CN102641732A

CN102641732A - Multi-morphology rare earth doped BiVO4 composite photocatalyst and preparation method thereof

Info

Publication number: CN102641732A
Application number: CN2012101120868A
Authority: CN
Inventors: 张莉莉; 龙金鑫; 仲慧; 周守勇; 赵宜江; 汪信
Original assignee: Huaiyin Normal University
Current assignee: Huaiyin Normal University
Priority date: 2012-04-17
Filing date: 2012-04-17
Publication date: 2012-08-22
Anticipated expiration: 2032-04-17
Also published as: CN102641732B

Abstract

The invention discloses a multi-morphology rare earth doped BiVO4 composite photocatalyst and a preparation method thereof. The composite photocatalyst comprises the component of Ln(1-x)BiVO4, wherein Ln is equal to La, Ce, Pr, Nd, Sm, Gd, Dy, Er and Y, and x is equal to 0.01-0.3mol%. The photocatalyst disclosed by the invention has different morphologies and has the advantages of simple preparation technology, controllable morphology and crystalline phase structure of a target product and big specific surface area, and various organic pollutants, such as toxic and harmful phenols, aldehydes, and dyes, can be decomposed within a wider wavelength range.

Description

The rear-earth-doped BiVO of multiform looks 4Composite photo-catalyst and preparation method thereof

Technical field

The invention belongs to catalysis material, relate in particular to the rear-earth-doped BiVO of a kind of multiform looks ₄Composite photo-catalyst and preparation method thereof.

Technical background

Solar energy it is believed that it is that a kind of reserves enrich the natural energy resources that sustainability is utilized always, but human still very limited to its utilization.Photocatalysis technology is as a kind of new catalytic technology that can directly utilize high toxicity organic pollution in solar energy hydrolysis hydrogen manufacturing and the degree of depth degraded environment, 21 century the energy with application facet such as environment all ten minutes have prospect.BiVO ₄As a kind of novel semi-conductor catalysis material, paid close attention to by Many researchers with avirulence, high stability and strong advantage such as visible light-responded.

Along with people's finds that to the further investigation of photochemical catalyst it all is the key factor that influences its photocatalysis performance that the microscopic appearance of catalyst, particle size and lattice are formed.And in reaction system, add the surface-active auxiliary agent or rare-earth metal doped ion can both exert an influence to pattern, size and the lattice structure of catalyst, be a kind of catalyst modification method relatively more commonly used.For example: with sodium ethylene diamine tetracetate (EDTA) is surfactant, under hydrothermal condition, can obtain the BiVO of five-pointed star shape chip shape ₄, its photocatalytic activity has improved (S.M. Sun et al. Ind. Eng. Chem. Res. 2009,48: 1735 – 1739) more than 50% without surfactant-modified sample.People such as Cao pass through La ³⁺Be doped to TiO _2-xF _xIn the photochemical catalyst, improved the visible light-responded of catalyst and to the degradation effect (G.X. Gao et al. J. Am. Ceram. Soc., 2010,93:25 – 27) of methylene blue.

Summary of the invention

The objective of the invention is to: provide a kind of multiform looks rear-earth-doped BiVO ₄Composite photo-catalyst and preparation method thereof, the advantage of mating surface activating agent and rare earth ion doping vario-property photochemical catalyst aspect through control rare earth ion, material proportion and hydrothermal synthesizing condition, obtains the Ln of different-shape _xBi _(1-x)VO ₄Catalyst, specific surface area of catalyst is big, and has good visible light catalytic performance.

Technical solution of the present invention is: this rear-earth-doped BiVO ₄Consisting of of composite photo-catalyst: Ln _xBi _(1-x)VO ₄, Ln=La wherein, Ce, Pr, Nd, Sm, Gd, Dy, Er, Y; X=0.01-0.3 mol%.

The preparation method of this composite photo-catalyst may further comprise the steps:

1) HNO of molar concentration such as configuration ₃With NaOH solution, molar concentration is 1 ~ 6mol/L;

2) get a certain amount of Bi (NO ₃) ₃5H ₂O is dissolved in the HNO of certain volume ₃Solution adds the ultrasonic 10～30min dissolving of a certain amount of EDTA then and obtains solution a;

3) get a certain amount of NH ₄VO ₃Be dissolved in the NaOH solution of certain volume and obtain solution b, then solution b is added drop-wise among the solution a gradually, stir 1 ~ 3h, add doping lanthanide series Ln (NO ₃) ₃Obtain yellow suspension;

4) get a certain amount of absolute ethyl alcohol and join in the above-mentioned suspension, continue to stir 1～2h and obtain reacting precursor;

5) precursor is put into autoclave, in 100～200 ℃ hydrothermal temperature, hydro-thermal reaction 2～10h gets product, and product is used absolute ethyl alcohol and water washing respectively 2-3 time, puts into 40～100 ℃ of vacuum drying chambers dry several hours, obtains catalyst.

Wherein, Bi (NO ₃) ₃5H ₂O and NH ₄VO ₃Molal weight is than being 1:0.5 ~ 1:1.5, Bi (NO ₃) ₃5H ₂O is 1:0.1 ~ 1:2 with the molal weight ratio of EDTA.

Wherein, Bi (NO ₃) ₃With doping lanthanide series Ln (NO ₃) ₃Molal weight than for 1:0.01～1:0.3.

Wherein, HNO ₃With NaOH volume ratio 1:0.5 ~ 1:3, HNO ₃With CH ₃CH ₂The volume ratio of OH is 1:0.2 ~ 1:10.

The present invention has following advantage: 1, under alcohol-hydrothermal condition, be the doping ion with EDTA as surfactant and rare earth element with special peripheral electron structure, to BiVO ₄Carry out modification and handle, the photochemical catalyst that has obtained having multiple pattern, high-specific surface area and high catalytic performance,

The synthetic cost of catalyst is lower, pollution-free; 2, appearance structure is controlled, the Ln of preparation _xBi _(1-x)VO ₄Catalyst has multiple patterns such as hollow tubular, hollow ellipsoid shape and regular polyhedron; 3, the catalyst of modification has bigger specific area; 4, to the photocatalytic degradation effect of methylene blue apparently higher than unmodified BiVO ₄

Description of drawings

Fig. 1 is different rare-earth element modified BiVO ₄Sem photograph, wherein (a) is the BiVO of Sm doping vario-property ₄, (b) be the BiVO of Ce doping vario-property ₄, (c) be the BiVO of Dy doping vario-property ₄

The different rare-earth element modified BiVO of Fig. 2 ₄Specific area.

Fig. 3 is different rare-earth element modified BiVO ₄To the Photocatalytic Activity for Degradation curve map of methylene blue, wherein a, b, c are respectively the catalytic degradation curve map of instance 1,2,3 samples.

The specific embodiment

The present invention will be described below in conjunction with the practical implementation instance, and these embodiment are used to understand technical solution, can not be interpreted as it is the restriction to technical solution.

Embodiment 1: according to the BiVO of the synthetic Sm doping of following step ₄:

1) takes by weighing 2.425g Bi (NO ₃) ₃5H ₂O is dissolved in the HNO of 10mL 2mol/L ₃In the solution, the ultrasonic 30min dissolving of EDTA that adds 0.9304g then obtains solution a, takes by weighing 0.5800g NH ₃VO ₄The NaOH solution that is dissolved in 20mL 2mol/L obtains solution b;

2) constantly under the condition of stirring above-mentioned solution b is being added drop-wise among the solution a gradually, is adding the Sm (NO of 0.0005mol behind the stirring 2h ₃) ₃, continue to stir 1h and get yellow suspension, add 10mL absolute ethyl alcohol continuation stirring 2h again and must react precursor;

3) will react that precursor moves to the white polytetrafluoroethylpipe is in the stainless steel cauldron of liner, puts into 140 ℃ of insulating box hydrothermal treatment consists 6h;

4) filter the abstraction reaction product, the product that obtains is neutrality with deionized water and absolute ethanol washing 2 ~ 3 times to pH value of filtrate, dry 6h in 80 ℃ of baking ovens again obtains the BiVO of the Sm doping of hollow tubular ₄Catalyst is shown in Fig. 1 (a).

Embodiment 2: according to the BiVO of the synthetic Ce of following step ₄:

1) takes by weighing 2.425g Bi (NO ₃) ₃5H ₂O is dissolved in the HNO of 5mL 4mol/L ₃In the solution, the ultrasonic 20min dissolving of EDTA that adds 0.9304g then obtains solution a, takes by weighing 0.5510g NH ₃VO ₄The NaOH solution that is dissolved in 10mL 4mol/L obtains solution b;

2) constantly under the condition of stirring above-mentioned solution b is being added drop-wise among the solution a gradually, is adding the Ce (NO of 0.001mol behind the stirring 1.5h ₃) ₃, continue to stir 30min and get yellow suspension, add 15mL absolute ethyl alcohol and stirring 1h again and must react precursor;

3) will react that precursor moves to the white polytetrafluoroethylpipe is in the stainless steel cauldron of liner, puts into 120 ℃ of insulating box hydrothermal treatment consists 6h;

4) filter the abstraction reaction product, the product that obtains is neutrality with deionized water and absolute ethanol washing 2 ~ 3 times to pH value of filtrate, dry 6h in 80 ℃ of baking ovens again obtains the BiVO of the Ce doping of hollow ellipsoid shape ₄Catalyst is shown in Fig. 1 (b).

Embodiment 3: according to the BiVO of the synthetic Dy doping of following step ₄:

1) takes by weighing 2.425g Bi (NO ₃) ₃5H ₂O is dissolved in the HNO of 2.5mL 6mol/L ₃In the solution, the ultrasonic 10min dissolving of EDTA that adds 0.9304g then obtains solution a, takes by weighing 0.5220g NH ₃VO ₄The NaOH solution that is dissolved in 5mL 6mol/L obtains solution b;

2) constantly under the condition of stirring above-mentioned solution b is being added drop-wise among the solution a gradually, is adding the Dy (NO of 0.00025mol behind the stirring 1h ₃) ₃, continue to stir 30min and get yellow suspension, add 20mL absolute ethyl alcohol 30min again and must react precursor;

3) will react that precursor moves to the white polytetrafluoroethylpipe is in the stainless steel cauldron of liner, puts into 160 ℃ of insulating box hydrothermal treatment consists 4h;

4) filter the abstraction reaction product, the product that obtains is neutrality with deionized water and absolute ethanol washing 2 ~ 3 times to pH value of filtrate, dry 6h in 80 ℃ of baking ovens again obtains the BiVO of the Dy doping of regular polyhedron ₄Catalyst is shown in Fig. 1 (c).

Embodiment 4: according to the synthetic Y doping BiVO of following step ₄

1) takes by weighing 2.425g Bi (NO ₃) ₃5H ₂O is dissolved in the HNO of 10mL 2mol/L ₃In the solution, the ultrasonic 30min dissolving of EDTA that adds 1.3959g then obtains solution a, takes by weighing 0.5800g NH ₃VO ₄The NaOH solution that is dissolved in 20mL 2mol/L obtains solution b;

2) constantly under the condition of stirring above-mentioned solution b is being added drop-wise among the solution a gradually, is adding the Y (NO of 0.00075mol behind the stirring 2h ₃) ₃, continue to stir 1h and get yellow suspension, add 15mL absolute ethyl alcohol continuation stirring 0.5h again and must react precursor;

4) filter the abstraction reaction product, the product that obtains is neutrality with deionized water and absolute ethanol washing 2 ~ 3 times to pH value of filtrate, dry 6h in 80 ℃ of baking ovens again obtains the BiVO of the Y doping of hollow tubular ₄Catalyst.

Embodiment 5: according to the synthetic Er doping BiVO of following step ₄

1) takes by weighing 2.425g Bi (NO ₃) ₃5H ₂O is dissolved in the HNO of 10mL 2mol/L ₃In the solution, the ultrasonic 30min dissolving of EDTA that adds 0.4536g then obtains solution a, takes by weighing 0.5800g NH ₃VO ₄The NaOH solution that is dissolved in 20mL 2mol/L obtains solution b;

2) constantly under the condition of stirring above-mentioned solution b is being added drop-wise among the solution a gradually, is adding the Er (NO of 0.00025mol behind the stirring 2h ₃) ₃, continue to stir 1h and get yellow suspension, add 10mL absolute ethyl alcohol continuation stirring 0.5h again and must react precursor;

4) filter the abstraction reaction product, the product that obtains is neutrality with deionized water and absolute ethanol washing 2 ~ 3 times to pH value of filtrate, dry 6h in 80 ℃ of baking ovens again obtains the BiVO of the Er doping of hollow tubular ₄Catalyst.

The Ln that in the quartz test tube of the 10 mg/L methylene blue solutions that fill 250mL, adds 0.25 g modification _xBi _(1-x)VO ₄(Ln=La wherein, Ce, Pr, Nd, Sm, Gd, Dy, Er, Y) catalyst after stirring 30min under the no optical condition and reaching adsorption equilibrium, is placed under the xenon lamp of 500W and carries out visible light photocatalytic degradation; Every separated 20min gets a solution and centrifugalizes, and surveys the absorbance of the upper strata stillness of night, contrasts their photocatalysis performance, according to Lambert-Beer's law, calculates methylene blue concentration, is calculated as follows the degradation rate of methylene blue:

Degradation rate %=

Figure 2012101120868100002DEST_PATH_IMAGE002

A in the formula ₀, A _i---be respectively the absorbance of degraded front and back methylene blue.

Accompanying drawing 1 of the present invention is rare earth doped modification BiVO ₄Sem photograph, as can be seen from the figure, different rare earth is mixed, the pattern of the catalyst of preparation is difference to some extent, wherein the BiVO that mixes of Sm ₄Be the hollow tubular pattern, the BiVO that Ce mixes ₄Be the hollow ellipsoid pattern, the BiVO that Dy mixes ₄Be the regular polyhedron pattern, show that rare earth element is a key factor that influences the catalyst pattern.

Chart 2 of the present invention is rare earth doped BiVO ₄Specific area, the as can be seen from the figure Ln of this method preparation _xBi _(1-x)VO ₄All have very big specific area (BET), wherein Sm _xBi _(1-x)VO ₄Specific area be 16.997m ²/ g, Ce _xBi _(1-x)VO ₄Specific area be 17.216m ²/ g, Dy _xBi _(1-x)VO ₄Specific area be 46.878m ²/ g is apparently higher than the synthetic down BiVO of general condition ₄Specific area (2 ~ 5m ²/ g).

Fig. 3 of the present invention is rare earth doped BiVO ₄To the Photocatalytic Activity for Degradation curve map of methylene blue, it is thus clear that find out that the clearance of methylene blue all reaches more than 80%, particularly sample Sm after the catalyst visible light photocatalysis reaction 3h of preparation _xBi _(1-x)VO ₄Clearance to methylene blue reaches about 95%, shows that prepared catalyst is for having good photocatalytic activity.

Claims

1. the rear-earth-doped BiVO of multiform looks ₄Composite photo-catalyst is characterized in that consisting of of this composite photo-catalyst: Ln _xBi _(1-x)VO ₄, Ln=La wherein, Ce, Pr, Nd, Sm, Gd, Dy, Er, Y; X=0.01-0.3 mol%.

2. the rear-earth-doped BiVO of multiform looks ₄The preparation method of composite photo-catalyst is characterized in that the preparation method of this composite photo-catalyst may further comprise the steps:

3. the rear-earth-doped BiVO of multiform looks according to claim 2 ₄The preparation method of composite photo-catalyst is characterized in that: wherein, wherein, Bi (NO ₃) ₃5H ₂O and NH ₄VO ₃Molal weight is than being 1:0.5 ~ 1:1.5, Bi (NO ₃) ₃5H ₂O is 1:0.1 ~ 1:2 with the molal weight ratio of EDTA.

4. the rear-earth-doped BiVO of multiform looks according to claim 2 ₄The preparation method of composite photo-catalyst is characterized in that: wherein, and Bi (NO ₃) ₃With doping lanthanide series Ln (NO ₃) ₃Molal weight than for 1:0.01～1:0.3.

5. the rear-earth-doped BiVO of multiform looks according to claim 2 ₄The preparation method of composite photo-catalyst is characterized in that: wherein, and HNO ₃With NaOH volume ratio 1:0.5 ~ 1:3, HNO ₃With CH ₃CH ₂The volume ratio of OH is 1:0.2 ~ 1:10.