AgNO₃Has a concentration of 8mmol/L, HCl 2mol/L, ascorbic acid 0.12mol/L, cetyltrimethylammonium bromide 0.08mol/L, HAuCl₄The concentration of (B) was 1.2 mmol/L.

S3, adding 120 mu L of the seed solution into the mixed solution with the same volume to start the growth of gold NRs, placing the mixture at 30 ℃ to continue stirring for 5 hours to ensure the complete growth of gold rods, and then adding deionized water to carry out centrifugal treatment to remove redundant CTAB, thus obtaining the composite material.

In addition, the composite material is dispersed in 50mL of water, mixed with 0.1 mL of 5 wt% perfluorosulfonic acid (Nafion) solution, ultrasonically treated for 10min, and then spin-coated on a cleaned FTO conductive substrate, so that the electrode for photoelectrochemical water splitting can be prepared.

Example 5

The embodiment provides a composite material for photoelectrochemical water splitting, and the preparation method comprises the following steps:

s1, mixing Cetyl Trimethyl Ammonium Bromide (CTAB) and HAuCl₄And Ti₃C₂Preparing a solution from the (MXene) nanosheets, and adding NaBH₄Mixing and stirring for 2h at the temperature of 30 ℃ to obtain a seed solution for later use; wherein, the concentration of hexadecyl trimethyl ammonium bromide in the seed solution is 0.12mol/L, and HAuCl₄Has a concentration of 0.8mmol/L, Ti₃C₂Concentration of-MXene nanosheet is 1.2mg/mL, NaBH₄The concentration of (2) was 8 mmol/L.

S2, mixing cetyl trimethyl ammonium bromide and HAuCl₄Preparing into solution, and adding AgNO₃Mixing with HCl, and adding ascorbic acid for mixing to obtain a mixed solution; wherein, in the mixed solution, AgNO₃Has a concentration of 12mmol/L, a concentration of HCl of 2mol/L, a concentration of ascorbic acid of 0.08mol/L, a concentration of cetyltrimethylammonium bromide of 0.12mol/L, HAuCl₄The concentration of (B) was 0.8 mmol/L.

S3, adding 120 mu L of the seed solution into the mixed solution with the same volume to start the growth of gold NRs, placing the mixture at 30 ℃ to continue stirring for 5 hours to ensure the complete growth of gold rods, and then adding deionized water to carry out centrifugal treatment to remove redundant CTAB, thus obtaining the composite material.

In addition, the composite material is dispersed in 50mL of water, mixed with 0.1 mL of 5 wt% perfluorosulfonic acid (Nafion) solution, ultrasonically treated for 10min, and then spin-coated on a cleaned FTO conductive substrate, so that the electrode for photoelectrochemical water splitting can be prepared.

Experimental example:

firstly, observing the composite material prepared in the embodiment 1 by using an electron microscope, wherein the appearance of the composite material is shown as the attached figure 1; in addition, the X-ray diffraction pattern and the XPS spectrum of the composite material obtained in example 1 are shown in FIGS. 2 and 3, respectively. In FIGS. 2 and 3, TC is Ti₃C₂-MXene nanoplatelets, TC-Au NRs refer to the composite prepared in example 1. As can be seen from FIGS. 1 to 3, the preparation method provided by the embodiment of the invention can be successfully applied to Ti₃C₂-MXene nanosheets in situ grown gold nanorods.

Secondly, the composite material prepared in the example 1 is respectively subjected to absorption spectrum analysis, electrochemical impedance spectrum analysis and linear sweep voltammetryThe results of the tests are shown in FIGS. 4-6. In FIGS. 4 to 6, TC is Ti₃C₂-MXene nanoplatelets, TC-Au NRs for the composite prepared in example 1, Au NRs for the gold nanorods. As can be seen from FIGS. 4 to 6, the embodiment of the present invention is implemented by two-dimensional Ti₃C₂Growing the gold nanorods in situ to form a composite material with a Schottky junction, expanding an absorption spectrum and realizing a wide ultraviolet-visible-near infrared absorption spectrum; in addition, the introduction of the gold nanorods can improve Ti₃C₂Can also enhance Ti₃C₂The photoelectric response of (a).

Thirdly, I-t characteristic curves and hydrogen production rate per hour of the electrode prepared in the above example 1 under different wavelength excitation (UV (< 420 nm), Vis (420-700 nm), NIR (>700 nm)) are measured, and the results are respectively shown in FIG. 7 and FIG. 8. As can be seen from fig. 7 to 8, the photoelectrochemical water splitting electrode prepared by using the composite material provided by the embodiment of the invention can realize full-band photoelectric response, and has good photoelectric conversion efficiency and hydrogen production rate.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims (4)

1. Composite material for photoelectrochemical water splitting, characterised in that it comprises Ti₃C₂-MXene nanoplatelets and in situ growth in said Ti₃C₂-gold nanorods on MXene nanoplates;

the preparation method of the composite material comprises the following steps:

cetyl trimethyl ammonium bromide and HAuCl₄And Ti₃C₂Preparing a solution from the (MXene) nanosheets, and adding NaBH₄Mixing and stirring to obtain a seed solution;

cetyl trimethyl ammonium bromide and HAuCl₄Preparing into solution, and adding AgNO₃Mixing with HCl, and adding ascorbic acid for mixing to obtain a mixed solution;

adding the seed solution into the mixed solution, mixing and stirring, and then adding deionized water for centrifugal treatment to obtain the composite material;

wherein, in the seed solution, the concentration of the hexadecyl trimethyl ammonium bromide is 0.05-0.15 mol/L, and HAuCl₄The concentration of (A) is 0.5-1.5 mmol/L;

in the seed solution, Ti₃C₂The concentration of the-MXene nano-sheet is 0.5-1.5 mg/mL, and NaBH₄The concentration of (A) is 5-15 mmol/L;

in the mixed solution, AgNO₃The concentration of the ascorbic acid is 5-15 mmol/L, the concentration of HCl is 1-3 mol/L, and the concentration of ascorbic acid is 0.05-0.15 mol/L;

in the mixed solution, the concentration of hexadecyl trimethyl ammonium bromide is 0.05-0.15 mol/L, and HAuCl₄The concentration of (B) is 0.5 to 1.5 mmol/L.

2. Use of the composite material of claim 1 in photoelectrochemical water splitting.

3. An electrode for photoelectrochemical water splitting comprising an electrically conductive substrate, wherein said electrically conductive substrate has the composite material of claim 1 disposed thereon.

4. The photoelectrochemical water splitting electrode of claim 3, wherein the electrode is prepared by a method comprising the steps of:

and dispersing the composite material in water, mixing the composite material with a perfluorinated sulfonic acid solution, and then spin-coating the mixture on a conductive substrate to obtain the electrode.

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