CN106964388B - A kind of preparation method of stannous tungstate doped two-dimensional graphite phase carbon nitride composite photocatalyst - Google Patents

Abstract

The invention relates to the preparation of a composite photocatalyst doped with two-dimensional graphite phase carbon nitride (g-C3N4) by stannous tungstate (α‑SnWO4), comprising the steps of: preparing stannous tungstate (α‑SnWO4), two The preparation of two-dimensional graphitic carbon nitride (g-C3N4) and the preparation of SnWO-doped two-dimensional graphitic carbon nitride composite photocatalyst. The beneficial effect of the invention is that the preparation process of the composite photocatalyst is simple and the conditions are easy to control. According to the structural characterization and performance characterization experiments, it can be found that the prepared stannous tungstate doped two-dimensional graphitic carbon nitride composite photocatalyst has the advantages of stable chemical properties, uniform morphology, high catalytic efficiency, etc., and because of its easy-to-obtain raw materials , and the preparation cost is low, so it has certain research and application value.

Description

Preparation of a two-dimensional graphitic carbon nitride composite photocatalyst doped with tin tungstate method

technical field

The invention belongs to the technical field of nanomaterial preparation and application, and relates to the preparation and application of a two-dimensional graphite-phase carbon nitride composite photocatalyst doped with stannous tungstate.

Background technique

With the progress of industry, the problem of environmental pollution is becoming more and more serious. As a new type of environmental pollution control means, photocatalytic technology has gradually attracted extensive research by scientists at home and abroad. The development and utilization of new and effective photocatalysts is the cornerstone of the industrialization of photocatalytic technology. Among many photocatalysts, graphitic carbon nitride (gC ₃ N ₄ ) is a new type of visible light-responsive organic polymer photocatalyst, which has the advantages of stable chemical properties, low cost and non-toxicity. At present, it has been widely studied in the research fields of photocatalytic degradation and photocatalytic hydrogen production, and has achieved a series of landmark results. However, studies have shown that single-component gC ₃ N ₄ photocatalysts have problems such as low solar energy utilization, high photogenerated electron-hole recombination rate, and low quantum efficiency. These problems greatly limit the application and development of gC ₃ N ₄ photocatalysts. Therefore, in recent years, the research on the modification of photocatalytic properties of photocatalysts has gradually become a hot spot in the subject of photocatalysis. Currently known modification methods include: noble metal deposition, semiconductor recombination, non-metal doping, lamellar exfoliation and pore structure and other methods. The study found that graphite-like carbon nitride has a stack of sheet-like carbon nitride nanosheets. If these stacked sheets can be successfully peeled off, the ratio of graphite-like carbon nitride can be effectively improved. Surface area, and at the same time increase the active sites of carbon nitride, reduce the recombination efficiency of photogenerated carriers, thereby improving the photocatalytic performance of carbon nitride. In addition, the composite modification method of combining two kinds of semiconductors can effectively improve the separation efficiency of photogenerated electrons and holes, thereby improving the photocatalytic performance of a single catalyst, and finally improving the photocatalytic efficiency. In addition, if the lamellar exfoliation is combined with the method of constructing a composite system, the photocatalytic efficiency of graphite-like carbon nitride can be effectively improved.

In recent years, studies have found that stannous tungstate (α-SnWO ₄ ) as a tungstate (AWO ₄ type) photocatalyst has the advantages of narrow band gap energy, wide visible light response range, and abundant raw materials. It has gradually attracted the attention of researchers in the field of photocatalysis. However, the single stannous tungstate photocatalyst has the disadvantages of low photocatalytic efficiency, small specific surface area, and poor adsorption performance. Therefore, based on the synthesis of two-dimensional graphite-like carbon nitride and stannous tungstate, we combined two-dimensional graphite-like carbon nitride and stannous tungstate to construct a new type of composite photocatalyst, which can not only The photoresponsiveness, adsorption performance and specific surface area of stannous tungstate can effectively improve the separation efficiency of photogenerated holes, thereby improving the photocatalytic performance. Therefore, it is very meaningful to research and develop this new type of composite photocatalyst. At present, there is no relevant report on this new type of SnWO-doped graphitic carbon nitride composite photocatalyst.

Contents of the invention

The technical problem to be solved by the present invention is: based on the above problems, the present invention provides a preparation method of a stannous tungstate-doped two-dimensional graphite phase carbon nitride composite photocatalyst.

A technical scheme that the present invention adopts to solve its technical problem is: a kind of preparation method of stannous tungstate doped two-dimensional graphite phase carbon nitride composite photocatalyst, comprises the following steps:

(1) Preparation of two-dimensional graphitic carbon nitride (gC ₃ N ₄ ): mix the carbon nitrogen source and the leavening agent evenly, put them into a crucible, heat to 450-550°C, heat for 4-6 hours, and cool naturally to The product was obtained after grinding at room temperature;

(2) Preparation of stannous tungstate (α-SnWO ₄ ): Dissolve stannous chloride (SnCl ₂ ) in 20-50ml of solvent I to form solution A, then mix sodium tungstate (NaWO ₄ .H ₂ O) and Cetyltrimethylammonium bromide (CTAB) was dissolved in 20-50ml of solvent I to form solution B respectively. Add B dropwise to A, adjust the pH to 7~8 with 10mol/L NaOH solution, stir for 20~60min, then transfer to the reaction kettle at 180~200℃ for 12~24h, centrifuge, wash at 60~80 Dry at ℃ for 12-24 hours, and grind to obtain stannous tungstate (α-SnWO ₄ );

(3) Preparation of SnWO 4 (SnWO ₄ ) doped two-dimensional graphitic carbon nitride (gC ₃ N ₄ ) composite photocatalyst: Nitriding a certain mass of two-dimensional graphitic phase after drying in step (1) Add carbon (gC ₃ N ₄ ) and stannous tungstate (SnWO ₄ ) into beakers respectively, put them into 30ml dispersant, and ultrasonicate for 2h. Then, the SnWO ₄ suspension was added dropwise into the two-dimensional graphite phase nitrided suspension, stirred for 12 h, transferred to an autoclave at 120° C., and reacted for 4 h. The product was dried by centrifugal filtration.

Further, in the step (1), the carbon and nitrogen sources are urea, dicyandiamide, cyanamide, melamine, etc., and the leavening agent is ammonium chloride, ammonium bromide, or ammonium nitrate, etc.

Further, the solvent I in the step (2) is deionized water or ethylene glycol, ethanol, etc.; the dispersant in the step (3) is deionized water or ethanol.

Further, the quality of the carbon and nitrogen source in the described step (1) is 5 to 10 g, and the quality of the leavening agent is 2 to 3 times that of the carbon and nitrogen source; the quality of the stannous chloride in the described step (2) The mass ratio to sodium tungstate is 1:1.5 or 1:2; the mass ratio of stannous chloride to cetyltrimethylammonium bromide (CTAB) is 6:1 or 5:1.

Further, the mass ratio of stannous tungstate in the step (3) is two-dimensional graphitic carbon nitride with a mass ratio of 1:10 or 10:1.

Furthermore, the preparation method of the stannous tungstate-doped two-dimensional graphitic carbon nitride composite photocatalyst in the step (3) is characterized by: stirring for 12 hours, hydrothermal temperature of 120° C., and reaction time of 6 hours.

The beneficial effects of the invention are: the composite photocatalyst prepared by the method has good stability, no secondary pollution, and the catalytic efficiency can reach 90.37% of the target pollutant rhodamine B within 80 minutes. In addition, the preparation method of the composite photocatalyst has the advantages of simplicity, easy control of preparation conditions, no secondary pollution and the like. Therefore, it has certain research and application value.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1 is the scanning electron micrograph of pure stannous tungstate and stannous tungstate doped two-dimensional graphite phase carbon nitride composite photocatalyst prepared by the embodiment of the present invention 1;

Fig. 2 is the pure carbon nitride prepared by the embodiment of the present invention 1, the X-ray diffraction pattern of pure stannous tungstate and stannous tungstate doped two-dimensional graphite phase carbon nitride composite photocatalyst;

Fig. 3 is a diagram showing the UV-visible absorption spectrum of the degradation of rhodamine B by the stannous tungstate-doped two-dimensional graphitic carbon nitride composite photocatalyst prepared in Example 1 of the present invention as a function of illumination time.

Detailed ways

The present invention will now be further described in conjunction with specific examples, and the following examples are intended to illustrate the present invention rather than further limit the present invention.

Example 1

(1) Preparation of graphite-phase carbon nitride (gC ₃ N ₄ ): Mix 5 g of melamine and 10 g of leavening agent evenly and put them in a crucible, heat to 450°C in a muffle furnace for 4 hours, and naturally cool to room temperature The product is obtained after grinding;

(2) Preparation of stannous tungstate (α-SnWO ₄ ): 1.8g of stannous chloride (SnCl ₂ ) was dissolved in 20ml of ethanol to form solution A, and then 2.7g of sodium tungstate (NaWO ₄ .H ₂ O ) and 0.3 g of cetyltrimethylammonium bromide (CTAB) were dissolved in 20 ml of water to form solution B. Add B dropwise to A, adjust the pH to 7 with 10mol/L NaOH solution, stir for 20min, then transfer to the reaction kettle for 12h at 180°C, centrifuge, wash and dry at 60°C for 12h, and grind to obtain tungstate Tin (α-SnWO ₄ );

(3) Preparation of a two-dimensional graphitic carbon nitride composite photocatalyst doped with stannous tungstate: add 10 g of two-dimensional graphitic carbon nitride and 1 g of stannous tungstate in step (1) to a beaker respectively, and put in 30 ml Dispersant, ultrasonic 2h. Then, the SnWO ₄ suspension was added dropwise into the two-dimensional graphite phase nitrided suspension, stirred for 12 h, transferred to an autoclave at 120° C., and reacted for 4 h. The product was dried by centrifugal filtration.

1. Morphology and component determination of SnWO3-doped two-dimensional graphitic carbon nitride composite photocatalyst

Adopt Japanese JSM-6360A type scanning electron microscope to observe the morphology of the stannous tungstate doped two-dimensional graphite phase carbon nitride composite photocatalyst prepared in Example 1, the scanning electron microscope picture is shown in Figure 1, as can be seen from the figure, The appearance of the stannous tungstate-doped two-dimensional graphitic carbon nitride composite photocatalyst prepared in this embodiment is that the surface of the two-dimensional graphitic carbon nitride is loaded with granular stannous tungstate nanoparticles, and the distribution is relatively uniform.

The crystal phase structure of the pure stannous tungstate prepared in embodiment 1, pure carbon nitride and stannous tungstate/two-dimensional graphitic carbon nitride composite photocatalyst is analyzed by Japan Rigaku D/max2500PC rotation X-ray diffractometer, Among them, X-ray is Cu target The voltage is 40kV, the current is 100mA, the step size is 0.02°, and the scanning range is 5°～80°. The X-ray diffraction pattern is shown in Figure 2. It can be seen from the figure that the XRD diffraction pattern of the prepared stannous tungstate/two-dimensional graphite phase carbon nitride composite photocatalyst can be seen at 25.06°, 31.84°, 32.94°, 36.3° , 52.76°, 57.46° and 60.86° appear the characteristic diffraction peaks of stannous tungstate respectively corresponding to (111)(200)(210)(002)(161)(232) and (123) crystal planes of stannous tungstate, 12.78° and 27.8° are the characteristic diffraction peaks of two-dimensional graphitic carbon nitride, corresponding to the (100) and (002) crystal planes of carbon nitride, respectively. Therefore, it can be proved that the composite photocatalyst only contains two-dimensional graphitic carbon nitride and stannous tungstate, and the chemical structure and crystal form of the two have not been changed during the composite process.

2. Photocatalytic performance and potential application of SnWO3-doped two-dimensional graphitic carbon nitride composite photocatalyst

The stannous tungstate/two-dimensional graphite phase carbon nitride composite photocatalyst degraded rhodamine B solution prepared in embodiment 1, wherein rhodamine B solution concentration 10mg/L, takes stannous tungstate/two-dimensional graphite phase nitriding Carbon composite photocatalyst 25mg, dark reaction for 30 minutes to achieve adsorption and desorption equilibrium, and then visible light catalytic reaction, use 1000w xenon lamp as light source, use a dropper to extract 5ml of reaction solution at regular intervals, put it in a high-speed centrifuge and centrifuge for 4 minutes, Rodin The photodegradation of Ming B was detected by UV-Vis spectrophotometer.

The degradation performance of the stannous tungstate/two-dimensional graphitic carbon nitride composite photocatalyst prepared in Example 1 on rhodamine B is shown in Figure 3 . It can be seen from Fig. 3 that the degradation rate of rhodamine B reaches 90.37% within 80 minutes, and it can be seen that the prepared stannous tungstate/two-dimensional graphitic carbon nitride composite photocatalyst has higher photocatalytic activity.

Claims (5)

1. a kind of wolframic acid stannous adulterates the preparation method of two-dimentional graphite phase carbon nitride composite photo-catalyst, it is characterized in that: include with Lower step:

(1) two-dimentional graphite phase carbon nitride (g-C₃N₄) preparation: carbon nitrogen source and leavening agent are put into crucible after mixing, added Heat heats 4~6h, obtains product after cooled to room temperature grinding to 450~550 DEG C；

(2) wolframic acid stannous α-SnWO₄Preparation: by stannous chloride (SnCl₂) it is dissolved in the formation solution A of 20~50mL solvent I, then will Sodium tungstate (NaWO₄·H₂O) it is dissolved in 20~50mL solvent I respectively and forms solution B with cetyl trimethylammonium bromide (CTAB), B is added dropwise in A dropwise, pH to 7~8 is adjusted with the NaOH solution of 10mol/L, is moved into reaction kettle after stirring 20~60min 180~200 DEG C of reactions 12~for 24 hours, centrifugation, washing in 60~80 DEG C dry 12~for 24 hours, after grinding wolframic acid stannous α-SnWO₄；

(3) wolframic acid stannous α-SnWO₄Adulterate two-dimentional graphite phase carbon nitride (g-C₃N₄) composite photo-catalyst preparation: by step (1) Two-dimentional graphite phase carbon nitride (the g-C of certain mass after middle drying₃N₄) and wolframic acid stannous α-SnWO₄It is separately added into beaker, puts Enter in 30mL dispersing agent, ultrasonic 2h, then by SnWO₄Suspension is added dropwise to dropwise in the suspension of two-dimentional graphite phase carbon nitride, Stir 12h, shift 120 DEG C of autoclave, react 6h, centrifugal filtration it is dry product.

2. the preparation side that a kind of wolframic acid stannous according to claim 1 adulterates two-dimentional graphite phase carbon nitride composite photo-catalyst Method, it is characterized in that: carbon nitrogen source is urea, dicyandiamide, cyanamide, melamine in the step (1), leavening agent is chlorination Ammonium, ammonium bromide or ammonium nitrate.

3. the preparation side that a kind of wolframic acid stannous according to claim 1 adulterates two-dimentional graphite phase carbon nitride composite photo-catalyst Method, it is characterized in that: solvent I is deionized water or ethylene glycol, ethyl alcohol in the step (2)；Dispersing agent in the step (3) For deionized water or ethyl alcohol.

4. the preparation side that a kind of wolframic acid stannous according to claim 1 adulterates two-dimentional graphite phase carbon nitride composite photo-catalyst Method, it is characterized in that: the quality of carbon nitrogen source is 5~10g in the step (1), leavening agent quality is the 2~3 of carbon nitrogen source quality Times；The mass ratio of the quality of stannous chloride and sodium tungstate is 1:1.5 or 1:2 in the step (2)；Stannous chloride and hexadecane Base trimethylammonium bromide (CTAB) the mass ratio of the material is 6:1 or 5:1.

5. the preparation side that a kind of wolframic acid stannous according to claim 1 adulterates two-dimentional graphite phase carbon nitride composite photo-catalyst Method, it is characterized in that: the quality of wolframic acid stannous and two-dimentional graphite phase carbon nitride mass ratio are 1:10 or 10 in the step (3): 1。