CN-121972238-A - Temperature-sensitive platinum catalyst and preparation method and application thereof

Abstract

The invention discloses a temperature-sensitive platinum catalyst and a preparation method and application thereof, relating to the technical field of catalysts, the platinum catalyst with a core-shell structure is obtained by precisely regulating and controlling the proportion of gold salt and platinum salt, the concentration of a reducing agent and the reaction condition; the platinum catalyst has excellent oxygen reduction catalytic activity and temperature-sensitive adaptability, has stable performance in a wide temperature range, and can be widely applied to oxygen reduction half reaction and proton exchange membrane fuel cells.

Inventors

• WU CHANGZHENG
• PAN ZHOU
• CHENG HAN
• GUI RENJIE

Assignees

• 中国科学技术大学

Dates

Publication Date

20260505

Application Date

20260205

Claims (10)

1. 1. The preparation method of the temperature-sensitive platinum catalyst is characterized by comprising the following steps of: s1, adding gold salt and a ligand into deionized water for coordination reaction, adding a strong reducing agent, and stirring to form gold sol; S2, after the strong reducing agent is completely deactivated, adding platinum salt and weak reducing agent into the gold sol, and stirring to form platinum sol with a core-shell structure; and S3, adding a carrier into the platinum sol, stirring to enable the platinum nano particles to be loaded on the surface of the carrier, centrifugally separating, washing and drying to obtain the temperature-sensitive platinum catalyst.
2. 2. The method according to claim 1, wherein the gold salt is at least one of chloroauric acid, sodium chloroaurate, and potassium chloroaurate; preferably, the platinum salt is at least one of chloroplatinic acid, potassium chloroplatinic acid, sodium chloroplatinate and potassium chloroplatinate.
3. 3. The method according to claim 1, wherein the ligand is at least one of sodium citrate, polyvinylpyrrolidone, and cetyltrimethylammonium bromide.
4. 4. The method according to claim 1, wherein the strong reducing agent is at least one of sodium borohydride and potassium borohydride.
5. 5. The preparation method of the metal oxide/metal oxide composite material, which is characterized in that the molar ratio of the metal salt to the ligand to the strong reducing agent is 1 (0.8-1.2): 1.4-2; Preferably, the concentration of the gold salt is 0.05-0.15 mmol/L, and the concentration of the strong reducing agent is 0.01-0.02 mmol/L.
6. 6. The method according to claim 1, wherein the weak reducing agent is at least one of ascorbic acid, ethylene glycol and glucose.
7. 7. The method according to claim 1, wherein the molar ratio of the platinum salt to the weak reducing agent is 1 (3-20); preferably, the concentration of the platinum salt is 0.05-0.15 mmol/L; Preferably, the concentration of the weak reducing agent is 0.05-0.15 mmol/mL.
8. 8. The method according to claim 1, wherein the carrier is at least one of mesoporous carbon, graphene, and carbon nanotubes; Preferably, the concentration of the carrier is 10-40 mg/L; preferably, the particle size of the carrier is 20-50 nm.
9. 9. A temperature-sensitive platinum catalyst prepared by the preparation method of any one of claims 1 to 8.
10. 10. The use of the temperature-sensitive platinum catalyst of claim 9 in oxygen reduction half reactions and fuel cell full reactions.

Description

Temperature-sensitive platinum catalyst and preparation method and application thereof Technical Field The invention relates to the technical field of catalysts, in particular to a temperature-sensitive platinum catalyst and a preparation method and application thereof. Background With the acceleration of global industrialization process and the continuous rising of energy demand, the excessive consumption of fossil fuels causes increasingly severe environmental pollution and greenhouse effect problems, and the development of clean, efficient and sustainable energy conversion technology has become a core strategic direction in the global energy field. Hydrogen energy, a renewable clean energy source with high energy density and combustion products being only water, is recognized as one of the most potential alternative energy sources for fossil fuels. Proton Exchange Membrane Fuel Cells (PEMFCs) are used as a core device for hydrogen energy conversion, and show wide application prospects in the fields of highway automobiles and the like by virtue of the prominent advantages of zero carbon emission, low working temperature, high energy conversion efficiency, quick start-stop and the like, and become a key core technology for promoting hydrogen energy industrialization to fall to the ground. The energy conversion process of the PEMFC is based on electrochemical coupling of anodic hydrogen oxidation reaction and cathodic oxygen reduction reaction, the reaction kinetics of the two electrodes are obviously different, and the reaction rate of cathodic oxygen reduction is at least 1 order of magnitude slower than that of anodic hydrogen oxidation reaction, so that the development of the cathodic oxygen reduction catalytic material with high catalytic activity and stability is a key point for breaking through the application bottleneck of the fuel cell technology. Platinum and its alloys have so far been the material systems with the best catalytic performance for oxygen reduction. In order to improve the utilization rate of platinum atoms, design strategies for constructing a thin platinum layer on the surface of the nano-structured platinum-based alloy are widely adopted. According to the d-band center theory, when the platinum layer generates compressive strain, the d-band center of the platinum shifts to the lower part of the Fermi energy level, so that the adsorption strength of an oxygen-containing intermediate in the oxygen reduction process is weakened, the desorption and reaction process of the intermediate are accelerated, and the catalytic activity is obviously improved, otherwise, the tensile strain can lead the d-band center to shift upwards, the adsorption of the intermediate is enhanced, and the oxygen reduction kinetics is inhibited. However, under the actual working condition temperature (353K) of the fuel cell, the conventional platinum-carbon catalyst and the conventional platinum-based alloy catalyst can cause significant tensile strain of the platinum layer due to the lattice thermal expansion effect, so that the optimal intrinsic catalytic activity of the platinum-carbon catalyst cannot be fully exerted, and the working condition output performance and stability of the fuel cell are severely limited. Disclosure of Invention In order to solve the defects of the prior art, the invention provides the temperature-sensitive platinum catalyst and the preparation method thereof, wherein the catalyst adopts a core-shell structure design, realizes good lattice matching of a gold core and a platinum shell by accurately regulating and controlling preparation process parameters, and endows the catalyst with excellent oxygen reduction catalytic activity and temperature-sensitive adaptability, and the preparation method is simple, mild in condition and suitable for large-scale production. The design strategy of the temperature-sensitive core-shell structure catalyst based on the negative thermal expansion effect is to take small-size gold nanoparticles as cores, have the negative thermal expansion characteristic in the temperature range from room temperature to the working condition of a fuel cell, continuously shrink the gold core crystal lattice along with the temperature rise, form a core-shell structure by growing a platinum layer on the outer layer, and apply a certain compressive strain to the platinum atoms on the surface layer by utilizing the temperature-sensitive crystal lattice shrinkage effect of the gold core. The design has the core advantages that dynamic regulation and control of the strain state of the platinum shell at the working condition temperature is realized, and the platinum shell actively forms compressive strain at the working condition temperature of the fuel cell by the negative thermal expansion characteristic of the gold core, so that the adsorption of an oxygen-containing intermediate is effectively weakened, the reaction kinetics is accelerated, the catalytic activity of the