Synthesis of nickel nanopowders
View Patent ↗The invention relates to a method of making a nickel powder having an average particle size of less than about 100 nanometers, comprising contacting, at a temperature of about 50° C. to about 95° C., a reduction solution with a nickel solution to form a reaction mixture. The reduction solution comprises a base and a reducing agent. The nickel solution comprises a nickel compound water, a nucleation agent, a surfactant or dispersant, and combinations thereof. The yield of nickel nanoparticles is greater than about 90% relative to starting moles of nickel compound. The nickel powder is suitable for use in electronics applications and sintered metal applications.
1. A method of making a nickel powder having an average particle size of less than 100 nanometers, comprising contacting, at a temperature of about 50° C. to about 95° C., a reduction solution with a nickel solution to form a reaction mixture and initiate a reaction,
a. wherein the reduction solution comprises
i. a base providing OH ions, and
ii. a reducing agent selected from the group consisting of hydrazine, sodium borohydride, potassium borohydride, lithium aluminum hydride,
b. wherein the nickel solution excludes alcohol and glycol and comprises
i. water,
ii. a nucleation agent,
iii. a surfactant selected from the group consisting of polyacrylamide, C 16 H 33 (OCH 2 CH 2 )OH, and gum arabic,
iv. a nickel compound selected from the group consisting of nickel acetate, nickel chloride, nickel sulfate, and nickel acetylacetonate said nickel compound providing nickel ions to the nickel solution at a concentration of from 0.5 to 1.5 M,
c. wherein the mole ratio of OH ions to nickel ions is 1:1 to 2.5:1,
d. wherein the mole ratio of reducing agent to nickel ions is from 1.5:1 to 8:1, and
e. wherein the reaction runs to completion in no greater than 30 minutes.
2. The method of claim 1 wherein the base is selected from the group consisting of KOH, NaOH, Na 2 CO 3 , NaHCO 3 , and NH 4 OH, and combinations thereof.
3. The method of claim 1 wherein the nickel solution further comprises a nucleation agent selected from the group consisting of PdC12, AgNO 3 , and K 2 PtCl 4 such that the mole ratio of nucleation agent to nickel is about 1:10000 to about 1:100.
4. The method of claim 1 wherein the average particle size does not exceed about 70 nm, wherein the temperature is about 60° C. to about 90° C., wherein the nickel compound is nickel acetate or nickel sulfate or nickel chloride, and wherein the mole ratio of nucleation agent to nickel is about 1:2000 to about 1:100.
5. The method of claim 1 , wherein the mole ratio of OH ions to nickel ions is from 1.5:1 to 2:1.
6. The method of claim 1 , wherein the mole ratio of reducing agent to nickel ions is from 2:1 to 7:1.
7. The method of claim 1 , wherein the mole ratio of reducing agent to nickel ions is from 3:1 to 6:1.
8. The method of claim 6 , wherein the mole ratio of OH ions to nickel ions is from 1.5:1 to 2:1.
9. The method of claim 7 , wherein the mole ratio of OH ions to nickel ions is from 1.5:1 to 2:1.
10. The method of claim 1 , wherein the yield of nickel powder is greater than 95% relative to starting moles of nickel.
11. The method of claim 1 , wherein the nickel powder having an average particle size of less than 70 nanometers.
12. The method of claim 1 , wherein the nickel compound provides nickel ions to the nickel solution at a concentration of from 0.606 to 1.5 M.
13. The method of claim 1 , wherein the nickel compound provides nickel ions to the nickel solution at a concentration of from 0.67 to 1.5 M.
14. The method of claim 1 , wherein the nickel compound provides nickel ions to the nickel solution at a concentration of from 1 to 1.5 M.