阅读说明：本技术 一种纳米金铂双金属@碳材料氧反应催化剂及其制备方法 (Nano gold-platinum bimetallic @ carbon material oxygen reaction catalyst and preparation method thereof ) 是由 罗鲲 罗志虹 尹连琨 李德贵 向利 李富杰 于 2020-04-16 设计创作，主要内容包括：本发明公开了一种纳米金铂双金属@碳材料氧反应催化剂及其制备方法。以碳材料为载体,有机配体封端的纳米金铂双金属为活性中心,通过一步还原法制备纳米金铂双金属@碳材料氧反应催化剂；所述碳材料为碳纳米管、石墨烯和碳黑中的一种或多种,所述封端剂为四羟甲基氯化磷、巯基琥珀酸和三苯基膦的一种或多种。纳米金铂双金属平均粒径为2.8 nm~3.2 nm,纳米金铂双金属负载量为10wt.%~15wt.%,金/铂摩尔比为0.5~1.7。本发明催化剂结构可控,反应条件温和,操作简单,成本低；制得的纳米金铂双金属@碳材料氧反应催化剂与商用20wt.% Pt/C相比,具有更好的氧还原和析氧催化活性和稳定性。(The invention discloses a nano gold-platinum bimetallic @ carbon material oxygen reaction catalyst and a preparation method thereof. Preparing a nano gold-platinum bimetal @ carbon material oxygen reaction catalyst by using a carbon material as a carrier and using an organic ligand-terminated nano gold-platinum bimetal as an active center through a one-step reduction method; the carbon material is one or more of carbon nano tube, graphene and carbon black, and the end-capping reagent is one or more of tetrakis hydroxymethyl phosphonium chloride, mercaptosuccinic acid and triphenylphosphine. The average grain diameter of the nano-Au-Pt bimetal is 2.8-3.2 nm, the loading capacity of the nano-Au-Pt bimetal is 10-15 wt.%, and the molar ratio of Au to Pt is 0.5-1.7. The catalyst has the advantages of controllable structure, mild reaction conditions, simple operation and low cost; compared with commercial 20wt.% Pt/C, the prepared nano gold-platinum bimetallic @ carbon material oxygen reaction catalyst has better oxygen reduction and oxygen evolution catalytic activity and stability.)

1. A nanometer gold platinum bimetal @ carbon material oxygen reaction catalyst is characterized in that the nanometer gold platinum bimetal @ carbon material oxygen reaction catalyst takes a carbon material as a matrix, and nanometer gold platinum bimetal with an organic ligand as a capping reagent as an oxygen reaction catalyst with an active center;

the carbon material is one or more of commercially available carbon nanotubes, graphene and carbon black;

the end-capping reagent is one or more of market-available tetrakis (hydroxymethyl) phosphonium chloride, mercaptosuccinic acid and triphenylphosphine, wherein the tetrakis (hydroxymethyl) phosphonium chloride is oxidized to generate trihydroxy phosphonium oxide;

the average grain diameter of the nano-Au-Pt bimetal is 2.8-3.2 nm, the loading capacity of the nano-Au-Pt bimetal is 10-15 wt.%, and the gold/Pt molar ratio is 0.5-1.7.

2. The preparation method of the nano-Au-Pt bimetallic @ carbon material oxygen reaction catalyst as claimed in claim 1, is characterized by comprising the following specific steps:

(1) putting 40-80 mg of carbon material into a 150 m L conical flask, and adding 100 m L deionized water;

(2) preserving the heat of the product obtained in the step (1) in a super constant temperature water bath at the temperature of 60-95 ℃ for 5 minutes, and then adding 0.5-1.5 m L with the concentration of 2.0 × 10^-4~ 3.0×10^-4The concentration of chloroauric acid in mol/L and 0.6-1.9 m L is 2.0 × 10^-4~3.0×10^-4Stirring and ultrasonically treating chloroplatinic acid of mol/L to obtain stable dispersion liquid with constant temperature;

(3) adding an alkali source with the concentration of 1 mol/L and an end-capping reagent with the concentration of 50 mmol/L of 1.9-2.4 m L into the stable dispersion liquid with the constant temperature obtained in the step (2) to obtain an alkaline mixed solution, and adding sodium borohydride with the concentration of 50 mmol/L of 3.8-4.8 m L if the end-capping reagent is mercaptosuccinic acid;

(4) stirring the product obtained in the step (3) in a constant-temperature water bath for reaction for 3 hours to obtain a mixed solution of reaction products; immediately placing the conical flask into an ice-water bath to stop reaction after the reaction is finished, then taking out the conical flask, standing the conical flask overnight at an air temperature, centrifuging the conical flask at 8000 rpm to be neutral, drying the conical flask, and fully grinding the conical flask to obtain nano gold-platinum bimetallic @ carbon nanotube oxygen reaction catalyst powder;

the carbon material is one or more of commercially available carbon nanotubes, graphene and carbon black;

the alkali source is sodium hydroxide or potassium hydroxide;

the end-capping reagent is one or more of commercial tetrakis hydroxymethyl phosphonium chloride, mercaptosuccinic acid and triphenylphosphine, wherein the tetrakis hydroxymethyl phosphonium chloride is oxidized in the reaction of the step (3) to generate trihydroxy phosphonium oxide.

Technical Field

The invention relates to the field of oxygen reaction catalysis, in particular to a nano gold-platinum bimetallic @ carbon material oxygen reaction catalyst and a preparation method thereof.

Background

The development in the field of electric vehicles has placed higher demands on the energy density of batteries (> 300 Wh/kg). The theoretical energy density of the lithium ion battery widely used at present is low, and is only 150-200Wh/kg, which can not meet the endurance requirement of the electric automobile. The metal air battery, such as a zinc air battery, a magnesium air battery, an aluminum air battery, a lithium air battery and the like, has high energy density and can meet the development requirements of electric automobiles. The metal-air battery positive electrode relates to oxygen reduction reaction and oxygen evolution reaction, but the oxygen electrode reaction kinetics is slow, and the energy efficiency of the metal-air battery is reduced.

The oxygen electrode reaction kinetics can be improved by adopting the catalyst, the current commercial platinum-carbon catalyst (20 wt.% Pt/C) has higher catalytic activity on the oxygen reaction, but the cost of the metal-air battery is increased due to high price of the catalyst because platinum resources are scarce. Moreover, platinum may dissolve or fall off during the battery cycle process, and the stability of the catalyst is poor, which is not favorable for maintaining high energy efficiency of the battery in long-term operation. Therefore, the development of a high catalytic activity, high stability, and low cost oxygen reaction catalyst is a problem to be solved.

Disclosure of Invention

In view of the above, the present invention aims to provide a nano-gold-platinum bimetallic @ carbon material oxygen reaction catalyst and a preparation method thereof.

The invention relates to a nano gold platinum bimetal @ carbon material oxygen reaction catalyst, which takes nano gold platinum bimetal with a carbon material as a carrier and an organic ligand as a capping reagent as an active center. The average grain diameter of the nano-Au-Pt bimetal is 2.8-3.2 nm, the loading capacity of the nano-Au-Pt bimetal is 10-15 wt.%, and the molar ratio of Au to Pt is 0.5-1.7.

The preparation method of the nano gold-platinum bimetallic @ carbon material oxygen reaction catalyst comprises the following specific steps:

(1) placing 40-80 mg of carbon material into a 150 m L conical flask, and adding 100 m L deionized water.

(2) Preserving the heat of the product obtained in the step (1) in a super constant temperature water bath at the temperature of 60-95 ℃ for 5 minutes, and then adding 0.5-1.5 m L with the concentration of 2.0 × 10^-4~ 3.0×10^-4The concentration of chloroauric acid in mol/L and 0.6-1.9 m L is 2.0 × 10^-4~ 3.0×10^-4And (3) chloroplatinic acid of mol/L, stirring and carrying out ultrasonic treatment to obtain a stable dispersion liquid with constant temperature.

(3) And (3) adding an alkali source with the concentration of 1 mol/L and the end-capping reagent with the concentration of 50 mmol/L of 1.9-2.4 m L into the stable dispersion liquid with the constant temperature obtained in the step (2) to obtain an alkaline mixed solution, and adding sodium borohydride with the concentration of 50 mmol/L of 3.8-4.8 m L if the end-capping reagent is mercaptosuccinic acid.

(4) Stirring the product obtained in the step (3) in a constant-temperature water bath for reaction for 3 hours to obtain a mixed solution of reaction products; and immediately placing the conical flask into an ice-water bath to stop reaction after the reaction is finished, then taking out the conical flask, standing the conical flask overnight at an air temperature, centrifuging the conical flask at 8000 rpm to be neutral, drying the conical flask, and fully grinding the conical flask to obtain the nano gold-platinum bimetallic @ carbon nano tube oxygen reaction catalyst powder.

The carbon material is one or more of commercially available carbon nanotubes, graphene and carbon black.

The alkali source is sodium hydroxide or potassium hydroxide.

The end-capping reagent is one or more of commercial tetrakis hydroxymethyl phosphonium chloride, mercaptosuccinic acid and triphenylphosphine, wherein the tetrakis hydroxymethyl phosphonium chloride is oxidized in the reaction of step (3) to generate trihydroxy phosphonium oxide.

The invention has no special requirements on ultrasonic power and ultrasonic time, and can produce uniform mixed liquid.

The invention has no special requirements on the type of the super constant temperature water bath, and can be realized by adopting a commercial instrument well known in the field.

The invention has no special requirement on the stirring speed, and only needs to uniformly mix the liquid; the invention has no special requirement on the stirring time as long as the constant temperature can be reached.

The method of centrifugation is not particularly required in the present invention, and the product can be centrifuged by a method well known in the art.

The invention has no special requirement on the washing times, and can clean the solid obtained by centrifugation.

The invention has no special requirements on the drying temperature and time, and can ensure that the water of the washed solid is removed.

The carbon material is used as a carrier of the catalyst, so that the catalyst is prevented from agglomerating, and a conductive network is provided for the catalyst. Because the organic ligand end capping agent is coordinated and complexed with the nano gold and the nano platinum, the nano gold and the nano platinum are tightly combined to form nano gold platinum bimetal, but not nano gold platinum alloy. The organic ligand end capping agent can prevent the growth of the nano gold-platinum bimetallic crystal and is beneficial to providing more active sites. The nano gold and the nano platinum can be used as oxygen reaction active sites, and the activity of the nano gold-platinum bimetal is higher than that of single nano gold or nano platinum due to the synergistic effect of the nano gold and the nano platinum. The combination of the nano gold and the nano platinum can inhibit the dissolution and precipitation of the nano platinum, so that the stability of the nano gold-platinum bimetal is good.

The method takes the carbon material as a matrix, the organic ligand end capping agent and the one-step reduction method to prepare the nano gold-platinum bimetallic @ carbon material oxygen reaction catalyst, the catalyst structure is controllable, the reaction condition is mild, the operation is simple and the cost is low; compared with commercial 20wt.% Pt/C, the prepared nano gold-platinum bimetallic @ carbon material oxygen reaction catalyst has better oxygen reduction and oxygen evolution catalytic activity and stability.

Drawings

FIG. 1 is a transmission electron micrograph of example 1.

FIG. 2 is a graph showing a particle size distribution in example 1.

FIG. 3 is a high-resolution TEM image of example 1.

FIG. 4 is an X-ray diffraction chart of example 1.

FIG. 5 is a diagram showing the distribution of gold, platinum and carbon elements in the nano-Au-Pt bimetal of example 1.

Fig. 6 is a graph comparing catalytic activity of oxygen reduction reaction of example 2, with a commercial platinum/carbon catalyst in dotted line and a nano-gold platinum bimetallic @ carbon material catalyst in solid line.

Fig. 7 is a graph comparing the catalytic activity of the oxygen evolution reaction of example 2 with a commercial platinum/carbon catalyst in dashed lines and a nano-gold-platinum bimetallic @ carbon material catalyst in solid lines.

FIG. 8 is a stability control curve for example 2 with the dashed line for the commercial platinum/carbon catalyst and the solid line for the nano-gold platinum bimetallic @ carbon material catalyst.

Fig. 9 is a graph comparing the catalytic activity of the oxygen reduction reaction of example 3, with a commercial platinum/carbon catalyst in dashed lines and a nano-gold-platinum bimetallic @ carbon material catalyst in solid lines.

FIG. 10 is a graph of the catalytic activity of the oxygen evolution reaction versus example 3 with the dashed line for the commercial platinum/carbon catalyst and the solid line for the nano-gold platinum bimetallic @ carbon material catalyst.

FIG. 11 is a stability control curve for example 3 with the dashed line for the commercial platinum/carbon catalyst and the solid line for the nano-gold platinum bimetallic @ carbon material catalyst.

Detailed Description