CN104959161A - Method for preparing conjugated molecular hybridization semiconductor photocatalytic material by using mechanochemistry - Google Patents

Abstract

The invention discloses a method for mechanochemically preparing conjugated molecular hybrid semiconductor photocatalytic materials, which belongs to the field of inorganic materials. In this method, molecules containing conjugated large π bonds and inorganic semiconductor nanomaterials are uniformly mixed according to a certain mass ratio, and added to the ball milling tank of the high-energy ball mill at a certain ball/material ratio, and at an appropriate ball milling speed, After processing for a certain period of time, a semiconductor photocatalytic material hybridized with conjugated molecules is obtained. The invention has the advantages of simple process flow, easy operation, no solvent, simple post-treatment, low production cost, high activity of the prepared composite catalytic material, and is suitable for preparing conjugated molecular hybrid modified semiconductor photocatalytic materials in batches.

Description

A Mechanochemical Method for Preparing Conjugated Molecular Hybrid Semiconductor Photocatalytic Materials

technical field

The invention relates to a method for preparing a modified semiconductor photocatalytic material, in particular to a mechanochemical preparation of a conjugated molecular hetero

The invention discloses a new method for converting semiconductor photocatalytic materials, which belongs to the field of inorganic materials.

Background technique

The energy efficiency, activity and photocorrosion stability of photocatalytic materials are the key to restrict their application. How to improve quantum efficiency and visible light absorption is still the core issue of photocatalytic materials. Based on the surface hybrid semiconductor of conjugated molecules to promote the separation effect of photogenerated carriers, surface hybridization can promote the migration of holes, effectively inhibit the recombination of photogenerated electrons and holes, improve the photocatalytic efficiency and inhibit the occurrence of photocorrosion, which is to improve Efficient pathways for photocatalytic performance.

Semiconductor hybrid modification treatment is generally carried out in a liquid phase system, which has many preparation process conditions, many solvents used, complicated post-treatment and separation processes, difficult reaction amplification, difficult scale production, etc., and it is difficult to completely remove impurities. The catalytic activity of the material and the system have a certain influence. Therefore, it is very necessary to explore efficient hybrid modification methods and simple synthetic routes.

Mechanochemistry generally refers to the physical and chemical changes of substances under the induction and action of mechanical force. It has the advantages of simple operation, low energy consumption, no secondary pollution, high yield, and easy scale production. Using mechanochemistry to prepare conjugated molecular hybrid modified semiconductor photocatalytic materials, no similar reports have been found so far.

Contents of the invention

For the preparation of conjugated molecular hybrid semiconductor photocatalytic materials by the current liquid phase method, the reaction conditions are harsh, the process is complicated, the separation and treatment steps are cumbersome, and it is difficult to achieve large-scale production. The purpose of the present invention is to provide a simple, low-cost, and reliable method for preparing hybrid semiconductor photocatalytic materials, which avoids the use of solvents, post-treatment separation problems, and has high product yields and can be mass-produced.

For realizing the object of the present invention, technical scheme is as follows:

1. Mix and grind molecular compounds containing conjugated large π bonds and inorganic semiconductor nanomaterials evenly according to the mass ratio, and the mass fraction of molecular compounds containing conjugated large π bonds accounts for 3% to 5% of the total mass of raw materials;

2. According to the ball/material mass ratio of 10-20:1, put the material into the ball mill tank, set the ball mill speed and ball mill time, and carry out ball mill treatment.

3. After taking out the ball milling product, carry out necessary post-processing according to the situation of the added materials.

The molecular compound containing large conjugated π bonds is carbon nitride, graphene or polyaniline, etc.

The inorganic semiconductor nanomaterials are titanium dioxide, zinc oxide, bismuth-based semiconductors, iron oxide, silver phosphate, etc. or their precursors.

A planetary high-energy ball mill is used, in which the materials of the ball and the ball mill are agate.

In the second step, the ball milling speed is 300-600 rpm, and the continuous ball milling time is 2-4 hours.

The invention utilizes mechanochemistry to prepare conjugated molecule hybridization modified semiconductor photocatalytic material, which is a solvent-free solid phase reaction and has high yield. The surface hybrid semiconductor-based photocatalytic material can be effectively prepared under normal temperature and normal pressure conditions, and is suitable for mass production. The production of waste liquid in the process of preparing the photocatalytic material is fundamentally avoided, the synthesis process is simplified, and the cost is reduced.

The nano-hybrid semiconductor photocatalytic material provided by the invention can be used for water pollution treatment, air purification, antibacterial and sterilization in the environmental field, as well as hydrogen production by photolysis of water and carbon dioxide conversion in the energy field.

Apply mechanochemistry to the modification of semiconductor photocatalytic materials, realize the diffusion and reaction of conjugated π molecules on the surface of semiconductors, form chemical bonds, etc. through mechanochemical action, and construct semiconductor photocatalytic materials hybridized on the surface of conjugated molecules. The hybrid structure and hybridization effect can effectively promote the effective separation of photogenerated carriers, and at the same time expand the light absorption range of the semiconductor, improve the photocatalytic activity of the semiconductor and generate visible light activity.

Description of drawings

Figure 1 is a high-resolution transmission electron micrograph of the conjugated molecular hybrid semiconductor photocatalytic material prepared in Example 1 of the present invention, where a, b are 3%-C ₃ N ₄ /TiO ₂ , c, d are 5%-C ₃ N ₄ /TiO ₂ ;

Fig. 2 is the XRD spectrum of the crystal structure analysis of the conjugated molecular hybrid semiconductor photocatalytic material prepared in Example 1 of the present invention;

Figure 3 is the photocatalytic degradation activity (a) and photocurrent diagram (b) of the conjugated molecular hybrid semiconductor photocatalytic material prepared in Example 1 under visible light irradiation;

Figure 4 is the photocatalytic degradation activity (a) and photocurrent spectrum (b) of the conjugated molecular hybrid semiconductor photocatalytic material prepared in Example 1 under ultraviolet light irradiation;

Figure 5 is a high-resolution transmission electron micrograph of the conjugated molecular hybrid semiconductor photocatalytic material prepared in Example 2 of the present invention, where a and b are 3%-C ₃ N ₄ /ZnO, c and d are 7%-C ₃ N ₄ /ZnO;

Figure 6 is the photocatalytic degradation activity (a) and photocurrent diagram (b) of the conjugated molecular hybrid semiconductor photocatalytic material prepared in Example 2 under visible light irradiation;

Fig. 7 is a stability cycle test of the conjugated molecular hybrid semiconductor photocatalytic material prepared in Example 2 under visible light irradiation.

Detailed ways

The technical scheme of the present invention will be further described below in conjunction with specific embodiments:

Example 1

The anatase-type nano-titanium dioxide (TiO ₂ ) and the conjugated molecular graphitic carbon nitride (gC ₃ N ₄ ) were weighed according to different mass ratios, and the mass fraction of the doping source gC ₃ N ₄ was 3% of the total mass of the raw materials. ~5%. Grind and mix them evenly in an agate mortar, add them into a 50 ml agate ball mill jar at a ball/material mass ratio of 10:1, and mill in a planetary high-energy ball mill at a speed of 350 rpm for 3 hours to obtain different proportions of gC ₃ N ₄ /TiO ₂ hybrid photocatalytic materials. Structural characterization was carried out, and methylene blue was used as a probe compound to evaluate its visible and ultraviolet photocatalytic activity. The results show that the visible light catalytic activity of gC ₃ N ₄ /TiO ₂ is about 3 times that of pure gC ₃ N ₄ and about 1.3 times that of pure TiO ₂ under ultraviolet light, and the corresponding photocurrents are about 2.5 times and 1.5 times.

Example 2

The nanometer zinc oxide (ZnO) and the conjugated molecule gC ₃ N ₄ are weighed according to different mass ratios, wherein the mass fraction of gC ₃ N ₄ is respectively 3%~5% of the total mass of raw materials. Grind and mix evenly in an agate mortar, put them into a 50 ml agate ball mill jar at a ball/material mass ratio of 20:1, and mill in a ball mill at a speed of 450 rpm for 2 hours to obtain different proportions of gC ₃ N ₄ /ZnO hybrid photocatalytic materials. Its structure was characterized, and its photocatalytic activity was evaluated at room temperature with methylene blue as a probe compound. The results show that the photocatalytic activity of gC ₃ N ₄ /ZnO is nearly three times that of pure gC ₃ N ₄ under visible light irradiation, and the corresponding photocurrent is about 2.5 times, and the catalyst performance is stable.

Claims (3)

1. mechanochemistry prepares conjugated molecule Hybrid semiconductor catalysis material method, it is characterized by, and realizes by the following method:

To contain molecular compound and the inorganic semiconductor nanometer material of the large π key of conjugation, mixed grinding is even in mass ratio, and the molecular compound mass fraction containing the large π key of conjugation accounts for 3% ~ 5% of raw material gross mass;

Then press ball/material mass ratio 10-20:1, material is joined in ball grinder, rotational speed of ball-mill, Ball-milling Time are set, carry out ball-milling treatment;

The molecular compound of the large π key of described conjugation is carbonitride, Graphene or polyaniline; Described inorganic semiconductor nanometer material is titanium dioxide, zinc oxide, bismuth based semiconductor, iron oxide or silver orthophosphate.

2. the preparation method of conjugated molecule Hybrid semiconductor catalysis material according to claim 1, is characterized in that: adopt planetary high-energy ball mill, ball grinder, Material quality of grinding balls are agate.

3. the preparation method of conjugated molecule Hybrid semiconductor catalysis material according to claim 1, it is characterized in that: rotational speed of ball-mill is 300 ~ 600 revs/min, the ball-milling treatment time is 2 ~ 4 hours.