Au-Mo 0.1 W 0.9 O 2.72 Bilayer plasmonic nanoreactor and method of making and using same

Abstract

The application discloses an Au-Mo 0.1 W 0.9 O 2.72 Double plasmonic nanoreactor and a preparation method and application thereof, wherein Mo 0.1 W 0.9 O 2.72 is used as a carrier, and 2-10 wt% Au nanoparticles are loaded on the carrier. 0.1 W 0.9 O 2.72 The Au-Mo 0.1 W 0.9 O 2.72 double plasmonic nanoreactor uses Mo as a carrier, and Au nanoparticles are loaded on the surface of the carrier; the double plasmonic nanoreactor has good light response; a hot electron-rich surface under light excitation improves adsorption and activation of nitrogen and nitrogen reduction intermediates, and obviously improves the activity of photocatalytic nitrogen fixation.

Description

Technical Field

[0001] The present invention belongs to the field of photocatalysis technology, and specifically relates to an Au-Mo 0.1 W 0.9 O 2.72 A dual plasmon nanoreactor and its preparation method and application. Background Art

[0002] Ammonia is a fundamental raw material for fertilizers and industrial chemicals, and a clean energy carrier with high hydrogen storage capacity. Therefore, the ammonia synthesis industry is crucial to the development of human society. Conventional thermal catalytic ammonia synthesis accounts for approximately 30% of total ammonia production. The Haber-Bosch process, employed in this process, consumes 1-3% of the energy released by global fossil fuel combustion and emits approximately 300 million tons of greenhouse gases annually. Therefore, developing green, clean, and efficient strategies for ammonia synthesis has always been a cutting-edge research topic. In 1977, Guth and Schrauzer first proposed the synthesis of ammonia under mild conditions using TiO2 as a photocatalyst and nitrogen and water as feedstocks. In recent years, the field of photocatalytic ammonia synthesis has attracted considerable research attention. In the photocatalytic ammonia synthesis process, two main limiting factors are the adsorption and activation of nitrogen, one of the reactants, and the light transmission during the photocatalytic reaction. The low solubility and high bond energy of nitrogen hinder its adsorption and activation on the catalyst surface. Traditional photocatalysts have low light utilization and low solar energy conversion efficiency, which directly leads to low efficiency of photocatalytic ammonia synthesis, seriously limiting the scale-up and even industrial application of photocatalytic ammonia synthesis process. Therefore, the development of high-efficiency photocatalytic ammonia synthesis catalysts is the core. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the present invention aims to provide an Au-Mo 0.1 W 0.9 O 2.72 Dual plasmon nanoreactor and its preparation method and application, the nanoreactor is Mo 0.1 W 0.9 O 2.72 As a carrier, the surface is loaded with Au nanoparticles, which has good light response. Under light excitation, the hot electron-rich surface improves the adsorption and activation of nitrogen and nitrogen reduction intermediates, and significantly enhances the activity of photocatalytic nitrogen fixation.

[0004] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0005] An Au-Mo 0.1 W 0.9 O 2.72 Dual plasmon nanoreactor, based on Mo 0.1 W 0.9 O 2.72The carrier is loaded with 2-10wt% Au nanoparticles.

[0006] Preferably, the loading amount of the Au nanoparticles is 4-6 wt %.

[0007] Au-Mo of the present invention 0.1 W 0.9 O 2.72 The dual plasmon nanoreactor has a dual plasmon resonance coupling effect, that is, the LSPR effect of metal nanoparticles is coupled with the SPR effect of non-metals. The hot electrons generated are concentrated in the nanoscale area near the surface, which can generate high energy and high local electromagnetic fields in a very small space, which is conducive to the interaction between hot electrons and surface adsorbed molecules and promotes the activation of inert molecules.

[0008] The present invention also provides the above-mentioned Au-Mo 0.1 W 0.9 O 2.72 The preparation method of the dual plasmon nanoreactor comprises the following steps: firstly dissolving a tungsten source and a molybdenum source in ethanol to obtain a tungsten-molybdenum mixed solution; then subjecting the tungsten-molybdenum mixed solution to solvent thermal synthesis to molybdenum-doped tungsten oxide; then impregnating a mixture of chloroauric acid solution and molybdenum-doped tungsten oxide to obtain a precursor; and finally calcining the precursor in a reducing atmosphere to obtain Au-Mo. 0.1 W 0.9 O 2.72 Dual plasmon nanoreactor.

[0009] Preferably, the tungsten source is selected from one of tungsten pentachloride, tungsten hexachloride and tungsten hexacarbonyl; and the molybdenum source is molybdenum pentachloride.

[0010] Preferably, the solvent thermal temperature is 140-200° C. and the time is 12-24 hours.

[0011] Preferably, the concentration of the chloroauric acid solution is 10-50 mmol / L.

[0012] Preferably, the calcination process is: heating to 60-100°C at 2-10°C / min and maintaining for 0.5-1h, then heating to 200-240°C at 2-10°C / min and maintaining for 1-3h; the reducing atmosphere is a H2 / Ar mixed atmosphere.

[0013] The present invention also provides the above-mentioned Au-Mo 0.1 W 0.9 O 2.72 Application of dual plasmon nanoreactor for photocatalytic nitrogen fixation.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] Au-Mo of the present invention 0.1 W0.9 O 2.72 Double plasmonic nanoreactor, Mo 0.1 W 0.9 O 2.72 Au nanoparticles, has good optical response, and the hot electron-rich surface improves the adsorption and activation of nitrogen and nitrogen reduction intermediates under light excitation, significantly improving the photocatalytic nitrogen fixation activity. For example, under full-spectrum light irradiation, the ammonia production rate of the Au-Mo 0.1 W 0.9 O 2.72 of Example 1 (AMWO) reached 562.3 μmol / g / h. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 XRD patterns of samples prepared in Example 1 (AMWO) and Comparative Example 1 (WO);

[0017] Figure 2 SEM images of samples prepared in Example 1 (a) and Comparative Example 1 (b);

[0018] Figure 3 HAADF-STEM of the sample prepared in Example 1;

[0019] Figure 4 Photocatalytic nitrogen fixation performance diagrams of samples prepared in Comparative Example 1 (WO 2.72 ), Comparative Example 2 (MoWO 2.72 ), Comparative Example 3 (Au-WO 2.72 ), Comparative Example 4 (CuWO 2.72 ), and Comparative Example 5 (LaWO 2.72 );

[0020] Figure 5 Photocatalytic nitrogen fixation performance diagrams of samples prepared in Example 1 (AMWO) and Comparative Example 1 (WO);

[0021] Figure 6 UV-vis diagrams of samples prepared in Example 1 (AMWO) and Comparative Example 1 (WO);

[0022] Figure 7 OCP diagrams of samples prepared in Example 1 (AMWO) and Comparative Example 1 (WO);

[0023] Figure 8 N2-TPD diagrams of samples prepared in Example 1 (AMWO) and Comparative Example 1 (WO). DETAILED DESCRIPTION

[0024] The present invention is further described in detail below with reference to the embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0025] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; the reagents, materials, etc. used in the following examples are all commercially available unless otherwise specified.

[0026] Photocatalytic synthesis of ammonia:

[0027] Weigh 5 mg of catalyst powder and add it to 10 ml of ultrapure water. Disperse the mixture under ultrasound for 10 minutes, then transfer the mixture to a reaction tube. Evacuate the tube and backfill with ultrapure nitrogen three times. Irradiate the mixture with a xenon lamp under full-spectrum light for 1 hour while stirring. After the reaction, centrifuge the mixture to remove the supernatant, filter it through a 0.22 μm water filter, and measure the ammonium ion concentration using an ion-selective electrode and a colorimetric method.

[0028] Example 1

[0029] 100 mg of W(CO)6 was mixed with 28.75 mL of ethanol under vigorous stirring until the solid was completely dissolved. Then, 1.25 mL of HCl solution (36 wt%) and 5 mg of MoCl5 were measured and mixed with the above solution and stirred for 30 minutes. The final mixture was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and treated at 160°C for 16 hours. After cooling to room temperature, it was separated by centrifugation, washed three times with a mixture of ethanol and water in a volume ratio of 1:1, and dried in a vacuum oven at 100°C to obtain a light blue product, MoWO. 2.72 50mg MoWO 2.72 0.6 ml of 25 mM HAuCl4 was dissolved in 20 mL of saturated Ar water and stirred at room temperature for 120 min. The solid was collected by centrifugation and dried in a vacuum at 60 ° C. The solid was finely ground and transferred to a porcelain boat and placed in a tube furnace. The temperature was increased at 5 ° C / min to 80 ° C and held for 30 min. Then the temperature was increased at 5 ° C / min to 220 ° C and held for 120 min. The sample was cooled naturally. The obtained sample was recorded as Au-Mo 0.1 W 0.9 O 2.72 , ICP-OES further confirmed that the loading amount of Au nanoparticles was approximately 5.5 wt%.

[0030] like Figure 1 As shown in Figure 2, the X-ray diffraction (XRD) pattern confirms that MWO shows two strong diffraction peaks at 23.2° and 47.6°, corresponding to the standard WO 2.72The (010) and (020) crystal planes of the composite catalyst (JCPDS-PDF#841516) lack characteristic peaks of molybdenum oxide crystals, indicating that the catalyst lacks molybdenum oxide and that molybdenum exists as an elemental dopant within the tungsten oxide. Furthermore, the (111) crystal plane of Au (JCPDS-PDF#040784) is visible at 38.2°, confirming the presence of Au particles in the composite catalyst.

[0031] like Figure 2 As shown, Au-Mo 0.1 W 0.9 O 2.72 Scanning electron microscope (SEM) images of dual plasmon nanoreactors confirmed that Au-Mo 0.1 W 0.9 O 2.72 The size of the medium carrier is about 15 nm with a narrow size distribution. SEM characterization cannot observe the surface-loaded Au nanoparticles, proving that their size is small.

[0032] like Figure 3 As shown, high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) reveals that Au-Mo 0.1 W 0.9 O 2.72 The morphological characteristics of the Au nanoparticles loaded on the surface are shown in Figure 2. The average radius of the Au nanoparticles loaded on the surface is about 5 nm, and they are regular spherical. The lattice fringes of the carrier and the loaded particles can be clearly identified by aberration-corrected annular dark-field scanning transmission electron microscopy. The lattice spacing of the carrier is 0.381 nm, which is the lattice spacing of the typical 010 crystal plane of tungsten oxide. The lattice spacing of the Au nanoparticles is 0.231 nm, which also corresponds to the 111 crystal plane of gold. In addition, in the magnified image, there are no obvious bright spots on the carrier, confirming that Au exists mainly in the form of nanoparticles.

[0033] Example 2

[0034] 100 mg of W(CO)6 was mixed with 28.75 mL of ethanol under vigorous stirring until the solid was completely dissolved. Then, 1.25 mL of HCl solution (36 wt%) and 5 mg of MoCl5 were measured and mixed with the above solution and stirred for 30 minutes. The final mixture was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and treated at 160°C for 16 hours. After cooling to room temperature, it was separated by centrifugation, washed three times with a mixture of ethanol and water in a volume ratio of 1:1, and dried in a vacuum oven at 100°C to obtain a light blue product, MoWO. 2.72 50mg MoWO 2.720.3 ml of 25 mM HAuCl4 was dissolved in 20 mL of saturated Ar water and stirred at room temperature for 120 min. The solid was collected by centrifugation and dried in a vacuum at 60 ° C. The solid was finely ground and transferred to a porcelain boat and placed in a tube furnace. The temperature was increased at 5 ° C / min to 80 ° C and held for 30 min. Then the temperature was increased at 5 ° C / min to 220 ° C and held for 120 min. The sample was cooled naturally. The obtained sample was recorded as Au-Mo 0.1 W 0.9 O 2.72 -2, and ICP-OES further confirmed that the loading amount of Au nanoparticles was approximately 2.8 wt%.

[0035] Example 3

[0036] 100 mg of W(CO)6 was mixed with 28.75 mL of ethanol under vigorous stirring until the solid was completely dissolved. Then, 1.25 mL of HCl solution (36 wt%) and 5 mg of MoCl5 were measured and mixed with the above solution and stirred for 30 minutes. The final mixture was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and treated at 160°C for 16 hours. After cooling to room temperature, it was separated by centrifugation, washed three times with a mixture of ethanol and water in a volume ratio of 1:1, and dried in a vacuum oven at 100°C to obtain a light blue product, MoWO. 2.72 50mg MoWO 2.72 1.2 ml of 25 mM HAuCl4 was dissolved in 20 mL of saturated Ar water and stirred at room temperature for 120 min. The solid was collected by centrifugation and dried in a vacuum at 60 °C. The solid was finely ground and transferred to a porcelain boat and placed in a tube furnace. The temperature was increased at 5 °C / min to 80 °C and held for 30 min. Then the temperature was increased at 5 °C / min to 220 °C and held for 120 min. The sample was cooled naturally. The obtained sample was recorded as Au-Mo 0.1 W 0.9 O 2.72 -3, and ICP-OES further confirmed that the loading amount of Au nanoparticles was approximately 9.8 wt%.

[0037] Comparative Example 1

[0038] 100 mg of W(CO)6 was mixed with 28.75 mL of ethanol under vigorous stirring until the solid was completely dissolved, then transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and treated at 160°C for 16 hours. After cooling to room temperature, the mixture was centrifuged, washed three times with a mixture of ethanol and water in a volume ratio of 1:1, and dried in a vacuum oven at 100°C. The obtained sample was recorded as WO 2.72 .

[0039] Comparative Example 2

[0040] 100 mg of W(CO)6 was mixed with 28.75 mL of ethanol under vigorous stirring until the solid was completely dissolved. Then, 1.25 mL of HCl solution (36 wt%) and 5 mg of MoCl5 were measured and mixed with the above solution and stirred for 30 minutes. The final mixture was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and treated at 160°C for 16 hours. After cooling to room temperature, it was separated by centrifugation, washed three times with a mixture of ethanol and water with a volume ratio of 1:1, and dried in a vacuum oven at 100°C. The obtained sample was recorded as MoWO 2.72 .

[0041] Comparative Example 3

[0042] 100 mg of W(CO)6 was mixed with 28.75 mL of ethanol under vigorous stirring until the solid was completely dissolved, transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave, and treated at 160 ° C for 16 hours. After cooling to room temperature, it was separated by centrifugation, washed three times with a mixture of ethanol and water with a volume ratio of 1:1, and dried in a vacuum oven at 100 ° C to obtain the product WO 2.72 50mg WO 2.72 0.6 ml of 25 mM HAuCl4 was dissolved in 20 mL of saturated Ar-containing water and stirred at room temperature for 120 min. The solid was collected by centrifugation and dried in a vacuum at 60°C. The solid was finely ground and transferred to a porcelain boat and placed in a tube furnace. The temperature was increased at 5°C / min to 80°C and held for 30 min. The temperature was then increased at 5°C / min to 220°C and held for 120 min. The sample was then cooled naturally. The resulting sample was designated Au-WO. 2.72 .

[0043] Comparative Example 4

[0044] 100 mg of W(CO)6 was mixed with 28.75 mL of ethanol under vigorous stirring until the solid was completely dissolved. Then, 1.25 mL of HCl solution (36 wt%) and 0.05 mmol of CuCl2 were measured and mixed with the above solution and stirred for 30 minutes. The final mixture was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and treated at 160°C for 16 hours. After cooling to room temperature, it was separated by centrifugation, washed three times with a mixture of ethanol and water with a volume ratio of 1:1, and dried in a vacuum oven at 100°C. The obtained sample was recorded as CuWO 2.72 .

[0045] Comparative Example 5

[0046] 100 mg of W(CO)6 was mixed with 28.75 mL of ethanol under vigorous stirring until the solid was completely dissolved. Then, 1.25 mL of 36 wt% HCl solution and 0.05 mmol of LaCl3 were added to the solution and stirred for 30 minutes. The final mixture was transferred to a 100 mL polytetrafluoroethylene-lined stainless steel autoclave and treated at 160°C for 16 hours. After cooling to room temperature, the mixture was centrifuged, washed three times with a mixture of ethanol and water in a 1:1 volume ratio, and dried in a vacuum oven at 100°C. The resulting sample was designated LaWO. 2.72 .

[0047] The samples prepared in Comparative Examples 1, 2, 3, 4 and 5 were used for photocatalytic synthesis of ammonia. The results were as follows: Figure 4 Shown: WO 2.72 、MoWO 2.72 、CuWO 2.72 、LaWO 2.72 and Au-WO 2.72 The ammonia production rates of MoWO were 21.2 μmol / g / h, 261.3 μmol / g / h, 79.4 μmol / g / h, 46.8 μmol / g / h and 34.7 μmol / g / h, respectively. 2.72 The catalytic activity is obviously better than that of other comparative examples.

[0048] The samples prepared in Example 1 and Comparative Example 1 were used for photocatalytic synthesis of ammonia for 4 hours. Figure 5 Shown: Au-Mo 0.1 W 0.9 O 2.72 The dual plasmon nanoreactor has excellent photocatalytic nitrogen fixation performance and is significantly better than the supported catalyst. Under full-spectrum light irradiation, without adding any sacrificial agent, the ammonia production rate is as high as 562.3 μmol / g / h.

[0049] like Figure 6 As shown, Au-Mo 0.1 W 0.9 O 2.72 Compared with WO 2.72 The catalyst enhances the light absorption in the visible region and broadens the light absorption in the near-infrared region, making Au-Mo 0.1 W 0.9 O 2.72 Has good full spectrum absorption.

[0050] like Figure 7 As shown, Au-Mo 0.1 W 0.9 O 2.72 Compared with WO2.72 The catalyst exhibits good photocurrent response.

[0051] like Figure 8 As shown, Au-Mo 0.1 W 0.9 O 2.72 Compared with WO 2.72 The catalyst has a stronger chemical adsorption for nitrogen.

Claims

1. An Au-Mo 0.1 W 0.9 O 2.72 The dual plasmon nanoreactor is characterized by: The Au-Mo 0.1 W 0.9 O 2.72 Dual plasmon nanoreactor based on Mo 0.1 W 0.9 O 2.72 As a carrier, loaded with 2-10wt% Au nanoparticles; The specific preparation process is as follows: First, a tungsten source and a molybdenum source are dissolved in ethanol to obtain a tungsten-molybdenum mixed solution; the tungsten-molybdenum mixed solution is solvent-thermally synthesized into molybdenum-doped tungsten oxide; then, a chloroauric acid solution and molybdenum-doped tungsten oxide are mixed and impregnated to obtain a precursor; finally, the precursor is calcined in a reducing atmosphere to obtain Au-Mo 0.1 W 0.9 O 2.72 Dual plasmon nanoreactor.

2. The Au-Mo according to claim 1 0.1 W 0.9 O 2.72 The dual plasmon nanoreactor is characterized by: The loading amount of the Au nanoparticles is 4-6 wt %.

3. The Au-Mo according to claim 1 0.1 W 0.9 O 2.72 The dual plasmon nanoreactor is characterized by: The tungsten source is selected from one of tungsten pentachloride, tungsten hexachloride and tungsten hexacarbonyl; the molybdenum source is molybdenum pentachloride.

4. The Au-Mo according to claim 1 0.1 W 0.9 O 2.72 The dual plasmon nanoreactor is characterized by: The solvent thermal temperature is 140-200° C. and the time is 12-24 hours.

5. The Au-Mo according to claim 1 0.1 W 0.9 O 2.72 The dual plasmon nanoreactor is characterized by: The concentration of the chloroauric acid solution is 10-50 mmol / L.

6. The Au-Mo according to claim 1 0.1 W 0.9 O 2.72 The dual plasmon nanoreactor is characterized by: The calcination process is: heating to 60-100° C. at 2-10° C. / min and maintaining for 0.5-1 hour, then heating to 200-240° C. at 2-10° C. / min and maintaining for 1-3 hours; the reducing atmosphere is a H2 / Ar mixed atmosphere.

7. The Au-Mo according to any one of claims 1 to 6 0.1 W 0.9 O 2.72 The application of the dual plasmon nanoreactor is characterized by: It is used for photocatalytic nitrogen fixation.

Images