Electrocatalysts, the preparation thereof, and using the same for fuel cells

Patent metadata

Field	Value
Publication number	US-2020194804-A1
Application number	US-201816641378-A
Country	US
Kind code	A1
Filing date	Aug 23, 2018
Priority date	Aug 24, 2017
Publication date	Jun 18, 2020
Grant date	—

Abstract

Compositions comprised of a tin film, coated by a shell of less than 50 nm thick made of palladium and tin in a molar ratio ranging from 1:4 to 3:1, respectively, are disclosed. Uses of the compositions as an electro-catalyst e.g., in a fuel cell, and particularly for the oxidation of various materials are also disclosed.

First claim

1 . A composition, comprising a tin (Sn) film, wherein said Sn film is coated by a shell, wherein said shell:
comprises palladium (Pd) and Sn, wherein the Pd: Sn molar ratio is in the range of 1:4 to 3:1, respectively; and is characterized by a thickness of less than 50 nm.

2 . The composition of claim 1 , wherein said thickness is in the range of 2 nm to 10 nm.

3 . The composition of claim 1 , wherein said shell further comprises a platinum (Pt).

4 . The composition of claim 3 , wherein said Pt and said Sn are present in the shell in a molar ratio of 2:1 to 1:1, respectively.

5 . The composition of claim 1 , wherein the shell is in the form of crystals having a median crystallite size in the range of 3.5 to 6 nm.

6 . The composition of claim 3 , characterized by an X-Ray Powder Diffraction which is devoid of peaks at positions that correspond to a pristine oxide of at least one element selected from Pt, Pd, and Sn.

7 . The composition of claim 1 , further comprising a substrate, wherein said Sn film:
(a) is deposited on at least one surface of said substrate; (b) is coated by said shell.

8 . The composition of claim 7 , wherein said substrate is in the form of plurality of nanoparticles (NPs), wherein said plurality of NPs is characterized by a median size of from about 1 to about 50 nanometers.

9 . The composition of claim 7 , wherein said substrate is a material selected from a carbon, a metal oxide, a polymer, or any combination thereof.

10 . The composition of claim 9 , wherein said carbon is selected from the group consisting of activated carbon, graphite, carbon nanotube, or any combination thereof.

11 . The composition of claim 1 , wherein said Pd: Sn molar ratio is from 3:4 to 1:4.

12 . The composition of claim 1 , being an electro-catalyst.

13 . The composition of claim 3 , characterized by a specific activity of at least 0.05 mA cm −2 Pt.

14 . The composition of claim 12 , wherein the electro-catalyst is capable of promoting a hydrogen oxidation reaction (HOR) with an onset potential of between about 0 mV in alkaline media.

15 . The composition of claim 14 , wherein the electro-catalyst is present in an anode of a fuel cell.

16 . (canceled)

17 . A method for oxidizing a material selected from the group consisting of methanol, ethanol, formic acid, formaldehyde, dimethyl ether, methyl formate, hydrogen, glucose, ammonia, and hydrazine, the method comprising contacting the composition of claim 1 with said material.

18 . The method of claim 17 , wherein any one of: (i) said oxidizing of said hydrogen is performed in an alkaline electrolyte solution; (ii) said alkaline electrolyte solution is characterized by a pH of least 11; and (iii) said alkaline electrolyte solution is a sodium hydroxide (NaOH) solution.

19 .- 20 . (canceled)

21 . A fuel cell comprising an electro-catalyst, the electro-catalyst comprising a tin (Sn) film, wherein said Sn film is coated by a shell, wherein said shell comprises palladium (Pd) and Sn having a molar ratio in the range of 1:4 to 3:1, respectively, wherein said catalyst is capable of catalyzing a hydrogen oxidation reaction.

22 . The fuel cell of claim 21 , wherein any one of: (i) the fuel cell further comprises a membrane electrode assembly (MEA); (ii) the fuel cell having an anode comprising said electro-catalyst; and (iii) said catalyst is characterized by an electrochemically active surface area of at least 75 m 2 g −1 .

23 .- 24 . (canceled)

25 . A process for manufacturing an electro-catalyst comprising a substrate having attached thereon an Sn film, wherein:
(a) said Sn film is coated by an alloy comprising Pd and Sn, wherein the Pd: Sn molar ratio is in the range of 1:4 to 3:1, respectively, and (b) said substrate comprises one or more materials selected from carbon, a metal oxide, a polymer, or any combination thereof, the process comprising the steps of:
(i) electro-depositing said Sn film on said substrate; and
(ii) depositing said alloy on said Sn film, optionally by a process selected from electro-deposition or electroless deposition;
thereby obtaining said catalyst.

26 .- 29 . (canceled)

Assignees

• Ariel Scient Innovations Ltd

Inventors

• Schechter Alex
• Teller Hanan
• Kashyap Diwakar
• Arulrajan Antony Cyril

Classifications

• H01M8/1004

  characterised by membrane-electrode assemblies [MEA] (H01M8/12 takes precedence) · CPC title

• H01M4/9041 Primary

  Metals or alloys (H01M4/92 takes precedence) · CPC title

• H01M4/926

  on carbon or graphite · CPC title

• H01M4/921 Primary

  Alloys or mixtures with metallic elements · CPC title

• H01M4/8652

  as mixture · CPC title