Preparation method and application of perovskite oxide nanofibers anchoring Ru single atoms

Abstract

The present invention relates to a preparation method and application of perovskite oxide nanofibers anchored with Ru single atoms. The method comprises the following steps: 1) Mixing a polyvinylpyrrolidone solution, La(NO3)3·6H2O and Ni(NO3)3·6H2O for 10 - 14 h to obtain a spinning precursor solution; 2) Electrospinning the spinning precursor solution to obtain a polyvinylpyrrolidone nanofiber membrane; 3) Calcining the polyvinylpyrrolidone nanofiber membrane to obtain La 0.9 NiO3; 4) Immersing La 0.9 NiO3 in a methanol solution of RuCl3 to obtain La 0.9 NiO3 impregnated with Ru; 5) Calcining La 0.9 NiO3 impregnated with Ru to obtain Ru-La 0.9 NiO3. The nanofibers obtained in the present invention are used for the electrocatalytic reaction of furfural to produce 1,2-bis(furan-2-yl)ethane-1,2-diol (HDF), and the furfural conversion rate can reach 82%.

Description

Technical Field

[0001] The present invention relates to the technical field of electrocatalytic biomass conversion, and particularly relates to a preparation method and application of ruthenium single-atom anchored perovskite oxide nanofibers. Background Art

[0002] Biomass energy is a renewable and sustainable resource in nature. It is rich in variety, widely distributed, and has low usage costs. These advantages make it the most competitive substance for addressing energy shortage problems. Biomass compounds can be used as carriers for hydrogen energy storage and transportation. The method of electrocatalytic organic hydrogenation is a promising technology for the efficient utilization and conversion of biomass compounds. Compared with thermal catalysis, electrocatalysis avoids high-temperature and high-pressure reaction conditions, reduces the use of additional hydrogen, and has the advantages of being green and safe, meeting the sustainable development strategy.

[0003] Furfural can be obtained from agricultural and forestry waste. Furfural is an important intermediate for the production of key furan compounds such as 5-hydroxymethylfurfural and furan resin. High-value-added chemicals such as furfuryl alcohol, 1,2-bis(furan-2-yl)ethane-1,2-diol (HDF), and tetrahydrofuran obtained by the selective hydrogenation of furfural are widely used in the fields of energy, chemicals, and materials.

[0004] In electrocatalytic methods, noble metal catalysts (such as Pt, Ru, and Pd) are one of the ideal catalysts with high catalytic activity and stability. However, due to problems such as high noble metal costs and limited resources, their widespread application is restricted. Therefore, there is an urgent need to develop stable and effective electrocatalysts to replace noble metal catalysts. Although perovskite oxides have rich elemental compositions and flexible and adjustable structures, their electrocatalytic performance still has many limitations, such as limited adsorption capacity for substrates and insufficient number of active sites. Currently, although materials with single atoms anchored in oxides have been studied, materials with noble metal single atoms anchored in perovskite oxides have not been prepared. Summary of the Invention

[0005] The purpose of the present invention is to provide a preparation method and application of ruthenium single-atom anchored perovskite oxide nanofibers for the limitations existing in the current technology. This method initially anchors ruthenium single atoms through physical adsorption by optimizing the impregnation solution concentration, and then further allows ruthenium single atoms to enter the defect sites of La to form Ru-O bonds by controlling the calcination temperature and using chemical adsorption, ultimately obtaining La 0.9 NiO 3 ruthenium single-atom anchored perovskite oxide nanofibers and applying them to the electrocatalytic furfural C-C coupling reaction. In the electrocatalytic furfural reaction of the nanofibers obtained in the present invention, the furfural conversion rate can reach 82%.

[0006] To achieve the above-mentioned invention objectives, the present invention provides the following technical solutions:

[0007] A preparation method of perovskite oxide nanofibers anchored with Ru single atoms, comprising the following steps:

[0008] 1) Mix a polyvinylpyrrolidone (PVP) solution, La(NO 3 ) 3 ·6H 2 O and Ni(NO 3 ) 3 ·6H 2 O for 10 - 14 h to obtain a spinning precursor solution;

[0009] Among them, the mass ratio of La(NO 3 ) 3 ·6H 2 O to Ni(NO 3 ) 3 ·6H 2 O is 0.56 - 0.60:0.41 - 0.45;

[0010] The mass ratio of the polyvinylpyrrolidone solution to La(NO 3 ) 3 ·6H 2 O is 8 - 11:0.56 - 0.60.

[0011] 2) Electrospin the spinning precursor solution to obtain a polyvinylpyrrolidone nanofiber membrane;

[0012] The voltage of the electrospinning is 14 - 18 kV, and the spinning distance is 14 - 18 cm.

[0013] 3) Calcinate the polyvinylpyrrolidone nanofiber membrane to obtain La 0.9 NiO 3 ;

[0014] Among them, the calcination treatment includes a first calcination treatment and a second calcination treatment; in the first calcination treatment, the temperature is 200 - 280 °C and the time is 2.5 - 4.5 h; in the second calcination treatment, the temperature is 750 - 840 °C and the time is 1.5 - 3.5 h.

[0015] The rate of heating from room temperature to the first calcination temperature and the rate of heating from room temperature to the second calcination temperature in the calcination treatment are independently 5 - 8 °C / min.

[0016] 4) Mix the obtained La 0.9 NiO 3 and RuCl 3Add it to methanol and impregnate for 8 - 16 h. After taking it out, La impregnated with Ru is obtained. 0.9 NiO 3 ; Add 0.1 - 0.6 g of RuCl to every 15 mL of methanol. 3 ;

[0017] 5) Calcinate the La impregnated with Ru 0.9 NiO 3 to obtain Ru - La 0.9 NiO 3 , that is, La 0.9 NiO 3 perovskite oxide nanofibers with Ru single atoms anchored;

[0018] In step 1), the solvent of the polyvinylpyrrolidone solution is N,N - dimethylformamide (DMF). In the polyvinylpyrrolidone solution, the mass fraction of polyvinylpyrrolidone is 8 - 12%.

[0019] In step 3), the first calcination treatment of the calcination treatment is carried out in a tubular furnace with an argon atmosphere; the second calcination treatment is carried out in a muffle furnace.

[0020] In step 4), the mass ratio of La 0.9 NiO 3 to RuCl 3 is 0.09 - 0.15:0.1 - 0.6.

[0021] In step 5), the calcination treatment includes a one - step calcination treatment. During the calcination treatment, the temperature is 300 - 380 °C and the time is 1.5 - 2.5 h.

[0022] In step 5), the heating rate of the calcination treatment from room temperature to the one - step calcination treatment temperature is 4 - 6 °C / min.

[0023] In step 5), the one - step calcination treatment of the calcination treatment is carried out in a tubular furnace with a nitrogen atmosphere.

[0024] Application of the La 0.9 NiO 3 perovskite oxide nanofibers with Ru single atoms anchored prepared by the method for electrocatalytic furfural C - C coupling reaction to prepare HDF.

[0025] Specifically, it includes the following steps: Carry out electrocatalysis for 1 - 10 hours under a single electrolytic cell and a three - electrode system; among them, the reference electrode is an Ag / AgCl electrode, the counter electrode is graphite, and the working electrode is a hydrophilic carbon paper loaded with La 0.9 NiO 3 perovskite oxide nanofibers with Ru single atoms anchored;

[0026] Every 1 cm2 The hydrophilic carbon paper is loaded with 1 - 1.2 mg of La anchored with Ru single atoms 0.9 NiO 3 Perovskite oxide nanofibers; the electrolyte is a phosphate buffer solution of 10 - 100 mmol / L of furfural.

[0027] The substantial features of the present invention are as follows:

[0028] The obtained La anchored with Ru single atoms in the present invention 0.9 NiO 3 Perovskite oxide nanofibers, combining single - atom catalysts and perovskite oxide catalysts. Compared with single - atom catalysts, the amount of precious metals used is reduced, and compared with perovskite oxide catalysts, the number of active sites is increased. First, control the mass ratio of La(NO 3 ) 3 ·6H 2 O and Ni(NO 3 ) 3 ·6H 2 O in the electrospinning solution to prepare La 0.9 NiO 3 Perovskite oxide nanofibers with La defect sites. Second, optimize the mass ratio of RuCl 3 to La 0.9 NiO 3 in the impregnation solution. If the concentration of the RuCl 3 solution is high, Ru clusters are likely to form on the surface of the nanofibers; if the concentration of the RuCl 3 solution is low, it is not sufficient to anchor at the La defect sites. Finally, optimize the calcination temperature so that Ru is anchored at the La 0.9 NiO 3 defect sites of the perovskite oxide and forms a bond with O to form a stable catalyst structure.

[0029] The beneficial effects of the present invention include:

[0030] 1) The present invention combines the electrospinning method, impregnation method and high - temperature calcination method to prepare perovskite oxide nanofibers Ru - La 0.9 NiO 3 anchored with Ru single atoms.

[0031] 2) The present invention provides an effective method to anchor precious metal single - atom Ru in the La 0.9 NiO 3 La defect sites, realizing the synergistic catalytic effect of precious metal single - atoms and perovskite oxides for the electrocatalytic C - C coupling reaction of furfural to prepare HDF, and the furfural conversion rate can reach 82%. Description of the Drawings

[0032] Figure 1 The La 0.9 NiO 3 Scanning electron microscopy image of perovskite oxide nanofibers obtained in Example 1.

[0033] Figure 2 The Ru-La 0.9 NiO 3 Scanning electron microscopy image of perovskite oxide nanofibers obtained in Example 1.

[0034] Figure 3 Scanning electron microscopy image of the substance obtained in Example 2.

[0035] Figure 4 The Ru-La 0.9 NiO 3 X-ray diffraction pattern of perovskite oxide nanofibers obtained in Example 3.

[0036] Figure 5 The Ru-La 0.9 NiO 3 Transmission electron microscopy image and elemental mapping of perovskite oxide nanofibers obtained in Example 4.

[0037] Figure 6 The Ru-La 0.9 NiO 3 Conversion rate effect diagram of perovskite oxide nanofibers for electrocatalytic furfural reaction at different voltages.

[0038] Figure 7 The Ru-La 0.9 NiO 3 1H NMR spectral data of the product HDF obtained from the electrocatalytic furfural C-C coupling reaction using perovskite oxide nanofibers. Detailed implementation manners

[0039] The present invention provides a method for preparing perovskite oxide nanofibers anchored with Ru single atoms. The anchored Ru perovskite oxide nanofibers are Ru-La 0.9 NiO 3 , and the method comprises the following steps:

[0040] 1) Mix a polyvinylpyrrolidone solution, La(NO 3 ) 3 ·6H 2 O and Ni(NO 3 ) 3 ·6H 2 O to obtain a spinning precursor solution;

[0041] 2) Electrospin the spinning precursor solution to obtain a polyvinylpyrrolidone nanofiber membrane;

[0042] 3) Calcinate the polyvinylpyrrolidone nanofiber membrane to obtain La 0.9 NiO 3 .

[0043] 4) Immerse La 0.9 NiO 3 in a methanol solution of RuCl 3 to obtain La impregnated with Ru 0.9 NiO 3 .

[0044] 5) Calcinate La 0.9 NiO 3 impregnated with Ru to obtain Ru-La 0.9 NiO 3 .

[0045] In the present invention, the solvent of the polyvinylpyrrolidone solution in step 1) is preferably N,N-dimethylformamide (DMF). In the polyvinylpyrrolidone solution, the mass fraction of polyvinylpyrrolidone (PVP) is preferably 8-12%, more preferably 10%.

[0046] In the present invention, when the perovskite oxide nanofiber is La 0.9 NiO 3 , the mass ratio of La(NO 3 ) 3 ·6H 2 O and Ni(NO 3 ) 3 ·6H 2 O is preferably 0.57-0.59:0.42-0.44, more preferably 0.58:0.43.

[0047] In the present invention, the mass ratio of the polyvinylpyrrolidone solution and La(NO 3 ) 3 ·6H 2 O is preferably 9-11:0.57-0.59, more preferably 10:0.58.

[0048] In the present invention, the mixing time in step 1) is preferably 11-13 h, more preferably 12 h; the mixing temperature is preferably room temperature; the mixing is preferably carried out under stirring conditions.

[0049] In the present invention, the voltage of the electrospinning in step 2) is preferably 15-17 kV, more preferably 16 kV; the spinning distance is preferably 15-17 cm, more preferably 16 cm.

[0050] In the present invention, the calcination treatment in step 3) preferably includes a first calcination treatment and a second calcination treatment; in the first calcination treatment, the temperature is preferably 240-250 °C; the time is preferably 2.5-3.5 h, more preferably 3 h; in the second calcination treatment, the temperature is preferably 770-820 °C, more preferably 780-800 °C; the time is preferably 2.5-3.5 h, more preferably 3 h.

[0051] In the present invention, the rate of heating from room temperature to the first calcination temperature and the rate of heating from the first calcination temperature to the second calcination temperature are independently preferably 4-6 °C / min, more preferably 5 °C / min.

[0052] In the present invention, the first calcination treatment is preferably carried out in a tubular furnace under an argon atmosphere; the second calcination treatment is preferably carried out in a muffle furnace, and the process of heating from room temperature to the first calcination temperature is preferably an argon atmosphere.

[0053] In the present invention, La 0.9 NiO 3 and RuCl 3 are added together to methanol for impregnation. The mass ratio of La 0.9 NiO 3 to RuCl 3 is preferably 0.11-0.13:0.2-0.4, more preferably 0.12:0.3. The volume of methanol is preferably 12-18 mL, more preferably 15 mL; the impregnation duration is preferably 10-14 h, more preferably 12 h.

[0054] In the present invention, the Ru-impregnated La 0.9 NiO 3 is subjected to a one-step calcination treatment. In the one-step calcination treatment, the temperature is preferably 320-360 °C, more preferably 340-350 °C; the time is preferably 1.5-2.5 h, further preferably 2 h.

[0055] In the present invention, the rate of heating from room temperature to the one-step calcination treatment temperature is preferably 4-6 °C / min, more preferably 5 °C / min. The one-step calcination treatment is preferably carried out in a tubular furnace under a nitrogen atmosphere, and the process of heating from room temperature to the one-step calcination treatment temperature is preferably a nitrogen atmosphere.

[0056] The technical solutions provided by the present invention will be described in detail below in conjunction with the embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0057] Example 1:

[0058] In a 5 g PVP solution (in the PVP solution, the solvent is DMF and the mass fraction of PVP is 10%), 0.2923 g of La(NO 3 ) 3 ·6H 2 O and 0.2181 g of Ni(NO 3 ) 3 ·6H 2 O are added. Stir at a speed of 400 rmp at room temperature for 12 h to obtain a uniformly mixed spinning precursor solution. The spinning precursor solution is electrospun at a voltage of 16 kV with a spinning distance of 16 cm to obtain a PVP nanofiber membrane with a thickness of about 1 mm. The PVP nanofiber membrane is placed in a tube furnace for calcination. First, it is heated from room temperature to 250 °C at a rate of 5 °C / min in an argon atmosphere and calcined at 250 °C in an argon atmosphere for 3 h. Then it is transferred to a muffle furnace and heated from 20 °C to 800 °C at a rate of 5 °C / min and kept at 800 °C for 3 h to obtain La 0.9 NiO 3 perovskite oxide nanofibers. 0.12 g of La 0.9 NiO 3 perovskite oxide nanofibers and 0.3 g of RuCl 3 are simultaneously added to 15 mL of methanol solution and soaked for 12 h. The soaked material is calcined at 350 °C in a nitrogen atmosphere for 2 h. Ru-La 0.9 NiO 3 perovskite oxide nanofibers are obtained.

[0059] Example 2:

[0060] Change the mass of La(NO 3 ) 3 ·6H 2 O in Example 1 to 0.2598 g, and keep other conditions the same as in Example 1. The target substance is not obtained.

[0061] Example 3:

[0062] Change the mass fraction of Ru in Example 1 to 2.8%, and keep other conditions the same as in Example 1. Ru-La 0.9 NiO 3 perovskite oxide nanofibers are obtained.

[0063] Example 4:

[0064] In 4.8 g of PVP solution (in the PVP solution, the solvent is DMF and the mass fraction of PVP is 12%), 0.2900 g of La(NO 3 )3 ·6H 2 O and 0.2170 g Ni(NO 3 ) 3 ·6H 2 O were stirred at 400 rmp for 13 h at room temperature to obtain a uniformly mixed spinning precursor solution. The spinning precursor solution was electrospun at a voltage of 15 kV with a spinning distance of 15 cm to obtain a PVP nanofiber membrane. The PVP nanofiber membrane was calcined. First, it was heated from room temperature to 240 °C at a rate of 4.8 °C / min in an argon atmosphere and calcined for 2.8 h, then transferred to a muffle furnace and heated from room temperature to 780 °C and calcined for 3 h to obtain La 0.9 NiO 3 perovskite oxide nanofibers. 0.13 g of La 0.9 NiO 3 perovskite oxide nanofibers and 0.31 g of RuCl 3 were simultaneously added to 15 mL of methanol solution and soaked for 11 h. The soaked material was heated from room temperature to 340 °C at a rate of 4.8 °C / min in a nitrogen atmosphere and calcined for 1.9 h. Ru-La 0.9 NiO 3 perovskite oxide nanofibers were obtained.

[0065] Example 5:

[0066] This example provides a method for electrocatalytic furfural C-C coupling reaction, which is carried out according to the following steps:

[0067] 15 mL of 50 mmol / L phosphate buffer solution of furfural (pH = 6.86) was added to a single electrolytic cell, and electrochemical tests were carried out using the three-electrode system of Chenhua CHI760E electrochemical workstation. Among them, the reference electrode was an Ag / AgCl electrode, the counter electrode was a graphite rod, and the working electrode was a hydrophilic carbon paper loaded with 1 - 1.2 mg / cm 2 Ru-La 0.9 NiO 3 catalyst. Using chronoamperometry, the reaction was carried out for 4 h at a given voltage. The products were detected by gas chromatography, and the conversion rate of furfural was calculated to reach 82% at -1.4 V vs. RHE.

[0068] Preparation of the working electrode: 3 mg of Ru-La 0.9 NiO 3 , 340 µL of pure water, 160 µL of ethanol and 20 µL of Nafion were mixed evenly and sonicated for 5 min to obtain a uniformly mixed catalyst ink. On an area of 1 cm 2180 µL of the uniformly mixed catalyst ink was dropped onto the hydrophilic carbon paper to obtain a working electrode with a catalyst loading of 1.038 mg / cm 2 Working electrode.

[0069] Characterization results:

[0070] The La 0.9 NiO 3 perovskite oxide nanofibers obtained in Example 1 were characterized by scanning electron microscopy. As can be seen from Figure 1 it, the La 0.9 NiO 3 perovskite oxide nanofibers were successfully prepared in this invention.

[0071] The Ru-La 0.9 NiO 3 perovskite oxide nanofibers obtained in Example 1 were characterized by scanning electron microscopy. As can be seen from Figure 2 it, the Ru-La 0.9 NiO 3 perovskite oxide nanofibers were successfully prepared in this invention.

[0072] The substance obtained in Example 2 was characterized by scanning electron microscopy. As can be seen from Figure 3 it, the target substance was not successfully prepared. Since the mass ratio of the polyvinylpyrrolidone solution and La(NO 3 ) 3 ·6H 2 O was increased, there was excess metal La that could not enter the perovskite oxide lattice to form a stable structure. After calcination, high molecular compounds such as polyvinylpyrrolidone volatilized, resulting in morphological collapse and the destruction of the nanofiber morphology.

[0073] The Ru-La 0.9 NiO 3 perovskite oxide nanofibers obtained in Example 3 were characterized by X-ray diffraction. As can be seen from Figure 4 it, the Ru-La 0.9 NiO 3 perovskite oxide nanofibers were successfully prepared in this invention.

[0074] The Ru-La 0.9 NiO 3 perovskite oxide nanofibers obtained in Example 4 were characterized by transmission electron microscopy and elemental scanning tests. As can be seen from (a) in Figure 5 , the Ru-La 0.9 NiO 3 perovskite oxide nanofibers were successfully prepared in this invention. As can be seen from (b-f) in Figure 5 , the elemental scanning map contains four elements: La, Ni, O, and Ru.

[0075] The Ru-La 0.9 NiO 3 perovskite oxide nanofibers obtained in Example 4 were subjected to the tests given in Example 5. As Figure 6 can be seen, the conversion rate of furfural reached 82% at -1.4 V vs. RHE.

[0076] Figure 7 Shown is the 1H NMR spectrum of the product HDF. The peak positions correspond to the H marked a-d in Figure 7 .

[0077] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

[0078] Matters not covered by the present invention are well-known techniques.

Claims

1. A method for preparing perovskite oxide nanofibers anchoring Ru single atoms, characterized in that: The method comprises the following steps: 1) Mixing polyvinyl pyrrolidone solution, La(NO3)3·6H2O and Ni(NO3)3·6H2O for 10-14 h to obtain a spinning precursor solution; Among them, the mass ratio of La(NO3)3·6H2O and Ni(NO3)3·6H2O is 0.56~0.60:0.41~0.45; The mass ratio of polyvinyl pyrrolidone solution and La(NO3)3·6H2O is 8~11:0.56~0.60; 2) electrospinning the spinning precursor solution to obtain a polyvinyl pyrrolidone nanofiber membrane; The voltage of the electrospinning is 14-18 kV, and the spinning distance is 14-18 cm; 3) The polyvinyl pyrrolidone nanofiber membrane is calcined to obtain La 0.9 NiO3; The calcination treatment includes a first calcination treatment and a second calcination treatment; in the first calcination treatment, the temperature is 200-280°C and the time is 2.5-4.5 h; in the second calcination treatment, the temperature is 750-840°C and the time is 1.5-3.5 h; 4) The obtained La 0.9 NiO3 and RuCl3 were added to methanol and immersed for 8-16 hours, and then La impregnated with Ru was obtained. 0.9 NiO3; add 0.1~0.6 g of RuCl3 per 15 mL of methanol; 5) La impregnated with Ru 0.9 NiO3 is calcined to obtain Ru-La 0.9 NiO3, i.e., perovskite oxide nanofibers anchoring Ru single atoms.

2. The method for preparing the Ru single atom anchored perovskite oxide nanofiber according to claim 1, characterized in that: Step 1) The solvent of the polyvinyl pyrrolidone solution is N,N-dimethylformamide, and the mass fraction of polyvinyl pyrrolidone in the polyvinyl pyrrolidone solution is 8-12%.

3. The method for preparing the Ru single atom anchored perovskite oxide nanofiber according to claim 1, characterized in that: Step 3) the first calcination treatment is carried out in a tube furnace with an argon atmosphere; the second calcination treatment is carried out in a muffle furnace; The rate of heating from room temperature to the first calcination temperature and the rate of heating from room temperature to the second calcination temperature in the calcination treatment are independently 5-8°C / min.

4. The method for preparing Ru single-atom anchored perovskite oxide nanofibers according to claim 1, characterized in that the steps 4) Medium 0.9 The mass ratio of NiO3 to RuCl3 is 0.09~0.15:0.1~0.

6.

5. The method for preparing the Ru single-atom anchored perovskite oxide nanofibers according to claim 1, characterized in that: Step 5) The calcination temperature is 300-380°C, the time is 1.5-2.5h; the heating rate is 4-6°C / min; the calcination treatment is carried out in a tubular furnace with a nitrogen atmosphere.

6. Application of the perovskite oxide nanofiber anchoring Ru single atoms prepared by the method of claim 1, characterized in that: Used for electrocatalytic furfural CC coupling reaction to prepare HDF.

7. The use according to claim 6, characterized in that: The method comprises the following steps: performing electrocatalysis for 1 to 10 hours in a single electrolytic cell and three-electrode system; wherein the reference electrode is an Ag / AgCl electrode, the counter electrode is graphite, and the working electrode is a hydrophilic carbon paper loaded with perovskite oxide nanofibers anchoring single Ru atoms; Every 1cm 2 The hydrophilic carbon paper is loaded with 1~1.2 mg of perovskite oxide nanofibers anchoring Ru single atoms; the electrolyte is 10~100 mmol / L furfural in phosphate buffer.

Images