Cobalt ion doped modified upconversion photocatalyst and its preparation method and application

Abstract

The present invention discloses a cobalt ion-doped and modified upconversion photocatalyst, its preparation method and application, which include the following steps: Bi2O3 and NH4F are placed in an agate mortar, alcohol is added and ground thoroughly until dry, then it is loaded into a corundum crucible and placed in a muffle furnace, and the precursor BiOF is obtained by high-temperature sintering; the precursor is placed in an agate mortar, and at the same time TiO2, Er2O3, Yb2O3 and a cobalt source are added, alcohol is added and ground thoroughly until dry, then it is loaded into a corundum crucible and placed in a muffle furnace or a reducing atmosphere furnace, and high-temperature sintering is carried out to obtain the product. The present invention can convert low-energy near-infrared light into high-energy ultraviolet light or visible light emission, thereby expanding the spectral response range and improving the utilization rate of sunlight; it has a high spectral absorption intensity and a high carrier separation efficiency, showing high photocatalytic activity; it is applied as a photocatalyst in the degradation of organic dyes, endocrine substances, antibiotics and heavy metal pollutants.

Description

Technical Field

[0001] The invention belongs to the technical field of up-conversion photocatalysts, and in particular relates to an up-conversion photocatalyst modified by doping with cobalt ions, and a preparation method and application thereof. Background Art

[0002] At present, energy crisis and environmental pollution have become two major problems facing human society. Finding and developing green, environmentally friendly and sustainable new energy sources has become the focus of common concern of countries around the world. As a clean, pollution-free renewable resource, solar energy is considered to be the most promising future energy source. How to effectively utilize solar energy has become the common goal pursued by many scientists. Semiconductor photocatalytic technology can use solar energy to drive a series of chemical reactions to achieve CO2 reduction, N2 fixation, hydrolysis to produce hydrogen and pollutant degradation, etc., and is considered to be a new technology with great potential.

[0003] Bismuth-based semiconductor photocatalysts have attracted extensive attention due to their adjustable solar absorption range and unique layered structure. Among them, Bi3Ti2O8F is a new bismuth-based layered photocatalyst with a band gap of 3.32 eV and a conduction band position of approximately –1.21 eV, indicating that it has a strong reduction ability. In addition, Bi3Ti2O8F consists of positively charged [Bi2O2] 2+ layers and negatively charged perovskite [BiTi2O6F] 2- The layer composition can form a self-built electric field and accelerate the migration of photogenerated electron-hole pairs. Therefore, Bi3Ti2O8F exhibits excellent photocatalytic performance in photodegradation. However, the monomer Bi3Ti2O8F has problems such as low spectral utilization and high recombination rate of photogenerated carriers, which seriously restricts its practical application.

[0004] Rare earth-doped upconversion materials are considered to be one of the important ways to broaden the spectral response range of photocatalysts due to their unique ability to convert near-infrared light into visible light or ultraviolet light. 3+ , Er 3+ Co-doped photocatalysts, in Yb 3+ Under the sensitization effect of 3+ Absorbing low-energy near-infrared light and converting it into visible light or high-energy ultraviolet light for use in the photocatalytic process can improve the photocatalytic efficiency.

[0005] In addition, the variable valence state and 3d orbital of transition metal Co have a great influence on the photoelectrochemical properties of semiconductors, which can enhance the absorption of light by semiconductors. Moreover, Co doping can also introduce lattice defects in semiconductors or change the crystallinity of semiconductors, thereby inhibiting electron-hole separation and prolonging carrier lifetime, thereby achieving an improvement in photocatalytic efficiency.

[0006] Therefore, this paper proposes a cobalt ion doped modified upconversion photocatalyst and its preparation method and application. Summary of the invention

[0007] In order to solve the above technical problems, the present invention designs a cobalt ion doped modified upconversion photocatalyst and its preparation method and application, which can convert low-energy near-infrared light into high-energy ultraviolet light or visible light emission, thereby expanding the spectral response range and improving the utilization rate of sunlight; the variable valence state of the transition metal Co and the influence of the 3d orbit on the photoelectrochemical properties of the semiconductor photocatalyst make it have a higher spectral absorption intensity and a higher carrier separation efficiency, showing efficient photocatalytic activity.

[0008] In order to achieve the above technical effects, the present invention is implemented by the following technical scheme: a cobalt ion doped modified upconversion photocatalyst, characterized in that its chemical formula is x%Co 2+ / y%Co 3+ -Bi 3-0.03(x+y+m+n) Ti2O8F:m%Yb 3+ ,n%Er 3+ , x∈[1,10], y∈[1,10], m∈[2,20], n∈[1,4].

[0009] Another object of the present invention is to provide a method for preparing a cobalt ion doped and modified upconversion photocatalyst, characterized in that it comprises the following steps:

[0010] Step 1: Place Bi2O3 and NH4F in an agate mortar, add alcohol and grind thoroughly until dry; put the obtained powder into a corundum crucible and place it in a muffle furnace, and sinter at high temperature to obtain the precursor BiOF;

[0011] Step 2: Place the precursor BiOF in an agate mortar, add TiO2, Er2O3, Yb2O3 and cobalt source at the same time, add alcohol and grind thoroughly until dry; put the obtained powder into a corundum crucible and place it in a muffle furnace or a reducing atmosphere furnace, and sinter it at high temperature.

[0012] Furthermore, in the Step 1, the molar ratio of Bi2O3 to NH4F is 0.5~1:1.

[0013] Furthermore, in the Step 1, the high temperature sintering temperature is 200-500° C., and the sintering time is 4-24 h.

[0014] Furthermore, in the Step 2, the molar ratio of BiOF to TiO2 is 0.5-1:1; the molar ratio of Er2O3 to BiOF is 0.5-2:100; and the molar ratio of Yb2O3 to BiOF is 1-10:100.

[0015] Furthermore, in the Step 2, the cobalt source is one or more of CoO, Co2O3, and Co3O4; and the molar ratio of the cobalt source to BiOF is 1-10:100.

[0016] Furthermore, the sintering temperature in Step 2 is 400-800° C., and the sintering time is 4-24 h.

[0017] Furthermore, the reducing atmosphere in Step 2 includes one of hydrogen, carbon monoxide and carbon powder.

[0018] Furthermore, the amount of alcohol used in Step 1 is 2-10 ml per 0.5 mol Bi2O3; the amount of alcohol used in Step 2 is 2-10 ml per 0.5 mol BiOF; and the concentration of alcohol is 70-75%.

[0019] Another object of the present invention is to provide an application of a cobalt ion-doped modified upconversion photocatalyst, characterized in that the catalyst is used as a photocatalyst in the degradation of organic dyes, endocrine substances, antibiotics and heavy metal pollutants.

[0020] The beneficial effects of the present invention are:

[0021] The upconversion photocatalyst prepared by the present invention can convert low-energy near-infrared light into high-energy ultraviolet light or visible light emission due to the upconversion luminescence function of rare earth ions, thereby expanding the spectral response range and improving the utilization rate of sunlight; the variable valence state of the transition metal Co and the influence of the 3d orbit on the photoelectrochemical properties of the semiconductor photocatalyst make it have higher spectral absorption intensity and higher carrier separation efficiency, and show efficient photocatalytic activity; the preparation method of the material of the present invention is simple, low-cost, suitable for large-scale production, and has industrial and market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0023] Figure 1 To prepare Co ion doped modified Bi3Ti2O8F:Yb 3+ ,Er 3+ XRD patterns of upconversion photocatalysts;

[0024] Figure 2 To prepare Co ion doped modified Bi3Ti2O8F:Yb 3+ ,Er3+ UV-visible absorption spectra of upconversion photocatalysts;

[0025] Figure 3 To prepare Co ion doped modified Bi3Ti2O8F:Yb 3+ ,Er 3+ Full spectrum catalytic degradation diagram of upconversion photocatalyst. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0027] A cobalt ion doped upconversion photocatalyst with a chemical formula of 1%Co 2+ -Bi 2.64 Ti2O8F:10%Yb 3+ ,1%Er 3+ , the preparation method of the material is as follows:

[0028] (1) Place a certain amount of Bi2O3 and NH4F in an agate mortar, add an appropriate amount of alcohol and grind thoroughly until dry. The resulting powder is placed in a corundum crucible and placed in a muffle furnace, and sintered at 200~500℃ for 4~24h to obtain the precursor BiOF.

[0029] (2) According to Bi 3+ 、Ti 4+ , Er 3+ , Yb 3+ 、Co 2+ The precursors BiOF, TiO2, Er2O3, Yb2O3 and CoO obtained in step (1) were weighed in a molar ratio of 2.64:5:0.03:0.3:0.03, and an appropriate amount of alcohol was added and fully ground to dryness. The obtained powder was placed in a corundum crucible and placed in a muffle furnace, and sintered at 400-800 °C for 4-24 h to obtain a 1%Co 2+ -Bi 2.64 Ti2O8F:10%Yb 3+ ,1%Er 3+ Co ion doping modified Bi3Ti2O8F:Yb 3+ ,Er 3+ Upconversion photocatalysts. Example 2

[0030] A cobalt ion doped upconversion photocatalyst with a chemical formula of 1%Co 3+ -Bi 2.64 Ti2O8F:10%Yb 3+ ,1%Er 3+ , the preparation method of the material is as follows:

[0031] (1) Place a certain amount of Bi2O3 and NH4F in an agate mortar, add an appropriate amount of alcohol and grind thoroughly until dry. The resulting powder is placed in a corundum crucible and placed in a muffle furnace, and sintered at 200~500℃ for 4~24h to obtain the precursor BiOF.

[0032] (2) According to Bi 3+ 、Ti 4+ , Er 3+ , Yb 3+ 、Co 3+ The precursors BiOF, TiO2, Er2O3, Yb2O3 and Co2O3 obtained in step (1) were weighed in a molar ratio of 2.64:5:0.03:0.3:0.03, and an appropriate amount of alcohol was added and fully ground to dryness. The obtained powder was placed in a corundum crucible and placed in a muffle furnace, and sintered at 400-800 °C for 4-24 h to obtain a 1% Co 3+ -Bi 2.64 Ti2O8F:10%Yb 3+ ,1%Er 3+ Co ion doping modified Bi3Ti2O8F:Yb 3+ ,Er 3+ Upconversion photocatalysts. Example 3

[0033] A cobalt ion doped upconversion photocatalyst with a chemical formula of 1% Co 2+ / Co 3+ -Bi 2.64 Ti2O8F:10%Yb 3+ ,1%Er 3+ , the preparation method of the material is as follows:

[0034] (1) Place a certain amount of Bi2O3 and NH4F in an agate mortar, add an appropriate amount of alcohol and grind thoroughly until dry. The resulting powder is placed in a corundum crucible and placed in a muffle furnace, and sintered at 200~500℃ for 4~24h to obtain the precursor BiOF.

[0035] (2) According to Bi 3+ 、Ti 4+ , Er 3+ , Yb 3+ 、Co 2+ / Co 3+The precursors BiOF, TiO2, Er2O3, Yb2O3 and Co3O4 obtained in step (1) were weighed in a molar ratio of 2.64:5:0.03:0.3:0.03, and an appropriate amount of alcohol was added and fully ground to dryness. The obtained powder was placed in a corundum crucible and placed in a muffle furnace, and sintered at 400-800 °C for 4-24 h to obtain a 1% Co 2 + / Co 3+ -Bi 2.64 Ti2O8F:10%Yb 3+ ,1%Er 3+ Co ion doping modified Bi3Ti2O8F:Yb 3+ ,Er 3+ Upconversion photocatalysts. Example 4

[0036] A cobalt ion doped upconversion photocatalyst with a chemical formula of 4% Co 2+ / Co 3+ -Bi 2.55 Ti2O8F:10%Yb 3+ ,1%Er 3+ , the preparation method of the material is as follows:

[0037] (1) Place a certain amount of Bi2O3 and NH4F in an agate mortar, add an appropriate amount of alcohol and grind thoroughly until dry. The resulting powder is placed in a corundum crucible and placed in a muffle furnace, and sintered at 200~500℃ for 4~24h to obtain the precursor BiOF.

[0038] (2) According to Bi 3+ 、Ti 4+ , Er 3+ , Yb 3+ 、Co 2+ / Co 3+ The precursors BiOF, TiO2, Er2O3, Yb2O3 and Co3O4 obtained in step (1) were weighed in a molar ratio of 2.55:5:0.03:0.3:0.12, and an appropriate amount of alcohol was added and fully ground to dryness. The obtained powder was placed in a corundum crucible and placed in a muffle furnace, and sintered at 400-800 °C for 4-24 h to obtain a 1% Co 2 + / Co 3+ -Bi 2.55 Ti2O8F:10%Yb 3+ ,1%Er 3+ Co ion doping modified Bi3Ti2O8F:Yb 3+ ,Er 3+ Upconversion photocatalysts. Example 5

[0039] A cobalt ion doped upconversion photocatalyst with a chemical formula of 4% Co 2+ / Co 3+ -Bi 2.7 Ti2O8F:5%Yb 3 + ,1%Er 3+ , the preparation method of the material is as follows:

[0040] (1) Place a certain amount of Bi2O3 and NH4F in an agate mortar, add an appropriate amount of alcohol and grind thoroughly until dry. The resulting powder is placed in a corundum crucible and placed in a muffle furnace, and sintered at 200~500℃ for 4~24h to obtain the precursor BiOF.

[0041] (2) According to Bi 3+ 、Ti 4+ , Er 3+ , Yb 3+ 、Co 2+ / Co 3+ The precursors BiOF, TiO2, Er2O3, Yb2O3 and Co3O4 obtained in step (1) were weighed in a molar ratio of 2.7:5:0.03:0.15:0.12, and an appropriate amount of alcohol was added and fully ground to dryness. The obtained powder was placed in a corundum crucible and placed in a muffle furnace, and sintered at 400~800℃ for 4~24h to obtain a 4% Co 2 + / Co 3+ -Bi 2.7 Ti2O8F:5%Yb 3+ ,1%Er 3+ Co ion doping modified Bi3Ti2O8F:Yb 3+ ,Er 3+ Upconversion photocatalysts. Example 6

[0042] A cobalt ion doped upconversion photocatalyst with a chemical formula of 4% Co 2+ / Co 3+ -Bi 2.67 Ti2O8F:5%Yb 3 + ,2%Er 3+ , the preparation method of the material is as follows:

[0043] (1) Place a certain amount of Bi2O3 and NH4F in an agate mortar, add an appropriate amount of alcohol and grind thoroughly until dry. The resulting powder is placed in a corundum crucible and placed in a muffle furnace, and sintered at 200~500℃ for 4~24h to obtain the precursor BiOF.

[0044] (2) According to Bi 3+ 、Ti 4+ , Er 3+ , Yb 3+ 、Co 2+ / Co 3+ The precursors BiOF, TiO2, Er2O3, Yb2O3 and Co3O4 obtained in step (1) were weighed in a molar ratio of 2.67:5:0.06:0.15:0.12, and an appropriate amount of alcohol was added to fully grind until dry. The obtained powder was placed in a corundum crucible and placed in a muffle furnace, and sintered at 400~800℃ for 4~24h to obtain a 4% Co 2 + / Co 3+ -Bi 2.67 Ti2O8F:5%Yb 3+ ,2%Er 3+ Co ion doping modified Bi3Ti2O8F:Yb 3+ ,Er 3+ Upconversion photocatalysts. Example 7

[0045] A cobalt ion doped upconversion photocatalyst with the chemical formula x%Co 2+ / (4-x) Co 3+ -Bi 2.67 Ti2O8F:5%Yb 3+ ,2%Er 3+ , the preparation method of the material is as follows:

[0046] (1) Place a certain amount of Bi2O3 and NH4F in an agate mortar, add an appropriate amount of alcohol and grind thoroughly until dry. The resulting powder is placed in a corundum crucible and placed in a muffle furnace, and sintered at 200~500℃ for 4~24h to obtain the precursor BiOF.

[0047] (2) According to Bi 3+ 、Ti 4+ , Er 3+ , Yb 3+ 、Co 2+ / Co 3+ The precursors BiOF, TiO2, Er2O3, Yb2O3 and Co3O4 obtained in step (1) were weighed in a molar ratio of 2.67:5:0.06:0.15:0.12, and an appropriate amount of alcohol was added and fully ground to dryness. The obtained powder was placed in a corundum crucible and placed in a reducing atmosphere furnace, and sintered at 400~800℃ for 4~24h to obtain a chemical formula of x%Co 2+ / (4-x)Co 3+ -Bi2.67 Ti2O8F:5%Yb 3+ ,2%Er 3+ Co ion doping modified Bi3Ti2O8F:Yb 3+ ,Er 3+ Upconversion photocatalysts. Example 8

[0048] A cobalt ion doped upconversion photocatalyst with the chemical formula x%Co 2+ / (4-x)Co 3+ -Bi 2.67 Ti2O8F:5%Yb 3+ ,2%Er 3+ , the preparation method of the material is as follows:

[0049] (1) Place a certain amount of Bi2O3 and NH4F in an agate mortar, add an appropriate amount of alcohol and grind thoroughly until dry. The resulting powder is placed in a corundum crucible and placed in a muffle furnace, and sintered at 200~500℃ for 4~24h to obtain the precursor BiOF.

[0050] (2) According to Bi 3+ 、Ti 4+ , Er 3+ , Yb 3+ 、Co 3+ The precursors BiOF, TiO2, Er2O3, Yb2O3 and Co2O3 obtained in step (1) were weighed in a molar ratio of 2.67:5:0.06:0.15:0.12, and an appropriate amount of alcohol was added and fully ground to dryness. The obtained powder was placed in a corundum crucible and placed in a reducing atmosphere furnace, and sintered at 400-800 °C for 4-24 h to obtain a chemical formula of x%Co 2+ / (4-x)Co 3+ -Bi 2.67 Ti2O8F:5%Yb 3+ ,2%Er 3+ Co ion doping modified Bi3Ti2O8F:Yb 3+ ,Er 3+ Upconversion photocatalysts. Example 9

[0051] Photocatalytic activity test

[0052] The photocatalytic activity of the samples for the degradation of organic dyes, endocrines, antibiotics, and heavy metal ions was evaluated under a 300 W xenon lamp (CEL-LAX500). The reactor used was a custom-made quartz reactor with a volume of 100 ml. 10 mg of the sample was added to the pollutant solution (40 mL, 10 mg / L) and stirred in the dark for 0.5 h to ensure adsorption-desorption equilibrium. 4 mL of the reaction solution was removed periodically. The supernatant was analyzed using a UV-1800 spectrophotometer.

[0053] Depend on Figure 1 It can be seen that the Co ion doped modified Bi3Ti2O8F:Yb prepared in the embodiment 3+ ,Er 3+ Upconversion photocatalysts and pristine Bi3Ti2O8F:Yb 3+ ,Er 3+ All of them correspond to the characteristic peaks of standard Bi3Ti2O8F, and there are no impurity peaks, indicating that Co ion doping is successful. Figure 2 It can be seen that the Co ion doped modified Bi3Ti2O8F:Yb prepared in the embodiment 3+ ,Er 3+ Upconversion photocatalysts compared to pristine Bi3Ti2O8F:Yb 3+ ,Er 3+ The photocatalyst has a strong visible-near infrared absorption response. Figure 3 It can be seen that the Co ion doped modified Bi3Ti2O8F:Yb prepared in the embodiment 3+ ,Er 3+ Upconversion photocatalysts compared to pristine Bi3Ti2O8F:Yb 3+ ,Er 3+ Photocatalysts significantly improve the efficiency of photocatalytic degradation of pollutants.

Claims

1. A cobalt ion doped and modified upconversion photocatalyst, characterized in that: Using x%Co 2+ ,y%Co 3+ 、m%Yb 3+ 、n%Er 3+ Doped Bi3Ti2O8F, where x∈[1,10], y∈[1,10], m∈[2,20], n∈[1,4], where x, y, m and n are Co 2+ 、Co 3+ , Yb 3+ and Er 3+ The percentage of Bi ions.

2. The method for preparing a cobalt ion-doped upconversion photocatalyst according to claim 1, characterized in that: The following steps are involved: Step 1: Weigh Bi2O3 and NH4F in a molar ratio of Bi2O3: NH4F = 0.5~1:1, put Bi2O3 and NH4F in an agate mortar, add alcohol and grind them thoroughly until dry; put the obtained powder into a corundum crucible and place it in a muffle furnace, and sinter at high temperature to obtain the precursor BiOF; Step 2: The precursor BiOF is placed in an agate mortar, and TiO2, Er2O3, Yb2O3 and cobalt source are added at the same time. Alcohol is added and ground thoroughly until dry. The obtained powder is loaded into a corundum crucible and placed in a muffle furnace, and sintered at high temperature.

3. The method for preparing a cobalt ion doped and modified upconversion photocatalyst according to claim 1, characterized in that: The following steps are involved: Step 1: Weigh Bi2O3 and NH4F in a molar ratio of Bi2O3: NH4F = 0.5~1:1, put Bi2O3 and NH4F in an agate mortar, add alcohol and grind them thoroughly until dry; put the obtained powder into a corundum crucible and place it in a muffle furnace, and sinter at high temperature to obtain the precursor BiOF; Step 2: The precursor BiOF is placed in an agate mortar, and TiO2, Er2O3, Yb2O3 and cobalt source are added at the same time. Add alcohol and grind thoroughly until dry; the obtained powder is loaded into a corundum crucible and placed in a reducing atmosphere furnace and sintered at high temperature.

4. The method for preparing a cobalt ion doped upconversion photocatalyst according to claim 2 or 3, characterized in that: In the Step 1, the high temperature sintering temperature is 200-500° C., and the sintering time is 4-24 hours.

5. The method for preparing a cobalt ion-doped upconversion photocatalyst according to claim 2 or 3, characterized in that: In the Step 2, the molar ratio of BiOF to TiO2 is 0.5-1:1; the molar ratio of Er2O3 to BiOF is 0.5-2:100; and the molar ratio of Yb2O3 to BiOF is 1-10:

100.

6. The method for preparing a cobalt ion-doped upconversion photocatalyst according to claim 2 or 3, characterized in that: In the Step 2, the cobalt source is one or more of CoO, Co2O3, and Co3O4; and the molar ratio of the cobalt source to BiOF is 1-10:

100.

7. The method for preparing a cobalt ion-doped upconversion photocatalyst according to claim 2 or 3, characterized in that: The sintering temperature in Step 2 is 400-800° C., and the sintering time is 4-24 hours.

8. The method for preparing a cobalt ion doped and modified upconversion photocatalyst according to claim 3, characterized in that: In the Step 2, the reducing atmosphere in the reducing atmosphere furnace includes one of hydrogen and carbon monoxide.

9. The method for preparing a cobalt ion-doped upconversion photocatalyst according to claim 2 or 3, characterized in that: In the step 1, the amount of alcohol used for every 0.5 mol Bi2O3 is 2-10 mL; in the step 2, the amount of alcohol used for every 0.5 mol BiOF is 2-10 mL; the concentration of alcohol is 70-75%.

10. The use of a cobalt ion-doped modified upconversion photocatalyst according to claim 1, characterized in that: The catalyst is used as a photocatalyst in degrading organic dyes and antibiotic pollutants.

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