阅读说明：本技术 一种电负性杂原子-过渡金属共掺杂碳基非贵金属电催化剂及其制备方法 (Electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst and preparation method thereof ) 是由 李开喜 许菲菲 于 2020-05-19 设计创作，主要内容包括：本发明公开了一种电负性杂原子-过渡金属共掺杂碳基非贵金属电催化剂及其制备方法,属于新能源及电催化材料领域。制备方法为：将碳源,磷源,氮源,硫源以及过渡金属盐在溶剂中充分搅拌反应,进行溶剂热反应,氮气气氛中高温碳化处理,最后经过酸洗干燥处理,即得电负性杂原子-过渡金属共掺杂碳基非贵金属电催化剂。该催化剂在分子合成过程中原位引入磷源、氮源和硫源,有效提高了金属负载量和分散性,碳材料的存在极大提高了催化剂导电性,另外充分利用磷与反应中间产物的相互作用,与质子受体和氢化物形成表面受体位点,导致高活性。本发明所用催化剂制备方法简单,原料易得,成本低廉,过程易于控制,制备周期短,产率高,适于大规模生产。(The invention discloses an electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst and a preparation method thereof, belonging to the field of new energy and electrocatalytic materials. The preparation method comprises the following steps: fully stirring a carbon source, a phosphorus source, a nitrogen source, a sulfur source and transition metal salt in a solvent for reaction, carrying out solvothermal reaction, carrying out high-temperature carbonization treatment in a nitrogen atmosphere, and finally carrying out acid washing and drying treatment to obtain the electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst. The catalyst has the advantages that a phosphorus source, a nitrogen source and a sulfur source are introduced in situ in the molecular synthesis process, the metal loading capacity and the dispersity are effectively improved, the catalyst conductivity is greatly improved due to the existence of the carbon material, and in addition, the surface receptor sites are formed with proton receptors and hydrides by fully utilizing the interaction of phosphorus and reaction intermediate products, so that the high activity is caused. The catalyst used in the invention has the advantages of simple preparation method, easily available raw materials, low cost, easily controlled process, short preparation period, high yield and suitability for large-scale production.)

1. A preparation method of an electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst is characterized by comprising the following steps: the electronegative heteroatoms include phosphorus and one or both of nitrogen or sulfur; the preparation method comprises the following steps:

fully stirring a carbon source, a phosphorus source, a nitrogen source, a sulfur source and transition metal salt in a solvent for 0.5-30 h; placing the obtained mixed solution into a reaction kettle for solvothermal reaction at the reaction temperature of 100-240 ℃ for 2-48 h; then drying the obtained reactant, placing the dried reactant in a tubular furnace, heating the reactant to 150-900 ℃ at a heating rate of 0.5-20 ℃/min in a nitrogen atmosphere, keeping the temperature for 0.5-10 h, and cooling the reactant to room temperature; and taking the product out of the tubular furnace, washing with 1M dilute hydrochloric acid, washing with deionized water to be neutral, and drying to obtain the electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst.

2. The preparation method of the electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst according to claim 1, wherein the preparation method comprises the following steps: the carbon source is cyclobutanecarboxylic acid, quinoline-5-carboxylic acid, quinoline-3-carboxylic acid, 5-pyrrolecarboxylic acid, 1-methyl-2-pyrrolecarboxylic acid, 1-methylpyrazole-3-carboxylic acid, indole-3-carboxylic acid, pyridine-2, 5-dicarboxylic acid, 4-acetylbenzoic acid, cis-4-aminocyclohexanecarboxylic acid, pyridazine-4-carboxylic acid, pyridazine-3-carboxylic acid, 3-carboxycyclobutylamine, 8-hydroxyquinoline-7-carboxylic acid, 5-methyl-2-pyrazinecarboxylic acid, 4-methylphthalic acid, pyrimidine-2-carboxylic acid, 1-cyclopentenecarboxylic acid, pyridine-3, 5-dicarboxylic acid, pyrrole-2-carboxylic acid, one or more of 4-hydroxybenzamide, 2, 4-dihydroxybenzamide, 3-hydroxyphenylacetic acid, 4-hydroxycyclohexanecarboxylic acid, 2-hydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid and 2, 4-dihydroxybenzoic acid;

the phosphorus source is one or more of phosphoric acid, hypophosphorous acid, polyphosphoric acid, phosphomolybdic acid, phosphotungstic acid, sodium phosphomolybdate, boron phosphate, sodium hypophosphite, potassium dihydrogen phosphate, ammonium hydrogen phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, melamine phosphate, guanylurea phosphate, 3-aminopropyl phosphoric acid, diethyl dithiophosphate, dibutyl phosphate, ditolyl phosphate and diphenyl phosphate;

the nitrogen source is one or more of ammonia water, nitric acid, melamine, urea, sodium dicyanamide, methylamine, dimethylamine, butyramide, 5-aminoquinoline, 2, 3-diaminopyridine, ethylenediamine and 2, 3-diaminotoluene;

the sulfur source is one or more of thiourea, thioacetic acid, methyl thiocyanate, thiopropionamide, methyl propyl disulfide, thioacetamide, dithioacetamide and thiopropylene;

the transition metal salt is one or more of chloride, nitrate, acetate, phosphate or sulfate of Cr, Mn, Fe, Co, Ni, Cu, Zn, W, V and Mo.

3. The preparation method of the electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst according to claim 1, wherein the preparation method comprises the following steps: the molar ratio of the raw materials is carbon source: a phosphorus source: nitrogen source: a sulfur source: transition metal salt = 1: (0.001-4): (0-5): (0-5): (1-6); the nitrogen source and the sulfur source cannot be 0 at the same time.

4. The preparation method of the electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst according to claim 3, wherein the preparation method comprises the following steps: the molar ratio of the raw materials is carbon source: a phosphorus source: nitrogen source: a sulfur source: transition metal salt = 1: (0.01-2)(1.5-3): (1-2.5): (2-4).

5. The preparation method of the electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst according to claim 1, wherein the preparation method comprises the following steps: the solvent is one or more of water, ethanol, ethylene glycol, methanol and isopropanol.

6. The preparation method of any one of claims 1 to 5, wherein the electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst is prepared by the method comprising the following steps: the dried electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst is in a powder shape; ratio range of each element C: p: n: s: o: m is (50-80): (0.1-8): (0-10): (0-9): (8-30): (0.1-15), wherein M is a metal element, and the specific surface area of the catalyst is 400-2000M²/g。

7. The electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst according to claim 6, wherein: the proportion range of each element in the catalyst is as follows: c: p: n: s: o: m is (58-75): (0.6-4.2): (1.2-5.3): (3.1-5.5): (3-18): (2.1-9.3), wherein M is a metal element.

8. The use of the electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst according to claim 6 or 7 in the preparation of oxygen reduction reactions, hydrogen evolution reactions, and oxygen evolution reaction electrocatalytic electrodes.

Technical Field

The invention relates to an electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst and a preparation method thereof, belonging to the field of new energy and electrocatalytic materials.

Background

The development of clean electrochemical energy conversion and storage technologies, such as fuel cells, metal air cells and water electrolysers, is an ideal choice to solve the current problems of energy safety and environmental pollution. Oxygen Reduction Reactions (ORR), Oxygen Evolution Reactions (OER) and Hydrogen Evolution Reactions (HER) are among the most critical electrochemical reactions in these technologies to achieve energy storage and conversion. Although platinum, iridium or ruthenium based materials show the highest activity in these electrochemical reactions, they cannot be applied on a commercial scale due to the problems of scarce reserves and high prices of these noble metals. Therefore, in the last decade, high activity, low cost, and durable non-noble metal catalysts prepared from abundant elements have received much attention.

In the search for non-noble metal catalysts, transition metal sulfides, phosphides, carbides and selenides, in addition to the well studied metal oxides and hydroxides, have proven to be extremely potential electrocatalysts. Among these materials, transition metal phosphides are considered to be one of the most promising classes. In electrocatalytic processes, moderate interaction of phosphorus in the metal phosphide with reaction intermediates, forms surface acceptor sites with proton acceptors and hydrides, resulting in high activity. However, the low conductivity, limited specific surface area and difficulty of preparation of phase-pure nanostructured phosphides make it challenging to achieve the desired electrocatalytic properties.

In order to solve these existing problems and effectively improve the electrocatalytic performance of metal phosphide, Tan et al (Energy environ. sci. 2016, 9, 2257) adopt a method combining metallurgical alloy technology and selective electrochemical corrosion, and bimetallic phosphide (Co1-xFex)2P can improve the catalytic activity thereof. However, the strict requirements of stoichiometry on valence equilibria make them impractical to implement by traditional chemical synthetic routes. In addition, during the catalytic process, the close packing between the foreign catalyst and the electrode substrate can hinder charge transfer. The possible accumulation of material on the electrode surface can block mass and charge diffusion channels, reduce the number of active centers, and is detrimental to the long-term stability of the electrode. Chinese patent CN 110904468A discloses a method for preparing a cerium-doped phosphide composite material, which improves the performance of tungsten phosphide as a catalyst for water electrolysis, but in the preparation process of the catalyst, carbon fiber paper, nickel foam or copper foam and other substrate materials are needed, which causes the catalyst and the substrate materials to be unable to be effectively separated, thereby limiting the application of the catalyst, and the metal phosphide has poor conductivity, and still has a great difference from the platinum-based catalyst in terms of catalytic activity and stability.

Disclosure of Invention

The invention aims to provide an electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst and a preparation method thereof.

The invention is improved according to the synthetic mechanism of the phenolic resin, the raw materials containing sulfur and nitrogen are selected, heteroatoms (nitrogen, sulfur, phosphorus and the like) with strong electronegativity are doped in the carbon material in situ in the synthetic process of the material, the electronic structure around the carbon atom is changed, the carbon material is promoted to have electrocatalytic activity, the transition metal doped in the carbon material is also a recognized active site, the carbon material and the transition metal are effectively combined through reasonable design, and the catalytic performance of the carbon material can be obviously improved. Furthermore, in electrocatalytic processes, moderate interaction of phosphorus in the metal phosphide with reaction intermediates, with proton acceptors and hydrides forms surface acceptor sites, resulting in high activity.

The invention provides a preparation method of an electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst, wherein the electronegative heteroatom comprises phosphorus and one or two of nitrogen or sulfur; the preparation method comprises the following steps:

fully stirring a carbon source, a phosphorus source, a nitrogen source, a sulfur source and transition metal salt in a solvent for 0.5-30 h; placing the obtained mixed solution into a reaction kettle for solvothermal reaction at the reaction temperature of 100-240 ℃ for 2-48 h; then drying the obtained reactant, placing the dried reactant in a tubular furnace, heating the reactant to 150-900 ℃ at a heating rate of 0.5-20 ℃/min in a nitrogen atmosphere, keeping the temperature for 0.5-10 h, and cooling the reactant to room temperature; and taking the product out of the tubular furnace, washing with 1M dilute hydrochloric acid, washing with deionized water to be neutral, and drying to obtain the electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst.

In the above production process, the carbon source is cyclobutanecarboxylic acid, quinoline-5-carboxylic acid, quinoline-3-carboxylic acid, 5-pyrrolecarboxylic acid, 1-methyl-2-pyrrolecarboxylic acid, 1-methylpyrazole-3-carboxylic acid, indole-3-carboxylic acid, pyridine-2, 5-dicarboxylic acid, 4-acetylbenzoic acid, cis-4-aminocyclohexanecarboxylic acid, pyridazine-4-carboxylic acid, pyridazine-3-carboxylic acid, 3-carboxycyclobutylamine, 8-hydroxyquinoline-7-carboxylic acid, 5-methyl-2-pyrazinecarboxylic acid, 4-methylphthalic acid, pyrimidine-2-carboxylic acid, 1-cyclopentenecarboxylic acid, pyridine-3, 5-dicarboxylic acid, one or more of pyrrole-2-formic acid, 4-hydroxybenzamide, 2, 4-dihydroxybenzamide, 3-hydroxyphenylacetic acid, 4-hydroxycyclohexanecarboxylic acid, 2-hydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid and 2, 4-dihydroxybenzoic acid;

the phosphorus source is one or more of phosphoric acid, hypophosphorous acid, polyphosphoric acid, phosphomolybdic acid, phosphotungstic acid, sodium phosphomolybdate, boron phosphate, sodium hypophosphite, potassium dihydrogen phosphate, ammonium hydrogen phosphate, sodium dihydrogen phosphate, disodium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium phosphate, melamine phosphate, guanylurea phosphate, 3-aminopropyl phosphoric acid, diethyl dithiophosphate, dibutyl phosphate, ditolyl phosphate and diphenyl phosphate;

the nitrogen source is one or more of ammonia water, nitric acid, melamine, urea, sodium dicyanamide, methylamine, dimethylamine, butyramide, 5-aminoquinoline, 2, 3-diaminopyridine, ethylenediamine and 2, 3-diaminotoluene;

the sulfur source is one or more of thiourea, thioacetic acid, methyl thiocyanate, thiopropionamide, methyl propyl disulfide, thioacetamide, dithioacetamide and thiopropylene;

the transition metal salt is one or more of chloride, nitrate, acetate, phosphate or sulfate of Cr, Mn, Fe, Co, Ni, Cu, Zn, W, V and Mo;

the solvent is one or more of water, ethanol, ethylene glycol, methanol and isopropanol.

In the preparation method, the molar ratio of the raw materials is carbon source: a phosphorus source: nitrogen source: a sulfur source: transition metal salt = 1: (0.001-4): (0-5): (0-5): (1-6); the nitrogen source and the sulfur source cannot be 0 at the same time. Preferably, the carbon source: a phosphorus source: nitrogen source: a sulfur source: transition metal salt = 1: (0.01-2)(1.5-3): (1-2.5): (2-4).

The invention provides the electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst prepared by the preparation method, and the dried electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst is in a powder shape; ratio range of each element C: p: n: s: o: m is (50-80): (0.1-8): (0-10): (0-9): (8-30): (0.1-15), wherein M is a metal element, and the specific surface area of the catalyst is 400-2000M²/g。

Preferably, the ratio of each element in the catalyst ranges from: c: p: n: s: o: m is (58-75): (0.6-4.2): (1.2-5.3): (3.1-5.5): (3-18): (2.1-9.3), wherein M is a metal element.

The invention provides application of the electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst in preparation of electrocatalytic electrodes for oxygen reduction reaction, hydrogen evolution reaction and oxygen evolution reaction. The dried powdery product electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst can be directly used for preparing Oxygen Reduction Reaction (ORR), Hydrogen Evolution Reaction (HER) and Oxygen Evolution Reaction (OER) electrocatalytic electrodes without crushing and powdering.

The invention has the beneficial effects that:

(1) according to the electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst, due to the moderate interaction of phosphorus and a reaction intermediate product, a surface receptor site is formed with a proton receptor and a hydride, so that the prepared catalyst has high activity. A catalyst structure which takes carbon as a leading factor is formed through polymerization reaction in the catalyst synthesis, so that the conductivity of the catalyst is greatly improved, and the performance of the catalyst is further improved;

(2) according to the electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst, a phosphorus element, a sulfur element and a nitrogen element with strong electronegativity are introduced in the preparation process, and the loading capacity of the transition metal in the electrocatalyst is effectively improved, the number of active sites is effectively improved, and the catalytic activity of the catalyst is remarkably improved through the bonding effect between the phosphorus element, the sulfur element and the nitrogen element;

(3) the electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst shows excellent electrocatalytic performance in oxygen reduction reaction, hydrogen evolution reaction and oxygen evolution reaction, is a multifunctional catalyst, can be applied to multiple fields of fuel cells, metal air cells, industrial electrolyzed water and the like, and has wide application;

(4) the electronegative heteroatom-transition metal co-doped carbon-based non-noble metal electrocatalyst is simple in preparation process flow, easy to operate, low in cost, green in solvent, and easy to produce in a large scale, and has the potential of large-scale application in the development of fuel cells, metal air cells and industrial electrolyzed water catalysts.

Drawings

FIG. 1 is a linear scan polarization plot of ORR reaction of catalysts C-1, C-2, C-3, C-4 in 0.1M KOH electrolyte (electrode rotation rate 1600 rpm) in examples 1-4;

FIG. 2 is a plot of the linear scan polarization of the OER reaction of catalysts C-1, C-2, C-3, C-4 in 0.1M KOH electrolyte in examples 1-4 (electrode rotation 1600 rpm);

FIG. 3 is a linear scan polarization plot (electrode rotation rate 1600 rpm) of the HER reaction in 0.11M KOH electrolyte for catalysts C-1, C-2, C-3, C-4 of examples 1-4.

Detailed Description

The present invention is further illustrated by, but is not limited to, the following examples.