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Method for preparing graphene-loaded nano alloy catalyst

A nano-alloy and graphene technology, applied in chemical instruments and methods, organic compound/hydride/coordination complex catalysts, physical/chemical process catalysts, etc., can solve the problem of inhomogeneous nanoparticle composition and metal ion reduction rate Inconsistency and other issues

Inactive Publication Date: 2011-08-10
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

On the other hand, in the process of preparing alloy catalysts, due to the inconsistent reduction rate of metal ions, the composition of nanoparticles is not uniform, which also puts forward requirements on the synthesis route of alloy catalysts.

Method used

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  • Method for preparing graphene-loaded nano alloy catalyst
  • Method for preparing graphene-loaded nano alloy catalyst
  • Method for preparing graphene-loaded nano alloy catalyst

Examples

Experimental program
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preparation example Construction

[0021] Step 1. Preparation of graphene oxide (GO):

[0022] Graphite adopts one of natural flake graphite or colloidal graphite, etc., using P 2 O 5 , KMnO 4 , K 2 S 2 O 8 , CrO 3 , HClO 4 , concentrated H 2 SO 4 One or several mixtures in the graphite are pre-oxidized to obtain expanded graphite, and then concentrated H 2 SO 4 and KMnO 4 Strong oxidation is carried out to obtain graphite oxide. For safe operation and proper oxidation degree, the oxidation temperature here is 20~80℃, and the time is 10~12h.

[0023] A large amount of ultrapure water was injected into the mixed solution after the reaction for dilution, an appropriate amount of hydrogen peroxide was added dropwise, and the impurity ions were removed by suction filtration and centrifugation. Under the assistance of ultrasound, the graphite oxide flakes were exfoliated to obtain a brown suspension. In order to achieve effective exfoliation of graphite oxide, the ultrasonic power was 200-300 W and the ...

Embodiment 1

[0031] Embodiment 1. Preparation of graphene-supported Pd-Pt nano-alloy catalyst

[0032] The synthetic route of graphene-supported Pd-Pt nanoalloy catalyst is as follows figure 1 shown.

[0033] First, the graphene oxide (GO) aqueous solution was obtained by oxidative exfoliation of flake graphite by a modified Hummers method (W. S. Hummers, R. E. Offeman, J. Am. Chem. Soc. , 1958, 80, 1339.), see appendix figure 2 . The specific operation route is as follows: 1) 80mL concentrated H 2 SO 4 , 11g K 2 S 2 O 8 , 18g P 2 O 5 The mixture was placed in a three-necked flask, heated to 80 °C, and 10 g of dried natural graphite was added. When the reactant completely turned blue-black, the heating was stopped, and the mixture was cooled to room temperature for 6 h. Rinse thoroughly with water, filter the reactant until the filtrate is neutral, and then dry at room temperature to obtain expanded graphite. 2) Under the condition of ice bath, add concentrated H to the ab...

Embodiment 2

[0038] Example 2. Preparation of graphene-supported Pt-Au (3:1) nano-alloy catalyst

[0039] Following the same approach as Example 1, the flake graphite was oxidized and exfoliated to obtain a 10 mg / mL graphene oxide (GO) aqueous solution. To 10 mL of GO aqueous solution, 50 mg of PDDA (MW ≈ 8500) aqueous solution with a concentration of 40% was slowly added dropwise, and the mixed solution was stirred for more than 12 h. The PDDA molecules were electrostatically adsorbed to the GO surface, realizing the functionalization of GO. Then, dialysis (about 48h) was performed, and the ultrapure water was continuously replaced during the dialysis process, and finally a PDDA-GO aqueous solution with a content of about 10 mg / mL was obtained. Measure 5 mL of PDDA-GO aqueous solution and place it in a three-necked flask, and add 20 mL of Na with a total metal mass concentration of 10 mg / mL. 2 PtCl 6 and HAuCl 4 (molar ratio of 3:1) mixed solution. After stirring overnight, the neg...

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Abstract

The invention provides a method for preparing a graphene-loaded nano alloy catalyst, which is characterized by sequentially comprising the following steps of: 1, oxidizing and stripping graphite to obtain GO (Graphene Oxide); 2, carrying out surface functionalization on the GO by cationic polyelectrolyte; 3, carrying out static assembly on binary metal ions because the surface of the functionalized GO the surface is provided with positive charges; and 4, carrying out in-situ reduction on the bounded metal ions and simultaneously reducing the GO into graphene to obtain high dispersion graphene-loaded nano alloy particles which can be directly used as an electro-catalyst of a methanol fuel cell. By the method, the problems that graphene is aggregated and is difficult to disperse, metal atoms are preferably nucleated and grow at the defect positions on the surface of graphene to cause low particle dispersion degree and two metal ions have different reduction speeds to cause inhomogenous alloy components are solved.

Description

technical field [0001] The invention relates to a preparation method of a graphene-loaded nano-alloy catalyst, which belongs to the electrocatalyst for direct methanol fuel cells. Background technique [0002] Direct methanol fuel cell (DMFC) directly converts the chemical energy of methanol into electrical energy through an electrochemical reaction, with high energy conversion efficiency, and the reaction products are water and CO 2 , no pollution to the environment, and the storage and supply of methanol fuel is convenient, the structure of the battery is simple and reliable, and the flexibility is large, so it has a good application prospect in the fields of power energy and portable equipment. However, its development still faces urgent problems, especially for cathode electrocatalysts, such as high noble metal usage, slow oxygen reduction reaction (ORR) kinetics, insufficient stability, and “mixed potential” caused by methanol permeation. At present, the most widely st...

Claims

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Application Information

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IPC IPC(8): B01J31/28H01M4/90
CPCY02E60/50
Inventor 张校刚何卫杨辉杨苏东
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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