阅读说明：本技术 一维硫化镉/二维碳化钛复合光催化剂及其制备方法与应用 (One-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst and preparation method and application thereof ) 是由 徐艺军 李婧宇 于 2019-11-11 设计创作，主要内容包括：本发明公开了一维硫化镉/二维碳化钛复合光催化剂及其制备方法,其是采用溶剂热法制备一维硫化镉纳米线,氟化锂/盐酸刻蚀法制备二维碳化钛纳米片,然后通过简单的静电自组装方法,制备得到所述一维硫化镉/二维碳化钛复合光催化剂。本发明制备过程简单,反应条件温和,不含成本高昂的贵金属,且所得复合光催化剂具有比一维硫化镉纳米线材料更高的光催化乙醇转换为1,1-二乙氧基乙烷的性能,并可同时产生氢气,在发展清洁能源以及光催化选择性有机合成领域具有广泛地应用前景,符合绿色化学的要求。(The invention discloses a one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst and a preparation method thereof. The preparation method disclosed by the invention is simple in preparation process, mild in reaction conditions and free of expensive noble metals, the obtained composite photocatalyst has higher performance of converting ethanol into 1, 1-diethoxyethane through photocatalysis than a one-dimensional cadmium sulfide nanowire material, can generate hydrogen simultaneously, has a wide application prospect in the fields of development of clean energy and photocatalytic selective organic synthesis, and meets the requirements of green chemistry.)

1. A preparation method of a one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst is characterized by comprising the following steps: the method comprises the following steps:

(1) preparing a one-dimensional cadmium sulfide nanowire by a solvothermal method:

dropwise adding 0.3 g/mL sodium diethyldithiocarbamate aqueous solution into 16.7 g/mL cadmium chloride solution to obtain cadmium diethyldithiocarbamate; adding the obtained cadmium diethyldithiocarbamate into ethylenediamine to prepare a solution with the concentration of 0.03 g/mL, then adding the solution into a polytetrafluoroethylene lining, sealing the polytetrafluoroethylene lining in a stainless steel high-pressure kettle, keeping the stainless steel high-pressure kettle at 180 ℃ for 24 hours, cooling the stainless steel lining to room temperature, collecting bright yellow precipitates in the lining, washing the precipitates for 3 to 4 times respectively by using absolute ethyl alcohol and deionized water, and drying the precipitates in a 60 ℃ drying oven for 12 hours to obtain the one-dimensional cadmium sulfide nanowire;

(2) preparing a two-dimensional titanium carbide nanosheet by a lithium fluoride/hydrochloric acid etching method:

adding 1 g of titanium aluminum carbide powder into a plastic bottle filled with 1 g of lithium fluoride, 3 mL of water and 7 mL of hydrochloric acid by 5-6 times, stirring for 24 h in an oil bath environment at 35 ℃, washing the obtained product with deionized water for multiple times until the pH value of a washing solution is neutral, adding the washed product into 200 mL of water, ultrasonically dispersing for 60min, centrifuging for 60min at 3500 rpm, collecting dark green supernatant, and preparing a two-dimensional titanium carbide nanosheet aqueous solution;

(3) preparing a one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst by an electrostatic self-assembly method:

ultrasonically dispersing the cadmium sulfide nanowires obtained in the step (1) in deionized water, then dropwise adding a two-dimensional titanium carbide nanosheet aqueous solution, stirring for 30-60min, performing suction filtration, washing with deionized water and vacuum drying to obtain the one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst.

2. The preparation method of the one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst as claimed in claim 1, wherein the preparation method comprises the following steps: the volume ratio of the cadmium chloride solution to the sodium diethyldithiocarbamate solution used in the step (1) is 1: 1.

3. The preparation method of the one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst as claimed in claim 1, wherein the preparation method comprises the following steps: the ion concentration in the wash liquor after washing in step (1) should be <10 ppm.

4. The preparation method of the one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst as claimed in claim 1, wherein the preparation method comprises the following steps: the concentration of the two-dimensional titanium carbide nanosheet aqueous solution in the step (2) is 1 g/L.

5. The preparation method of the one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst as claimed in claim 1, wherein the preparation method comprises the following steps: the mass fraction of titanium carbide contained in the obtained one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst is 5-30%.

6. A one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst prepared by the method of any one of claims 1 to 5.

7. The use of the one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst as defined in claim 6, wherein: the one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst can convert ethanol into 1, 1-diethoxyethane and simultaneously generate hydrogen under an acidic condition by taking visible light as a driving force.

8. The use of the one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst as claimed in claim 7, wherein: the wavelength of the visible light is greater than 420 nm.

Technical Field

The invention belongs to the field of photocatalytic materials, and particularly relates to a one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst as well as a preparation method and application thereof.

Background

Since the industrial revolution, environmental pollution and energy crisis have become two major problems facing people. Therefore, the development of new green sustainable energy to alleviate people's dependence on non-renewable energy has become a focus of attention in recent years. Hydrogen energy is widely considered as an ideal clean energy source. To date, a great deal of research has been devoted to the photocatalytic technology to achieve efficient photolysis of water to produce hydrogen with the introduction of a sacrificial agent. However, this strategy not only greatly wastes the oxidizing power of the photogenerated holes, but also may release carbon dioxide gas, thereby exacerbating the deterioration of the environment. In contrast, a bifunctional photocatalytic system combining the selective conversion of ethanol to value-added fine chemicals (1, 1-diethoxyethane) and hydrogen production, using both photo-generated electrons and holes, is certainly a better choice.

The one-dimensional cadmium sulfide nanowire is a semiconductor with an ideal band gap and an appropriate energy band structure, has better response under visible light, and the larger length-diameter ratio of the nanowire can promote the rapid and long-range transmission of electrons. However, the photocatalytic activity is limited due to the rapid recombination of electron-hole pairs. The two-dimensional titanium carbide nanosheet is a novel two-dimensional material which has good conductivity, rich functional groups on the surface, proper Fermi level and large specific surface area. Titanium carbide has been used to date as an effective promoter in the fields of photocatalytic carbon dioxide reduction, sterilization, organic synthesis, and photolysis of water. The two-dimensional titanium carbide nanosheets and the one-dimensional cadmium sulfide nanowires are compounded, so that the specific surface area of a cadmium sulfide catalyst is increased, the separation and transfer of photon-generated carriers are promoted, and meanwhile, active sites for hydrogen production are introduced, so that the efficiency of photocatalytic reaction is greatly improved.

Disclosure of Invention

The invention aims to provide a one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst with mild, simple and convenient production process, environmental protection and regular shape and a preparation method thereof, and protect the application of the photocatalytic composite material in selective conversion of photocatalytic ethanol and hydrogen production.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst comprises the following steps:

(1) preparing a one-dimensional cadmium sulfide nanowire by a solvothermal method:

dropwise adding 0.3 g/mL sodium diethyldithiocarbamate aqueous solution into 16.7 g/mL cadmium chloride solution according to the volume ratio of 1:1 to obtain cadmium diethyldithiocarbamate; adding the obtained cadmium diethyldithiocarbamate into ethylenediamine to prepare a solution with the concentration of 0.03 g/mL, then adding the solution into a polytetrafluoroethylene lining, sealing the polytetrafluoroethylene lining in a stainless steel high-pressure autoclave, placing the high-pressure autoclave in an oven at 180 ℃ for 24 hours, cooling to room temperature, collecting bright yellow precipitates in the lining, washing the bright yellow precipitates for 3-4 times respectively by using absolute ethyl alcohol and deionized water (until the ion concentration in a washing solution is less than 10 ppm), and drying in the oven at 60 ℃ for 12 hours to obtain the one-dimensional cadmium sulfide nanowire;

(2) preparing a two-dimensional titanium carbide nanosheet by a lithium fluoride/hydrochloric acid etching method:

adding 1 g of titanium aluminum carbide powder into a plastic bottle filled with 1 g of lithium fluoride, 3 mL of water and 7 mL of hydrochloric acid by 5-6 times, stirring for 24 hours in an oil bath environment at 35 ℃, washing the obtained product with deionized water for multiple times until the pH value of a washing solution is neutral (6-7), adding the washed product into 200 mL of water, ultrasonically dispersing for 60min, centrifuging for 60min at 3500 rpm, collecting dark green supernatant, and preparing 1 g/L of two-dimensional titanium carbide nanosheet aqueous solution;

(3) preparing a one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst by an electrostatic self-assembly method:

ultrasonically dispersing the cadmium sulfide nanowires obtained in the step (1) in deionized water, then dropwise adding a two-dimensional titanium carbide nanosheet aqueous solution, stirring for 30-60min, performing suction filtration, deionized water washing and vacuum drying to obtain the one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst, wherein the mass fraction of titanium carbide is 5-30%.

The one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst prepared by the invention can catalyze ethanol to be selectively converted into 1, 1-diethoxyethane under the irradiation of visible light and simultaneously produce hydrogen, and the specific operation steps are as follows: 10 mL of absolute ethyl alcohol, 5mg of one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst and 16 mu L of concentrated sulfuric acid are put into a reactor, and after vacuumizing, the reactor is placed under visible light (lambda is more than 420 nm) for illumination for 1 hour, so that 1, 1-diethoxyethane and hydrogen can be obtained.

Under the irradiation of visible light, photo-generated electrons generated by cadmium sulfide in the composite photocatalyst can be effectively transferred to titanium carbide through proper energy band position arrangement of the cadmium sulfide and the titanium carbide, so that the separation of photo-generated carriers is promoted. And the oxygen group on the surface of the titanium carbide can be used as an active site for hydrogen production, so that the half reaction of catalytic reduction can be effectively carried out. In addition, the invention also has the following advantages:

(1) the invention applies the one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst to a bifunctional photocatalytic system which can be used for selectively oxidizing ethanol to generate 1, 1-diethoxyethane and producing hydrogen simultaneously, and is beneficial to the sustainable development of environment and energy.

(2) The one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst obtained by the invention has the advantages of good cycle performance, high selectivity, no expensive noble metal, and simple and mild production process.

Drawings

FIG. 1 is SEM and TEM images of different materials, wherein (A) is an SEM image of one-dimensional cadmium sulfide prepared in example 1; (B) SEM image of two-dimensional titanium carbide prepared in example 2; (C) an SEM image of the one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst prepared in example 4; (D) example 4 is a TEM image of the one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst prepared in example 4.

FIG. 2 shows the UV-visible diffuse reflectance spectrum (A) and the X-ray diffraction spectrum (B) of different materials.

FIG. 3 is a photo-catalytic hydrogen production (A) and ethanol conversion activity diagram (B) of different materials under visible light irradiation.

FIG. 4 shows the selectivity of different materials for photocatalytic production of 1, 1-diethoxyethane under irradiation of visible light.

FIG. 5 is a cyclic activity diagram (A) and a long-term activity diagram (B) of the one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst under the irradiation of visible light.

Detailed Description

The specific preparation steps of the one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst are as follows:

(1) preparing a one-dimensional cadmium sulfide nanowire by a solvothermal method:

dropwise adding 0.3 g/mL sodium diethyldithiocarbamate aqueous solution into 16.7 g/mL cadmium chloride solution according to the volume ratio of 1:1 to obtain cadmium diethyldithiocarbamate; adding the obtained cadmium diethyldithiocarbamate into ethylenediamine to prepare a solution with the concentration of 0.03 g/mL, then adding the solution into a polytetrafluoroethylene lining, sealing the polytetrafluoroethylene lining in a stainless steel high-pressure autoclave, placing the high-pressure autoclave in an oven at 180 ℃ for 24 hours, cooling to room temperature, collecting bright yellow precipitates in the lining, washing the bright yellow precipitates for 3-4 times respectively by using absolute ethyl alcohol and deionized water (until the ion concentration in a washing solution is less than 10 ppm), and drying in the oven at 60 ℃ for 12 hours to obtain the one-dimensional cadmium sulfide nanowire;

(2) preparing a two-dimensional titanium carbide nanosheet by a lithium fluoride/hydrochloric acid etching method:

adding 1 g of titanium aluminum carbide powder into a plastic bottle filled with 1 g of lithium fluoride, 3 mL of water and 7 mL of hydrochloric acid by 5-6 times, stirring for 24 hours in an oil bath environment at 35 ℃, washing the obtained product with deionized water for multiple times until the pH value of a washing solution is neutral (6-7), adding the washed product into 200 mL of water, ultrasonically dispersing for 60min, centrifuging for 60min at 3500 rpm, collecting dark green supernatant, and preparing 1 g/L of two-dimensional titanium carbide nanosheet aqueous solution;

(3) preparing a one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst by an electrostatic self-assembly method:

ultrasonically dispersing the cadmium sulfide nanowires obtained in the step (1) in deionized water, then dropwise adding a two-dimensional titanium carbide nanosheet aqueous solution, stirring for 30-60min, performing suction filtration, deionized water washing and vacuum drying to obtain the one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst, wherein the mass fraction of titanium carbide is 5-30%.

The one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst prepared by the invention can be used for irradiating and catalyzing ethanol to be selectively converted into 1, 1-diethoxyethane under visible light and simultaneously produce hydrogen, and the specific operation steps are as follows: 10 mL of absolute ethyl alcohol, 5mg of one-dimensional cadmium sulfide/two-dimensional titanium carbide composite photocatalyst and 16 mu L of concentrated sulfuric acid are put in a reactor and placed under visible light (lambda is more than 420 nm) for illumination for 1 hour in a vacuum state, the photocatalytic product is subjected to gas chromatography analysis, and qualitative and quantitative analysis is carried out through retention time and peak area.

In order to make the present invention more comprehensible, the technical solutions of the present invention are further described below with reference to specific embodiments, but the present invention is not limited thereto.