CN102489298A - Preparation method of precious metal loaded Bi2WO6 visible light photocatalyst - Google Patents

Abstract

The invention discloses a preparation method of precious metal loaded Bi2WO6 visible light photocatalyst, which is mainly characterized in that the photo-induced electrons and positive holes of the Bi2WO6 photocatalyst are easy to be re-combined to reduce the photocatalytic activity thereof, and a precious metal is loaded on the surface of the Bi2WO6 photocatalyst to greatly improve the separation of the photo-induced electrons and the positive holes so as to improve the photocatalytic performance of the Bi2WO6 visible light photocatalyst. The preparation method comprises the following steps of: (1) synthesizing Bi2WO6 by a liquid phase method: firstly dissolving bismuth salt in certain amount of acetic acid, blending the solution with tungsten salt according to a metering ratio, uniformly stirring, filling the mixture in a reaction kettle to react at 120-240 DEG C for 10-20 h, centrifugally separating the obtained products and drying the same at 50-100 DEG C in vacuum; (2) the Bi2WO6 synthesized by the liquid phase method is of a flower-shaped grade structure assembled by nanometer pieces, dispersing the obtained Bi2WO6 with flower-shaped structure in a mixed solvent of methanol and water, adding different dosages of such acids or salts containing precious metals as chloroplatinic acid or chloroauric acid, uniformly stirring, and ultrasonic dispersing for 10-120 min; (3) putting the mixed solution under an ultraviolet lamp, and irradiating for 10-240 min to obtain the precious metal loaded Bi2WO6 visible light photocatalyst. The method has the advantages of simple technique and low cost, and the prepared precious metal loaded Bi2WO6 visible light photocatalyst has high visible light catalytic activity.

Description

A kind of noble metal support type Bi 2WO 6The preparation method of visible light catalyst

Technical field

The invention belongs to photocatalysis technology, relate to the method reduction noble metal that adopts ultraviolet lighting, be deposited on flower-shaped social estate system structure Bi ₂WO ₆The surface obtains a kind of Bi of noble metal support type ₂WO ₆Visible light catalyst.

Background technology

The seriousness of environmental pollution has at present become a direct threats human survival, needs the focal issue of solution badly.Photocatalysis technology is at the energy and environmental area the green technology of important application prospect to be arranged from what twentieth century progressively grew up the seventies.This technology can make the organic pollution generation oxidative decomposition in the environment, and final degradation is CO ₂, small-molecule substance such as water and inorganic ions, so non-secondary pollution, palliating degradation degree height are considered to the most promising pollution treatment method at present.

Bismuth based semiconductor photochemical catalyst can be had good photocatalytic activity by excited by visible light, and degradable organic pollutant has bright development prospect effectively.Their common feature and significant advantage have absorption exactly in visible-range, have good photocatalysis performance.Yet bismuth based semiconductor photochemical catalyst is Bi particularly ₂WO ₆Photochemical catalyst exists light induced electron-hole to combine easily again, to problems such as absorption of visible light are quite limited, has limited Bi greatly ₂WO ₆The large-scale application of photochemical catalyst.Therefore, must take certain measure to improve the light induced electron transport efficiency, effectively limit electronics-hole and combine again, further widen Bi ₂WO ₆Photochemical catalyst improves visible light-responded Bi to the absorption of visible light scope ₂WO ₆The photocatalytic activity of photochemical catalyst.Noble metal decorated semiconductor catalyst through the electron distributions in the change system, influences semi-conductive surface nature, and then improves its photocatalytic activity.At noble metal and Bi ₂WO ₆In the space charge layer that forms after the photochemical catalyst contact, the metal surface will obtain unnecessary negative electrical charge, Bi ₂WO ₆Negative electrical charge complete obiteration on the surface, thus the speed that light induced electron is transported to adsorb oxygen improved greatly.In addition, Bi ₂WO ₆Can be with and just will bend towards the surface and generate depletion layer, at metal-Bi ₂WO ₆Form shallow potential well-Schottky (Schottky) energy barrier of ability trapped electron on the interface, further suppress the compound of light induced electron and hole.

Summary of the invention

The object of the present invention is to provide a kind of noble metal support type Bi ₂WO ₆The synthetic method of visible light catalyst, this method technology is simple, with low cost, synthetic noble metal support type Bi ₂WO ₆Visible light catalyst photocatalytic degradation effect is fine.

The present invention is provided for the noble metal support type Bi of degradable organic pollutant ₂WO ₆The preparation method of visible light catalyst is characterized in that:

(1) preparation Bi ₂WO ₆Precursor solution: a certain amount of bismuth salt is dissolved in the 2-10ml acetic acid, forms clear solution, under stirring, add the tungsten salt solution of metering ratio, wherein the concentration of tungsten salt is controlled at 0.02-0.08mol/L, stirs 0.5-1h, obtains Bi ₂WO ₆Presoma suspension.

Wherein bismuth salt can be bismuth nitrate, bismuth chloride; Tungsten salt can be sodium tungstate or the villaumite that contains W.

(2) flower-shaped social estate system Bi ₂WO ₆Preparation: with above-mentioned Bi ₂WO ₆Presoma suspension changes 50mL over to and contains in the teflon-lined stainless steel autoclave, and 120-240 ℃ of reaction 10-20h with the products therefrom centrifugation, and 50-100 ℃ of vacuum drying, obtains the Bi of flower-shaped social estate system structure ₂WO ₆Photochemical catalyst.

(3) with the flower-shaped social estate system structure Bi of step (2) gained ₂WO ₆Be dispersed in the mixed solvent of methyl alcohol and water, the volume ratio of methyl alcohol and water was controlled at 1: 3 to 3: 1, stirred; Add chloroplatinic acid, the gold chloride of different amounts then, silver nitrate etc. contain the acid or the salt of noble metal, stir; Ultrasonic dispersion 10-120min obtains homodisperse suspension.

(4) suspension with above-mentioned steps (3) gained places under the uviol lamp, and marginal ray stirs according to the limit, and illumination 10-240min stops illumination, leaves standstill 30min, centrifugation, and, obtain the Bi of noble metal load 50-100 ℃ of vacuum drying ₂WO ₆Visible light catalyst.

The present invention compared with prior art has remarkable advantage:

(1) the present invention adopts liquid-phase synthesis process to obtain flower-shaped social estate system structure Bi earlier ₂WO ₆Photochemical catalyst, the method for utilizing ultraviolet lighting again is at flower-shaped social estate system structure Bi ₂WO ₆The surface deposition noble metal, this method technology is simple, easy to operate.

(2) the noble metal support type Bi of the present invention's preparation ₂WO ₆Photochemical catalyst has been inherited flower-shaped social estate system structure Bi ₂WO ₆Shape characteristic, this structure has been avoided the agglomeration of nano particle, can produce big specific area, and is beneficial to recycling.

(3) noble metal of the present invention loads on Bi ₂WO ₆The surface of photochemical catalyst has significantly increased Bi ₂WO ₆Photochemical catalyst is to the absorption of visible light scope, the Bi after the load ₂WO ₆The photochemical catalyst visible light catalysis activity significantly improves.

Description of drawings

Bi after the load of Fig. 1 noble metal platinum ₂WO ₆The scanning electron microscopy picture of visible light catalyst;

Bi before and after the load of Fig. 2 noble metal platinum ₂WO ₆The X-ray diffraction spectrogram of visible light catalyst;

Bi before and after the load of Fig. 3 noble metal platinum ₂WO ₆The ultraviolet-visible diffuse reflection spectrum of visible light catalyst.

The specific embodiment

(1) preparation Bi ₂WO ₆Precursor solution: a certain amount of bismuth salt is dissolved in the 2-10ml acetic acid, forms clear solution, under stirring, add the tungsten salt solution of metering ratio, wherein the concentration of tungsten salt is controlled at 0.02-0.08mol/L, stirs 0.5-1h, obtains Bi ₂WO ₆Presoma suspension.

Wherein bismuth salt can be bismuth nitrate, bismuth chloride; Tungsten salt can be sodium tungstate or the villaumite that contains W.

(2) flower-shaped social estate system Bi ₂WO ₆Preparation: with above-mentioned Bi ₂WO ₆Presoma suspension changes 50mL over to and contains in the teflon-lined stainless steel autoclave, and 120-240 ℃ of reaction 10-20h with the products therefrom centrifugation, and 50-100 ℃ of vacuum drying, obtains the Bi of flower-shaped social estate system structure ₂WO ₆Photochemical catalyst.

(3) with the flower-shaped social estate system structure Bi of step (2) gained ₂WO ₆Be dispersed in the mixed solvent of methyl alcohol and water, the volume ratio of methyl alcohol and water was controlled at 1: 3 to 3: 1, stirred; Add chloroplatinic acid, the gold chloride of different amounts then, silver nitrate etc. contain the acid or the salt of noble metal, stir; Ultrasonic dispersion 10-120min obtains homodisperse suspension.

(4) suspension with above-mentioned steps (3) gained places under the uviol lamp, and marginal ray stirs according to the limit, and illumination 10-240min stops illumination, leaves standstill 30min, centrifugation, and, obtain the Bi of noble metal load 50-100 ℃ of vacuum drying ₂WO ₆Visible light catalyst.

For a better understanding of the present invention, further illustrate content of the present invention, but content of the present invention is not limited to following given instance below in conjunction with instance.

The side's of enforcement instance 1: a kind of noble metal support type Bi of the present invention ₂WO ₆The preparation method of visible light catalyst may further comprise the steps:

(1) preparation Bi ₂WO ₆Precursor solution: the 2mmol bismuth nitrate is dissolved in the 5ml acetic acid, forms clear solution, under stirring, add the sodium tungstate solution 20mL of 0.05mol/L, stir 0.5h, obtain Bi ₂WO ₆The presoma white suspension.

(2) flower-shaped social estate system Bi ₂WO ₆Preparation: with above-mentioned Bi ₂WO ₆Presoma suspension changes 50mL over to and contains in the teflon-lined stainless steel autoclave, and 180 ℃ of reaction 15h naturally cool to room temperature, with the products therefrom centrifugation, and 50 ℃ of vacuum drying, obtain the Bi of flower-shaped social estate system structure ₂WO ₆Photochemical catalyst.

(3) get the flower-shaped social estate system structure Bi of step (2) gained ₂WO ₆150mg is dispersed in the mixed solvent of 40mL methyl alcohol and water, and the volume ratio of methyl alcohol and water was controlled at 1: 1, stirs, and adds 10 then ^-3Mol/L platinum acid chloride solution 5mL stirs, and ultrasonic dispersion 30min obtains homodisperse suspension.

(4) suspension with above-mentioned steps (3) gained places under the 200W uviol lamp, and marginal ray stirs according to the limit, and illumination 30min stops illumination, leaves standstill 30min, centrifugation, and, obtain the Bi of noble metal platinum load 50 ℃ of vacuum drying ₂WO ₆Visible light catalyst.

Through SEM to noble metal support type Bi ₂WO ₆The pattern of visible light catalyst characterizes, and its pattern has well been inherited Bi ₂WO ₆Flower-shaped social estate system structure, as shown in Figure 1.To Bi before and after the carried noble metal ₂WO ₆Thing characterize mutually, as shown in Figure 2, Bi before and after the load ₂WO ₆Thing do not change mutually, obvious variation does not take place in the intensity of each diffraction maximum yet, maybe be less relevant with the load capacity of noble metal.Through ultraviolet-diffuse reflection spectrum to Bi before and after the load ₂WO ₆The absorption of visible light situation is characterized, as shown in Figure 3, Bi after the noble metal platinum load ₂WO ₆The absorption of visible region significantly strengthens again.

Embodiment 2: a kind of noble metal support type Bi of the present invention ₂WO ₆The preparation method of visible light catalyst may further comprise the steps:

(1) preparation Bi ₂WO ₆Precursor solution: the 1mmol bismuth nitrate is dissolved in the 5ml acetic acid, forms clear solution, under stirring, add the sodium tungstate solution 10mL of 0.05mol/L, stir 0.5h, obtain Bi ₂WO ₆The presoma white suspension.

(2) flower-shaped social estate system Bi ₂WO ₆Preparation: with above-mentioned Bi ₂WO ₆Presoma suspension changes 50mL over to and contains in the teflon-lined stainless steel autoclave, and 170 ℃ of reaction 20h naturally cool to room temperature, with the products therefrom centrifugation, and 50 ℃ of vacuum drying, obtain the Bi of flower-shaped social estate system structure ₂WO ₆Photochemical catalyst.

(3) get the flower-shaped social estate system structure Bi of step (2) gained ₂WO ₆150mg is dispersed in the mixed solvent of 40mL methyl alcohol and water, and the volume ratio of methyl alcohol and water was controlled at 2: 1, stirs, and adds 10 then ^-3Mol/L platinum acid chloride solution 6mL stirs, and ultrasonic dispersion 30min obtains homodisperse suspension.

(4) suspension with above-mentioned steps (3) gained places under the 200W uviol lamp, and marginal ray stirs according to the limit, and illumination 30min stops illumination, leaves standstill 30min, centrifugation, and, obtain the Bi of Precious Metals-Gold load 50 ℃ of vacuum drying ₂WO ₆Visible light catalyst.

Embodiment 3: a kind of noble metal support type Bi of the present invention ₂WO ₆The preparation method of visible light catalyst may further comprise the steps:

(1) preparation Bi ₂WO ₆Precursor solution: the 2mmol bismuth nitrate is dissolved in the 10ml acetic acid, forms clear solution, under stirring, add the sodium tungstate solution 20mL of 0.05mol/L, stir 0.5h, obtain Bi ₂WO ₆The presoma white suspension.

(2) flower-shaped social estate system Bi ₂WO ₆Preparation: with above-mentioned Bi ₂WO ₆Presoma suspension changes 50mL over to and contains in the teflon-lined stainless steel autoclave, and 160 ℃ of reaction 20h naturally cool to room temperature, with the products therefrom centrifugation, and 550 ℃ of vacuum drying, obtain the Bi of flower-shaped social estate system structure ₂WO ₆Photochemical catalyst.

(3) get the flower-shaped social estate system structure Bi of step (2) gained ₂WO ₆150mg is dispersed in the mixed solvent of 40mL methyl alcohol and water, and the volume ratio of methyl alcohol and water was controlled at 2: 1, stirs, and adds 10 then ^-3Mol/L liquor argenti nitratis ophthalmicus 5mL stirs, and ultrasonic dispersion 30min obtains homodisperse suspension.

(4) suspension with above-mentioned steps (3) gained places under the 200W uviol lamp, and marginal ray stirs according to the limit, and illumination 20min stops illumination, leaves standstill 30min, centrifugation, and, obtain the Bi of noble metal silver load 50 ℃ of vacuum drying ₂WO ₆Visible light catalyst.

Claims (1)

1. noble metal support type Bi who is used for degradable organic pollutant ₂WO ₆The preparation method of visible light catalyst is characterized in that, comprises the steps:

(1) preparation Bi ₂WO ₆Precursor solution: a certain amount of bismuth salt is dissolved in the 2-10ml acetic acid, forms clear solution, under stirring, add the tungsten salt solution of metering ratio, wherein the concentration of tungsten salt is controlled at 0.02-0.08mol/L, stirs 0.5-1h, obtains Bi ₂WO ₆Presoma suspension.

Wherein bismuth salt can be bismuth nitrate, bismuth chloride; Tungsten salt can be sodium tungstate or the villaumite that contains W.

(2) flower-shaped social estate system Bi ₂WO ₆Preparation: with above-mentioned Bi ₂WO ₆Presoma suspension changes 50mL over to and contains in the teflon-lined stainless steel autoclave, and 120-240 ℃ of reaction 10-20h with the products therefrom centrifugation, and 50-100 ℃ of vacuum drying, obtains the Bi of flower-shaped social estate system structure ₂WO ₆Photochemical catalyst.

(3) with the flower-shaped social estate system structure Bi of step (2) gained ₂WO ₆Be dispersed in the mixed solvent of methyl alcohol and water, the volume ratio of methyl alcohol and water was controlled at 1: 3 to 3: 1, stirred; Add chloroplatinic acid, the gold chloride of different amounts then, silver nitrate etc. contain the acid or the salt of noble metal, stir; Ultrasonic dispersion 10-120min obtains homodisperse suspension.

(4) suspension with above-mentioned steps (3) gained places under the uviol lamp, and marginal ray stirs according to the limit, and illumination 10-240min stops illumination, leaves standstill 30min, centrifugation, and, obtain the Bi of noble metal load 50-100 ℃ of vacuum drying ₂WO ₆Visible light catalyst.

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