阅读说明：本技术 偏磷酸钴/氮碳氧还原催化剂及其制备方法和应用 (Cobalt metaphosphate/nitrogen carbon oxygen reduction catalyst and preparation method and application thereof ) 是由 单丹 徐莲花 刘子萱 鲁昆昆 于 2019-08-30 设计创作，主要内容包括：本发明公开了一种偏磷酸钴/氮碳氧还原催化剂及其制备方法和应用,属于催化剂材料领域。所述的催化剂为Co(PO<Sub>3</Sub>)<Sub>2</Sub>/NC纳米材料,其中,NC为氮掺杂的碳材料,其步骤为：将ATMP水溶液逐滴缓慢的滴入硝酸钴的甲醇溶液中,反应15-120分钟后,离心,洗涤,干燥处理得到前驱体；将前驱体在保护气气氛下,700-900℃煅烧1-3 h,得到所述催化剂。本发明制得的偏磷酸钴/氮碳是由许多超薄纳米片紧凑的竖直交叉在一起的,纳米片的厚度为20-50 nm,长度介于0.5-2μm之间,纳米片上负载有许多偏磷酸钴纳米颗粒,大小为10 nm左右,该催化剂具有较高的起始电位和半波电位、稳定性强、甲醇耐受性强。(The invention discloses a cobalt metaphosphate/nitrogen carbon oxygen reduction catalyst, a preparation method and application thereof, and belongs to the field of catalyst materials. The catalyst is Co (PO) 3 ) 2 NC nanometer material, wherein NC is nitrogen-doped carbon material, and the method comprises the following steps: dropwise and slowly dropping ATMP water solution into methanol solution of cobalt nitrate, reacting for 15-120 minutes, centrifuging, washing, and drying to obtain precursor; and calcining the precursor at the temperature of 700-900 ℃ for 1-3 h in a protective gas atmosphere to obtain the catalyst. The cobalt metaphosphate/nitrogen carbon prepared by the method is formed by compactly and vertically crossing a plurality of ultrathin nano sheets, the thickness of the nano sheets is 20-50 nm, the length of the nano sheets is between 0.5 and 2 mu m, a plurality of cobalt metaphosphate nano particles are loaded on the nano sheets, the size of the nano sheets is about 10nm, and the catalyst has a higher catalyst activityInitial potential and half-wave potential, strong stability and strong methanol tolerance.)

1. The cobalt metaphosphate/nitrogen carbon oxygen reduction catalyst is characterized in that the catalyst is Co (PO)₃)₂the/NC nanometer material, wherein NC is a nitrogen-doped carbon material.

2. The catalyst of claim 1 wherein the catalyst structure is of the "physalis" type.

3. The method for preparing a catalyst according to claim 1 or 2, comprising the steps of:

step one, dropwise and slowly dropping an amino trimethylene phosphonic acid aqueous solution into a cobalt nitrate methanol solution, reacting for 15-120 minutes, centrifuging, washing, and drying to obtain a cobalt metaphosphate coordination polymer precursor;

and step two, calcining the cobalt metaphosphate coordination polymer precursor for 1-3 h at the temperature of 900 ℃ under the protective atmosphere to obtain the cobalt metaphosphate/nitrogen carbon oxygen reduction catalyst.

4. The method of claim 3, wherein in step one, the molar concentration of the methanolic solution of cobalt nitrate is 0.1 ~ 0.5.5 mol/L.

5. The method of claim 3, wherein in step one, the aqueous solution of ATMP has a mass concentration of 50wt.% ~ 75 wt.%.

6. The method of claim 3, wherein in the first step, the mass ratio of ATMP to cobalt nitrate is 1 (6 ~ 12).

7. The method of claim 3, wherein in step two, the protective atmosphere is one of nitrogen, argon, and a mixture of nitrogen and argon.

8. Use of the catalyst of claim 1 or 2 as an oxygen reduction catalyst material for a fuel cell or a metal-air cell.

Technical Field

The invention relates to the field of catalyst materials, in particular to a cobalt metaphosphate/nitrogen carbon-oxygen reduction catalyst and a preparation method and application thereof.

Background

The traditional fuel oil automobile is one of the main sources of environmental pollution, and the control of energy consumption and emission of the fuel oil automobile is an important means for solving the environmental problem. In recent years, with the increasingly prominent environmental and energy problems, new energy automobiles are gradually replacing traditional fuel automobiles due to the excellent characteristics of cleanness and no pollution, and become research hotspots of automobile manufacturers and scientific research institutions all over the world. The fuel cell automobile can really realize zero emission and is considered as a final solution of a new energy automobile. There are many problems in the large-scale commercialization of fuel cell vehicles, and the main technical factors include the durability of fuel cells, key materials and core components. Based on the current state of China, the commercial development of fuel cell automobiles is to be realized, the reliability and durability of a fuel cell power system are further improved, the consumption of platinum is reduced, and the development of a non-Pt-based catalyst is one of the solutions.

The slow oxygen reduction reaction of the cathode in a fuel cell is a short plate of the fuel cell. Catalysts play an important role in improving the kinetics of oxygen reduction reactions. At present, the catalytic performance of the Pt-based catalyst in oxygen reduction is the most excellent, but Pt is a noble metal element, so the cost is high, the resource is rare, and the large-scale commercial production of the fuel cell is seriously restricted. Cobalt oxide materials are excellent substitutes for ORR noble metal oxides. In order to rationally design the oxygen reduction catalyst, the coordination environment of the metal ions and the associated electronic structure of the cobalt-based oxide material should be considered to ensure rapid progress of the reaction. Transition metal metaphosphates/phosphates make a positive contribution to structural stability and can withstand structural deformation and stabilize the intermediate state of transition metal ions, thus attracting wide interest to scientists. Many methods have been developed to synthesize cobalt phosphate/metaphosphate nanostructured materials, such as the hydrothermal method (J Mater Chem a 2016, 4, 8155-; thermal Molecular Precursor (TMP) method (Adv Funct Mater 2013, 23, 227-; sol-gel method (Inorg Chem 2005, 44, 6314-. Although these cobalt phosphates/metaphosphates show the most advanced performance in ORR or Oxygen Evolution Reaction (OER), the synthesis steps are complex, the starting potential and half-wave potential are not high, and thus the cost, durability and complexity of the synthesis limit their sustainable use on a commercial scale.

Disclosure of Invention

The invention aims to overcome the defects that the prior transition metal metaphosphate is responsible for the synthesis step of the oxygen reduction catalyst of the fuel cell and has low initial potential and half-wave potential, and provides a 'groundcherry fruit' type nitrogen-doped carbon-coated cobalt metaphosphate oxygen reduction catalyst and a preparation method thereof. Co (PO) can be prepared by the method₃)₂Nc nanomaterial, and Co (PO) obtained₃)₂the/NC material has higher initial potential and half-wave potential, strong stability and strong methanol tolerance.

In order to achieve the purpose, the technical scheme provided by the invention is as follows:

the invention relates to a cobalt metaphosphate/nitrogen carbon oxygen reduction catalyst, which is Co (PO)₃)₂The catalyst is a 'groundcherry' type catalyst structure.

The catalyst is formed by compactly and vertically crossing a large number of ultrathin nano sheets, the thickness of the nano sheets is 20-50 nm, the length of the nano sheets is 0.5-2 mu m, and a plurality of cobalt metaphosphate nano particles are loaded on the nano sheets and have the size of about 10 nm.

The preparation method of the catalyst comprises the following steps:

step one, dropwise and slowly dropping an aqueous solution of aminotrimethylene phosphonic Acid (ATMP) into a methanol solution of cobalt nitrate, reacting for 15-120 minutes, centrifuging, washing, and drying to obtain a cobalt metaphosphate coordination polymer precursor;

and step two, calcining the cobalt metaphosphate coordination polymer precursor for 1-3 h at the temperature of 900 ℃ under the protective atmosphere to obtain the cobalt metaphosphate/nitrogen carbon oxygen reduction catalyst.

Preferably, in the step one, the molar concentration of the methanol solution of the cobalt nitrate is 0.1 ~ 0.5.5 mol/L.

Preferably, in step one, the mass concentration of the aqueous solution of ATMP is 50wt.% ~ 75 wt.%.

Preferably, in the first step, the mass ratio of ATMP to cobalt nitrate is 1 (6 ~ 12);

preferably, in the second step, the protective atmosphere may be one of nitrogen, argon and a mixture of nitrogen and argon.

Compared with the prior art, the invention has the following remarkable effects:

(1) the cobalt metaphosphate coordination polymer precursor using amino trimethylene phosphonic Acid (ATMP) as chelating agent is designed and synthesized for the first time by a one-pot method, the method is simple, the raw materials are cheap and easy to obtain, and the synthesis path is free from pollution.

(2) Due to N doping with carbon and Co (PO)₃)₂The synergistic effect between the two makes the Co (PO) with the 'groundcherry' appearance₃)₂ORR performance of/NC is enhanced.

(3) Electronic modulation of the cobalt central ion by the metaphosphate group promotes the electrocatalytic activity of the material.

Drawings

FIG. 1 is an X-ray diffraction diagram of the product obtained in example 1 according to the invention.

FIG. 2 is a scanning electron micrograph of a product obtained in example 1 according to the present invention.

FIG. 3 is a high resolution TEM image of the product obtained in example 1 according to the present invention.

FIG. 4 is a plot of the linear voltammogram of the product obtained in example 1 and 20% commercial Pt in 0.1mol/L KOH in accordance with the invention.

FIG. 5 is a graph of the stability of the product obtained in example 1 and 20% commercial Pt according to the invention in 0.1mol/L KOH solution at 1600 rpm.

FIG. 6 is a graph of methanol tolerance of the product obtained in example 1 according to the invention and 20% commercial Pt in 0.1mol/L KOH solution at a voltage of 0.4V.

Detailed Description

For a further understanding of the invention, reference will now be made to the following detailed description taken in conjunction with the accompanying drawings and examples.