阅读说明：本技术 一种正交相MoO3电催化剂及其制备方法和应用 (Quadrature phase MoO3Electrocatalyst and preparation method and application thereof ) 是由 滕飞 阮万生 梁舒予 袁晨 卢子霖 王丹 郝唯一 马奔 于 2021-09-16 设计创作，主要内容包括：本发明提供一种正交相MoO-(3)电催化剂及其制备方法和应用,所述制备方法包括以下步骤：S1.将钼酸盐、聚乙二醇和水混合,搅拌得到混合溶液；S2.向S1得到的混合溶液中加入浓硝酸,并持续搅拌；S3.将步骤S2得到的混合溶液加入到水热釜内衬中,进行水热反应；S4.冷却至室温,经离心、洗涤和干燥,即得正交相MoO-(3)电催化剂,制得的MoO-(3)电催化剂是直径为200-300nm,长度为5-10μm的纳米线形貌,本发明还公开了其在电催化水氧化、产氢和染料降解中的应用,具有较高催化活性的同时能够有效降解环境污染物。(The invention provides an orthorhombic phase MoO 3 An electrocatalyst, a preparation method and application thereof, wherein the preparation method comprises the following steps: s1, mixing molybdate, polyethylene glycol and water, and stirring to obtain a mixed solution; s2. mixing to S1Adding concentrated nitric acid into the mixed solution, and continuously stirring; s3, adding the mixed solution obtained in the step S2 into a lining of a hydrothermal kettle to perform hydrothermal reaction; s4, cooling to room temperature, centrifuging, washing and drying to obtain the orthorhombic phase MoO 3 Electrocatalyst, MoO produced 3 The electrocatalyst is in the shape of a nanowire with the diameter of 200-300nm and the length of 5-10 mu m, and the invention also discloses the application of the electrocatalyst in electrocatalysis water oxidation, hydrogen production and dye degradation, and the electrocatalyst has higher catalytic activity and can effectively degrade environmental pollutants.)

1. Quadrature phase MoO₃The preparation method of the electrocatalyst is characterized by comprising the following steps: the method comprises the following steps:

s1, mixing molybdate, polyethylene glycol and water, and stirring to obtain a mixed solution;

s2, adding concentrated nitric acid into the mixed solution obtained in the step S1, and continuously stirring;

s3, adding the mixed solution obtained in the step S2 into a lining of a hydrothermal kettle to perform hydrothermal reaction;

s4, cooling to room temperature, centrifuging, washing and drying to obtain the orthorhombic phase MoO₃An electrocatalyst.

2. The orthorhombic MoO of claim 1₃The preparation method of the electrocatalyst is characterized by comprising the following steps: step S1 provides that the molybdate is ammonium molybdate.

3. The orthorhombic MoO of claim 1₃The preparation method of the electrocatalyst is characterized by comprising the following steps: in step S1, 1.23g of ammonium molybdate, 0.4g of polyethylene glycol and 30mL of water are mixed; step S2, adding 5mL of concentrated nitric acid with the concentration of 65-68%; and step S3, carrying out constant-temperature hydrothermal reaction at 160 ℃ for 24 h.

4. An orthorhombic MoO prepared by the method of claim 1₃An electrocatalyst, characterized by: the quadrature phase MoO₃The morphology of the electrocatalyst is a nanowire, the diameter of the nanowire is 200-300nm, and the length of the nanowire is 5-10 μm.

5. The orthorhombic MoO of claim 4₃Use of an electrocatalyst for electrocatalytic water oxidation.

6. The orthorhombic MoO of claim 4₃Application of the electrocatalyst in hydrogen production and dye degradation.

Technical Field

The invention belongs to the technical field of electrocatalysis water oxidation, and particularly relates to an orthorhombic phase MoO₃An electrocatalyst, a method of making and use thereof.

Background

In recent years, the problems of energy shortage and environmental pollution are highlighted, and the development of clean and renewable energy sources is accelerated. Hydrogen energy is widely spotlighted as a clean energy source because of its high energy and no pollution of products. At present, the conventional methods for producing hydrogen on a large scale mainly comprise water electrolysis, steam reforming, coal gasification and the like, but the latter two methods can produce a large amount of CO₂Aggravate the climate warming; the electrolyzed water product is pollution-free and is a good choice. Electrocatalysts are key to water electrolysis, noble metals such as Pt, RuO being one of the most effective electrocatalysts₂And IrO₂Have been studied extensively. However, its practical application is limited due to its scarcity and high cost. Transition metal oxides are the best choice for replacing noble metals due to their relatively low cost and stability.

Among transition metal oxides, molybdenum trioxide (MoO)₃) Have received much attention due to the diversity of their structures and functions. In the existing reports, Jiangjun et al disclose a preparation method and application of black molybdenum trioxide nanosheetsThe invention is mainly applied to the solar drive seawater desalination (publication number: CN 112694125A), but the preparation scheme is complex; in addition, Weishizhong et al reported a nano MoO for photocatalytic degradation₃Method for preparing powder (application publication No. CN 108786786A), the invention mainly uses MoO₃The method is applied to the field of photocatalytic degradation.

On the other hand, the organic dye wastewater contains stable polycyclic aromatic hydrocarbon and is difficult to naturally degrade, so that the dye wastewater discharge has serious influence on environment and ecology. The preparation method of the catalyst for electrically and catalytically degrading organic wastewater (application publication number: CN 106669678A) and the method for flexibly and electrically and catalytically degrading dye-containing wastewater (application publication number: CN 110510701A) are respectively reported by Marsfeng et al and Wanyaong et al, and although the invention of the catalyst and the method effectively degrade industrial wastewater, hydrogen energy with high added value cannot be obtained. The invention not only can degrade organic dye pollutants, but also can realize hydrogen production at low voltage. The invention provides a new strategy with environmental protection and energy saving, which is expected to directly utilize industrial wastewater to realize hydrogen production and wastewater purification. Therefore, the method has obvious practical application value.

Investigations have shown that MoO of different crystal phases has not been synthesized₃(quadrature phase:α-MoO₃and a hexagonal phase:h-MoO₃) Electrolytic water was reported.

Disclosure of Invention

In order to solve the technical problems of scarcity and high price of noble metal in electrocatalysis, the invention provides an orthorhombic phase MoO₃An electrocatalyst, a method of making and use thereof.

The invention adopts the following technical scheme:

quadrature phase MoO₃A method of preparing an electrocatalyst, comprising the steps of:

s1, mixing molybdate, polyethylene glycol and water, and stirring to obtain a mixed solution;

s2, adding concentrated nitric acid into the mixed solution obtained in the step S1, and continuously stirring;

s3, adding the mixed solution obtained in the step S2 into a lining of a hydrothermal kettle to perform hydrothermal reaction;

s4, cooling to room temperature, centrifuging, washing and drying to obtain the orthorhombic phase MoO₃An electrocatalyst.

Further, step S1 provides that the molybdate is ammonium molybdate.

Further, 1.23g of ammonium molybdate, 0.4g of polyethylene glycol and 30mL of water are mixed in step S1; step S2, adding 5mL of concentrated nitric acid with the concentration of 65-68%; and step S3, carrying out constant-temperature hydrothermal reaction at 160 ℃ for 24 h.

Orthorhombic phase MoO prepared by the preparation method₃Electrocatalyst of said orthorhombic phase MoO₃The morphology of the electrocatalyst is a nanowire, the diameter of the nanowire is 200-300nm, and the length of the nanowire is 5-10 μm.

The quadrature phase MoO₃Use of an electrocatalyst for electrocatalytic water oxidation.

The quadrature phase MoO₃Application of the electrocatalyst in hydrogen production and dye degradation.

The invention has the beneficial effects that:

(1) the invention provides an orthorhombic phase molybdenum oxideα-MoO₃The application in electrocatalysis water oxidation, electrocatalysis hydrogen production and pollutant decomposition, when the electrocatalysis water oxidation is applied, under the overpotential of 450mV,α-MoO₃has an anodic current density ofh-MoO₃2.8 times of the total amount of the anode oxygen evolution catalyst, has higher anode oxygen evolution reaction activity, and greatly promotes the performance of water electrolysis;

(2) to reach 40mA/cm^-2The cell voltage of a KOH system is 1.93V, while the cell voltage of an MB/KOH system added with organic matters is only 1.597V, the cell voltage is reduced by 17.56%, the efficiency of water electrolysis is improved, which shows that the catalytic activity of the system can be improved by a certain organic matter MB content, and along with the proceeding of the electrolysis process, the structures of the organic matters MB and the conjugated diene are destroyed, and phenyl derivatives are formed, which shows that MB is effectively degraded.

Drawings

FIG. 1 is a molybdenum-based electrocatalyst preparedh-MoO₃Andα-MoO₃XRD pattern of (a);

FIG. 2 is prepared (a)h-MoO₃And (b)α-MoO₃SEM image of electrocatalyst;

FIG. 3 is preparedh-MoO₃Andα-MoO₃testing the electrocatalysis performance of the electrocatalyst in 1 MKOH;

FIG. 4 ish-MoO₃Andα-MoO₃current density histogram of electrocatalyst at 1 MKOH;

FIG. 5 is preparedα-MoO₃Respectively testing the electrocatalysis performance of the electrocatalysis at 1MKOH and 1MKOH +10 mg/LMB;

FIG. 6 isα-MoO₃Current density histograms of the electrocatalyst at 1MKOH and 1MKOH +10mg/LMB, respectively;

FIG. 7 is a UV-Vis spectrum of KOH/MB solution at different operating times.

Detailed Description

The present invention is further described with reference to the following examples, which are provided for illustration only and are not to be construed as limiting the scope of the claims, and other alternatives which may occur to those skilled in the art are also within the scope of the claims.

Example 1

Quadrature phase MoO₃A method of preparing an electrocatalyst, comprising the steps of:

s1, mixing 1.23g of molybdate, 0.4g of polyethylene glycol and 30mL of water, and stirring for 30min to obtain a mixed solution;

s2, adding 5ml of concentrated nitric acid with the concentration of 65-68% into the mixed solution obtained in the step S1, and continuously stirring for 30 min;

s3, adding the mixed solution obtained in the step S2 into a 50mL hydrothermal kettle lining, and carrying out hydrothermal reaction for 24 hours at a constant temperature of 160 ℃;

s4, cooling to room temperature, centrifuging, washing with ethanol, washing with water and drying to obtain alpha-MoO₃An electrocatalyst, as shown in the lower half of FIG. 1, withα-MoO₃The standard card (JCPDS: 89-7112) is consistent, and the prepared alpha-MoO₃The morphology of the electrocatalyst is a nanowire, as shown in FIG. 2 (b), the diameter of the nanowire is 200 nm and 300nm, and the length is 5-10 μm.

Comparative example 1

Adding 2.43g of ammonium molybdate into a beaker containing 10mL of aqueous solution, and stirring for 15 minutes; then adding 5ml of nitric acid with the concentration of 65-68%, stirring for half an hour, transferring the mixture into a 50ml of polytetrafluoroethylene lining, and carrying out hydrothermal reaction for 3 hours at the constant temperature of 180 ℃; after reacting for 3 hours, naturally cooling to room temperature, washing with water, centrifuging and drying to obtain the producth-MoO₃As shown in the upper half of FIG. 1, withh-MoO₃Standard card (JCPDS: 21-0569), as shown in FIG. 2 (a), was producedh-MoO₃The diameter is 2-5 μm and the length is about 20-30 μm.

Test applied to electrocatalytic water oxidation:

prepared in example 1α-MoO₃Mixing the electrocatalyst, the acetylene black and the polyvinylidene fluoride according to the mass ratio of 8:1:1, dispersing 1g of mixed powder in 2mL of 1-methyl-2-pyrrolidone, and stirring to form uniform slurry. The slurry was coated on a nickel foam and then dried at room temperature for 24 hours with a coating area of 1cm × 1cm to obtainα-MoO₃An electrode; prepared by comparative exampleh-MoO₃The electrode preparation of (1) was as above. The prepared electrode material is used as an anode, a platinum wire is used as a counter electrode, Ag/AgCl is used as a reference electrode, and a certain voltage is applied to the three-electrode system to perform an electrocatalytic performance test in 1 MKOH.

As can be seen from the view of figure 3,α-MoO₃electrode ratioh-MoO₃Has higher current and initial potential, which indicates that the catalyst has higher water oxidation intrinsic electrocatalytic activity. FIG. 4 shows the current densities at different overpotentials, at 250mV, 350mV and 450mV overpotentials,α-MoO₃the current density of the electrode is 2.38 mAcm^-2、19.06 mAcm^-2And 99.4mAcm^-2Is obviously higher thanh-MoO₃Electrode (0.67 mAcm)^-2、12.68 mAcm^-2And 34.87mAcm^-2). Wherein, at the value of 450mV,α-MoO₃the current density of the electrode ish-MoO₃2.8 times higher, because the phase structure affects the activity difference of the transition metal oxide,α-MoO₃electrode for electrochemical cellHigher anodic oxygen evolution reaction activity promotes the performance of water electrolysis, therefore,α-MoO₃the catalyst has good application prospect when being used as an electrocatalyst.

The method is applied to the test of hydrogen production and dye degradation:

will be preparedα-MoO₃Mixing the electrocatalyst, acetylene black and polyvinylidene fluoride according to the mass ratio of 8:1:1, dispersing 1g of mixed powder in 2mL of 1-methyl-2-pyrrolidone, and stirring to form uniform slurry. The slurry was coated on a nickel foam and then dried at room temperature for 24 hours with a coating area of 1cm × 1cm to obtainα-MoO₃And an electrode.

Prepared by the above methodα-MoO₃The electrode is used as an anode, a platinum wire is used as a counter electrode, Ag/AgCl is used as a reference electrode, and in the three-electrode system, a certain voltage is applied to carry out electrocatalysis performance tests in 1MKOH and 1MKOH +10mg/LMB respectively. As can be seen from FIG. 5, the addition of MB greatly reduces the overpotential of the electrolyzed water. For anodic oxidation, in KOH electrolytic systems, water oxidation requires a high pressure of 1.611V to reach 40mAcm^-2While the KOH/MB electrolytic system can reach 40mAcm only at 1.349V^-2. As shown in FIG. 6, for the cathodic reaction, the HER of the electrolytic KOH system and the KOH/MB system required voltages of-0.319V and-0.242V, respectively, to reach 40mAcm^-2. To reach 40mA/cm^-2The cell voltage of the KOH system is 1.93V, while the cell voltage of the MB/KOH system is only 1.597V, the cell voltage is reduced by 17.56 percent, and the water electrolysis efficiency is further improved.

As shown in FIG. 7, the UV-visible spectra of KOH/MB solutions were measured at different operating times, and two absorption peaks were observed in the visible region for 1MKOH/10mg/LMB solutions, at 610nm and 664nm, respectively. In the UV region, the two peaks are located at 219nm and 283nm, respectively. The absorption peaks at 610nm and 664nm are characteristic absorption peaks of MB, while the absorption peaks at 219nm and 283nm are attributed to conjugated diene and aldehyde structures, respectively. In addition, the absorption peak at 241nm is formed of benzene rings. As a result, the absorption peaks at 610nm and 664nm were significantly reduced, the absorption peaks at 219nm and 283nm disappeared, and the absorption peaks at 241nm appeared as the electrolytic process proceeded, indicating that the structures of MB and the conjugated diene were destroyed and the phenyl derivative was formed. After 2h, the peak in the visible range was clearly reduced, with a peak only at 241 nm. The above results indicate that MB has been effectively degraded, but some intermediates (benzene derivatives) remain, which is a common phenomenon of MB degradation. In conclusion, it is obvious that the design is energy-saving, and environmental pollutants are effectively degraded while water is electrolyzed at low pressure with high efficiency.

It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.