阅读说明：本技术 一种红磷/碳酸氧铋s型异质结光催化剂及其制备方法 (Red phosphorus/bismuthyl carbonate S-type heterojunction photocatalyst and preparation method thereof ) 是由 马玉花 王转虎 李云鹏 张雨 李煜宸 于 2021-09-01 设计创作，主要内容包括：一种红磷/碳酸氧铋S型异质结光催化剂及其制备方法,将热水处理后的红磷(HRP)和碳酸氧铋(Bi-(2)O-(2)CO-(3))混合后分散于蒸馏水中,经过恒温、洗涤、干燥等过程得到目标产物Bi-(2)O-(2)CO-(3)/HRP,通过改变HRP与Bi-(2)O-(2)CO-(3)的配比,即可获得不同摩尔比的异质结光催化剂,通过瞬态荧光光谱和X-射线光电子能谱分析表征证明该物质是一种S型异质结光催化剂,光催化性能测试试验表明,该催化剂能由将废水中的Cr(Ⅵ)还原为Cr(Ⅲ),效率达95%以上,且经过连续5次光催化反应后,效率仍在85%以上,证明了该S型异质结光催化剂在λ≥420nm的可见光范围内,表现出优异的光催化活性；并且处理废水的同时,能够产氢,其平均产氢速率可达纯HRP产氢速率的3倍,该催化剂制备简单,成本低廉。(A red phosphorus/bismuth oxycarbonate S-type heterojunction photocatalyst is prepared by treating red phosphorus (HRP) and bismuth oxycarbonate (Bi) with hot water 2 O 2 CO 3 ) Mixing, dispersing in distilled water, and performing constant temperature, washing, drying and other processes to obtain a target product Bi 2 O 2 CO 3 HRP by varying HRP and Bi 2 O 2 CO 3 The heterojunction photocatalyst with different molar ratios can be obtainedTransient fluorescence spectrum and X-ray photoelectron spectroscopy analysis and characterization prove that the material is an S-type heterojunction photocatalyst, and a photocatalytic performance test shows that the catalyst can reduce Cr (VI) in wastewater into Cr (III), the efficiency is over 95 percent, and after continuous 5 times of photocatalytic reaction, the efficiency is still over 85 percent, so that the S-type heterojunction photocatalyst is proved to show excellent photocatalytic activity in a visible light range with lambda being more than or equal to 420 nm; and the catalyst can produce hydrogen while treating wastewater, the average hydrogen production rate can reach 3 times of the hydrogen production rate of the pure HRP, the preparation is simple, and the cost is low.)

1. A red phosphorus/bismuthyl carbonate S-type heterojunction photocatalyst is characterized in that: the red phosphorus/bismuth oxycarbonate S-type heterojunction photocatalyst consists of a (102) crystal face of red phosphorus, and (011) and (013) diffraction crystal faces of bismuth oxycarbonate, wherein the bismuth oxycarbonate is uniformly attached to the surface of the red phosphorus and is in close contact with the red phosphorus to form a heterojunction structure.

2. A preparation method of a red phosphorus/bismuthyl carbonate S-type heterojunction photocatalyst is characterized by comprising the following steps:

s1, hydrothermal treatment of red phosphorus: dispersing a certain amount of commercial Red Phosphorus (RP) in a proper amount of distilled water, reacting for 12 hours at a constant temperature of 200 ℃, washing, and carrying out freeze drying treatment on the red phosphorus at-41 ℃ for 18 hours to obtain red phosphorus (HRP) subjected to hydrothermal treatment.

S2, synthesizing bismuth oxycarbonate (Bi)₂O₂CO₃): taking a certain amount of bismuth nitrate pentahydrate (Bi (NO)₃)₃·5H₂O) dissolving in a proper amount of glycol, and continuously performing ultrasonic treatment for more than 10min to obtain a clear and transparent solution A; taking a certain amount of sodium carbonate (Na)₂CO₃) Dissolving in appropriate amount of distilled water to obtain clear and transparent solution B, adding solution B into solution A dropwise under ultrasonic vibration condition for reaction, continuing ultrasonic vibration for more than 30min after dropwise addition, standing for 20min for complete reaction, centrifuging the mixed solution at high speed (12000 r/min) for 10min, washing the obtained lower layer substance, and freeze-drying at-41 deg.C for 18h to obtain target product bismuth subcarbonate (Bi)₂O₂CO₃）。

S3. preparation of Bi₂O₂CO₃HRP complex: HRP and Bi obtained in steps S1 and S2₂O₂CO₃Mixing at a certain mass ratio, placing in appropriate amount of distilled water, reacting at constant temperature of 150 deg.C for 4 hr, washing the solid, and freeze drying at-41 deg.CProcessing for 18h to obtain Bi with different proportions₂O₂CO₃The HRP complex.

5. The method for preparing the red phosphorus/bismuthyl carbonate S-type heterojunction photocatalyst according to claim 2, wherein the method comprises the following steps: the Bi₂O₂CO₃In the/HRP complex, Bi₂O₂CO₃The mass fraction of the component (A) is 1% -8%.

Technical Field

The invention belongs to the technical field of wastewater treatment, and particularly relates to a red phosphorus/bismuthyl carbonate S-type heterojunction photocatalyst and a preparation method thereof.

Background

Chromium is a common heavy metal pollutant in the environment and mainly comes from the industries of electroplating, metallurgy, textile, printing and dyeing, tanning, ceramics, medicine and the like. In nature, Cr (VI) and Cr (III) exist in two forms, the toxicity of Cr (VI) is far greater than that of Cr (III), and the Cr (VI) is enriched to a certain extent in vivo and can induce a series of pathological changes such as distortion, canceration and the like of organisms. Because of the high toxicity and wide source of Cr (VI), Cr pollution is widely concerned by countries in the world. The prior method for processing Cr (VI) mainly comprises the following steps: electrolytic reduction, chemical precipitation, ion exchange, biological, membrane separation, xanthate, photocatalytic, etc., chemical being one of the most commonly used methods, mainly the reduction of Cr (vi) to harmless Cr (iii) (usually with Na)₂S₂O₃、Fe₂(SO₄)₃Etc.), then Cr (III) is generated into Cr (OH) under neutral or alkaline conditions₃Precipitating and removing.

The reaction of Cr (VI) under acidic conditions is:

the photocatalytic method is applied to the treatment of Cr (VI) in a precedent way, and the mechanism mainly comprises two mechanisms:

(1) cr (VI) semiconductor lightGenerating electrons e^-Directly reducing into Cr (III).

(2) Cr (VI) is indirectly reduced into Cr (III), i.e. other substances in the system are photogenerated holes h before Cr (VI)⁺Or hydroxyl radical OH is oxidized or photogenerated electron e^-Reducing the intermediate product to reduce Cr (VI).

However, the catalyst is usually Ti or Pt, so that the cost is high, the large-area popularization is difficult, and the method only stays in the laboratory research stage at present.

The hydrogen has the advantages of cleanness and reproducibility, and has the characteristics of good combustion performance, high energy conversion efficiency and the like, so that the hydrogen is regarded as the most ideal clean energy. In 2012, the semiconductor element red phosphorus is firstly proposed to be used as a visible light photocatalyst to decompose water to produce hydrogen, but the efficiency is not high, and the hydrogen production rate is about 50 mu mol^-1•h^-1Left and right, F Wang in YPO₄The surface is loaded with red phosphorus, and P/YPO is successfully prepared₄The hydrogen production performance of the photocatalyst is improved by about 7 times compared with pure red phosphorus, and the photocatalyst shows good photocatalytic activity, but no red phosphorus is disclosed in the aspect of water treatment.

In summary, we propose a red phosphorus/bismuthyl carbonate S-type heterojunction photocatalyst and a preparation method thereof, which can generate clean hydrogen while treating wastewater.

Disclosure of Invention

The invention aims to provide a red phosphorus/bismuthyl carbonate S-type heterojunction photocatalyst and a preparation method thereof, and aims to solve the problems that the cost for reducing Cr (VI) by the photocatalyst is high and the hydrogen production efficiency of pure red phosphorus is low in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme:

a red phosphorus/bismuth oxycarbonate S-type heterojunction photocatalyst is composed of a red phosphorus (102) crystal face, bismuth oxycarbonate (011) and bismuth oxycarbonate (013) diffraction crystal faces, wherein bismuth oxycarbonate is uniformly attached to the surface of red phosphorus, and the two are in close contact with each other to form a heterojunction structure.

The preparation method of the catalyst comprises the following steps:

s1, hydrothermal treatment of red phosphorus: dispersing a certain amount of commercial Red Phosphorus (RP) in a proper amount of distilled water, reacting for 12 hours at a constant temperature of 200 ℃, washing, and carrying out freeze drying treatment on the red phosphorus at-41 ℃ for 18 hours to obtain red phosphorus (HRP) subjected to hydrothermal treatment.

S2, synthesizing bismuth oxycarbonate (Bi)₂O₂CO₃): taking a certain amount of bismuth nitrate pentahydrate (Bi (NO)₃)₃·5H₂O) dissolving in a proper amount of glycol, and continuously performing ultrasonic treatment for more than 10min to obtain a clear and transparent solution A; taking a certain amount of sodium carbonate (Na)₂CO₃) Dissolving in appropriate amount of distilled water to obtain clear and transparent solution B, adding solution B into solution A dropwise under ultrasonic vibration condition for reaction, continuing ultrasonic vibration for more than 30min after dropwise addition, standing for 20min for complete reaction, centrifuging the mixed solution at high speed (12000 r/min) for 10min, washing the obtained lower layer substance, and freeze-drying at-41 deg.C for 18h to obtain target product bismuth subcarbonate (Bi)₂O₂CO₃）。

S3, preparing Bi₂O₂CO₃HRP complex: HRP and Bi obtained in steps S1 and S2₂O₂CO₃Mixing according to a certain mass ratio, placing in a proper amount of distilled water, reacting with constant temperature at 150 ℃ for 4h, washing the solid, placing at-41 ℃ for freeze drying for 18h to obtain Bi with different ratios₂O₂CO₃The HRP complex.

Preferably, said Bi₂O₂CO₃In the/HRP complex, Bi₂O₂CO₃The mass fraction of the component (A) is 1% -8%.

Compared with the prior art, the invention has the beneficial effects that:

1. the photocatalysis technology comprises the following steps: the light is used as energy to degrade organic matters into carbon dioxide and water, and the technology is a cheap, efficient and safe environment purification technology.

2. The red phosphorus/bismuth oxycarbonate S-type heterojunction photocatalyst which is applied to mixed wastewater treatment and can produce hydrogen energy is prepared by a simple hydrothermal method, and the synthesis process is simple (hydrothermal method) and low in cost (the price of the red phosphorus raw material is low).

3. The red phosphorus/bismuth oxycarbonate S-type heterojunction photocatalyst has excellent performance, inhibits the recombination of useful photo-generated electrons and holes due to the formation of the S-type heterojunction, and accelerates the recombination of relatively useless photo-generated electrons and holes, so that the photocatalyst has stronger light absorption capacity and higher carrier separation efficiency.

Drawings

FIG. 1 shows HRP and Bi₂O₂CO₃And Bi₂O₂CO₃Transient fluorescence spectrum of HRP;

FIG. 2 shows 5% Bi₂O₂CO₃An X-ray photoelectron energy spectrum of HRP;

FIG. 3 shows HRP and Bi₂O₂CO₃、1%Bi₂O₂CO₃/HRP、3%Bi₂O₂CO₃/HRP、5%Bi₂O₂CO₃HRP and 7% Bi₂O₂CO₃X-ray diffraction pattern of HRP;

FIG. 4 shows 5% Bi₂O₂CO₃A circulation experiment chart of HRP treated wastewater;

FIG. 5 shows HRP and Bi₂O₂CO₃、1%Bi₂O₂CO₃/HRP、3%Bi₂O₂CO₃/HRP、5%Bi₂O₂CO₃HRP and 7% Bi₂O₂CO₃Graph of photocatalytic hydrogen production by HRP.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention provides the following technical implementation scheme: a

Example one

A red phosphorus/bismuth oxycarbonate S-type heterojunction photocatalyst is composed of a red phosphorus (102) crystal face, bismuth oxycarbonate (011) and bismuth oxycarbonate (013) diffraction crystal faces, wherein bismuth oxycarbonate is uniformly attached to the surface of red phosphorus, and the two are in close contact with each other to form a heterojunction structure.

The preparation method of the catalyst comprises the following steps:

s1, hydrothermal treatment of red phosphorus: 0.6g of commercial Red Phosphorus (RP) is dispersed in 20mL of distilled water, and is reacted for 12 hours at the constant temperature of 200 ℃, after washing, the red phosphorus is subjected to freeze drying treatment for 18 hours at the temperature of-41 ℃, and then the red phosphorus (HRP) after hydrothermal treatment is obtained.

S2, synthesizing bismuth oxycarbonate (Bi)₂O₂CO₃): 0.485g (1mol) of bismuth nitrate pentahydrate (Bi (NO)₃)₃·5H₂O) dissolving in 20mL of glycol, and continuously performing ultrasonic treatment for more than 10min to obtain a clear and transparent solution A; 0.212g (2mol) of sodium carbonate (Na) is taken₂CO₃) Dissolving in 10mL of distilled water to obtain clear and transparent solution B, then dropwise adding the solution B into the solution A under the ultrasonic vibration condition for reaction, continuing ultrasonic vibration for more than 30min after dropwise adding, then standing for 20min for complete reaction, finally centrifuging the mixed solution at high speed (12000 r/min) for 10min, washing the obtained lower layer substance, and freeze-drying at-41 ℃ for 18h to obtain the target product bismuth oxycarbonate (Bi) which is a target product₂O₂CO₃）。

S3, preparing Bi₂O₂CO₃HRP complex: HRP and Bi obtained in steps S1 and S2₂O₂CO₃According to the mass ratio of 99: 1, placing the mixture into 20mL of distilled water, reacting for 4h at a constant temperature of 150 ℃, washing the solid, and placing the solid into a freeze drying treatment for 18h at a temperature of-41 ℃ to obtain Bi₂O₂CO₃HRP Complex, labeled 1% Bi₂O₂CO₃/HRP。

Example two

The preparation method of the present example is different from that of the first example in that the step S3:

s3, preparing Bi₂O₂CO₃HRP complex: HRP and Bi obtained in steps S1 and S2₂O₂CO₃According to the mass ratio of 97: 3, placing the mixture into 20mL of distilled water, reacting for 4 hours at a constant temperature of 150 ℃, washing the solid, and placing the solid into a temperature of-41 ℃ for freeze drying for 18 hours to obtain Bi₂O₂CO₃HRP Complex, labeled 3% Bi₂O₂CO₃/HRP。

EXAMPLE III

The preparation method of the present example is different from that of the first example in that the step S3:

s3, preparing Bi₂O₂CO₃HRP complex: HRP and Bi obtained in steps S1 and S2₂O₂CO₃According to the mass ratio of 19: 1, placing the mixture into 20mL of distilled water, reacting for 4h at a constant temperature of 150 ℃, washing the solid, and placing the solid into a freeze drying treatment for 18h at a temperature of-41 ℃ to obtain Bi₂O₂CO₃HRP Complex, labeled 5% Bi₂O₂CO₃/HRP。

Example four

The preparation method of the present example is different from that of the first example in that the step S3:

s3, preparing Bi₂O₂CO₃HRP complex: HRP and Bi obtained in steps S1 and S2₂O₂CO₃According to the mass ratio of 93: 7, placing the mixture into 20mL of distilled water, reacting for 4 hours at a constant temperature of 150 ℃, washing the solid, and placing the solid into a temperature of-41 ℃ for freeze drying for 18 hours to obtain Bi₂O₂CO₃HRP Complex, labeled 7% Bi₂O₂CO₃/HRP。

As can be seen from FIG. 1, Bi₂O₂CO₃the/HRP compound has specific ratios of HRP and Bi₂O₂CO₃Smaller transient fluorescence spectrum peak, which benefits from the increase of specific surface area to increase the number of S-shaped heterojunction sites, so that the unique electron-hole separation effect greatly counteracts the free path of motionThe short-lived problem of recombination of photogenerated carriers and confirms that Bi₂O₂CO₃The valence band conduction band position of the/HRP compound is stronger in the constraint of electron-hole than the recombination capability of carriers.

As can be seen from FIG. 2, for Bi₂O₂CO₃The P2P binding energy is transferred to lower energy by the/HRP composite material, and Bi 4f, O1 s and CO₃ ^2-The result indicates that electrons are hybridized from Bi₂O₂CO₃Transferred to HRP and in Bi₂O₂CO₃And an internal electric field is generated at the interface of the HRP. This built-in electric field contributes to Bi₂O₂CO₃The construction of the HRP photocatalyst and the effective separation of the charge carriers.

Combining FIG. 1 with FIG. 2, Bi can be confirmed₂O₂CO₃the/HRP photocatalyst is an S-type heterojunction photocatalyst.

Synthetic HRP and Bi were analyzed by X-ray diffraction (XRD) from FIG. 3₂O₂CO₃And Bi in different proportions₂O₂CO₃The crystal phase structure and the composition of the/HRP composite material are characterized. In XRD pattern of composite sample, 1% Bi₂O₂CO₃HRP and 3% Bi₂O₂CO₃Only the characteristic diffraction peak of HRP was observed for the/HRP composite sample, because Bi₂O₂CO₃Too low a content of (b) cannot be detected. And 5% Bi₂O₂CO₃HRP and Bi simultaneously appear on an XRD (X-ray diffraction) spectrum of the/HRP composite sample₂O₂CO₃Typical diffraction peak positions of (a) are 2 theta =14.6 °, 2 theta =23.5 ° and 2 theta =29.7 °, respectively corresponding to the (102) crystal plane of HRP, Bi₂O₂CO₃The (011) and (013) diffraction crystal planes preliminarily determine that the compound has good crystallinity at the ratio and has the common property of the two monomers.

Adding Bi₂O₂CO₃Recovering the Cr (VI) after the/HRP composite material is subjected to photocatalytic reduction, and then washing, centrifuging and drying the Cr (VI)After drying, the product was reused for Cr (VI) reduction under the same reaction conditions, and the results are shown in FIG. 4. First time of Bi₂O₂CO₃The photoreduction rate of the/HRP compound to Cr (VI) is 99.2%, and then the photoreduction rate is gradually reduced slightly, after five continuous photocatalytic reduction cycles, the efficiency is reduced to 88.2%, and strong photoreduction activity is still shown.

As can be seen from FIG. 5, Bi₂O₂CO₃The hydrogen generation is not detected under the irradiation of visible light, and the hydrogen production rate of the pure HRP is relatively low due to the rapid recombination of the photo-generated electrons and the holes. A small amount of Bi is loaded on the surface of HRP₂O₂CO₃After that, the activity is drastically increased, which is attributable to the formation of the S-type heterojunction. And Bi₂O₂CO₃Hydrogen production rate of/HRP composite sample with Bi₂O₂CO₃Increased content of Bi of 5%₂O₂CO₃The sample has the highest photocatalytic hydrogen production rate, and the average hydrogen production rate is 157.2 mu mol.h^-1•g^-1Is HRP (53.1. mu. mol. h)^-1•g^-1) 3.0 times of the total weight of the powder.

The invention uses the photocatalysis technology: the light is used as energy to degrade organic matters into carbon dioxide and water, and the technology is a cheap, efficient and safe environment purification technology. The red phosphorus/bismuth oxycarbonate S-type heterojunction photocatalyst which is applied to mixed wastewater treatment and can produce hydrogen energy is prepared by a simple hydrothermal method, and the synthesis process is simple (hydrothermal method) and low in cost (the price of the red phosphorus raw material is low). The red phosphorus/bismuth oxycarbonate S-type heterojunction photocatalyst has excellent performance, inhibits the recombination of useful photo-generated electrons and holes due to the formation of the S-type heterojunction, and accelerates the recombination of relatively useless photo-generated electrons and holes, so that the photocatalyst has stronger light absorption capacity and higher carrier separation efficiency.

The above description is only for the purpose of illustrating the technical solutions of the present invention and not for the purpose of limiting the same, and other modifications or equivalent substitutions made by those skilled in the art to the technical solutions of the present invention should be covered within the scope of the claims of the present invention without departing from the spirit and scope of the technical solutions of the present invention.