CN-121976214-A - Preparation and application of iron-nickel trinuclear cluster-based metal-organic framework loaded with Keggin type polyacid

Abstract

The invention relates to the technical field of electrocatalytic materials, and discloses a preparation method of an iron-nickel trinuclear cluster-based metal-organic framework (PMo 12 @Fe 2 Ni-MOF) loaded with Keggin type polyacid and application of the framework in electrocatalytic nitrate reduction synthesis of ammonia (NO 3 RR). According to the method, ferric nitrate nonahydrate, nickel nitrate hexahydrate, sodium acetate, fumaric acid and phosphomolybdic acid (PMo 12 ) are used as raw materials, a [ Fe 2 Ni(μ 3 -O)(CH₃COO) 6 ] trinuclear metal cluster is synthesized, and then in-situ loading of PMo 12 in MOF is realized by a one-step solvothermal method, so that the technical problems of easy agglomeration loss of polyacid and insufficient MOF electron transmission are solved. The catalysis performance of the material is obviously improved due to the synergistic effect of the trinuclear iron-nickel cluster and the PMo 12 , the Faraday efficiency is up to 82.78% at-0.8V vs. RHE potential, and the ammonia production rate is 14.03 mg h –1 mg –1 cat. , which is superior to most of the existing catalysts. The preparation process is mild and controllable, raw materials are easy to obtain, the nitrate recycling and the green ammonia synthesis can be realized at normal temperature and normal pressure, and the method has the advantages of environmental protection and energy value and good industrial application prospect.

Inventors

• WANG XINMING
• WANG ZHIWEI
• LI LIQING
• PANG HAIJUN

Assignees

• 哈尔滨理工大学

Dates

Publication Date

20260505

Application Date

20260205

Claims (9)

1. 1. The preparation method of the iron-nickel trinuclear cluster-based metal-organic framework (PMo 12 @Fe 2 Ni-MOF) loaded with Keggin type polyacid is characterized by comprising the following steps: (1) The synthesis of Fe 2 Ni(μ 3 ~O)(CH 3 COO) 6 metal cluster includes weighing ferric nitrate nonahydrate and nickel nitrate hexahydrate, dissolving in deionized water, setting in cone bottle with magneton, dissolving sodium acetate in deionized water to prepare sodium acetate solution, and dropping sodium acetate solution slowly into the mixed nitrate solution while stirring. After the dripping is finished, stirring is continued to fully carry out the reaction, after the reaction is finished, the obtained suspension is centrifugally separated, the supernatant is removed, the solid product is collected, and then deionized water and absolute ethyl alcohol are sequentially used for washing the solid for multiple times to purify. Finally, drying the purified product in an oven to obtain [ Fe 2 Ni(μ 3 ~O)(CH 3 COO) 6 ] metal clusters; (2) The PMo 12 @Fe 2 Ni-MOF material is prepared by weighing fumaric acid, dissolving in absolute ethyl alcohol, stirring to dissolve completely, dissolving [ Fe 2 Ni(μ 3 ~O)(CH 3 COO) 6 ] metal cluster synthesized in the step (1) in a proper amount of deionized water, adding the aqueous solution into an ethanol solution of fumaric acid, continuously stirring at room temperature to form a stable yellow suspension, adding Keggin type polyacid PMo 12 (phosphomolybdic acid, chemical formula H 3 PMo 12 O 40 ) into the yellow suspension, continuously stirring to disperse uniformly, transferring the uniformly mixed suspension into a stainless steel high-pressure reaction kettle with 50mL polytetrafluoroethylene lining, sealing, placing into an oven, reacting at a specific temperature for a period of time, opening the reaction kettle after the reaction system is naturally cooled to room temperature, centrifugally separating and collecting the obtained precipitate, and reversely washing the obtained precipitate with deionized water until the supernatant is neutral. Finally, the resulting solid was dried to obtain PMo 12 @Fe 2 Ni-MOF material.
2. 2. The preparation method of claim 1, wherein in the step (1), the mass of ferric nitrate nonahydrate is 8-9 g, the mass of nickel nitrate hexahydrate is 29-30 g, and the volume of deionized water for dissolving the ferric nitrate nonahydrate and the nickel nitrate hexahydrate is 70-80 mL.
3. 3. The preparation method according to claim 1, wherein in the step (1), the mass of sodium acetate is 25-26 g.
4. 4. The preparation method according to claim 1, wherein in the step (1), the stirring temperature is 20-30 ℃, and the continuous stirring time after the dropwise addition of the sodium acetate solution is 10-12 hours.
5. 5. The method according to claim 1, wherein in the step (2), the mass of fumaric acid is 0.20 to 0.30 g, and the volume of absolute ethanol in which fumaric acid is dissolved is 20 to 30 mL.
6. 6. The method according to claim 1, wherein in the step (2), the mass of the [ Fe 2 Ni(μ 3 ~O)(CH 3 COO) 6 ] metal cluster is 0.4-0.6 g, and the volume of deionized water for dissolving the metal cluster is 20-30 mL.
7. 7. The method according to claim 1, wherein in the step (2), the mass of PMo 12 (phosphomolybdic acid) is 0.5 to 0.6 g.
8. 8. The method according to claim 1, wherein in the step (2), the volume of the autoclave is 50 mL, the constant pressure reaction temperature is 60 to 70 ℃, and the constant temperature reaction time is 70 to 80 hours.
9. 9. The use of PMo 12 @Fe 2 Ni-MOF material prepared according to the method of any one of claims 1 to 8 in electrocatalytic nitrate reduction synthesis of ammonia.

Description

Preparation and application of iron-nickel trinuclear cluster-based metal-organic framework loaded with Keggin type polyacid Technical Field The invention relates to the technical field of electrocatalytic materials, in particular to a preparation method of an iron-nickel trinuclear cluster-based metal-organic framework (PMo 12@Fe2 Ni-MOF) electrocatalyst loaded with Keggin type polyacid and application of the electrocatalyst in electrocatalytic nitrate reduction synthesis of ammonia. Background Ammonia (NH 3) is one of the chemicals with the greatest yield in the world and is widely used in various fields such as dye, medicine and fertilizer production. At the same time, NH 3 is also a potential carbon-free energy carrier, and has the advantages of higher energy density and high hydrogen content. At present, the large-scale synthesis of ammonia mainly depends on a Haber-Bosch (Haber-Bosch) process, which needs to be carried out under high temperature and high pressure conditions, consumes about 2% of energy sources worldwide, accounts for 1.4% of the emission of carbon dioxide worldwide, and has the remarkable defects of high energy consumption and high pollution. In order to solve the problems, the electrocatalytic ammonia synthesis technology has been developed, and the technology can be driven by renewable energy sources, realizes the synthesis of ammonia at normal temperature and normal pressure, reduces equipment cost and energy consumption cost, has no CO 2 emission, and meets the development requirements of green low carbon. The electrocatalytic nitrate ammonia (NO 3 RR) can remove pollutant nitrate in water, can generate high-quality high-value zero-carbon hydrogen-rich fuel ammonia, can improve environmental pollution and simultaneously relieve energy crisis, and the reasonable design of high-activity and high-selectivity electrocatalyst is a key for realizing high-efficiency NO 3 RR. Metal Organic Frameworks (MOFs) are used as a porous material and have a high specific surface area and an adjustable pore structure, but most MOFs have the problems of poor chemical stability and insufficient intrinsic electron transport in electrolyte, and limit the application of the MOFs in the field of electrocatalysis. By introducing specific metal clusters as MOF nodes, not only the stability of the framework structure can be enhanced, but also the material can be endowed with catalytic active sites, and the method is an effective way for improving the electrocatalytic performance of the MOF. Polyoxometallate (POM) is a metal oxygen cluster compound composed of d 0 pre-transition metal and oxygen. Wherein Keggin type polyacids (such as phosphomolybdic acid, PMo 12) are widely applied in the field of electrocatalysis due to reversible redox activity and electron-rich characteristics. However, the polyacid material has the key technical problems of easy agglomeration and easy dissolution loss in electrolyte, and the catalytic stability and the cycle performance of the polyacid material are seriously affected. In the prior art, although an attempt of compounding polyacid and MOF is made, a physical mixing or stepwise loading method is mostly adopted, the problems of weak combination of a compound interface, easy falling of polyacid, low electron transmission efficiency and the like exist, and no report on preparing an electrocatalyst by taking trinuclear iron-nickel cluster ([ Fe 2Ni(μ3~O)(CH3COO)6 ]) as an MOF node and Keggin type PMo 12 through one-step in-situ compounding is yet seen. Therefore, the invention provides a preparation method for loading PMo 12 in a trinuclear iron-nickel cluster-based metal-organic framework, which realizes the synergistic effect of MOF nodes and polyacid through structural design, solves the technical problems and obtains the high-performance NO 3 RR electrocatalyst. Disclosure of Invention The invention aims to overcome the technical defects of insufficient electron transmission performance, easy agglomeration of polyacid, easy dissolution loss in electrolyte and the like of the MOF-based electrocatalyst in the prior art, and provides preparation and application of an iron-nickel trinuclear cluster-based metal-organic framework (PMo 12@Fe2 Ni-MOF) loaded with Keggin-type polyacid, and the activity, selectivity and stability of electrocatalytic nitrate reduction ammonia synthesis are improved through the synergistic effect of trinuclear iron-nickel cluster nodes and PMo 12. In order to achieve the purpose, the invention is specifically realized by the following technical scheme: 1. The synthesis of Fe 2Ni(μ3~O)(CH3COO)6 metal cluster includes weighing ferric nitrate nonahydrate and nickel nitrate hexahydrate, dissolving in deionized water, setting inside conical flask and adding magneton, and dissolving sodium acetate in deionized water to prepare sodium acetate solution. Slowly adding sodium acetate solution dropwise into the nitrate mixed solution under continuous rapid stirri