Preparation method and new application of metal organogel catalyst based on MIL-53
阅读说明：本技术 基于mil-53的金属有机凝胶催化剂的制备方法及其新用途 (Preparation method and new application of metal organogel catalyst based on MIL-53 ) 是由 李东升 魏君华 吴亚盘 张其春 兰亚乾 吴涛 张健 于 2019-11-19 设计创作，主要内容包括：本发明提供用于电催化甲醇氧化的MIL-53多金属有机凝胶催化剂及其制备方法,包括以铝盐和对苯二甲酸(BDC)为原料制备单金属有机凝胶；以铝盐、镍盐和对苯二甲酸为原料制备双金属有机凝胶；以铝盐、镍盐、铜盐和对苯二甲酸为原料制备三金属有机凝胶；将合成材料组装成三电极体系进行甲醇氧化的测试。本发明操作简单方便、产率高,可重复性好、成分可控,制备的多金属有机凝胶具有优异的电催化甲醇氧化性能。(The invention provides an MIL-53 multi-metal organogel catalyst for electrocatalytic methanol oxidation and a preparation method thereof, wherein the preparation method comprises the steps of preparing single-metal organogel by taking aluminum salt and terephthalic acid (BDC) as raw materials; preparing a bimetallic organogel by taking aluminum salt, nickel salt and terephthalic acid as raw materials; preparing trimetal organogel by taking aluminum salt, nickel salt, copper salt and terephthalic acid as raw materials; the synthetic materials were assembled into a three-electrode system for methanol oxidation testing. The method has the advantages of simple and convenient operation, high yield, good repeatability and controllable components, and the prepared multi-metal organogel has excellent electrocatalytic methanol oxidation performance.)
1. A preparation method of a MIL-53-based metal organic gel catalyst is characterized by comprising the following steps:
(1) aluminum nitrate nonahydrate Al (NO)3)3•9H2Dissolving O in N, N-dimethylacetamide;
(2) dissolving terephthalic acid in N, N-dimethylacetamide;
(3) pouring the solution in the step (1) into the solution in the step (2), and uniformly dispersing by ultrasonic; and then transferring the mixed solution into a reaction kettle, preserving the heat at the temperature of 120-180 ℃ for 2-10h, naturally cooling, and washing to obtain the aluminum-single metal organic gel material.
2. The method for preparing MIL-53 based metal organogel catalyst according to claim 1, wherein said step (1) further comprises mixing aluminum nitrate nonahydrate Al (NO)3)3•9H2O, Nickel nitrate hexahydrate Ni (NO)3)2•6H2Dissolving O in N, N-dimethyl acetamide to obtain the product of aluminum/nickel-bimetal organogel material.
3. The method for preparing MIL-53 based metal organogel catalyst according to claim 1 or 2, wherein the step (1) further comprises mixing aluminum nitrate nonahydrate Al (NO)3)3•9H2O, Nickel nitrate hexahydrate Ni (NO)3)2•6H2O, copper nitrate trihydrate Cu (NO)3)2•3H2Dissolving O in N, N-dimethylacetamide; the obtained product is an aluminum/nickel/copper-trimetal organogel material.
4. Use of a MIL-53 based metal organogel catalyst according to any of claims 1-3 for electrocatalytic methanol oxidation.
Technical Field
The invention belongs to the technical field of synthesis and application of catalysts, and particularly relates to a preparation method of a metal organic gel with electrocatalytic performance and application of the metal organic gel in electrocatalytic methanol oxidation.
Background
The direct methanol fuel cell is a proton exchange membrane fuel cell taking methanol as liquid fuel, and has the advantages of rich fuel source, low price, convenient and safe storage and transportation and the like, and the methanol has high energy density and is widely concerned. However, the development of methanol fuel cells is limited by the slow reaction kinetics of the anode methanol reaction and the susceptibility of the platinum metal catalysts to poisoning, which requires increased platinum loading. Therefore, the number of exposed active sites of the catalyst, the surface structure, the composition and the atomic arrangement are very important for improving the utilization rate and the catalytic performance of the platinum. At present, a great deal of research is focused on exploring the formation of alloy or heterostructure catalysts of different transition metals and platinum so as to modify a platinum electronic structure and achieve the purposes of reducing the platinum loading capacity and improving the platinum utilization rate. The open-pore structured nanomaterial such as nanocages, nano frames, hollow spheres and the like also maximizes the utilization of the active metal to reduce costs by imparting a high specific surface area, porosity to the catalyst and an active surface with which the reactants can come into contact in three-dimensional directions. The Metal Organic Gels (MOGs) are expanded on the basis of the structure of metal organic framework Materials (MOFs), and the metal organic framework material particles can form a three-dimensional network structure in a self-assembly mode. Therefore, MOGs become a porous metal organic material with a hierarchical structure, and the porous metal organic material has the characteristics of high specific surface area, size-adjustable pore channels, low density, inherent metal sites and the like, so that the porous metal organic material has potential application values in the aspects of mass transfer, adsorption, catalyst carrier and the like. As one of the porous materials, it has a characteristic that the pore diameter is adjustable as compared with an inorganic porous material (e.g., molecular sieve), which is generally fixed in pore size. Compared with the hotter MOFs (also belongs to a porous material) researched in recent years, the metal organogel has the characteristics of large pore diameter and stability, and for the MOFs, in order to obtain larger pore diameter, the length of a ligand is the most commonly used method, but the synthesized MOFs are unstable when the ligand is increased, so that the application of the MOFs is greatly limited. Therefore, the synthesis and performance research of the metal organogel have good application prospects. In general, a noble metal material is often used as an electrode material of a methanol fuel cell, but the noble metals Pt and Pb are expensive, have a small storage amount, and are easily poisoned by being combined with a CO intermediate. The alkaline direct methanol fuel cell can utilize non-noble metals Ni and Cu as electrode materials, but Ni and Cu react with ligands to generate MOF, so that gel cannot be formed generally, the yield of the electrode materials is too low, the use cost is increased, and the synthesis process of the MOF is complex and long in time consumption. Therefore, in the invention, the methanol oxidation performance of the MIL-53(Al) metal organic gel is improved by utilizing the multi-metal synergistic effect through synthesizing the MIL-53(Al) metal organic gel and introducing nickel/copper into the MIL-53(Al) metal organic gel.
Disclosure of Invention
The invention provides a method for preparing single metal, double metal and tri-metal organogel materials, and the composite material is applied to electrocatalytic methanol oxidation, and the preparation method is simple and convenient and has high yield. The invention aims at the application of polymetallic organogel in the field of methanol oxidation, and provides a preparation method and application of an electrocatalytic material, namely an aluminum-
The purpose of the invention is realized by the following technical scheme, the three materials are an aluminum-single
(1) dissolving metal salt in N, N-dimethylacetamide solvent, and performing ultrasonic treatment to obtain a mixed solution.
(2) Dissolving terephthalic acid in N, N-dimethylacetamide solvent, and performing ultrasonic treatment to prepare a ligand solution containing terephthalic acid.
(3) And (3) pouring the solution obtained in the step (1) into the solution obtained in the step (2), performing ultrasonic treatment at room temperature for a period of time to fully mix the solution, transferring the mixture into a reaction kettle, and reacting at the temperature of 120-.
(4) And (4) washing the wet gel obtained in the step (3) with ethanol for three times to obtain an MIL-53-based aluminum-single metal
The metal salt is aluminum nitrate or nickel nitrate or copper nitrate.
The amount of the N, N-dimethylacetamide is only needed to be immersed in the metal salt and the terephthalic acid, and the molar ratio of the aluminum nitrate and/or the nickel nitrate and/or the copper nitrate to the ligand terephthalic acid is 1-2: 1.
3 kinds of metal organic gel materials prepared by the steps are used as electro-catalysts to carry out electro-catalytic methanol oxidation tests. The method comprises the following specific steps:
1) weighing 4mg of the obtained metal organogel material, adding 0.2ml of naphthol, 1.3ml of deionized water and 0.5ml of ethanol, and carrying out ultrasonic mixing for 30min to prepare an electrode solution for later use.
2) Coating 4 microliter of the electrode solution obtained in the step 1) on a glassy carbon electrode to form a working electrode, taking a platinum wire as a counter electrode and taking a Hg/HgO electrode as a reference electrode to form a three-electrode system, and inserting the three-electrode system into electrolyte to perform methanol oxidation reaction.
The invention has the following advantages:
(1) the gel synthesized by the method has simple reaction conditions, is easy to repeat mass synthesis, and has lower cost. The method synthesizes the aluminum-nickel-containing bimetallic gel and the aluminum-nickel-copper trimetal gel, provides reference for simplifying the preparation process and synthesizing other gels of different metal types, and has certain guiding significance.
(2) The metal in the multi-metal organogel has synergistic effect (geometric effect and electronic effect), and the introduction of nickel/copper can effectively enhance the methanol oxidation performance of the catalyst.
Drawings
FIG. 1 is a diagram of a metal organogel material prepared according to the present invention, wherein A is an aluminum-single metal organogel material, B is an aluminum/nickel-double metal organogel material, and C is an aluminum/nickel/copper-triple metal organogel material.
FIG. 2 is an X-ray powder diffraction pattern of the metal organogel material prepared in accordance with the present invention.
FIG. 3 is a Fourier infrared plot of a metal organogel material prepared according to the present invention.
FIG. 4 is SEM and energy spectrum of the aluminum-single metal organogel material prepared by the present invention.
Fig. 5 is SEM and energy spectrum of the aluminum/nickel-bimetal organogel material prepared by the present invention.
FIG. 6 is SEM and energy spectrum of the aluminum/nickel/copper-trimetal organogel material prepared by the present invention.
FIG. 7 is a cyclic voltammogram of a metal organogel material prepared according to the present invention in a 0.1M potassium hydroxide solution.
FIG. 8 is a cyclic voltammogram of the metal organogel material prepared in the invention in 0.1M potassium hydroxide and 1M methanol solution.
FIG. 9 is a graph showing the current decay degree of the metal organogel material prepared in the present invention in 0.1M KOH and 1M MeOH solutions.
Detailed Description
The following examples are further illustrative of the present invention and are not intended to limit the scope of the present invention. The starting materials described in the present invention were all purchased commercially and the reagents were not further purified.