CN103599803B - A kind of silver phosphate/graphene/snanocomposite nanocomposite and preparation method - Google Patents

Abstract

The invention discloses a silver phosphate/graphene/silver nanocomposite material and a preparation method thereof. The silver phosphate/graphene/silver nanocomposite material prepared by the invention is composed of silver phosphate nanoparticles, graphene nanosheets and silver nanocrystals. Among them, graphene nanosheets are tightly coated on the surface of spherical silver phosphate nanoparticles with a size of about 200nm, forming a close interface contact, and silver nanocrystals with a size of 5-10nm are evenly grown on the graphene nanosheets. The silver phosphate/graphene/silver nanocomposite material of the invention is an efficient and stable visible light catalyst.

Description

A kind of silver phosphate/graphene/silver nanocomposite material and preparation method

technical field

The invention relates to a preparation method of silver phosphate/graphene/silver nano composite material, which belongs to the technical field of nano composite material and photocatalysis.

Background technique

With the excessive exploitation of natural resources and the continuous deterioration of the natural environment, human society is facing increasingly serious problems such as energy shortage and environmental pollution. Due to the low energy consumption required, simple operation, non-toxic and harmless, and no secondary pollution, photocatalytic technology has broad application prospects in the development and utilization of solar energy and sewage treatment. Semiconductor nanomaterials have a photoelectric conversion effect and are the basic constituent materials of photocatalysts. However, most of the photocatalysts used in practice, such as titanium dioxide and zinc oxide, are wide-bandgap semiconductors, and their light absorption wavelength range is narrow, mainly in the ultraviolet region. The utilization efficiency is low, and the photoelectric conversion efficiency is low. Therefore, the development of new and efficient visible light catalysts has gradually become a hot spot in catalyst research.

Silver phosphate is a visible light catalyst discovered by Ye et al. (Nature Mater., 2010, 9, 559-564) in 2010 and has received widespread attention. Oxidation ability, can effectively photolyze water or rapidly degrade organic pollutants in water. However, subsequent researchers also found that silver phosphate is easy to be corroded by light, has poor stability, and silver phosphate has a certain solubility in the solution, so it is difficult to recycle and use.

The invention patent (CN102614902A) reports a synthesis method of supported silver phosphate/silver photocatalyst, and the invention patent (CN102631939A) reports a graphene/silver phosphate composite photocatalyst and its preparation method. So far, no relevant reports on silver phosphate/graphene/silver composite nanomaterials and their preparation methods have been found in the literature.

Contents of the invention

The object of the present invention is to address the above problems, provide a silver phosphate/graphene/silver nanocomposite material and a preparation method thereof, which solves the problems of low photocatalytic efficiency and poor stability in the prior art.

In order to achieve the above object, the present invention adopts the following technical scheme: a kind of silver phosphate/graphene/silver nanocomposite material, is to use silver phosphate/graphene oxide nanocomposite material as precursor, by adding excessive silver nitrate, utilize light Auxiliary reduction method, which is prepared by simultaneously reducing graphene oxide and silver ions adsorbed on graphene oxide to graphene and silver nanocrystals by means of photogenerated electrons on silver phosphate; the graphene nanosheets are tightly coated on silver phosphate nanocrystals. The surface of the particle, and a large number of silver nanocrystals uniformly grow on the graphene nanosheet; the particle diameter of the silver phosphate nanoparticle is 200nm, and the size of the silver nanocrystal is 5-10nm.

Further, the shape of the silver phosphate nanoparticles is spherical nanoparticles, and a close interfacial contact is formed between the graphene nanosheets and the silver phosphate nanoparticles.

The preparation method of described silver phosphate/graphene/silver nano composite material, comprises the following steps:

(1) Preparation of graphene oxide dispersion: weigh graphene oxide powder and dissolve it in deionized water, and ultrasonically disperse evenly to obtain a graphene oxide dispersion with a concentration of 0.5 mg/ml;

(2) Preparation of disodium hydrogen phosphate solution: weigh the disodium hydrogen phosphate solid and dissolve it in deionized water, and ultrasonically disperse evenly to obtain a disodium hydrogen phosphate solution with a concentration of 0.01-0.1mol/L;

(3) Preparation of precursor: Weigh silver nitrate solid and dissolve it in graphene oxide dispersion, wherein the concentration of silver nitrate is 0.04-0.4mol/L, and obtain precursor solution A after magnetic stirring; The prepared disodium hydrogen phosphate solution was added dropwise to the same volume of precursor solution A under continuous magnetic stirring and dark conditions, and the ratio of disodium hydrogen phosphate to silver nitrate was 1:4. The mixed solution continues to be magnetically stirred at room temperature for 0.5-2 hours, and the precipitate is centrifuged and washed repeatedly with deionized water and absolute ethanol for several times. After vacuum drying, the precipitate is dissolved in absolute ethanol and dispersed uniformly by ultrasound The concentration is 1-5mg/ml precursor solution B;

(4) Preparation of silver phosphate/graphene/silver nanocomposite material: Place the precursor solution B in step 3 under visible light for 10-30 minutes under magnetic stirring. Ionized water and absolute ethanol were repeatedly centrifuged and washed several times, and the precipitate was vacuum-dried to obtain a silver phosphate/graphene/silver nanocomposite material.

The beneficial effects of the present invention are: using silver phosphate/graphene oxide as the precursor, using the photo-assisted reduction method, adding excess silver nitrate, and simultaneously absorbing graphene oxide and graphene oxide by means of photo-generated electrons on silver phosphate The reduction of silver ions into graphene and the preparation of silver nanocrystals can prepare a special silver phosphate/graphene/silver nanocomposite material, in which silver phosphate nanoparticles and graphene with many excellent properties Combined together to form a close interface contact, not only can inhibit photocorrosion, improve the stability of silver phosphate, but also help the separation of photogenerated carriers and improve photoelectric conversion efficiency. In addition, the excess silver ions adsorbed on graphene are reduced to silver nanocrystals in the photo-assisted reduction process, and the silver nanocrystals with surface plasmon effect can greatly enhance the light absorption and electron transport properties of nanocomposites, so they also greatly Improved photocatalytic efficiency. Therefore, taking advantage of the synergy between silver phosphate nanoparticles, graphene nanosheets, and silver nanocrystals, silver phosphate/graphene/silver nanocomposites can be used as a new type of efficient and stable visible light catalyst.

Description of drawings

Fig. 1 is the X-ray diffraction picture of silver phosphate/graphene/silver nanocomposite of the present invention;

Fig. 2 is the scanning electron microscope picture of silver phosphate/graphene/silver nanocomposite of the present invention;

Fig. 3 is the transmission electron microscope picture of silver phosphate/graphene/silver nanocomposite material of the present invention;

Fig. 4 is a graph showing the photocatalytic degradation curve of rhodamine B when the silver phosphate/graphene/silver nanocomposite material of the present invention is used as a visible light catalyst.

detailed description

Example 1:

Dissolve 25mg of graphene oxide in 50ml of deionized water, and obtain a graphene oxide dispersion with a concentration of 0.5mg/ml after ultrasonic dispersion; weigh 0.0711g of disodium hydrogen phosphate solid, dissolve it in deionized water, and obtain a concentration after ultrasonic dispersion Disodium hydrogen phosphate solution of 0.01mol/L; Weigh 0.3397g silver nitrate solid and dissolve in the above-mentioned graphene oxide dispersion, wherein the concentration of silver nitrate is 0.04mol/L, obtain precursor solution A after magnetic stirring. Slowly add 50ml of the above-mentioned disodium hydrogen phosphate solution into 50ml of precursor solution A under continuous magnetic stirring and dark conditions. Deionized water and absolute ethanol were repeatedly centrifuged and washed several times, and dried in vacuum; weighed 0.05g of the dried powder and dissolved it in 50ml of absolute ethanol solution, and dispersed uniformly by ultrasonic to obtain precursor solution B. Under the condition of continuous magnetic stirring, the precursor solution B was placed under visible light for 10 minutes. After the light was over, the precipitate was centrifuged and washed repeatedly with deionized water and absolute ethanol, and dried in vacuum to obtain silver phosphate/ Graphene/silver nanocomposites;

Fig. 1 is the X-ray diffraction picture of the silver phosphate/graphene/silver nano-composite material that this example prepares, and the diffraction peak in the figure coincides completely with cubic silver phosphate, and the diffraction peak that occurs at 37.7 ⁰ place is consistent with silver simultaneously The (111) plane is consistent, indicating that the prepared nanocomposite contains silver phosphate and silver, and graphene is relatively weak in the diffraction peak intensity due to the small content in the nanocomposite, which cannot be observed in the figure.

Example 2:

Dissolve 25mg of graphene oxide in 50ml of deionized water, and obtain a graphene oxide dispersion with a concentration of 0.5mg/ml after ultrasonic dispersion; weigh 0.3555g of disodium hydrogen phosphate solid and dissolve it in deionized water, and obtain a concentration after ultrasonic dispersion Disodium hydrogen phosphate solution of 0.05mol/L; Weigh 1.6985g silver nitrate solid and dissolve in the above-mentioned graphene oxide dispersion, wherein the concentration of silver nitrate is 0.2mol/L, obtain precursor solution A after magnetic stirring. Slowly add 50ml of the above-mentioned disodium hydrogen phosphate solution into 50ml of precursor solution A under continuous magnetic stirring and dark conditions. Deionized water and absolute ethanol were repeatedly centrifuged and washed several times, and dried in vacuum; weighed 0.1 g of the dried powder and dissolved it in 50 ml of absolute ethanol solution, and dispersed it uniformly by ultrasonic to obtain precursor solution B. Under the condition of continuous magnetic stirring, the precursor solution B was placed under visible light for 20 minutes. After the illumination, the precipitate was centrifuged and washed repeatedly with deionized water and absolute ethanol. After vacuum drying, silver phosphate/ Graphene/silver nanocomposites.

Fig. 2 is the scanning electron microscope picture of the silver phosphate/graphene/silver nano-composite material that this example prepares, can see clearly from the figure that the spherical silver phosphate nano-particle with particle diameter about 200nm is tightly wrapped by graphene sheet However, the surface of graphene is very rough due to the growth of silver nanoparticles; Fig. 3 is a transmission electron microscope picture of the silver phosphate/graphene/silver nanocomposite material prepared in this example, as can be clearly seen from the figure Spherical silver phosphate nanoparticles with a particle size of about 200nm are tightly wrapped by transparent graphene sheets, and many silver nanoparticles with a particle size of about 5-10nm grow uniformly on the graphene sheets.

Example 3:

Dissolve 25mg of graphene oxide in 50ml of deionized water, and obtain a graphene oxide dispersion with a concentration of 0.5mg/ml after ultrasonic dispersion; weigh 0.7107g of disodium hydrogen phosphate solid, dissolve it in deionized water, and obtain a concentration of Disodium hydrogen phosphate solution of 0.1mol/L; Weigh 3.397g silver nitrate solid and dissolve in the above-mentioned graphene oxide dispersion, wherein the concentration of silver nitrate is 0.4mol/L, obtain precursor solution A after magnetic stirring. Slowly add 50ml of the above-mentioned disodium hydrogen phosphate solution into 50ml of precursor solution A under continuous magnetic stirring and dark conditions. Deionized water and absolute ethanol were repeatedly centrifuged and washed several times, and dried in vacuum; weighed 0.5g of the dried powder and dissolved it in 50ml of absolute ethanol solution, and dispersed uniformly by ultrasonic to obtain precursor solution B. Under the condition of continuous magnetic stirring, the precursor solution B was placed under visible light for 30 minutes. After the illumination, the precipitate was centrifuged and washed repeatedly with deionized water and absolute ethanol. After vacuum drying, silver phosphate/graphite was obtained. ene/silver nanocomposites.

Example 4:

The silver phosphate/graphene/silver nanocomposite prepared by the present invention is used as a visible light catalyst in the photocatalytic degradation experiment of the organic dye rhodamine B. The specific experimental process is as follows:

Get the silver phosphate/graphene/silver nanocomposite photocatalyst prepared in 50mg example 2 and be dissolved in the rhodamine B that 50ml concentration is 20mg/ml, the dispersion liquid obtained after ultrasonic dispersion is evenly transferred in the photocatalytic reactor, Place under dark conditions and continue magnetic stirring for 30 minutes. When the photocatalyst and dye molecules reach adsorption-desorption equilibrium, turn on the 500W halogen lamp equipped with a visible light filter (wavelength > 400nm) to irradiate the mixed solution vertically; Use a pipette gun to draw 3ml of the irradiated mixed solution, transfer it to the centrifuge tubes with sequential numbers, and transfer the supernatant to a quartz cuvette after centrifugation, and use a UV-visible spectrophotometer to measure the concentration of the solution at different time points. The absorbance of the silver phosphate/graphene/silver nanocomposite photocatalyst was drawn to draw the photocatalytic degradation curve of rhodamine B under visible light irradiation.

Fig. 4 is the photocatalytic degradation curve figure for rhodamine B when the silver phosphate/graphene/silver nanocomposite material prepared in example 2 is used as visible light catalyst, has excellent photocatalytic degradation to organic dye rhodamine B under visible light excitation Effect, the degradation rate of rhodamine B after 30 minutes of light is 100%.

Claims (1)

1. a silver phosphate/graphene/snanocomposite nanocomposite, it is characterized in that, it is made up of graphene nanometer sheet, silver orthophosphate nano particle and silver nanoparticle crystalline substance, described graphene nanometer sheet is closely coated on the surface of silver orthophosphate nano particle, and on graphene nanometer sheet, homoepitaxial has a large amount of silver nanoparticle brilliant; The particle diameter of described silver orthophosphate nano particle is 200nm, and silver nanoparticle crystalline substance is of a size of 5-10nm; The pattern of described silver orthophosphate nano particle is spherical nanoparticle, and defines interracial contact closely between graphene nanometer sheet and silver orthophosphate nano particle; Described silver phosphate/graphene/snanocomposite nanocomposite prepares by the following method:

(1) preparation of graphene oxide dispersion: weigh graphene oxide powder and be dissolved in deionized water, obtaining concentration after ultrasonic disperse is even is 0.5mg/ml graphene oxide dispersion;

(2) preparation of disodium phosphate soln: weigh sodium hydrogen phosphate solid and be dissolved in deionized water, obtains the disodium phosphate soln that concentration is 0.01-0.1mol/L after ultrasonic disperse is even;

(3) preparation of presoma: weigh silver nitrate dissolution of solid in graphene oxide dispersion, wherein, the concentration of silver nitrate is 0.04-0.4mol/L, obtains precursor solution A after magnetic agitation is even; The disodium phosphate soln of preparation in step (2) is stirred at continuing magnetic force and is added drop-wise in the precursor solution A of same volume under dark condition, and sodium hydrogen phosphate is 1:4 with the ratio of the amount of substance of silver nitrate, dropwise rear mixed solution and at room temperature continue magnetic agitation 0.5-2 hour, repeatedly clean after sediment centrifugation repeatedly with deionized water, absolute ethyl alcohol, sediment is dissolved in absolute ethyl alcohol after vacuum drying, and obtaining concentration after ultrasonic disperse is even is 1-5mg/ml precursor solution B;

(4) preparation of silver phosphate/graphene/snanocomposite nanocomposite: the precursor solution B in step (3) is placed under magnetic stirring illumination 10-30min under visible ray, by sediment centrifugation after illumination terminates, use deionized water respectively, absolute ethyl alcohol repeatedly eccentric cleaning repeatedly, sediment vacuum drying obtains silver phosphate/graphene/snanocomposite nanocomposite.