Noble metal monolayer shell coatings on transition metal ceramic nanoparticle cores

Patent metadata

Field	Value
Publication number	US-2017128917-A1
Application number	US-201615344544-A
Country	US
Kind code	A1
Filing date	Nov 6, 2016
Priority date	Nov 6, 2015
Publication date	May 11, 2017
Grant date	—

Abstract

Nanoparticles comprising a core including transition metal carbide, nitride, phosphide, sulfide, or boride and a noble metal shell can be made by transforming metal oxide core/noble metal shell materials coated in a ceramic material in a controlled environment. The noble metal shell can be a single monolayer. The self-assembly of metal carbide nanoparticles coated with atomically-thin noble metal monolayers results in a highly active, stable, and tunable catalytic platform.

First claim

What is claimed is:

1 . A composition comprising:
a plurality of nanoparticles, each nanoparticle, independently, including a core comprising a transition metal ceramics and a shell comprising a noble metal.

2 . The composition of claim 1 , wherein the transition metal ceramics includes a transition metal carbide, transition metal nitride, transition metal boride, transition metal sulfide or transition metal phosphide.

3 . The composition of claim 1 , wherein the shell is a monolayer.

4 . The composition of claim 1 , wherein the transition metal ceramics has a composition of formula (I)
M1 x M2 y M3 z X1 w1 X2 w2   (I)
wherein each of M1, M2 and M3, independently, is a transition metal element from the group consisting of group 3, group 4, group 5, group 6, 3d block, and f block; and each of X1 and X2, independently, is selected from the group consisting of O, C, N, S, B, and P, at least one of X1 and X2 being C, N, S, B, or P, wherein each of x, y, w1, w2, and z is a number between 0 and 3, where at least one of x, y, z, w1 and w2 is not zero and the combination of x, y, z, w1 and w2 completes the valence requirements of the formula.

5 . The composition of claim 4 , wherein the transition metal element includes Sc, Y, La, Ce, Nd, Sm, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, or Zn.

6 . The composition of claim 1 , wherein the shell includes Au, Pt, Pd, Ru, Rh, Ir, Os, Ag, Sn, Pb, or any combinations thereof.

7 . The composition of claim 1 , wherein the size of the nanoparticle is no more than 10 nm.

8 . The composition of claim 1 , wherein the size of the nanoparticle is no more than 5 nm.

9 . The composition of claim 4 , wherein M1 is tungsten, X1 is carbon, x is 1, w1 is 1, and y=z=w1=w2=0.

10 . A method of producing a plurality of nanoparticles comprising:
encapsulating nanoparticles comprising a metal oxide or metal core and a noble metal shell within an inorganic matrix, calcining the encapsulated nanoparticles in an oxidizing atmosphere or vacuum, heating the nanoparticles in the presence of a reducing agent; and converting the metal oxide core to metal ceramics including C, N, S, B, or P.

11 . The method of claim 10 , further comprising removing the inorganic matrix.

12 . The method of claim 10 , wherein converting the nanoparticles includes carburizing the nanoparticles in a methane atmosphere.

13 . The method of claim 11 , wherein the inorganic matrix includes silicon oxide, aluminum oxide, germanium oxide, zirconium oxide, cerium oxide, hafnium oxide, gallium oxide or titanium oxide.

14 . The method of claim 10 , wherein the nanoparticle includes a tungsten carbide nanoparticle, a molybdenum carbide nanoparticle, or heterometallic carbide nanoparticle.

15 . The method of claim 14 , wherein the heterometallic carbide nanoparticle includes a molybdenum tungsten carbide.

16 . The method of claim 10 , wherein converting the nanoparticles includes nitridizing the nanoparticles.

17 . The method of claim 10 , wherein converting the nanoparticles includes phosphidizing the nanoparticles.

18 . The method of claim 10 , wherein converting the nanoparticles includes sulfidizing the nanoparticles.

19 . The method of claim 10 , wherein converting the nanoparticles includes boridizing the nanoparticles.

20 . The method of claim 10 , wherein a plurality of the nanoparticles is dispersed on a support.

21 . The method of claim 20 , wherein the support is carbon black, graphene, carbon nanotubes, high-surface area carbide, a metal oxide including silica, alumina, titania, zirconia, ceria, or zeolites.

Assignees

• Massachusetts Inst Technology

Inventors

• Hunt Sean Thomas
• Roman-Leshkov Yuriy

Classifications

• B01J2235/00

  Indexing scheme associated with group B01J35/00, related to the analysis techniques used to determine the catalysts form or properties · CPC title

• B01J2235/30

  Scanning electron microscopy; Transmission electron microscopy · CPC title

• B01J35/45

  Nanoparticles · CPC title

• B01J2235/15

  X-ray diffraction · CPC title

• B01J35/70

  characterised by their crystalline properties, e.g. semi-crystalline (catalysts comprising carbon B01J21/18; molecular sieves B01J29/00) · CPC title