NL2031042A

NL2031042A - Ternary visible light photocatalytic nanocomposite and preparation method thereof

Info

Publication number: NL2031042A
Application number: NL2031042A
Authority: NL
Inventors: Shan Chuanfu; Li Ming
Original assignee: Univ Guilin Technology
Priority date: 2021-12-08
Filing date: 2022-02-22
Publication date: 2022-06-01
Also published as: NL2031042B1; CN114054054B; CN114054054A

Abstract

The disclosure discloses a ternary visible light photocatalytic nanocomposite and a preparation method thereof, and belongs to the technical field, of functional materials. The preparation. method comprises the following steps: Sl, preparing phosphorus—doped graphene quantum dots: preparing trinitro—pyrene from pyrene and nitric acid; and adding water into the trinitro—pyrene, adding a phosphorus source, adjusting pH to 10—11, and performing a hydrothermal reaction at 180 degrees Celsius to prepare the phosphorus—doped graphene quantum dots; and SZ, preparing an aqueous solution of the phosphorus—doped graphene quantum dots in Sl, mixing the aqueous solution with titanium dioxide nanoparticles, silver nitrate and potassium iodide, and filtering and drying the mixture to prepare the ternary visible light photocatalytic nanocomposite. The catalytic efficiency in 10 min can reach 99.35% when the prepared nanomaterial is put in a methyl orange solution. under visible light irradiation, and the nanomaterial shows excellent catalytic performance.

Description

TERNARY VISIBLE LIGHT PHOTOCATALYTIC NANOCOMPOSITE AND PREPARATION METHOD THEREOF

TECHNICAL FIELD The disclosure belongs to the technical field of functional materials, and particularly relates to a ternary visible light photocatalytic nanocomposite and a preparation method thereof.

BACKGROUND ART Organic dyestuff water pollution brings huge hidden danger to health and safety of people, and has become a major challenge in the world. Semiconductor photocatalysis is a prospective method for solving this problem. In semiconductor multielement photoca- talysis, multiple refractory pollutants from the environment are decomposed under ultraviolet/visible light irradiation, and tita- nium dioxide is the most potential in several known researched photocatalytic semiconductor materials, has the characteristics of being stable in performance, free of toxicity, low in cost, etc., and has been widely applied to multiple fields when it was applied to water decomposition for the first time in 1972. However, its photocatalytic efficiency is limited due to the defects such as broad band gap and high carrier recombination rate. A currently- prepared photocatalytic composite with the titanium dioxide as a main component can catalytically degrade organic dyestuff pollu- tants in water only under ultraviolet light, but is poor in cata- lytic effect in a visible light wavelength area, is extremely low in solar energy utilization rate and is hardly used commercially on a large scale.

SUMMARY In order to solve the above technical problems, the disclo- sure provides a ternary visible light photocatalytic nanocomposite and a preparation method thereof, titanium dioxide nanoparticles and phosphorus-doped graphene duantum dots are bonded with silver iodide through a simple and convenient method to form the nanocom- posite, the phosphorus-doped graphene quantum dots are introduced to the surface of titanium dioxide so as to improve photosensiti-

zation of the titanium dioxide, form P/N junctions with the tita- nium dioxide, remarkably improve carrier transport and reduce re- combination with photo-induced electrons, the silver iodide and the titanium dioxide are coupled to establish heterojunctions to form interface energy deviation between surfaces of semiconduc- tors, the charge hole separation efficiency can be improved, and the silver iodide has high absorption capacity for visible light radiation absorption; and the composite of the disclosure can ef- ficiently utilize sclar energy for decomposing different organic pollutants in water.

The disclosure is specifically achieved through the following technical solution.

The first objective of the disclosure is to provide a prepa- ration method of a ternary visible light photocatalytic nanocompo- site, comprising the following steps: Sl, preparing phosphorus-doped graphene quantum dots: preparing trinitro-pyrene from pyrene and nitric acid; and adding water into the trinitro-pyrene, adding a phosphorus source, adjusting pH to 10-11, and performing a hydrothermal reaction at 180 degrees Celsius to prepare the phosphorus-doped graphene quan- tum dots; and S2,; preparing an aqueous solution of the phosphorus-doped graphene quantum dots in S1, mixing the aqueous solution with ti- tanium dioxide nanoparticles, silver nitrate and potassium iodide, and filtering and drying the mixture to prepare the ternary visi- ble light photocatalytic nanocomposite.

Optionally, in S1, a usage ratio of the pyrene to the nitric acid is 1 g: 100 mL.

Optionally, in S1, the trinitro-pyrene is prepared by heating in a water bath at 80 degrees Celsius, flowing back and stirring for 12 h.

Optionally, in S81, the phosphorus source is sodium phosphate dibasic dodecahydrate.

Optionally, in S1, a usage ratio of the trinitro-pyrene to the water to the phosphorus source is 1 mg: 1 mL: 0.03 g.

Optionally, in Sl, time of the hydrothermal reaction is 6 h.

Optionally, in S1, a solution is dialyzed through a dialysis bag with the molecular weight cut-off of 3500 Da for 24-36 h after the hydrothermal reaction and then dried.

Optionally, in S2, the raw material adding sequence is as follows: the titanium dioxide nano-particles are dispersed in the aqueous solution of the phosphorus-doped graphene quantum dots, the silver nitrate is added, and after the materials are uniformly mixed, a potassium iodide aqueous solution is added dropwise in the stirring process.

Optionally, in S2, the concentration of the aqueous solution of the phosphorus-doped graphene quantum dots is 0.2 mg/mL, and the usage ratio of the titanium dioxide nanoparticles to the aque- ous solution of the phosphorus-doped graphene quantum dots to the silver nitrate to the potassium iodide is 0.5 g : 500 mL : 0.097 g : 0.092 g.

The second objective of the disclosure is to provide the ter- nary visible light photocatalytic nanocomposite prepared through the above preparation method.

Compared with the prior art, the disclosure has the following beneficial effects: (1) in the disclosure, the titanium dioxide nanoparticles and the phosphorus-doped graphene quantum dots are bonded with the silver iodide to form the nanocomposite, the titanium dioxide, the phosphorus-doped graphene quantum dots and the silver iodide are successfully recombined into the ternary nanomaterial through a simple manner of dissolving in water, stirring and suspension ad- sorption when the nanocomposite is synthesized, manners such as heating are not used, the cost is low, and the operation is con- venient.

{2) the catalytic efficiency in 10 min can reach 99.35% when the prepared nanomaterial is put in the methyl orange solution un- der visible light irradiation, and the nanomaterial shows excel- lent catalytic performance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a TEM diagram of a P25/PCDs/AgI material prepared in an embodiment 1; FIG. 2 is a HRTEM diagram of a P25/PCDs/AgI material prepared in an embodiment 1;

FIG. 3 is an FESEM diagram of a P25/PCDs/AgI material pre- pared in an embodiment 1; FIG. 4 is an EDS diagram of a P25/PCDs/AgI material prepared in an embodiment 1; FIG. 5 is an XPS spectrum diagram of a P25/PCDs/AgI material prepared in an embodiment 1; and FIG. 6 is a catalytic performance diagram of materials in an embodiment 1 and comparative examples 1-4 to methyl orange.

DETAILED DESCRIPTION OF THE EMBODIMENTS In order to make those skilled in the art better understand the technical solutions of the disclosure for implementation, the disclosure is further illustrated below with reference to specific embodiments and accompanying drawings, but the listed embodiments do not limit the disclosure.

Experimental methods and detection methods in the embodiments below are all conventional methods unless otherwise specified; and reagents and materials can be purchased on the market unless oth- erwise specified.

Embodiment 1 A preparation method of a ternary visible light photocatalyt- ic nanocomposite, comprises the following steps: (1) after 1 g of pyrene and 100 ml of nitric acid are mixed, the mixture is heated in a water bath at 80 degrees Celsius, flows back, and is stirred for 12 h, the reactant is added into 500 ml of purified water for filtering, a yellow solid, namely trinitro- pyrene is obtained, 40 mg of trinitro-pyrene is put in 40 ml of water, 1.2 g of sodium phosphate dibasic dodecahydrate is added as a phosphorus source, sodium hydroxide is added to enable the PH value of the mixed liquid to reach 10, and the mixed liquid is put in a 100 ml reaction still to be heated at 180 degrees Celsius for 6 h. Filtering is performed after cooling to obtain a solution, the solution is dialyzed through a dialysis bag at 3500 Da for 24 h, and then the dialyzed solution is dried by cooling to obtain phosphorus-doped graphene quantum dots (PCDs).

(2) 0.5 g of commercial-level titanium dioxide nanoparticles (P25) are taken and dispersed in 500 ml of aqueous solution of the phosphorus-doped graphene quantum dots (0.2 mg/ml) to be rapidly magnetically stirred for 0.5 h, 0.097 g of silver nitrate is put in the mixed solution to be rapidly magnetically stirred for 1 h, then 0.092 g of potassium iodide is dissolved in 20 ml of water, the mixture is added dropwise into the mixed solution, the mixture 5 is added dropwise into the mixed solution under stirring, it is found that the color obviously turns into yellow green, then fil- tering is performed and drying is performed at 60 degrees Celsius to obtain the novel ternary excellent visible light photocatalytic nanocomposite (P25/PCDs/AgI) with the titanium dioxide, phospho- rus-doped graphene quantum dots and silver iodide.

Embodiment 2 After 1 g of pyrene and 100 ml of nitric acid are mixed, the mixture is heated in a water bath at 80 degrees Celsius, flows back, and is stirred for 12 h, the reactant is added into 500 ml of purified water for filtering, a yellow solid, namely trinitro- pyrene is obtained, 40 mg of trinitro-pyrene is put in 40 ml of water, 1.2 g of sodium phosphate dibasic dodecahydrate is added as a phosphorus source, sodium hydroxide is added to enable the PH value of the mixed liquid to reach 11, and the mixed liquid is put in a 100 ml reaction still to be heated at 180 degrees Celsius for 6 h. Filtering is performed after cooling to obtain a solution, the solution is dialyzed through a dialysis bag at 3500 Da for 36 h, and then the dialyzed solution is dried by cooling to obtain phosphorus-doped graphene quantum dots.

0.5 g of commercial-level titanium dioxide nanoparticles (P25) are taken and dispersed in 500 ml of aqueous solution of the phosphorus-doped graphene quantum dots (0.2 mg/ml) to be rapidly magnetically stirred for 0.5 h, 0.097 g of silver nitrate is put in the mixed solution to be rapidly magnetically stirred for 1 h, then 0.092 g of potassium iodide is dissolved in 20 ml of water, the mixture is added dropwise into the mixed solution, the mixture is added dropwise into the mixed solution under stirring, it is found that the color obviously turns into yellow green, and then filtering is performed and drying is performed at 60 degrees Cel- sius to obtain the novel ternary excellent visible light photo- catalytic nanocomposite with the titanium dioxide, phosphorus- doped graphene quantum dots and silver iodide.

Comparative Example 1 Titanium dioxide nanoparticles (P25) are dispersed in 500 ml of aqueous solution of the phosphorus-doped graphene quantum dots (0.2 mg/ml) prepared in step (1) of the embodiment 1 to be rapidly magnetically stirred for 0.5 h, and then filtering is performed and drying is performed at 60 degrees Celsius to prepare a P25/PCDs material. Comparative Example 2 P25 is dispersed in 500 ml of aqusous solution of pure gra- phene quantum dots (0.2 mg/ml) to be rapidly magnetically stirred for 0.5 h, and then filtering is performed and drying is performed at 60 degrees Celsius to prepare a P25/CDs material. Comparative Example 3 P25 is dispersed in 500 ml of aqueous solution of pure gra- phene quantum dots {0.2 mg/ml) to be rapidly magnetically stirred for 0.5 h, 0.097 g of silver nitrate is put in the mixed solution to be rapidly magnetically stirred for 1 h, then 0.092 g of potas- sium iodide is dissolved in 20 ml of water, the mixture is added dropwise into the mixed solution, and then filtering is performed and drying is performed at 60 degrees Celsius to prepare a P25/CDs/AgI material. Comparative Example 4 Titanium dioxide nanoparticles (P25) The materials prepared in the embodiment 1 and the embodiment 2 have similar performance, the above material prepared in the em- bodiment 1 is taken as an example below, firstly, the material is represented, FIG. 1 is a TEM diagram of a P25/PCDs/AgI material, FIG. 2 is an HRTEM diagram of a P25/PCDs/AgI material, it can be seen from FIG. 2 that in three lattice distances, the plane lat- tice distance 0.35 nm corresponds to P25, the plane lattice dis- tance 0.231 nm corresponds to AgI, the plane lattice distance

0.243 nm corresponds to PCDs, and thus it proves that the compo- site is successfully synthesized; and FIG. 3 is an FESEM diagram of a material, it can be seen from FIG. 1 and FIG. 3 that TEM and FESEM images of the material are highly matched, they show that the nanocomposite is almost formed by spherical particles, and particle aggregation is observed due to the fact that the nanocom-

posite highly grows. FIG. 4 is an EDS diagram of a material, FIG. is an XPS spectrum diagram of a material, it can be clearly seen from FIG. 4 and FIG. 5 that a ternary catalyst sample contains C, FP, Ag, I, TI and O, and it shows that a ternary photocatalyst with 5 a stable structure is established through PCDs, AgI and TIOZ in a physical adsorption manner.

The comparative examples 1-4 are taken as controls below to represent the performance of P25/PCDs/AgI prepared in the embodi- ment 1, and the specific operation is as follows:

0.1 g of catalyst in the embodiment 1, 0.1 g of catalyst in the comparative example 1, 0.1 g of catalyst in the comparative example 2, 0.1 g of catalyst in the comparative example 3 and 0.1 g of catalyst in the comparative example 4 are taken and put in 10 mg/L of methyl orange solution respectively for ultrasonic treat- ment for 1 h in the dark to achieve adsorption equilibrium. Under 300 w visible light lamp irradiation, 5 ml of sample solution is filtered out every 5 min, and the methyl orange concentration in the solution is tested. The specific result is shown in FIG. 6, and it can be seen from the result in FIG. 6 that compared with the comparative examples 1-4, the catalytic efficiency in 10 min of the material prepared in the embodiment 1 can reach 99.35% un- der visible light irradiation, and the material shows excellent catalytic performance.

Obviously, those skilled in the art can make various modifi- cations and variations on the disclosure without departing from the spirit and the scope of the disclosure. Thus, if these modifi- cations and variations of the disclosure belong to the scope of the claims of the disclosure and equivalent technologies thereof, the disclosure also intends to include these modifications and variations.

Claims

CONCLUSIONS

Process for preparing a ternary visible light photocatalytic nanocomposite, characterized in that the process for preparing comprises the following steps: S1, preparing phosphorus-doped graphene quantum dots: preparation of trinitropyrene from pyrene and nitric acid ; and adding water to the trinitropyrene, adding a source of phosphorus, adjusting the pH to 10 to 11 and conducting a hydrothermal reaction at 180 degrees Celsius to prepare the phosphorus-doped graphene quantum dots; and S2, preparing an aqueous solution of the phosphorus-doped graphene quantum dots in S1, mixing the aqueous solution with titanium dioxide nanoparticles, silver nitrate and potassium iodide, and filtering and drying the mixture to form the ternary to prepare visible light photocatalytic nanocomposite.

Process for preparing the visible light ternary photocatalytic nanocomposite according to Claim 1, characterized in that in S1, a usage ratio of the pyrene to the nitric acid is 1 g:100 ml.

Process for the preparation of the visible light ternary photocatalytic nanocomposite according to claim 1, characterized in that in S1, the trinitropyrene is prepared by heating in a water bath at 80°C, reflux and stirring for 12 hours.

Process for the preparation of the ternary visible light photocatalytic nanocomposite according to claim 1, characterized in that in S81 the source of phosphorus is dibasic sodium phosphate dodecahydrate.

Process for the preparation of the ternary visible light photocatalytic nanocomposite according to claim 1, characterized in that in S1, a usage ratio of trinitropyrene to water to source of phosphorus is 1 mg: 1 ml: 0.03 g.

Process for preparing the ternary visible light photocatalytic nanocomposite according to claim 1, characterized in that in S 1 the time of the hydrothermal reaction is 6 hours.

Process for preparing the ternary visible light photocatalytic nanocomposite according to claim 1, characterized in that in S1, the solution is dialyzed through a dialysis bag having a molecular weight cutoff of 3500 Da for 24 to 36 hours after the hydrothermal reaction and then dried.

Process for preparing the ternary visible light photocatalytic nanocomposite according to claim 1, characterized in that in S2 the order of addition of raw materials is as follows: the nanoparticles of titanium dioxide are dispersed in the aqueous solution of the phosphorus-doped graphene duantum dots, the silver nitrate is added and after the materials are evenly mixed, an aqueous potassium iodide solution is added dropwise during stirring.

Process for preparing the ternary visible light photocatalytic nanocomposite according to claim 1, characterized in that in S 2 the concentration of the aqueous solution of the phosphorus-doped graphene quantum dots is 0.2 mg/ml and the use - ratio of the titanium dioxide nanoparticles to the aqueous solution of the phosphorus-doped graphene quantum dots to the silver nitrate to the potassium iodide is 0.5 g : 500 ml : 0.097 g : 0.092 g.

A ternary visible light photocatalytic nanocomposite prepared by the preparation method according to any one of claims 1 to 9.