Method for preparing CdS/CoWO4 heterojunction composite photocatalyst

A composite light and catalyst technology, applied in physical/chemical process catalysts, chemical instruments and methods, chemical/physical processes, etc., can solve the problems of serious electron-hole recombination and low catalytic activity, and achieve regular morphology and dispersion The effect of good properties and complete crystallization

Active Publication Date: 2016-11-09
JIANGSU UNIV
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  • Abstract
  • Description
  • Claims
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Problems solved by technology

[0002] Metal tungstates have been widely used in many fields due to their unique electrical and optical properties, among which transition metal tungstates (CoWO 4 ) has stable chemical properties, and has a higher conduction band position than other transition metal tungstates with visible light response, and has the ability to generate superoxide radicals, so it has become the focus of attention in the field of photocatalysis; the existing CoWO 4 The catalytic activity of transition metal tungstate catalysts is still very low, and electron-hole pair recombination is serious, which cannot meet the needs of practical applications. Therefore, it is still a challenge to improve the separation efficiency of electrons and holes to improve the catalytic activity of this type of photocatalyst. Challenging subjects
[0003] Due to the special energy band structure and carrier transport characteristics of the heterojunction, it can effectively inhibit the recombination of photogenerated electrons and holes in the photocatalytic reaction, improve the quantum efficiency, and then greatly improve the catalytic activity of the photocatalyst. Cadmium sulfide (CdS) With the characteristics of narrow energy band and high conduction band position, it is an ideal semiconductor photocatalyst for constructing heterostructures. At present, there is no information about the heterojunction between cobalt tungstate and cadmium sulfide and its application in photocatalysis Research on Degradation of Organic Pollutants

Method used

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  • Method for preparing CdS/CoWO4 heterojunction composite photocatalyst
  • Method for preparing CdS/CoWO4 heterojunction composite photocatalyst
  • Method for preparing CdS/CoWO4 heterojunction composite photocatalyst

Examples

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Embodiment 1

[0017] Example 1CdS / CoWO 4 Preparation of nanorods

[0018] Add the solution containing 1mmol cobalt chloride to the solution containing 1mmol sodium tungstate, adjust the pH value of the mixed solution to 8 with 1mmol / L sodium hydroxide solution, stir it magnetically, and then hydrothermally react at 180°C for 24 hours , the precipitate obtained by centrifuging and washing with water, and drying at 60°C to obtain cobalt tungstate nanoparticles; take the prepared cobalt tungstate nanoparticles and dissolve them in deionized water, ultrasonically disperse them, and add equimolar thiourea under stirring conditions and cadmium acetate, control the molar ratios of cadmium acetate and cobalt tungstate to be 0.1, 0.3, 0.5, 1 and 1.5 respectively, stir and mix evenly and carry out hydrothermal reaction at 180°C for 24 hours, and the blue product obtained after the reaction Wash with deionized water and ethanol, filter, and dry in a constant temperature drying oven at 60°C.

Embodiment 2

[0019] Example 2CdS / CoWO 4 Characterization and Analysis of Heterojunction Composite Photocatalysts

[0020] like figure 1 As shown, it can be seen from the figure that the composite sample has both CdS and CoWO 4 characteristic peaks, indicating that we have successfully prepared CdS / CoWO 4 Heterojunction composite photocatalysts.

[0021] like figure 2 As shown, pure CoWO can be seen in (a) 4 It is a nanoparticle with a size of about 30-50nm. The presence of CdS nanoparticles can be seen in the picture (b), and the size of the nanoparticle is about 5-10nm. The picture (c) is a transmission high-resolution electron microscope analysis of the prepared composite material As a result, CdS can be seen attached to CoWO 4 The surface of nanoparticles, (d) shows the presence of cobalt, tungsten, sulfur, cadmium, and oxygen elements.

[0022] like image 3 As shown in the figure, the presence of superoxide radicals and hydroxyl radical active species can be clearly seen in t...

Embodiment 3

[0023] Example 3CdS / CoWO 4 Visible light catalytic activity experiments of heterojunction composite photocatalysts

[0024] (1) Prepare a methylene blue solution with a concentration of 10 mg / L, and place the prepared solution in a dark place.

[0025] (2) Weigh CdS / CoWO 4 Heterojunction composite photocatalyst 100mg (when CdS and CoWO 4 The molar ratios are 0.1:1, 0.3:1, 0.5:1, 1:1, 1.5:1 and the samples obtained are respectively marked as C1, C2, C3, C4, C5), respectively placed in the photocatalytic reactor, adding 100mL of the target degradation solution prepared in step (1) was stirred magnetically for 30 minutes. After the composite photocatalyst was dispersed evenly, the water source and light source were turned on to carry out the photocatalytic degradation experiment.

[0026] (3) Draw the photocatalytic degradation solution in the reactor every 10 minutes, centrifuge and use it for the measurement of ultraviolet-visible absorbance.

[0027] (4) by Figure 4 It c...

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Abstract

The invention relates to transition metal tungstate, and concretely relates to a method for preparing a CdS / CoWO4 heterojunction composite photocatalyst by taking sodium hydroxide, sodium tungstate and cobalt nitrate as raw materials. The method comprises the following steps: taking a proper amount of sodium tungstate, adding the sodium tungstate in a cobaltous chloride-containing solution, adding a certain amount of sodium hydroxide while stirring, adjusting the pH value of the solution to 8, performing a hydrothermal reaction at the temperature of 180 DEG C for 12 hours, alternatively cleaning ethanol used for precipitation and deionized water for three times; performing ultrasonic disperse on CoWO4 in deionized water, adding equal amount of thiourea and cadmium acetate, continuously stirring the materials and uniformly mixing the materials, performing the hydrothermal reaction at the temperature of 180 DEG C for 24 hours, after the reaction is complete, filtering a precipitate, washing the precipitate, and drying the precipitate to obtain the CdS / CoWO4 heterojunction composite photocatalyst. The composite photocatalyst has good photocatalytic activity proved by methylene blue (MB) degradation experiment under visible light.

Description

technical field [0001] The present invention relates to transition metal tungstate, in particular to a kind of CdS / CoWO prepared from sodium hydroxide, sodium tungstate, cobalt chloride, thiourea and cadmium acetate as raw materials. 4 A method for heterojunction composite photocatalyst, especially a preparation method for nanocomposite photocatalyst with simple preparation process and good visible light catalytic activity. technical background [0002] Metal tungstates have been widely used in many fields due to their unique electrical and optical properties, among which transition metal tungstates (CoWO 4 ) has stable chemical properties, and has a higher conduction band position than other transition metal tungstates with visible light response, and has the ability to generate superoxide radicals, so it has become the focus of attention in the field of photocatalysis; the existing CoWO 4 The catalytic activity of transition metal tungstate catalysts is still very low, an...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J27/049B82Y30/00B82Y40/00
CPCB01J27/049B01J35/004B01J35/023B01J35/026B82Y30/00B82Y40/00
Inventor 施伟东延旭吕涛涛吴梓阳刘奎立
Owner JIANGSU UNIV
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