Boron nitride and method of producing boron nitride
BN nanosheets are prepared by a method comprising heating to a temperature of at least 500° C., a mixture comprising: (1) an alkali borohydride, and (2) an ammonium salt. NaN 3 may be included to increase the yield. No catalyst is required, and the product produced contains less than 0.1 atomic percent metal impurities.
1. A method of making BN nanosheets, comprising heating to a temperature of at least 500° C., a mixture comprising: (1) an alkali metal borohydride, and (2) an ammonium salt, wherein the BN nanosheets comprise h-BN nanosheets and contain less than 0.1 atomic percent metal impurities and have a full width at half maximum (FWHM) of the X-ray powder diffraction pattern for a d 002 peak of at most 0.50 degrees.
2. The method of claim 1 , wherein the alkali metal borohydride comprises KBH 4 .
3. The method of claim 1 , wherein the ammonium salt comprises NH 4 Cl.
4. The method of claim 1 , further comprising washing the product with water and/or acid to remove any byproducts.
5. The method of claim 1 , wherein the heating is carried out in a sealed container.
6. The method of claim 1 , wherein the heating is carried out at a temperature of at least 600° C.
7. The method of claim 1 , wherein the heating is carried out at a temperature of at least 800° C.
8. The method of claim 1 , wherein the heating is carried out for at least 24 hours.
9. The method of claim 1 , wherein the heating is carried out for at least 48 hours.
10. The method of claim 1 , wherein the mixture further comprises NaN 3 .
11. The method of claim 1 , wherein the BN nanosheets comprise h-BN nanosheets and do not contain r-BN, as determined by X-ray powder diffraction, and the h-BN nanosheets have a particle size of 250 to 900 nm.
12. The method of claim 1 , wherein the h-BN nanosheets are few layer h-BN nanosheets.
13. The method of claim 1 , wherein the h-BN nanosheets have 6 to 20 layers of BN.
14. The method of claim 1 , wherein the h-BN nanosheets do not contain r-BN, as determined by X-ray powder diffraction.
15. The method of claim 1 , wherein the h-BN nanosheets have a full width at half maximum (FWHM) of the X-ray powder diffraction pattern for a d 002 peak of at most 0.30 degrees.
16. The method of claim 1 , wherein the h-BN nanosheets have a full width at half maximum (FWHM) of the X-ray powder diffraction pattern for a d 100 peak of at most 0.50 degrees.
17. The method of claim 1 , wherein the h-BN nanosheets have a full width at half maximum (FWHM) of the X-ray powder diffraction pattern for a d 100 peak of at most 0.25 degrees.
18. The method of claim 1 , wherein the h-BN nanosheets have a particle size of 250 to 900 nm.
19. The method of claim 13 , wherein the h-BN nanosheets do not contain r-BN, as determined by X-ray powder diffraction, and the h-BN nanosheets have a particle size of 250 to 900 nm.
20. The method of claim 19 , wherein the alkali metal borohydride comprises KBH 4 , the ammonium salt comprises NH 4 Cl, and the heating is carried out at a temperature of at least 600° C.