Preparation and application of a phthalocyanine iron loaded metal oxide z-type heterojunction photocatalyst

Abstract

The present application relates to the field of photocatalytic degradation, and discloses a preparation method and application of a phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst.The present application aims to solve the problems of instability, low visible light utilization, easy recombination of photo-generated electron-hole pairs, high cost, and low resource recycling efficiency of high-performance photocatalysts synthesized by the prior art.A phthalocyanine iron (FePc) loaded metal oxide material XFePc / CeO2 is designed and developed.The method comprises the following steps: taking cerium oxide and phthalocyanine iron as raw materials, and adopting a one-pot method to prepare the phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst.Under visible light, the XFePc / CeO2 composite material can be applied to degrade 2,4-dichlorophenol pollutants, and has high degradation rate and high catalytic activity.Under visible light irradiation conditions, the catalytic degradation performance of the composite material is greatly improved compared with that of a single-component, for example, a 1FePc / CeO2 photocatalyst sample exhibits an ultrahigh degradation efficiency within 150 minutes, which is 3 times that of pure CeO2.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photocatalytic degradation. BACKGROUND

[0002] 2,4-dichlorophenol (2,4-DCP) is an important industrial raw material, widely used in chemical industry, preservative industry and other industries. It has malodor, peculiar smell and high toxicity, and is one of the important organic pollutants. Once the wastewater is discharged into the environment, it has a certain stability, and through migration, the pollution range can be further expanded. As a high-risk environmental pollutant, 2,4-DCP has been listed as a key pollutant by the United States, China and the European Union. The high conjugation interaction between the chlorine atom and the aromatic nucleus makes 2,4-DCP very stable in structure and highly toxic. Although traditional environmental purification technology can degrade it, its selectivity is poor, and toxic organic chlorine by-products may be produced, thereby bringing secondary environmental risk. Therefore, preferentially dechlorination by low-cost and sustainable methods is a key step for the complete degradation of 2,4-DCP. Photocatalytic technology has the advantages of low cost and low energy consumption, and has been widely studied in eliminating organic pollutants. Photocatalytic technology is an effective method for degrading water pollutants with high efficiency and no secondary pollution, which can degrade organic pollutants in water into carbon dioxide and water, and also can convert part of the wastewater into hydrogen energy, opening up a new way to solve the problem of energy shortage.

[0003] Cerium oxide (CeO2) is an important rare earth material, which has wide industrial applications in catalysts, fuel cells and solar cells due to its low price, high chemical stability, strong oxygen storage capacity and narrow band gap, etc. Compared with other semiconductor oxides, it has greater importance. Combining CeO2 with other substances into composite materials through some means is also a means to adjust the performance of the material itself. Previous studies have shown that the photocatalytic performance of heterojunction nanomaterials combined with metal semiconductor materials is better.

[0004] Iron phthalocyanine (FePc) is an excellent reduced semiconductor with wide visible light absorption and unique Fe-N4 catalytic sites, and is considered to be a good photocatalyst candidate. However, due to strong intermolecular interaction, FePc molecules are prone to aggregation, which makes the charge separation and visible light collection effect poor, so it is urgent to control the high dispersity of CeO2 on FePc. According to previous work, hydrogen bond interaction can effectively overcome the π-π stacking of phthalocyanine molecules to achieve molecular dispersion. Fortunately, the outer surface of CeO2 can naturally adsorb -OH groups, especially ultra-thin nanometers. Therefore, it is feasible to modify a small amount of layers of FePc on CeO2 through H bond interaction.

[0005] By modifying the few layers of FePc on CeO2 with hydrogen bonding interactions, we can achieve high dispersion and improve its photocatalytic activity and stability. This innovative approach provides a new way to develop efficient photocatalytic degradation materials, which is expected to play an important role in environmental protection, water treatment and sustainable energy utilization. By optimizing the design of catalysts, we can more effectively utilize visible light energy to convert organic pollutants into harmless carbon dioxide and water, thus making a substantial contribution to solving environmental problems and energy shortages. This research not only has a forward-looking perspective, but also has far-reaching social significance, which will promote important breakthroughs in the practical application of photocatalytic technology. SUMMARY

[0006] In order to overcome the above-mentioned shortcomings of high cost, low selectivity, and insufficient activation of oxygen of existing photocatalytic degradation, the present application provides a simple and low-cost method for preparing a phthalocyanine iron-loaded metal oxide ultrathin nanohetero material as a photocatalytic degradation agent with high photocatalytic performance and good stability.

[0007] The purpose of the present application is achieved as follows:

[0008] A method for preparing a phthalocyanine iron-loaded metal oxide Z-type heterojunction photocatalyst, comprising the following steps:

[0009] (1) Dissolve cerium nitrate hexahydrate in water, then add an ammonia solution, continuously stir the solution, and obtain cerium oxide by hydrothermal method. Centrifuge the obtained product and calcine to obtain cerium oxide nanoparticles.

[0010] (2) Dissolve phthalocyanine iron and cerium oxide in ethanol, then perform ultrasonic treatment, stirring, and dry distillation, and dry to obtain a phthalocyanine iron-loaded metal oxide Z-type heterojunction photocatalyst.

[0011] Preferably, the phthalocyanine iron-loaded metal oxide Z-type heterojunction photocatalyst, in step (1), the hydrothermal reaction temperature is 140-180℃, and the hydrothermal time is 8-16h.

[0012] Preferably, the phthalocyanine iron-loaded metal oxide Z-type heterojunction photocatalyst, characterized in that, in step (1), the calcination temperature is 500℃, and the calcination time is 1-3h.

[0013] Preferably, the phthalocyanine iron-loaded metal oxide Z-type heterojunction photocatalyst, characterized in that, in step (1), the stirring and dry distillation treatment temperature is 60-100℃.

[0014] Preferably, the phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst has the characteristics that in step (2), the drying is carried out at a temperature of 50-70 DEG C, and the drying time is 6-10 h.

[0015] Preferably, the application of the phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst has the characteristics that the phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst is applied to the field of photocatalytic degradation of pollution.

[0016] Preferably, the application has the characteristics that under visible light irradiation, the phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst is added to a 2,4-DCP solution, and photocatalytic degradation is carried out in an air atmosphere.

[0017] The application method is as follows: 20 mg per liter of 2,4-DCP solution 50 mL is added to a 200 mL beaker, 0.02 g of the composite material is weighed and added, dark reaction adsorption is carried out for 20 min under the condition of no natural light irradiation, and adsorption equilibrium is reached. The mixed solution is placed under 150 w xenon lamp irradiation to carry out photocatalytic degradation.

[0018] Compared with the prior art, the application has the following characteristics:

[0019] The application can efficiently degrade 2,4-DCP by preparing XFePc / CeO2 ultra-thin nano-heterojunction photocatalyst by one-pot method. The method can make FePc highly dispersed on the surface of CeO2, effectively reducing the aggregation phenomenon caused by intermolecular interaction, thereby improving the stability and activity of the material. Due to the natural adsorption of -OH groups on the outer surface of CeO2, especially the ultra-thin nano structure, the modification method is relatively simple and feasible. In addition, as an important rare earth material, CeO2 has a wide application in the fields of catalysts, fuel cells and solar cells due to its low cost, high chemical stability, strong oxygen storage capacity and narrow band gap (Eg= ~ 2.8eV). Due to the more negative conduction band position of CeO2, the coupling of FePc and CeO2 can provide a suitable energy platform for FePc to accept electrons, thereby more effectively improving its photocatalytic performance. Compared with CeO2, the XFePc / CeO2 nanocomposite greatly improves the visible light degradation activity of 2,4-DCP. By constructing a Z-type heterojunction between FePc and CeO2, which have matching band structures, the separation and transfer of charges can be significantly improved, and the separation and transfer of photo-generated carriers are also greatly promoted, enhancing the photo-oxidation and reduction capacity. Under visible light irradiation, the pure CeO2 photocatalyst shows weak photocatalytic performance for 2,4-DCP degradation after 150 minutes. The performance of the composite relative to the single component has been significantly improved, for example, the 1FePc / CeO2 photocatalyst sample shows an ultra-high degradation efficiency within 150 minutes, which is 3 times that of pure CeO2. Therefore, the XFePc / CeO2 composite has excellent performance and is more valuable in practical application in the fields of environment and industry, and provides a feasible way for preparing high-efficiency environmental remediation photocatalyst. This innovative method has innovation in modifying catalysts and provides a new idea for the design of photocatalytic materials. This innovative method provides a new way for the development of high-efficiency photocatalytic degradation materials, which is expected to have a profound impact on the fields of environmental protection, water resource management and sustainable energy utilization. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The XRD spectrum of a phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst prepared in embodiment 2 of the application.

[0021] Figure 2 The DRS graph of a phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst prepared in embodiment 2 of the application.

[0022] Figure 3 The transient photocurrent response of a nanocomposite photocatalytic degradation material prepared in embodiment 2 of the application.

[0023] Figure 4The electron microscope image of the semiconductor cerium oxide photocatalyst prepared in Example 2 of the present application.

[0024] Figure 5 The electron microscope image of the phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst prepared in Example 2 of the present application.

[0025] Figure 6 The cycle test of the nanocomposite photocatalytic degradation material prepared in Example 2 of the present application.

[0026] Figure 7 The degradation performance graph of the nanocomposite photocatalytic degradation material prepared in Example 2 of the present application in photocatalytic degradation of 2,4-DCP.

[0027] Figure 8 The photocatalytic mechanism graph of the nanocomposite material prepared in Examples 1-3 of the present application. DETAILED DESCRIPTION

[0028] The present application will be described in detail below with reference to the accompanying drawings and examples.

[0029] Example 1, a phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst (the mass ratio of phthalocyanine iron to cerium oxide is 1:200), includes the following preparation steps:

[0030] (1) 5 g of cerium nitrate (Ce(NO3)2·6H2O) was dissolved in 70 mL of deionized water under vigorous stirring, and then 15 mL of an ammonia solution (NH3·H2O) was added thereto. After the solution was continuously stirred for 2 h, it was transferred to a 100 mL volume Teflon-lined stainless steel high-pressure reaction kettle. The solution was hydrothermally treated at 160℃ for 12 h. Then the product was centrifuged and washed with deionized water and ethanol several times in turn. Finally, the white precipitate was annealed in air at 500℃ for 2 h (2℃ min -1 ), and then crushed into fine powder to obtain CeO2 nanoparticles.

[0031] (2) 0.001 g of FePc was dissolved in 25 ml of ethanol. Subsequently, 0.2 g of CeO2 was suspended in the FePc solution and stirred vigorously at 80℃ until the entire solvent was completely evaporated, and then dried in a 60℃ drying oven for 8 h to obtain a phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst, denoted as 0.5FePc / CeO2.

[0032] The application of the above-mentioned phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst is mainly in photocatalytic degradation.

[0033] The application method is as follows: 20 milligrams per liter of 2,4-DCP solution 50 mL is added to a 200 mL beaker, 0.02 g of 0.5FePc / CeO2 is weighed and added, and dark reaction adsorption is carried out for 20 min under the condition of no natural light irradiation and adsorption equilibrium is reached. The mixed solution is placed under 150w xenon lamp irradiation for photocatalytic degradation.

[0034] Example 2, a phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst (the mass ratio of phthalocyanine iron to cerium oxide is 1:100), includes the following preparation steps:

[0035] (1) 5 g of cerium nitrate (Ce(NO3)2·6H2O) is dissolved in 70 mL of deionized water under vigorous stirring, and then 15 mL of an ammonia solution (NH3·H2O) is added. After the solution is continuously stirred for 2 h, it is transferred to a 100 mL volume Teflon-lined stainless steel high-pressure reaction kettle. The solution is hydrothermally treated at 160℃ for 12 h. Then the product is centrifuged and washed with deionized water and ethanol several times in turn. Finally, the white precipitate is annealed in air at 500℃ for 2 h (2℃ min -1 ), and then crushed into fine powder to obtain CeO2 nanoparticles.

[0036] (2) 0.002 g of FePc is dissolved in 25 ml of ethanol. Subsequently, 0.2 g of CeO2 is suspended in the FePc solution and stirred vigorously at 80℃ until the entire solvent is completely evaporated, and then dried in a 60℃ drying box for 8 h to obtain a phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst, which is denoted as 1FePc / CeO2.

[0037] The application of the above-mentioned phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst is mainly in photocatalytic degradation.

[0038] The application method is as follows: 20 milligrams per liter of 2,4-DCP solution 50 mL is added to a 200 mL beaker, 0.02 g of 1FePc / CeO2 is weighed and added, and dark reaction adsorption is carried out for 20 min under the condition of no natural light irradiation and adsorption equilibrium is reached. The mixed solution is placed under 150w xenon lamp irradiation for photocatalytic degradation. As shown in Figure 8 , it can be seen that the phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst prepared in Example 2 exhibits very good photocatalytic activity, and the relative single-component performance of 1FePc / CeO2 is greatly improved, showing super-high degradation efficiency.

[0039] Example 3, a phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst (the mass ratio of phthalocyanine iron to cerium oxide is 1:50), includes the following preparation steps:

[0040] (1) 5 g cerium nitrate (Ce(NO3)2·6H2O) was dissolved in 70 mL deionized water under vigorous stirring, and then 15 mL ammonia solution (NH3·H2O) was added. After the solution was continuously stirred for 2 h, it was transferred into a 100 mL volume Teflon-lined stainless steel autoclave. The solution was hydrothermally treated at 160 °C for 12 h. Then the product was centrifuged, washed with deionized water and ethanol several times in turn. Finally, the white precipitate was annealed at 500 °C in air for 2 h (2 °C min -1 ), and then crushed into fine powder to obtain CeO2 nanoparticles.

[0041] (2) 0.004 g FePc was dissolved in 25 mL ethanol. Subsequently, 0.2 g CeO2 was suspended in the FePc solution, and stirred vigorously at 80 °C until the whole solvent was completely evaporated, and then dried in a 60 °C drying oven for 8 h to obtain a phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst, denoted as 2FePc / CeO2.

[0042] The phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst described above is mainly used in photocatalytic degradation.

[0043] The application method is as follows: 20 mg per liter 2,4-DCP solution 50 mL was added into a 200 mL beaker, and 0.02 g 2FePc / CeO2 was weighed and added, and a dark reaction adsorption was carried out for 20 min under the condition of no natural light irradiation and adsorption equilibrium was reached. The mixed solution was placed under 150 w xenon lamp irradiation for photocatalytic degradation.

[0044] The application will be further described in combination with the accompanying drawings and Examples 1-3:

[0045] Figure 1 The XRD spectrum of a phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst prepared in Example 2 of the application. X-ray diffraction (XRD) was used to characterize the phase structure of FePc, CeO2 and the composite material. As shown in the figure, the diffraction peak of CeO2 can be directed to the cubic phase, and is very consistent with the standard data of powder diffraction (JCPDS card No. 043-1002). The diffraction pattern of pure CeO2 is centered at four typical peaks of 28°, 33°, 47.5° and 56°, respectively, corresponding to (111), (200), (220) and (311) crystal faces. With the increase of FePc content, the crystal phase of CeO2 does not change, and no FePc peak appears in the 1FePc / CeO2 composite material. It can be concluded that the introduced FePc content is low.

[0046] Figure 2DRS spectra of a phthalocyanine iron loaded metal oxide ultrathin nano-heterojunction photocatalyst prepared in Example 2 of the present application. Compared with the original CeO2, the 1FePc / CeO2 composite material exhibits strong and good visible light absorption in the range of 550-800 nm. In addition, the spectral absorption of the FePc / CeO2 composite material is significantly enhanced with the increase of FePc content in the FePc / CeO2.

[0047] Figure 3 The transient photocurrent response of the nanocomposite photocatalytic degradation material prepared in Example 2 of the present application proves that the addition of FePc is beneficial to charge separation.

[0048] Figure 4 TEM image of the semiconductor cerium oxide photocatalyst prepared in Example 2 of the present application. The morphology of pure CeO2 is shown in the figure, which is composed of small stacked nanoparticles with a diameter of 5-10 nm.

[0049] Figure 5 TEM image of the phthalocyanine iron loaded metal oxide ultrathin nano-heterojunction photocatalyst prepared in Example 2 of the present application. The TEM image of 1FePc / CeO2 shows that uniform dispersed nanoscale CeO2 is formed on the thin FePc layer. CeO2 and FePc form a relatively tight heterojunction.

[0050] Figure 6 Cycling stability test of a phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst prepared in Example 2 of the present application, the results show that the test sample has very excellent stability.

[0051] Figure 7 Degradation performance graph of the nanocomposite photocatalytic degradation material prepared in Example 2 of the present application for photocatalytic degradation of 2,4-DCP. Under visible light irradiation, the pure CeO2 photocatalyst shows weak photocatalytic performance for the degradation of 2,4-DCP. The performance of the composite material is significantly improved compared with that of the single component, for example, the 1FePc / CeO2 photocatalyst sample shows super high degradation efficiency.

[0052] Figure 8 Photocatalytic mechanism graph of the nanocomposite material prepared in Examples 1-3 of the present application. The possible charge transfer path graph of the phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst is shown. The band gap of the CeO2 nanosheet is 2.84 eV, and the CB is -0.46 V (vs NHE). The HOMO energy level of FePc is 0.55 V (vs NHE), and the LUMO energy level is estimated to be -1.39 V (vs NHE). According to their band potential, a Z-type charge transfer mechanism of the FePc / CeO2 heterojunction is proposed.

[0053] In conclusion, the phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst prepared by one-pot method has excellent photocatalytic degradation performance of pollutants.

Claims

1. Use of a phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst, characterized in that, The phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst is applied to the field of photocatalytic degradation of pollution. The preparation method of the phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst comprises the following steps: (1) Dissolve cerium nitrate hexahydrate in water, then add an ammonia solution, continuously stir the solution, and obtain cerium oxide by using a hydrothermal method; centrifuge the obtained product, and obtain cerium oxide nanoparticles after calcination; (2) Dissolve phthalocyanine iron and cerium oxide in ethanol, then perform ultrasonic treatment, stirring, stirring and evaporation, and drying to obtain the phthalocyanine iron loaded metal oxide Z-type heterojunction photocatalyst; The application method is as follows: 20 mg per liter of 2,4-dichlorophenol solution 50 mL is added into a 200 mL beaker, 0.02 g of the composite material is weighed and added into the beaker, 20 min of dark reaction adsorption is performed under the condition of no natural light irradiation and adsorption equilibrium is reached, and the mixed solution is placed under 150 w xenon lamp irradiation to perform photocatalytic degradation.

2. Use according to claim 1, characterized in that, In step (1), the hydrothermal reaction temperature is 140-180 DEG C, and the hydrothermal time is 8-16 h.

3. Use according to claim 1, characterized in that, In step (1), the calcination temperature is 500 DEG C, and the calcination time is 1-3 h.

4. Use according to claim 1, characterized in that, In step (2), the stirring and evaporation treatment temperature is 60-100 DEG C.

5. The use according to claim 1, characterized in that, In step (2), drying is performed at a temperature of 50-70 DEG C, and the drying time is 6-10 h.

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