Catalyst

A catalyst and microstructuring technology, applied in the direction of catalyst activation/preparation, physical/chemical process catalyst, metal/metal oxide/metal hydroxide catalyst, etc., can solve loss of surface area, loss of specific activity of electrocatalyst, particle sintering Surface roughness loss etc.

Pending Publication Date: 2020-12-04
3M INNOVATIVE PROPERTIES CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For example, electrocatalyst specific activity can be lost due to dissolution of electrocatalyst alloying elements
Nanoparticle and nanoscale thin film electrocatalysts may lose surface area, e.g. due to Pt dissolution, particle sintering, agglomeration, and loss of surface roughness

Method used

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Examples

Experimental program
Comparison scheme
Effect test

preparation example A

[0098] Using microstructured catalyst transfer substrates (or MCTS) as described in U.S. Patent 6,136,412 (Spiewak et al.) 5039561 (Debe) (also incorporated herein by reference) for the preparation of microstructured whiskers for use as catalyst supports. The perylene red pigment (i.e., N,N'-bis(3,5-xylyl)perylene-3,4:9,10-bis(dicarboximide)) Pigment Red 149, also known as "PR149 ", available from Clariant, Charlotte, NC) by sublimation vacuum deposition onto MCTS with a nominal thickness of 200 nm and then annealed. After deposition and annealing, a highly oriented crystal structure is formed: its aspect ratio is very large, its controllable length is about 0.5 micron to 2 microns, its width is about 0.03 micron to 0.05 micron, and its domain density is about 30 whiskers per square micron , the structure is oriented substantially perpendicular to its underlying substrate.

Embodiment 1

[0125] The Example 1 catalyst was prepared and characterized as described for Comparative Example A, except that a layer of tantalum was deposited prior to Pt deposition, the Pt deposition conditions were modified to vary the Pt loading, and the catalyst was conditioned prior to assembly into a MEA. thermal annealing.

[0126] The NSTF catalyst layer, Preparation A, was prepared by sequentially sputtering the catalyst film onto the microstructured whisker layer using a DC-magnetron sputtering process. A vacuum sputter deposition system was used with a typical Ar sputter gas pressure of about 3.3 mTorr (0.44 Pa) and 5 inch by 15 inch (12.7 cm by 38.1 cm) rectangular Pt and Ta sputter targets. System base pressure is usually 2.5×10 -5 Torr (0.0033Pa), the background gas usually measured is water vapor. The coating was deposited by using ultra-high purity Ar as the sputtering gas.

[0127] A single Ta layer with a planar equivalent thickness of about 0.5 nm was first deposited...

Embodiment 2-7

[0130] Examples 2 to 7 were prepared and characterized as described for Example 1, except that the Pt deposition process was modified such that the Pt areal loading was about 10 micrograms / cm each 2 , 15 micrograms / cm 2 , 20 micrograms / cm 2 , 40 micrograms / cm 2 , 50 micrograms / cm 2 and 78 μg / cm 2 , and were additionally characterized as described below. The results are provided in Table 5 above.

[0131]After completing the characterization of the fuel cell, the catalyst of Example 2 was characterized by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). The Example 4 catalyst was characterized by TEM and EDS after deposition of the catalyst metal onto the microstructured whiskers, after thermal annealing of the catalyst, and after fuel cell characterization. The Pt:Ta atomic ratios are summarized in Table 6 below. The Pt:Ta atomic ratio of Example 2 was 1.09. The Pt:Ta atomic ratio of the catalyst of Example 4 ranged between 2.17 an...

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Abstract

Provided is a catalysts comprising a Ta layer having an outer layer with a layer comprising Pt directly thereon, wherein the Ta layer has an average thickness in a range from 0.04 to 30 nanometers, wherein the layer comprising Pt has an average thickness in a range from 0.04 to 50 nanometers, and wherein the Pt and Ta are present in an atomic ratio in a range from 0.01:1 to 10:1. Catalyst described herein are useful, for example, in fuel cell membrane electrode assemblies.

Description

[0001] Cross References to Related Applications [0002] This application claims the benefit of U.S. Provisional Patent Application 62 / 657,189, filed April 13, 2018, the disclosure of which is incorporated herein by reference in its entirety. [0003] This invention was made with Government support awarded by DOE, Contract No. DE-EE0007270. The government has certain rights in this invention. Background technique [0004] Fuel cells generate electricity through electrochemical oxidation of fuel and reduction of oxidant. Fuel cells are generally classified according to the type of electrolyte and the type of fuel and oxidant reactants. One type of fuel cell is a polymer electrolyte membrane fuel cell (PEMFC), where the electrolyte is a polymeric ion conductor and the reactants are hydrogen fuel and oxygen as the oxidant. Oxygen is usually provided by ambient air. [0005] PEMFCs generally require the use of electrocatalysts to increase the reaction rates of hydrogen oxidat...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/90B01J23/64B01J37/02B01J23/648H01M4/92
CPCH01M4/9058H01M4/921Y02E60/50H01M4/8657H01M4/9041H01M4/92
Inventor 安德鲁·J·L·斯坦巴克安德鲁·T·豪格克日什托夫·A·莱温斯基埃米·E·赫斯特格朗特·M·托马斯赛德利克·贝多亚曾振华杰弗瑞·P·格里利
Owner 3M INNOVATIVE PROPERTIES CO
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