Method for preparing C3N4 material with N defects and application

A C3N4, defect technology, applied in the field of preparation of nanomaterials, can solve the problems of limiting photocatalytic activity, energy consumption and time-consuming, and achieve the effect of major application prospects, good light absorption performance, and mild conditions.

Active Publication Date: 2015-07-22
TECHNICAL INST OF PHYSICS & CHEMISTRY - CHINESE ACAD OF SCI
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  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, its rapid recombination of photogenerated electron-hole pairs and low absorption edge limit the improvement of its photocatalytic activity.
in C 3 N 4 Constructing N defects in the structure is one of the ways to solve this problem, but there are two current preparation methods, one is high-temperature calcination (references P.Niu, L.-Ch.Yin, Y.-Q.Yang, G .Liu,H.-M.Ch,Adv.Mater.2014,1-7; P.Niu,G.Liu,H.-M.Cheng,J.Phys.Chem.C 2012,116,11013-11018. ), one is the C 3 N 4 Further hydrothermal treatment (reference Zh.Hong, B.Shen, Y.Chen, B.Lin B.Gao, J.Mater.Chem.A, 2013, 1, 11754–11761.), energy and time consuming
However, there is no N-deficient C in the next step at a relatively low temperature. 3 N 4 Methods

Method used

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  • Method for preparing C3N4 material with N defects and application
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  • Method for preparing C3N4 material with N defects and application

Examples

Experimental program
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Effect test

Embodiment 1

[0058] A C with N deficiency 3 N 4 The preparation method of photocatalytic material comprises the following steps:

[0059] 1) Dissolve 15g of urea in 50mL of water, then add 10mL of KOH (0.001g / mL) aqueous solution, sonicate for 10 minutes to dissolve, then dry the above mixture in an oven at 80°C overnight;

[0060] 2) The dried solid was put into a 100mL magnetic crucible, and calcined in a muffle furnace at 550°C for 4h, wherein the heating rate of the muffle furnace was 5°C min -1 ; get C with N deficiency 3 N 4 , named g-C 3 N x， Its scanning electron microscope pictures are as figure 1 Shown in B.

Embodiment 2

[0071] The comparative example in Example 1 was applied to the experiment of visible light photocatalytic water splitting to produce hydrogen.

[0072] 1) Determine C 3 N 4 As a catalyst, the amount of hydrogen produced and C 3 N 4 The relationship between dosage. Take 1,2,3,4,5,10,15,20,25,30mg Comparative Example C 3 N 4 Put into ten 60mL quartz tubes and add 20mL of lactic acid-water mixture with a volume ratio of 1:3. Nitrogen was passed into the quartz test tube for 30 minutes to remove the oxygen in the tube and sealed with a rubber stopper, and it was stirred and illuminated for 10 hours at room temperature. The light source is a 300W xenon lamp, and a 400nm filter is added to filter out ultraviolet light with a wavelength less than 400nm. The amount of hydrogen produced is measured with Shimadzu GC-2014 gas chromatograph every 1h, such as Image 6 shown. Before illumination, add 1wt% Pt precursor (H 2 PtCl 6 ), nitrogen was passed through for 30 minutes to e...

Embodiment 3

[0080] Repeat embodiment 1, prepare the catalyst of 0.01mg / mL (comparative example C 3 N 4 and C with N deficiency 3 N 4 ) aqueous solution, utilize the Hitachi-F4600 fluorescence spectrum to detect its fluorescence intensity under excitation at 380 nanometers, such as Figure 9 shown.

[0081] The results showed that compared to the comparative example C 3 N 4 ( Figure 9 a curve), C with N defects 3 N 4 ( Figure 9 The fluorescence intensity of curve b) is significantly reduced, which shows that the separation speed of photogenerated electrons and holes of the material has been improved to a certain extent.

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Abstract

The invention discloses a method for preparing C3N4 material with N defects. According to the method, the impact of N defects on the C3N4 photocatalytic activity is researched. The method is characterized in that urea and KOH are used as a precursor, and C3N4 with N defects can be obtained through calcination at 550 DEC C for 4 hours; by changing the ratio of urea to KOH, the degree of N defects and the photocatalytic activity of a product can be adjusted; the prepared C3N4 with N defects has the characteristics of being better in light absorption and improved in photocatalytic activity, so that the light absorption range of C3N4 is widened, and the photocatalytic property of C3N4 is improved; meanwhile, the preparation method is simplified, and a novel method for preparing C3N4 materials with high activity is provided; in addition, the energy band structure of the product can be continuously adjusted by adjusting the KOH dosage; the method also has high applicability; when other materials except urea are used as raw materials, such as thiourea, melamine, or other hydrogen oxides, similar results can be obtained through the method.

Description

technical field [0001] The invention belongs to the field of preparation of nanometer materials, in particular to a C 3 N 4 preparation methods and applications. Background technique [0002] C 3 N 4 It is a two-dimensional organic semiconductor conjugated with an oxazine ring or a triazine ring, and has attracted widespread attention due to its excellent thermal stability, chemical stability, and unique optical and electrical properties. Currently, C 3 N 4 It is widely used in photolysis of water to produce hydrogen and oxygen, degradation of organic pollutants, CO 2 Reduction, selective oxidation, and bioimaging, etc. Among them, due to its unique stability and energy band position, C 3 N 4 It has great development potential in the field of photocatalysis. However, its rapid recombination of photogenerated electron-hole pairs and low absorption edge limit the improvement of its photocatalytic activity. in C 3 N 4 Constructing N defects in the structure is one ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B21/082B01J27/24
Inventor 张铁锐余慧军吴骊珠佟振合
Owner TECHNICAL INST OF PHYSICS & CHEMISTRY - CHINESE ACAD OF SCI
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