# US 8,540,796 B1 · Sintering and ripening resistant noble metal nanostructures > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,540,796 B1 - Document ID: US8540796B1 - Status: Granted - Kind: B1 - Application number: 12/107,803 - Filed: 2008-04-23 - Granted: 2013-09-24 - Earliest claimed: 2008-04-23 - Assignees: Sandia Corporation - Applicants: Frank B. van Swol; Yujiang Song; John A. Shelnutt; James E. Miller; Sivakumar R. Challa - Inventors: Frank B. van Swol; Yujiang Song; John A. Shelnutt; James E. Miller; Sivakumar R. Challa - Web page: https://patentgrep.com/patent/US8540796B1 ## CPC - B22F 1/0551: {Flake form nanoparticles} - B22F 1/054: Nanosized particles - B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites - B22F 2999/00: Aspects linked to processes or compositions used in powder metallurgy - B22F: WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER (making alloys by powder metallurgy C22C); APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES ## Abstract Durable porous metal nanostructures comprising thin metal nanosheets that are metastable under some conditions that commonly produce rapid reduction in surface area due to sintering and/or Ostwald ripening. The invention further comprises the method for making such durable porous metal nanostructures. Durable, high-surface area nanostructures result from the formation of persistent durable holes or pores in metal nanosheets formed from dendritic nanosheets. ## Claims ### Claim 1 A durable porous metal nanostructure, comprising: a thin metal nanosheet, wherein the thin metal nanosheet has a thickness less than or equal to 20 nm and wherein the thin metal nanosheet has a distribution of pores, wherein a pore lateral dimension is greater than or equal to 80% of the thickness and wherein a structure of the thin metal nanosheet is at least 75% nonbranching. ### Claim 2 (depends on 1) The durable porous metal nanostructure of claim 1, wherein the pore lateral dimension is less than or equal to five times the thickness. ### Claim 3 (depends on 1) The durable porous metal nanostructure of claim 1, wherein the thickness is greater than or equal to approximately 6 atomic layers. ### Claim 4 (depends on 1) The durable porous metal nanostructure of claim 1, wherein the thin metal nanosheet has a surface area of at least 120% of a surface area of a solid sheet with a set of lateral dimensions approximately the same as a set of lateral dimensions of the thin metal nanosheet. ### Claim 5 (depends on 1) The durable porous metal nanostructure of claim 1, wherein the distribution of pores is nonperiodic. ### Claim 6 (depends on 1) The durable porous metal nanostructure of claim 1, wherein the durable porous metal nanostructure comprises a plurality of thin metal nanosheets combined to form a foam-like structure. ### Claim 7 (depends on 6) The durable porous nanostructure of claim 6, wherein the foam-like structure is a foam-like spheroid. ### Claim 8 (depends on 1) The durable porous metal nanostructure of claim 1, wherein a metal of the thin metal nanosheet is selected from the group consisting of Pt, Pd, Au, Ag, Ir, Ru, and Rh. ### Claim 9 A method for making a durable perforated metal nanostructure comprising: preparing a dendritic metal nanostructure, wherein the dendritic metal nanostructure comprises a two-dimensional sheet of branches with gaps between branches; and inducing diffusion by elevating a temperature of the dendritic metal nanostructure to close at least 75% of the gaps between branches to form pores to make the durable perforated metal nanostructure. ### Claim 10 (depends on 9) The method of claim 9, wherein a thickness of the two-dimensional sheet is less than or equal to approximately 10 nm. ### Claim 11 (depends on 9) The method of claim 9, wherein the branches of the dendritic metal nanostructure have substantially a uniform thickness except at tips of the branches. ### Claim 12 (depends on 9) The method of claim 9, wherein a ratio of a thickness of the two-dimensional sheet and the gaps between branches is between approximately 3 and approximately 1. ### Claim 13 (depends on 9) The method of claim 9, wherein the dendritic metal nanostructure comprises a plurality of two-dimensional sheets that are combined to form a foam-like structure. ### Claim 14 (depends on 13) The method of claim 13, wherein the foam-like structure is a foam-like spheroid. ### Claim 15 (depends on 13) The method of claim 13, wherein the foam-like structure has an irregular shape. ### Claim 16 (depends on 9) The method of claim 9, wherein the dendritic metal nanostructure comprises a plurality of two-dimensional sheets that have combined to form a nanocage. ### Claim 17 (depends on 9) The method of claim 9, wherein a metal of the durable perforated metal nanostructure is selected from the group consisting of Pt, Pd, Au, Ag, Ir, Ru, Rh, and alloys thereof. ### Claim 18 (depends on 9) The method of claim 9, wherein the step of inducing diffusion employs at least one of heating by electrical current, irradiating with light, irradiating with charged particles, and heating by at least one of convection and conduction. ### Claim 19 (depends on 9) The method of claim 9, wherein the step of inducing diffusion comprises causing at least one chemical reaction at a surface of the dendritic metal nanostructure, wherein the at least one chemical reaction is selected from the group consisting of a catalytic reaction, an electrochemical reaction, a coordination reaction, an acid-promoted solution-surface interaction, and a base-promoted solution-surface interaction.