METHOD OF MAKING NiO NANOPARTICLES FOR ELECTROCATALYTIC WATER SPLITTING

Patent metadata

Field	Value
Publication number	US-2019264342-A1
Application number	US-201815903732-A
Country	US
Kind code	A1
Filing date	Feb 23, 2018
Priority date	Feb 23, 2018
Publication date	Aug 29, 2019
Grant date	—

Abstract

A method of making NiO nanoparticles is described, as well as a method of using NiO nanoparticles as an electrocatalyst component to a porous carbon electrode. The carbon electrode may be made of carbonized filter paper. Together, this carbon-supported NiO electrode may be used for water electrolysis. Using a pamoic acid salt in the NiO nanoparticle synthesis leads to smaller and monodisperse nanoparticles, which support higher current densities.

First claim

1 . A method for making NiO nanoparticles, the method comprising:
mixing a nickel salt, pamoic acid or a pamoic acid salt, and an alcohol to form a dispersed mixture; drying the dispersed mixture to produce a dried mass; and heating the dried mass in air at a temperature of 420-700° C. for 1-6 h to produce the NiO nanoparticles, wherein the NiO nanoparticles have an average particle size of 5-50 nm.

2 . The method of claim 1 , wherein the nickel salt and the pamoic acid or the pamoic acid salt have a combined weight percentage of 0.8-2.5 wt % relative to a total weight of the dispersed mixture.

3 . The method of claim 1 , wherein the NiO nanoparticles are monodisperse and have an aspect ratio of 1:1-1.5:1.

4 . The method of claim 1 , wherein the NiO nanoparticles have a crystalline bunsenite morphology.

5 . The method of claim 1 , wherein at least 70% of the NiO nanoparticles have a particle size of 10-40 nm.

6 . The method of claim 1 , wherein a molar ratio of the pamoic acid or the pamoic acid salt to the nickel salt is 5:10-8:10.

7 . The method of claim 1 , wherein the nickel salt is Ni(NO 3 ) 2 or Ni(NO 3 ) 2 .6H 2 O.

8 . The method of claim 1 , wherein the pamoic acid salt is present, and the pamoic acid salt is disodium pamoate.

9 . The method of claim 1 , wherein the NiO nanoparticles have an average particle size that is substantially smaller than an average particle size of NiO nanoparticles produced by an otherwise identical method having no pamoic acid and no pamoic acid salt.

10 . A carbon-supported NiO electrode, comprising:
carbonized paper and NiO nanoparticles having an average particle size of 5-50 nm, deposited on the carbonized paper, wherein the carbon-supported NiO electrode is substantially free of Ni 0 .

11 . The carbon-supported NiO electrode of claim 10 , wherein a density of the NiO nanoparticles on the carbonized paper is 100-200 μg/cm 2 .

12 . The carbon-supported NiO electrode of claim 10 , wherein the NiO nanoparticles are aggregated into clusters having diameters of 1-15 μm.

13 . The carbon-supported NiO electrode of claim 12 , wherein the clusters have a nearest neighbor distance of 500 nm-5 μm.

14 . The carbon-supported NiO electrode of claim 10 , wherein the NiO nanoparticles are made by a method comprising:
mixing a nickel salt, pamoic acid or a pamoic acid salt, and an alcohol to form a dispersed mixture; drying the dispersed mixture to produce a dried mass; and heating the dried mass in air at a temperature of 420-700° C. for 1-6 h to produce the NiO nanoparticles.

15 . An electrochemical cell, comprising:
the carbon-supported NiO electrode of claim 10 ; a counter electrode; and an electrolyte solution in contact with both electrodes.

16 . The electrochemical cell of claim 15 , wherein the electrolyte solution comprises water and an inorganic base at a concentration of 0.05-0.4 M.

17 . The electrochemical cell of claim 16 , wherein the carbon-supported NiO electrode has a current density of 26-35 mA/cm 2 when the electrodes are subjected to a potential of 1.3-1.8 V.

18 . The electrochemical cell of claim 15 , further comprising a reference electrode in contact with the electrolyte solution.

19 . A method for decomposing water into H 2 and O 2 , the method comprising:
subjecting the electrodes of the electrochemical cell of claim 16 with a potential of 0.5-2.0 V.

20 . The method of claim 19 , further comprising separately collecting H 2 -enriched gas and O 2 -enriched gas.

Assignees

• Univ King Fahd Pet & Minerals

Inventors

• Aziz Md Abdul
• Qasem Mohammed Ameeh Ahmed

Classifications

• C01P2004/64

  Nanometer sized, i.e. from 1-100 nanometer · CPC title

• C01P2002/82

  by IR- or Raman-data · CPC title

• C01P2002/85

  by XPS, EDX or EDAX data · CPC title

• C01P2004/54

  Particles characterised by their aspect ratio, i.e. the ratio of sizes in the longest to the shortest dimension · CPC title

• C01P2002/72

  by d-values or two theta-values, e.g. as X-ray diagram · CPC title