阅读说明：本技术 一种CdS基复合光催化剂的制备方法及其在水裂解产氢方面的应用 (Preparation method of CdS-based composite photocatalyst and application of CdS-based composite photocatalyst in aspect of hydrogen production through water splitting ) 是由 朱艳超 李恩 赵河闯 于 2019-09-20 设计创作，主要内容包括：本发明公开了一种CdS基复合光催化剂的制备方法及其在水裂解产氢方面的应用。其制备包括如下步骤：将配制的氯化镉、石墨相g-C<Sub>3</Sub>N<Sub>4</Sub>、硫脲依次加入柠檬酸钠溶液中,搅拌溶解完全,加入碱调节pH为3.5-4.5；将上述溶液进行水热反应,后处理即得CdS基复合光催化剂。其在水裂解产氢方面的应用包括以下步骤：将催化剂粉末溶解到光化学反应器中的水中,加入氯铂酸和L-抗坏血酸,惰性气体氛围下在氙灯下照射可见光,检测其氢气产量。本发明制备方法简单、环保、成本低,制备得到纳米级CdS基复合光催化剂,用于水裂解产氢时催化效率高,产氢量大。(The invention discloses a preparation method of a CdS-based composite photocatalyst and application of the CdS-based composite photocatalyst in hydrogen production by water cracking. The preparation method comprises the following steps: prepared cadmium chloride and graphite phase g-C 3 N 4 Sequentially adding thiourea into the sodium citrate solution, stirring and dissolving completely, and adding alkali to adjust the pH value to 3.5-4.5; and carrying out hydrothermal reaction on the solution, and carrying out post-treatment to obtain the CdS-based composite photocatalyst. The application of the method in the aspect of hydrogen production by water splitting comprises the following steps: dissolving the catalyst powder in water in photochemical reactor, adding chloroplatinic acid and L-resistAnd (3) irradiating visible light under an inert gas atmosphere and a xenon lamp, and detecting the hydrogen yield of the ascorbic acid. The preparation method is simple, environment-friendly and low in cost, and the prepared nano CdS-based composite photocatalyst has high catalytic efficiency and large hydrogen production amount when being used for hydrogen production by water cracking.)

1. The preparation method of the CdS-based composite photocatalyst is characterized in that a CdS-based composite photocatalyst main body is CdSg-C₃N₄Providing a nitrogen source and a carbon source, and specifically comprising the following steps:

(1) cadmium chloride and graphite phase g-C₃N₄Sequentially adding thiourea into the sodium citrate solution, stirring and dissolving completely, and adding alkali to adjust the pH value to 3.5-4.5;

(2) and (2) carrying out hydrothermal reaction on the mixed solution obtained in the step (1), and carrying out post-treatment after the reaction is finished to obtain the CdS-based composite photocatalyst.

2. The preparation method according to claim 1, wherein in the step (1), the molar ratio of the cadmium chloride to the thiourea is 1: (3-4); the mol ratio of the cadmium chloride to the sodium citrate is 1 (1.6-2); graphite phase g-C₃N₄The mass ratio of the cadmium chloride to the cadmium chloride is (0.3-1.5): 1.

3. The preparation method according to claim 1, wherein in the step (2), the hydrothermal reaction conditions are as follows: the temperature is 160-200 ℃ and the time is 12-16 h.

4. The method according to claim 1, wherein in the step (1), the graphite phase g-C₃N₄The preparation method is derived from patent CN106540733B, and comprises the following specific steps: grinding and mixing dicyanodiamine and nano silicon dioxide, roasting the mixture respectively through a microwave oven and a muffle furnace, and performing post-treatment to obtain a graphite phase g-C₃N₄(ii) a In the step (2), the post-treatment comprises the following steps: respectively centrifugally cleaning with deionized water and absolute ethyl alcohol for three times, drying in a vacuum drying oven at 60-80 ℃ for 10-12h, and grinding for later use.

5. An application of the CdS-based composite photocatalyst prepared according to any one of claims 1-4 in hydrogen production by water cracking is characterized by specifically comprising the following steps of:

(1) dissolving a CdS-based composite photocatalyst in water in a photochemical reactor, respectively adding chloroplatinic acid and L-ascorbic acid, and uniformly mixing;

(2) and (2) introducing inert gas into the reactor in the step (1) to eliminate the influence of air in the reactor, and irradiating visible light under a xenon lamp in a stirring state to perform a water splitting hydrogen production reaction.

6. The application of the CdS-based composite photocatalyst in water splitting to produce hydrogen according to claim 5, wherein in the step (1), the mass-to-volume ratio of the CdS-based composite photocatalyst to water is (0.25-0.5) g/L.

7. The application of the CdS-based composite photocatalyst in water splitting to produce hydrogen according to claim 5, wherein in the step (1), the mass ratio of the CdS-based composite photocatalyst to L-ascorbic acid is 1 (100-120); the mass ratio of the CdS-based composite photocatalyst to chloroplatinic acid is 1: (0.015-0.03).

8. The application of the CdS-based composite photocatalyst in aspect of hydrogen production by water splitting, as claimed in claim 5, wherein in the step (2), the inert gas is argon or nitrogen, and the ventilation time is more than 30 min.

9. The application of the CdS-based composite photocatalyst in water splitting to produce hydrogen as claimed in claim 5, wherein in step (2), the distance from a xenon lamp light source to the optical reactor is 3-15cm, and the current is adjusted to 15-17 mA.

Technical Field

The invention belongs to the technical field of photocatalysis, and particularly relates to a preparation method of a CdS-based composite photocatalyst and application of the CdS-based composite photocatalyst in hydrogen production through water cracking.

Background

With the development of human science and technology, the consumption of non-renewable energy sources is increased day by day, and hydrogen energy is taken as secondary energy, has various extraction modes, has the advantages of cleanness, high efficiency, safety, storage and the like, is generally regarded, wherein the photocatalysis technology has unique development potential in the aspect of hydrogen production.

Many semiconductor materials are already applied to the field of hydrogen production through photocatalytic water splitting, wherein CdS is widely researched due to excellent performance of CdS, and a traditional unmodified CdS photocatalyst has the defects of serious photo-corrosion and easy recombination of photo-generated carriers, so that the quantum efficiency of CdS photocatalysis is low, and the separation efficiency of holes and electrons generated by photo-excitation is very low. In recent years, graphitized carbon nitride (g-C)₃N₄) The unique electronic band structure and high stability of the composite material are introduced into a promising visible light photocatalyst, and various materials such as CdS can be compounded to improve the photocatalytic efficiency of the composite material.

In recent years, research on hydrogen production by using composite CdS and graphite-phase nitrogen carbide materials as photocatalysts has been reported at home and abroad. For example, patent "a carbon dot/cadmium sulfide quantum dot/carbon nitride catalyst and its preparation method" (CN 107597166) discloses a photocatalytic hydrogen production material, which is composed of carbon quantum dots synthesized by electrochemical method, cadmium sulfide quantum dots synthesized by solvothermal method, and quasi-graphene phase carbon nitride synthesized by calcination method; the patent (CN108842159) discloses a preparation method of a cadmium sulfide nanowire and carbon nanotube composite flexible electrode with high hydrogen production activity, which prepares a hydrogen production composite material with high activity by using cadmium salt, CNT and amino acid; the materials have complex compounding steps and relatively low hydrogen production amount, so that the finding of a hydrogen production material with simple steps, cheap materials and large hydrogen production amount has important significance.

Disclosure of Invention

The invention aims to provide a preparation method of a CdS-based composite photocatalyst and application of the CdS-based composite photocatalyst in the aspect of hydrogen production by water cracking.

In order to solve the technical problems, the invention adopts the following technical scheme:

provides a preparation method of a CdS-based composite photocatalyst, wherein the CdS-based composite photocatalyst main body is CdS consisting of g-C₃N₄Providing a nitrogen source and a carbon source, and specifically comprising the following steps:

(1) cadmium chloride and graphite phase g-C₃N₄Sequentially adding thiourea into the sodium citrate solution, stirring to obtain a uniformly dispersed mixed solution, and adding alkali to adjust the pH value to 3.5-4.5;

(2) and (2) carrying out hydrothermal reaction on the mixed solution obtained in the step (1), and carrying out post-treatment after the reaction is finished to obtain the CdS-based composite photocatalyst.

According to the scheme, in the step (1), the molar ratio of cadmium chloride to thiourea is 1: (3-4); the mol ratio of the cadmium chloride to the sodium citrate is 1 (1.6-2); graphite phase g-C₃N₄The mass ratio of the cadmium chloride to the cadmium chloride is (0.3-1.5): 1.

According to the scheme, in the step (2), the hydrothermal reaction conditions are as follows: the temperature is 160-200 ℃; the time is 12-16 h.

According to the scheme, in the step (2), the post-treatment comprises the following steps: respectively centrifugally cleaning with deionized water and absolute ethyl alcohol for three times, drying in a vacuum drying oven at 60-80 ℃ for 10-12h, and grinding for later use.

According to the scheme, in the step (1), the graphite phase g-C₃N₄The preparation method is derived from patent CN106540733B, and comprises the following specific steps: grinding and mixing dicyanodiamine and nano silicon dioxide, roasting the mixture respectively through a microwave oven and a muffle furnace, and performing post-treatment to obtain a graphite phase g-C₃N₄。

The application of the CdS-based composite photocatalyst in the aspect of hydrogen production by water cracking is provided, and the method specifically comprises the following steps:

(1) dissolving the prepared CdS-based composite photocatalyst in water in a photochemical reactor, respectively adding chloroplatinic acid and L-ascorbic acid, and uniformly mixing;

(2) and (2) introducing inert gas into the reactor in the step (1) to eliminate the influence of air in the reactor, and irradiating visible light under a xenon lamp in a stirring state to perform a water splitting hydrogen production reaction.

According to the scheme, the mass-volume ratio of the CdS-based composite photocatalyst to water is (0.25-0.5) g/L.

According to the scheme, the mass ratio of the CdS-based composite photocatalyst to the L-ascorbic acid is 1 (100-120); the mass ratio of the CdS-based composite photocatalyst to chloroplatinic acid is 1: (0.015-0.03).

According to the scheme, in the step (2), the inert gas is argon or nitrogen, and the ventilation time is more than 30 min.

According to the scheme, in the step (2), the distance from the xenon lamp light source to the optical reactor is 3-15cm, and the current is regulated to be 15-17 mA.

In the preparation method of the CdS-based composite photocatalyst provided by the invention, sodium citrate is introduced, and a hydrothermal method is adopted to prepare nano CdS particles in one step as a main body and graphite phase g-C₃N₄Nano-composite photocatalyst providing carbon source and nitrogen source, CdS nanoparticles and g-C₃N₄The nanowires are tightly interwoven and mutually contacted, so that surface carrier transportation is facilitated, and the catalytic efficiency of the catalyst is improved. In addition, the composite photocatalyst has a nano-scale size, a large specific surface area and a large number of active sites, and the photocatalytic efficiency of the nano semiconductor catalyst is further improved.

When the CdS-based composite photocatalyst prepared by the method is used for hydrogen production through water splitting, L-ascorbic acid and chloroplatinic acid are added, so that on one hand, semiconductor photo-corrosion can be prevented, and the photo-catalytic efficiency is greatly improved; according to the invention, Pt can be obtained and loaded on the composite photocatalyst to form a shallow Schottky energy barrier capable of capturing electrons, the Pt can effectively serve as an electron trap to prevent the recombination of electron holes, and the photocatalytic hydrogen production performance is further improved.

The invention has the beneficial effects that:

1. the invention adopts a hydrothermal method to prepare nano CdS particles and graphite phase g-C with compact structures in one step₃N₄Heterojunction to obtain nano-scale CdSThe composite photocatalytic material has the advantages of easily obtained preparation raw materials, simple operation, safe preparation process and low cost.

2. The CdS-based composite photocatalytic material provided by the invention can efficiently carry out water cracking hydrogen production under the combined action of L-ascorbic acid and chloroplatinic acid, the hydrogen production rate can reach 40031 mu mol/g/h, and the hydrogen production efficiency is high.

Drawings

FIG. 1 is a scanning electron microscope image of a CdS-based composite photocatalytic material prepared in example 2.

FIG. 2 is a transmission electron micrograph of pure CdS prepared in comparative example 1.

FIG. 3 is a transmission electron microscope image of the CdS-based composite photocatalytic material prepared in example 2.

FIG. 4 is an XRD pattern of a CdS-based composite photocatalytic material prepared in examples 1-3.

Detailed Description

The invention will be further described with reference to specific examples, the advantages and features of which will become apparent from the description. The examples are merely illustrative and do not limit the scope of the invention in any way. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention, and that such changes and modifications may be made without departing from the spirit and scope of the invention.

In the following examples, g-C₃N₄Graphite phases g-C prepared according to patent CN106540733B₃N₄The method comprises the following specific steps:

weighing dicyandiamide and nano-silica in a mass ratio of 10:1, grinding and mixing, heating for 30min in a microwave oven under the power of 3kW and the vacuum degree of 0.08MPa, raising the temperature to 550 ℃ at the speed of 2.3 ℃/min in a muffle furnace, keeping the temperature for 4h, then reducing the temperature to 100 ℃ at the cooling rate of 1 ℃ per minute, naturally cooling to below 50 ℃, taking out the burnt material, weighing and grinding; weighing the fired material, adding sodium hydroxide in a mass ratio of 0.6:1, adding deionized water to make the concentration of the sodium hydroxide be 1.2g/ml, stirring in a constant-temperature water bath at 60 ℃ for 2 hours, and then performing suction filtration, water washing and drying to obtain the graphite-phase carbon nitride.