Preparation method and application of nickel-doped functional carbon quantum dots modified Cu-In-Zn-S quantum dot composite photocatalyst

Abstract

The present invention belongs to the field of composite material technology and relates to composite photocatalysts, particularly a method for preparing a nickel-doped functional carbon quantum dot-modified CIZS quantum dot (Ni-CDs / CIZS / WO3) composite photocatalyst. The method comprises first subjecting the composite photocatalyst to a hydrothermal reaction at 100-140°C for 3-5 hours to obtain a CIZS / WO3 precursor. Ni-CDs are then weighed and dissolved in an aqueous solution, and the CIZS / WO3 precursor is added. The mixture is ultrasonically stirred and subjected to a hydrothermal reaction at 100-140°C for 3-5 hours. After completion of the reaction, the mixture is washed to obtain the Ni-CDs / CIZS / WO3 composite photocatalyst. The present invention also discloses the application of the prepared catalyst in photocatalytic hydrogen production. The present invention prepares a composite photocatalyst in which a conductor and a semiconductor are bridged by carbon quantum dots. The preparation method is simple, and the resulting catalyst is a green, environmentally friendly, and highly efficient composite photocatalyst for photocatalytic water splitting to produce hydrogen.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials and relates to a composite photocatalyst, and in particular to a preparation method and application of a nickel-doped functional carbon quantum dot-modified CIZS quantum dot (Ni-CDs / CIZS / WO3) composite photocatalyst. Background Art

[0002] The use of solar energy to photocatalytically split water to produce hydrogen is considered to be the most ideal way to alleviate energy shortages and avoid ecological damage. Considering the basic principles of photocatalysis, limited light harvesting ability, rapid recombination of photogenerated electrons and holes, and insufficient surface reaction sites are the main factors leading to the poor efficiency of photocatalytic hydrogen production. For a long time, people have proposed a series of strategies, including doping, constructing heterojunctions, loading of co-catalysts, etc. to improve photocatalytic efficiency. Among these methods, constructing Z-type heterojunctions plays a key role in promoting charge separation and inhibiting recombination. Despite this, limited light harvesting ability and over-reliance on precious metals as reaction sites are still the key factors restricting the further development of Z-type heterojunctions.

[0003] Due to their structural diversity, carbon dots (CDs) have a variety of optical properties. In the field of photocatalysis, they can enhance light absorption, promote charge separation, and act as electron acceptors and storage media. These unique properties make them a very important multifunctional component in photocatalytic systems. However, there are few reports on how to efficiently utilize CDs after accepting electrons. Considering the work function advantage of metallic Ni, which can accept electrons in CDs as active sites, Ni-modified CDs (Ni-CDs) are expected to become a new generation of efficient hydrogen evolution co-catalysts to achieve efficient photocatalytic hydrogen production.

[0004] Cu-In-Zn-S (CIZS), a representative example of cadmium-free I-III-VI quantum dots, is a promising class of photocatalysts due to its widely tunable band gap and long lifetime. To achieve efficient charge separation and utilization, WO3, with its superior electron transport properties and unique light-harvesting pathway, was combined with Ni-CDs to form a Ni-CDs-modified CIZS / WO3Z heterojunction ternary composite material for application in photocatalytic hydrogen production. Summary of the Invention

[0005] In order to solve the above problems, the purpose of the present invention is to disclose a method for preparing a nickel-doped functional carbon quantum dot modified CIZS quantum dot (Ni-CDs / CIZS / WO3) composite photocatalyst.

[0006] A method for preparing a nickel-doped functional carbon quantum dot-modified CIZS quantum dot (Ni-CDs / CIZS / WO3) composite photocatalyst comprises the following steps:

[0007] A. Disperse CIZS quantum dots in water, add WO3, and stir evenly with ultrasonic stirring. Place in an autoclave for hydrothermal reaction at 100-140°C for 3-5 hours, preferably at 110°C for 4 hours, cool to room temperature, wash with ethanol, and dry to obtain a CIZS / WO3 precursor, wherein the mass and volume ratio of CIZS, WO3, and H2O is 9.948-9.345 mg:0.052-0.655 mg:10-20 mL, preferably 9.9 mg:0.1 mg:15 mL;

[0008] B. Disperse Ni-CDs in water, add CIZS / WO3 precursor, stir evenly with ultrasonic stirring, place in a high-pressure reactor for hydrothermal reaction at 100-140°C for 3-5 hours, preferably at 110°C for 4 hours, cool to room temperature, wash with ethanol and dry to obtain a Ni-CDs / CIZS / WO3 composite photocatalyst; wherein the mass volume ratio of Ni-CDs, CIZS / WO3 precursor and water is 0.05-0.700 mg:9.95-9.3 mg:10-20 mL, preferably 0.1 mg:9.9 mg:15 mL.

[0009] In a preferred embodiment of the present invention, the molar ratio of copper:indium:zinc in the CIZS quantum dots in step A is 12:14:7.

[0010] In the preferred disclosed example of the present invention, the CIZS quantum dots described in step A are homemade, and the following is a preparation method thereof: 0.2540g Cu(OAc)2·H2O, 0.4867g In(NO3)3∙4.5H2O and 0.1390g Zn(OAc)2∙2H2O (used as metal precursors) are dissolved in 8ml deionized water containing 0.4537g L-cysteine ​​(used as a protective agent), and ultrasonically dispersed uniformly. The pH value of the mixed solution is adjusted to 8.5 with 1.0M NaOH solution, and then 0.183g thioacetamide is added; after continuing to stir for 20min, it is transferred to a 50mL polytetrafluoroethylene-lined stainless steel autoclave and reacted at 110°C for 4h; after natural cooling, ethanol is added, collected by centrifugation, washed three times with deionized water / ethanol, dispersed in deionized water, and set aside.

[0011] In the preferred disclosed example of the present invention, the WO3 described in step A is homemade, and the following is a preparation method thereof: 0.330g Na2WO4·2H2O and 0.288g citric acid are dissolved in 30mL of deionized water in sequence, and then 3mL of 6mol / LHCl is added dropwise under stirring, stirred for 30min, and then transferred to a reactor and treated at 120°C for 10h. After natural drying, it is washed three times with deionized water and dried at 60°C for 12h to obtain WO3 powder.

[0012] In a preferred disclosed example of the present invention, the nickel-carbon quantum dots (Ni-CDs) described in step B are homemade, and the following is a preparation method thereof: 1.05 g of citric acid and 0.335 mL of ethylenediamine are dissolved in 10 mL of deionized water and stirred evenly; the solution is transferred to a 20 mL polytetrafluoroethylene-lined autoclave and heated at 180° C. for 5 h; the reactor is cooled to room temperature by water or naturally, 100 mg of anhydrous nickel sulfate is added, and Ni-CDs are obtained by dialysis, and the solution is black and transparent.

[0013] The Ni-CDs / CIZS / WO3 composite photocatalyst prepared according to the method of the present invention has a 0D-0D morphology supported on 2D nanosheets. High-resolution transmission electron microscopy (HRTEM) images of the Ni-CDs / CIZS / WO3 composite further show that the spacing of 0.24 nm is attributed to the CIZS (121) crystal plane, the spacing of 0.21 nm is attributed to the CDs (101) plane, and the spacing of 0.26 nm is attributed to the WO3 (200) crystal plane. This demonstrates the successful combination of CIZS, WO3, and Ni-CDs.

[0014] Another object of the present invention is to apply the prepared Ni-CDs / CIZS / WO3 composite photocatalyst to photocatalytic hydrogen production.

[0015] Photocatalytic activity evaluation:

[0016] Under visible light conditions, 0.01 g of catalyst and 0.528 g of L-ascorbic acid were added to the photoreactor, and N2 gas was introduced at a high flow rate. After the gas in the bottle was completely exhausted, a customized power (100 mW / cm2) was turned on under magnetic stirring conditions. -2 ) and sampled and analyzed every 1 h.

[0017] The amount of H2 is calculated. Beneficial effects

[0018] (1) The present invention first constructs a Z-type heterojunction using CIZS quantum dots and WO3 nanosheets, takes advantage of its spatial charge separation, and then uses Ni-CDs as a co-catalyst to further improve the visible light response capability and charge utilization efficiency, greatly reducing the recombination rate of photogenerated charges and achieving more efficient photocatalytic water splitting to produce hydrogen.

[0019] (2) WO3 has a nanosheet structure, CIZS quantum dots and Ni-CDs can be uniformly loaded on WO3, and the 0D / 2D combination effectively increases the specific surface area for charge consumption.

[0020] (3) This invention is the first to demonstrate the use of CDs as a charge transfer medium between a conductor and a semiconductor to enhance the charge transfer rate and achieve efficient photocatalytic hydrogen production. Under visible light excitation, photogenerated electrons are rapidly transferred through the carbon quantum dots to the nickel substrate to participate in the hydrogen evolution reaction, significantly reducing the occurrence of recombination and significantly improving photocatalytic performance.

[0021] (4) The process of the present invention is simple, cheap, easily available, convenient for mass production, non-toxic and harmless, and meets environmentally friendly requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 XRD diffraction patterns of CIZS, WO3, CIZS / WO3, Ni-CDs, and Ni-CDs / CIZS / WO3 photocatalysts;

[0023] Figure 2 Transmission image of Ni-CDs / CIZS / WO3 prepared in Example 5;

[0024] Figure 3 High-resolution transmission image of Ni-CDs / CIZS / WO3 obtained in Example 5;

[0025] Figure 4 UV-visible absorption spectra of CIZS, WO3, CIZS / WO3, Ni-CDs and Ni-CDs / CIZS / WO3 photocatalysts. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below with reference to the following examples so that those skilled in the art can better understand the present invention. However, the present invention is not limited to the following examples. Example 1

[0027] (1) Preparation of CIZS / WO3 precursor:

[0028] Transfer 9.9 mg of CIZS and 0.1 mg of WO3 into a transparent glass bottle and dilute to 20 mL. Hydrothermally react in an autoclave at 100 °C for 3 h and use in the next step after cooling.

[0029] (2) Preparation of Ni-CDs / CIZS / WO3 composite photocatalyst:

[0030] 0.1 mg Ni-CDs was weighed and dissolved in 12.00 mL water, 9.9 mg CIZS / WO3 precursor was added, and ultrasonic mixing was performed uniformly. The mixture was hydrothermally reacted in an autoclave at 100 °C for 3 h. After the reaction, the mixture was washed to obtain a Ni-CDs / CIZS / WO3 composite photocatalyst.

[0031] 10mg of NiCDs / CIZS / WO3 composite photocatalyst and 528mg of L-ascorbic acid were added to a photoreactor. N2 gas was introduced at a high flow rate until the gas in the reaction flask was completely vented. Irradiation with a custom xenon lamp was performed under magnetic stirring, and samples were collected and analyzed every hour.

[0032] Calculation shows that the hydrogen production rate is 2.02mmol / g / h. Example 2

[0033] (1) Preparation of CIZS / WO3 precursor:

[0034] Transfer 9.9 mg of CIZS and 0.1 mg of WO3 into a transparent glass bottle and dilute to 20 mL. Hydrothermally react in an autoclave at 100 °C for 4 h and use in the next step after cooling.

[0035] (2) Preparation of Ni-CDs / CIZS / WO3 composite photocatalyst:

[0036] 0.1 mg Ni-CDs was weighed and dissolved in 12.00 mL water, 9.9 mg CIZS / WO3 precursor was added, and ultrasonic mixing was performed uniformly. The mixture was hydrothermally reacted in an autoclave at 100 °C for 4 h. After the reaction was completed, the mixture was washed to obtain a Ni-CDs / CIZS / WO3 composite photocatalyst.

[0037] 10mg of Ni-CDs / CIZS / WO3 composite photocatalyst and 528mg of L-ascorbic acid were added to a photoreactor. N2 gas was introduced at a high flow rate until the gas in the reaction flask was completely vented. Irradiation with a custom xenon lamp was performed under magnetic stirring, and samples were collected and analyzed every hour.

[0038] Calculation shows that the hydrogen production rate is 2.52mmol / g / h. Example 3

[0039] (1) Preparation of CIZS / WO3 precursor:

[0040] Transfer 9.9 mg of CIZS and 0.1 mg of WO3 into a transparent glass bottle and dilute to 20 mL. Hydrothermally react in an autoclave at 100 °C for 5 h and use in the next step after cooling.

[0041] (2) Preparation of Ni-CDs / CIZS / WO3 composite photocatalyst:

[0042] 0.1 mg Ni-CDs was weighed and dissolved in 12.00 mL water, 9.9 mg CIZS / WO3 precursor was added, and ultrasonic mixing was performed uniformly. The mixture was hydrothermally reacted in an autoclave at 100 °C for 5 h. After the reaction was completed, the mixture was washed to obtain a Ni-CDs / CIZS / WO3 composite photocatalyst.

[0043] 10mg of Ni-CDs / CIZS / WO3 composite photocatalyst and 528mg of L-ascorbic acid were added to a photoreactor. N2 gas was introduced at a high flow rate until the gas in the reaction flask was completely vented. Irradiation with a custom xenon lamp was performed under magnetic stirring, and samples were collected and analyzed every hour.

[0044] Calculation shows that the hydrogen production rate is 2.32mmol / g / h. Example 4

[0045] (1) Preparation of CIZS / WO3 precursor:

[0046] Transfer 9.9 mg of CIZS and 0.1 mg of WO3 into a transparent glass bottle and dilute to 20 mL. Hydrothermally react in an autoclave at 110 °C for 5 h and use in the next step after cooling.

[0047] (2) Preparation of Ni-CDs / CIZS / WO3 composite photocatalyst:

[0048] 0.1 mg Ni-CDs was weighed and dissolved in 12.00 mL water, 9.9 mg CIZS / WO3 precursor was added, ultrasonically mixed evenly, and hydrothermally reacted in an autoclave at 110 °C for 5 h. After the reaction, the mixture was washed to obtain a Ni-CDs / CIZS / WO3 composite photocatalyst.

[0049] 10mg of Ni-CDs / CIZS / WO3 composite photocatalyst and 528mg of L-ascorbic acid were added to a photoreactor. N2 gas was introduced at a high flow rate until the gas in the reaction flask was completely vented. Irradiation with a custom xenon lamp was performed under magnetic stirring, and samples were collected and analyzed every hour.

[0050] Calculation shows that the hydrogen production rate is 2.82mmol / g / h. Example 5

[0051] (1) Preparation of CIZS / WO3 precursor:

[0052] Transfer 9.9 mg of CIZS and 0.1 mg of WO3 into a transparent glass bottle and dilute to 20 ml. Hydrothermally react in an autoclave at 110 °C for 4 h and use in the next step after cooling.

[0053] (2) Preparation of Ni-CDs / CIZS / WO3 composite photocatalyst:

[0054] 0.1 mg Ni-CDs was weighed and dissolved in 12.00 mL water, 9.9 mg CIZS / WO3 precursor was added, ultrasonically mixed evenly, and hydrothermally reacted in an autoclave at 110 °C for 4 h. After the reaction, the mixture was washed to obtain a Ni-CDs / CIZS / WO3 composite photocatalyst.

[0055] 10mg of Ni-CDs / CIZS / WO3 composite photocatalyst and 528mg of L-ascorbic acid were added to a photoreactor. N2 gas was introduced at a high flow rate until the gas in the reaction flask was completely vented. Irradiation with a custom xenon lamp was performed under magnetic stirring, and samples were collected and analyzed every hour.

[0056] Calculation shows that the hydrogen production rate is 4.26mmol / g / h. Example 6

[0057] (1) Preparation of CIZS / WO3 precursor:

[0058] Transfer 9.7 mg of CIZS and 0.3 mg of WO3 into a transparent glass bottle and dilute to 20 mL. Hydrothermally react in an autoclave at 110 °C for 4 h and use in the next step after cooling.

[0059] (2) Preparation of Ni-CDs / CIZS / WO3 composite photocatalyst:

[0060] 0.1 mg Ni-CDs was weighed and dissolved in 12.00 mL water, 9.9 mg CIZS / WO3 precursor was added, ultrasonically mixed evenly, and hydrothermally reacted in an autoclave at 110 °C for 4 h. After the reaction, the mixture was washed to obtain a Ni-CDs / CIZS / WO3 composite photocatalyst.

[0061] 10mg of Ni-CDs / CIZS / WO3 composite photocatalyst and 528mg of L-ascorbic acid were added to a photoreactor. N2 gas was introduced at a high flow rate until the gas in the reaction flask was completely vented. Irradiation with a custom xenon lamp was performed under magnetic stirring, and samples were collected and analyzed every hour.

[0062] Calculation shows that the hydrogen production rate is 4.01mmol / g / h. Example 7

[0063] (1) Preparation of CIZS / WO3 precursor:

[0064] Transfer 9.5 mg of CIZS and 0.5 mg of WO3 into a transparent glass bottle and dilute to 20 mL. Hydrothermally react in an autoclave at 110 °C for 4 h and use in the next step after cooling.

[0065] (2) Preparation of Ni-CDs / CIZS / WO3 composite photocatalyst:

[0066] 0.1 mg Ni-CDs was weighed and dissolved in 12.00 mL water, 9.9 mg CIZS / WO3 precursor was added, ultrasonically mixed evenly, and hydrothermally reacted in an autoclave at 110 °C for 4 h. After the reaction, the mixture was washed to obtain a Ni-CDs / CIZS / WO3 composite photocatalyst.

[0067] 10mg of Ni-CDs / CIZS / WO3 composite photocatalyst and 528mg of L-ascorbic acid were added to a photoreactor. N2 gas was introduced at a high flow rate until the gas in the reaction flask was completely vented. Irradiation with a custom xenon lamp was performed under magnetic stirring, and samples were collected and analyzed every hour.

[0068] Calculation shows that the hydrogen production rate is 4.06mmol / g / h. Example 8

[0069] (1) Preparation of CIZS / WO3 precursor:

[0070] Transfer 9.9 mg of CIZS and 0.1 mg of WO3 into a transparent glass bottle and dilute to 20 mL. Hydrothermally react in an autoclave at 110 °C for 4 h and use in the next step after cooling.

[0071] (2) Preparation of Ni-CDs / CIZS / WO3 composite photocatalyst:

[0072] 0.3 mg Ni-CDs was weighed and dissolved in 12.00 mL water, 9.7 mg CIZS / WO3 precursor was added, ultrasonically mixed evenly, and hydrothermally reacted in an autoclave at 110 °C for 4 h. After the reaction, the mixture was washed to obtain a Ni-CDs / CIZS / WO3 composite photocatalyst.

[0073] 10mg of Ni-CDs / CIZS / WO3 composite photocatalyst and 528mg of L-ascorbic acid were added to a photoreactor. N2 gas was introduced at a high flow rate until the gas in the reaction flask was completely vented. Irradiation with a custom xenon lamp was performed under magnetic stirring, and samples were collected and analyzed every hour.

[0074] Calculation shows that the hydrogen production rate is 3.81mmol / g / h. Example 9

[0075] (1) Preparation of CIZS / WO3 precursor:

[0076] Transfer 9.7 mg of CIZS and 0.3 mg of WO3 into a transparent glass bottle and dilute to 20 mL. Hydrothermally react in an autoclave at 110 °C for 4 h and use in the next step after cooling.

[0077] (2) Preparation of Ni-CDs / CIZS / WO3 composite photocatalyst:

[0078] 0.5 mg Ni-CDs was weighed and dissolved in 12.00 mL water, 9.5 mg CIZS / WO3 precursor was added, ultrasonically mixed evenly, and hydrothermally reacted in an autoclave at 110 °C for 4 h. After the reaction, the mixture was washed to obtain a Ni-CDs / CIZS / WO3 composite photocatalyst.

[0079] 10mg of Ni-CDs / CIZS / WO3 composite photocatalyst and 528mg of L-ascorbic acid were added to a photoreactor. N2 gas was introduced at a high flow rate until the gas in the reaction flask was completely vented. Irradiation with a custom xenon lamp was performed under magnetic stirring, and samples were collected and analyzed every hour.

[0080] Calculation shows that the hydrogen production rate is 3.56mmol / g / h. Example 10

[0081] (1) Preparation of CIZS / WO3 precursor:

[0082] Transfer 9.5 mg of CIZS and 0.5 mg of WO3 into a transparent glass bottle and dilute to 20 mL. Hydrothermally react in an autoclave at 110 °C for 4 h and use in the next step after cooling.

[0083] (2) Preparation of Ni-CDs / CIZS / WO3 composite photocatalyst:

[0084] 0.5 mg Ni-CDs was weighed and dissolved in 12.00 mL water, 9.5 mg CIZS / WO3 precursor was added, ultrasonically mixed evenly, and hydrothermally reacted in an autoclave at 110 °C for 4 h. After the reaction, the mixture was washed to obtain a Ni-CDs / CIZS / WO3 composite photocatalyst.

[0085] 10mg of Ni-CDs / CIZS / WO3 composite photocatalyst and 528mg of L-ascorbic acid were added to a photoreactor. N2 gas was introduced at a high flow rate until the gas in the reaction flask was completely vented. Irradiation with a custom xenon lamp was performed under magnetic stirring, and samples were collected and analyzed every hour.

[0086] Calculation shows that the hydrogen production rate is 3.21mmol / g / h. Example 11

[0087] (1) Preparation of CIZS / WO3 precursor:

[0088] Transfer 9.3 mg of CIZS and 0.7 mg of WO3 into a transparent glass bottle and dilute to 20 mL. Hydrothermally react in an autoclave at 110 °C for 4 h and use in the next step after cooling.

[0089] (2) Preparation of Ni-CDs / CIZS / WO3 composite photocatalyst:

[0090] 0.7 mg Ni-CDs was weighed and dissolved in 12.00 mL water, 9.3 mg CIZS / WO3 precursor was added, ultrasonically mixed evenly, and hydrothermally reacted in an autoclave at 110 °C for 4 h. After the reaction, the mixture was washed to obtain a Ni-CDs / CIZS / WO3 composite photocatalyst.

[0091] 10mg of the Ni-CDs / CIZS / WO3 composite photocatalyst and 528mg of L-ascorbic acid were added to a photoreactor. N2 gas was introduced at a high flow rate until the gas in the reaction flask was completely vented. Irradiation with a custom xenon lamp was performed under magnetic stirring, and samples were collected and analyzed every hour.

[0092] Calculation shows that the hydrogen production rate is 2.81mmol / g / h. Example 12

[0093] (1) Preparation of CIZS / WO3 precursor:

[0094] Transfer 9.95 mg of CIZS and 0.05 mg of WO3 into a transparent glass bottle and dilute to 20 mL. Hydrothermally react in an autoclave at 110 °C for 4 h and use in the next step after cooling.

[0095] (2) Preparation of Ni-CDs / CIZS / WO3 composite photocatalyst:

[0096] 0.1 mg Ni-CDs was weighed and dissolved in 12.00 mL water, 9.9 mg CIZS / WO3 precursor was added, ultrasonically mixed evenly, and hydrothermally reacted in an autoclave at 110 °C for 4 h. After the reaction, the mixture was washed to obtain a Ni-CDs / CIZS / WO3 composite photocatalyst.

[0097] 10mg of Ni-CDs / CIZS / WO3 composite photocatalyst and 528mg of L-ascorbic acid were added to a photoreactor. N2 gas was introduced at a high flow rate until the gas in the reaction flask was completely vented. Irradiation with a custom xenon lamp was performed under magnetic stirring, and samples were collected and analyzed every hour.

[0098] Calculation shows that the hydrogen production rate is 4.11 mmol / g / h.

[0099] The embodiments described are preferred implementations of the present invention, but the present invention is not limited to the above-mentioned implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention are within the scope of protection of the present invention.

Claims

1. A method for preparing nickel-doped functional carbon quantum dots modified CIZS quantum dot composite photocatalyst, characterized in that: The steps include: A. Dispersing Cu-In-Zn-S quantum dots (CIZS quantum dots) in water, adding WO3, and ultrasonically stirring the mixture until uniform. The mixture was placed in an autoclave for hydrothermal reaction at 100-140°C for 3-5 hours, cooled to room temperature, washed with ethanol, and dried to obtain a CIZS / WO3 precursor, wherein the mass and volume ratio of CIZS quantum dots, WO3, and H2O is 9.948-9.345 mg:0.052-0.655 mg:10-20 mL; B. Disperse nickel-carbon quantum dots, i.e., Ni-CDs quantum dots, in water, add CIZS / WO3 precursor, stir evenly with ultrasonication, place in a high-pressure reactor for hydrothermal reaction at 100-140°C for 3-5 hours, cool to room temperature, wash with ethanol and dry to obtain a Ni-CDs / CIZS / WO3 composite photocatalyst; wherein the mass and volume ratio of the Ni-CDs quantum dots, CIZS / WO3 precursor and water is 0.05-0.700 mg:9.95-9.3 mg:10-20 mL.

2. The method for preparing the nickel-doped functional carbon quantum dot-modified CIZS quantum dot composite photocatalyst according to claim 1, characterized in that: In step A, the molar ratio of copper:indium:zinc in the CIZS quantum dots is 12:14:

7.

3. The method for preparing nickel-doped functional carbon quantum dots modified CIZS quantum dot composite photocatalyst according to claim 1, characterized in that: In step A, CIZS quantum dots are dispersed in water, WO3 is added, ultrasonically stirred, placed in a high-pressure reactor for hydrothermal reaction at 110°C for 4 hours, cooled to room temperature, washed with ethanol and dried to obtain a CIZS / WO3 precursor.

4. The method for preparing nickel-doped functional carbon quantum dots modified CIZS quantum dot composite photocatalyst according to claim 1, characterized in that: In step A, the mass and volume ratio of the CIZS quantum dots, WO3 and H2O is 9.9 mg:0.1 mg:15 mL.

5. The method for preparing nickel-doped functional carbon quantum dots modified CIZS quantum dot composite photocatalyst according to claim 1, characterized in that: In step B, Ni-CDs quantum dots are dispersed in water, CIZS / WO3 precursor is added, ultrasonically stirred evenly, placed in a high-pressure reactor for hydrothermal reaction at 110°C for 4 hours, cooled to room temperature, washed with ethanol and dried to obtain a Ni-CDs / CIZS / WO3 composite photocatalyst.

6. The method for preparing nickel-doped functional carbon quantum dots modified CIZS quantum dot composite photocatalyst according to claim 1, characterized in that: In step B, the mass and volume ratio of the Ni-CDs quantum dots, CIZS / WO3 precursor and water is 0.1 mg:9.9 mg:15 mL.

7. A nickel-doped functional carbon quantum dot-modified CIZS quantum dot composite photocatalyst prepared according to the method of any one of claims 1 to 6.

8. The nickel-doped functional carbon quantum dot-modified CIZS quantum dot composite photocatalyst according to claim 7, characterized in that: Its morphology is 0D-0D loaded on 2D nanosheets.

9. An application of the nickel-doped functional carbon quantum dots modified CIZS quantum dot composite photocatalyst as claimed in claim 7 or 8, characterized in that: It is applied to photocatalytic hydrogen production.

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