# US 7,465,494 B2 · Density controlled carbon nanotube array electrodes

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- Number: US 7,465,494 B2
- Document ID: US7465494B2
- Status: Granted
- Kind: B2
- Application number: 10/424,295
- Filed: 2003-04-28
- Published: 2004-03-25
- Granted: 2008-12-16
- Earliest claimed: 2002-04-29
- Assignees: The Trustees of Boston College
- Inventors: Zhifeng F. Ren; Yi Tu
- Web page: https://patentgrep.com/patent/US7465494B2

## CPC

- C01B 32/162: characterised by catalysts
- B01J 23/76: combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J 23/866: {Nickel and chromium}
- B01J 37/0238: {via the gaseous phase-sublimation}
- B01J 37/349: {making use of flames, plasmas or lasers}
- B82Y 10/00: Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
- B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites
- B82Y 40/00: Manufacture or treatment of nanostructures
- D01F 9/1271: {Alkanes or cycloalkanes}
- D01F 9/1272: {Methane}
- D01F 9/1275: {Acetylene}
- D01F 9/1276: {Aromatics, e.g. toluene}
- C01B 2202/08: Aligned nanotubes
- C01B 2202/34: Length
- C01B 2202/36: Diameter
- H10K 85/221: {Carbon nanotubes}
- H10K 85/615: {Polycyclic condensed aromatic hydrocarbons, e.g. anthracene}
- Y10S 977/722: On a metal substrate
- Y10T 428/2918: including free carbon or carbide or therewith [not as steel]
- Y10T 428/30: Self-sustaining carbon mass or layer with impregnant or other layer
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- D01F: CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
- H10K: ORGANIC ELECTRIC SOLID-STATE DEVICES
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

CNT materials comprising aligned carbon nanotubes (CNTs) with pre-determined site densities, catalyst substrate materials for obtaining them and methods for forming aligned CNTs with controllable densities on such catalyst substrate materials are described. The fabrication of films comprising site-density controlled vertically aligned CNT arrays of the invention with variable field emission characteristics, whereby the field emission properties of the films are controlled by independently varying the length of CNTs in the aligned array within the film or by independently varying inter-tubule spacing of the CNTs within the array (site density) are disclosed. The fabrication of microelectrode arrays (MEAs) formed utilizing the carbon nanotube material of the invention is also described.

## Claims

### Claim 1

A carbon nanotube material comprising an array of substantially linear carbon nanotubes with pre-determined densities that are attached to a catalyst substrate material including a metallic conductive layer deposited on a non-metallic material and a plurality of catalytic transition metal microparticles deposited upon the metallic conductive layer, wherein individual carbon nanotubes are aligned with respect to one another within said array.

### Claim 2 (depends on 1)

The carbon nanotube material of claim 1, wherein the carbon nanotubes have pre-determined densities of up to 1×1012 cm−2.

### Claim 3 (depends on 1)

The carbon nanotube material of claim 1, wherein the non-metallic material is selected from the group consisting of silicon, silica, glass, alumina, quartz and graphite.

### Claim 4 (depends on 1)

The carbon nanotube material of claim 1, wherein the non-metallic material is a silicon wafer.

### Claim 5 (depends on 1)

The carbon nanotube material of claim 1, wherein the metallic conductive layer comprises a metal, metal alloy or mixture thereof.

### Claim 6 (depends on 1)

The carbon nanotube material of claim 1, wherein the metallic conductive layer comprises a metal selected from the group consisting of chromium (Cr), molybdenum (Mo), tungsten (W), ruthenium (Ru), copper (Cu), silver (Ag) and gold (Au).

### Claim 7 (depends on 1)

The carbon nanotube material of claim 1, wherein the metallic conductive layer is chromium (Cr).

### Claim 8 (depends on 1)

The carbon nanotube material of claim 1, wherein the catalytic transition metal microparticles comprise a catalytic transition metal selected from the group consisting of nickel (Ni), silver (Ag), gold (Au), platinum (Pt), palladium (Pd), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh) and iridium (Ir).

### Claim 9 (depends on 1)

The carbon nanotube material of claim 1, wherein the catalytic transition metal microparticles comprise nickel (Ni).

### Claim 10 (depends on 1)

The carbon nanotube material of claim 1, wherein the catalytic transition metal microparticles have an average diameter ranging from 50 nanometers to 200 nanometers.

### Claim 11 (depends on 1)

The carbon nanotube material of claim 1, wherein the catalytic transition metal microparticles have an average diameter ranging from 50 nanometers to 80 nanometers.

### Claim 12 (depends on 1)

The carbon nanotube material of claim 1, wherein the carbon nanotubes have a substantially uniform tubule length.

### Claim 13 (depends on 12)

The carbon nanotube material of claim 12, wherein the carbon nanotube length ranges between 1 and 100 micrometers.

### Claim 14 (depends on 12)

The carbon nanotube material of claim 12, wherein the carbon nanotube length is about 8 micrometers.

### Claim 15 (depends on 1)

The carbon nanotube material of claim 1, wherein the carbon nanotubes have a substantially uniform diameter.

### Claim 16 (depends on 15)

The carbon nanotube material of claim 15, wherein the carbon nanotube diameter ranges between 50 and 500 nanometers.

### Claim 17 (depends on 15)

The carbon nanotube material of claim 15, wherein the carbon nanotube diameter is about 100 nanometers.

### Claim 18

A method of forming a carbon nanotube material comprising:
forming a catalyst substrate material by depositing a metallic conductive layer on a non-metallic material and depositing a plurality of catalytic transition metal microparticles on the metallic conductive layer; and
contacting said catalyst substrate material with a carbon source gas so as to cause formation of an aligned array of individual carbon nanotubes with pre-determined densities on the surface of said catalytic substrate material.

### Claim 19 (depends on 18)

The method of claim 18, further comprising applying a plasma to the catalyst substrate material during formation of the aligned array of individual carbon nanotubes.

### Claim 20 (depends on 19)

The method of claim 19, wherein the plasma is direct current plasma.

### Claim 21 (depends on 18)

The method of claim 18, wherein said metallic conductive layer forms a substantially uniform surface layer on said non-metallic material.

### Claim 22 (depends on 21)

The method of claim 21, further comprising etching the catalyst substrate material.

### Claim 23 (depends on 21)

The method of claim 21, wherein the carbon source gas is a saturated, unsaturated linear, branched or cyclic hydrocarbon, or mixture thereof.

### Claim 24 (depends on 23)

The method of claim 23, wherein the carbon source gas is selected from the group consisting of acetylene, methane, propane, ethylene, benzene.

### Claim 25 (depends on 24)

The method of claim 24, wherein the carbon source gas is acetylene.

### Claim 26 (depends on 18)

The method of claim 18, wherein the metallic conductive layer is deposited on the non-metallic material by magnetron sputtering.

### Claim 27 (depends on 21)

The method of claim 21, wherein the catalytic transition metal microparticles are deposited on the layer of metallic conductive layer by a pulse-current electrochemical deposition process.

### Claim 28 (depends on 27)

The method of claim 27, wherein the pulse-current electrochemical deposition process comprises an electrolytic solution comprising a transition metal salt and a mineral acid.

### Claim 29 (depends on 27)

The method of claim 27, wherein the pulse-current electrochemical deposition process comprises utilizing an electrolytic solution comprising nickel sulfate (NiSO4) and boric acid (H3BO3).

### Claim 30 (depends on 18)

The method of claim 18, wherein the carbon nanotubes have pre-determined densities of up to about 1×1012 cm−2.

### Claim 31 (depends on 18)

The method of claim 18, wherein the non-metallic material is selected from the group consisting of silicon, silica, glass, alumina, quartz and graphite.

### Claim 32 (depends on 18)

The method of claim 18, wherein the non-metallic material is a silicon wafer.

### Claim 33 (depends on 18)

The method of claim 18, wherein the metallic conductive layer comprises a metal, metal alloy or mixture thereof.

### Claim 34 (depends on 18)

The method of claim 18, wherein the metallic conductive layer comprises a metal selected from the group consisting of chromium (Cr), molybdenum (Mo), tungsten (W), ruthenium (Ru), copper (Cu), silver (Ag) and gold (Au).

### Claim 35 (depends on 18)

The method of claim 18, wherein the metallic conductive layer is chromium (Cr).

### Claim 36 (depends on 21)

The method of claim 21, wherein the catalytic transition metal microparticles comprise a catalytic transition metal selected from the group consisting of nickel (Ni), silver (Ag), gold (Au), platinum (Pt), palladium (Pd), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh) and iridium (Ir).

### Claim 37 (depends on 21)

The method of claim 21, wherein the catalytic transition metal microparticles comprise nickel (Ni).

### Claim 38 (depends on 21)

The method of claim 21, wherein the microparticles have an average diameter ranging between 50 nanometers and 200 nanometers.

### Claim 39 (depends on 21)

The method of claim 21, wherein the microparticles have an average diameter ranging between 50 nanometers and 80 nanometers.

### Claim 40 (depends on 18)

The method of claim 18, wherein the carbon nanotubes have a substantially uniform tubule length.

### Claim 41 (depends on 40)

The method of claim 40, wherein the carbon nanotube length ranges from 1 to 100 micrometers.

### Claim 42 (depends on 40)

The method of claim 40, wherein the carbon nanotubes length is about 8 micrometers.

### Claim 43 (depends on 18)

The method of claim 18, wherein the carbon nanotubes have a substantially uniform diameter.

### Claim 44 (depends on 43)

The method of claim 43, wherein the carbon nanotube diameter ranges between 50 and 500 nanometers.

### Claim 45 (depends on 43)

The method of claim 43, wherein the carbon nanotube diameter is about 100 nanometers.

### Claim 46

A carbon nanotube material comprising a plurality of individual carbon nanotubes engaged to a catalyst substrate material including a metallic conductive layer, a non-metallic material and a plurality of catalytic transition metal microparticles deposited upon the metallic conductive layer, wherein the carbon nanotubes are substantially linear and aligned with pre-determined densities.

### Claim 47 (depends on 46)

The carbon nanotube material of claim 46, wherein the catalytic transition metal microparticles deposited upon the metallic conductive layer result in the fabrication of substantially linear individual carbon nanotubes.

### Claim 48 (depends on 46)

The carbon nanotube material of claim 46, wherein the plurality of carbon nanotubes have pre-determined densities of up to 1×1012 cm−2.

### Claim 49 (depends on 46)

The carbon nanotube material of claim 46, wherein the non-metallic material is selected from the group consisting of silicon, silica, glass, alumina, quartz and graphite.

### Claim 50 (depends on 46)

The carbon nanotube material of claim 46, wherein the non-metallic material is a silicon wafer.

### Claim 51 (depends on 46)

The carbon nanotube material of claim 46, wherein the metallic conductive layer comprises a metal, metal alloy or mixture thereof.

### Claim 52 (depends on 46)

The carbon nanotube material of claim 46, wherein the metallic conductive layer comprises a metal selected from the group consisting of chromium (Cr), molybdenum (Mo), tungsten (W), ruthenium (Ru), copper (Cu), silver (Ag) and gold (Au).

### Claim 53 (depends on 46)

The carbon nanotube material of claim 46, wherein the metallic conductive layer is chromium (Cr).

### Claim 54 (depends on 47)

The carbon nanotube material of claim 47, wherein the catalytic transition metal microparticles comprise a catalytic transition metal selected from the group consisting of nickel (Ni), silver (Ag), gold (Au), platinum (Pt), palladium (Pd), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh) and iridium (Ir).

### Claim 55 (depends on 47)

The carbon nanotube material of claim 47, wherein the catalytic transition metal microparticles comprise nickel (Ni).

### Claim 56 (depends on 47)

The carbon nanotube material of claim 47, wherein the catalytic transition metal microparticles have an average diameter ranging from about 50 nanometers to about 200 nanometers.

### Claim 57 (depends on 47)

The carbon nanotube material of claim 47, wherein the catalytic transition metal microparticles have an average diameter ranging from about 50 nanometers to about 80 nanometers.

### Claim 58 (depends on 46)

The carbon nanotube material of claim 46, wherein the plurality of individual carbon nanotubes have a substantially uniform tubule length.

### Claim 59 (depends on 58)

The carbon nanotube material of claim 58, wherein the length of the plurality of individual carbon nanotubes ranges between about 1 and about 100 micrometers.

### Claim 60 (depends on 58)

The carbon nanotube material of claim 58, wherein the length of the plurality of individual carbon nanotubes is about 8 micrometers.

### Claim 61 (depends on 46)

The carbon nanotube material of claim 46, wherein the plurality of individual carbon nanotubes have a substantially uniform diameter.

### Claim 62 (depends on 61)

The carbon nanotube material of claim 61, wherein the diameter of the plurality of individual carbon nanotubes ranges between about 50 and about 500 nanometers.

### Claim 63 (depends on 61)

The carbon nanotube material of claim 61, wherein the diameter of the plurality of individual carbon nanotubes is about 100 nanometers.

### Claim 64 (depends on 46)

The carbon nanotube material of claim 46, wherein the pre-determined densities of the plurality of individual carbon nanotubes defines the inter-tubule distance between the individual carbon nanotubes.

### Claim 65 (depends on 64)

The carbon nanotube material of claim 64, wherein each of the plurality of individual carbon nanotubes has a diameter that is smaller than the intertubule distance between each individual carbon nanotube, resulting in each carbon nanotube working as an individual nanoelectrode.

### Claim 66

A carbon nanotube material comprising a plurality of individual carbon nanotubes engaged to a catalyst substrate material including a metallic conductive layer, a non-metallic material and plurality of catalytic transition metal microparticles deposited upon the metallic conductive layer, wherein the carbon nanotubes are substantially liner with pre-determined densities.

### Claim 67 (depends on 66)

The carbon nanotube material of claim 66, wherein the plurality of carbon nanotubes have pre-determined densities of up to 1×1012 cm−2.

### Claim 68 (depends on 66)

The carbon nanotube material of claim 66, wherein the non-metallic material is selected from the group consisting of silicon, silica, glass, alumina, quartz and graphite.

### Claim 69 (depends on 66)

The carbon nanotube material of claim 66, wherein the non-metallic material is a silicon wafer.

### Claim 70 (depends on 66)

The carbon nanotube material of claim 66, wherein the metallic conductive layer comprises a metal, metal alloy or mixture thereof.

### Claim 71 (depends on 66)

The carbon nanotube material of claim 66, wherein the metallic conductive layer comprises a metal selected from the group consisting of chromium (Cr), molybdenum (Mo), tungsten (W), ruthenium (Ru), copper (Cu), silver (Ag) and gold (Au).

### Claim 72 (depends on 66)

The carbon nanotube material of claim 66, wherein the metallic conductive layer is chromium (Cr).

### Claim 73 (depends on 66)

The carbon nanotube material of claim 66, wherein the catalytic transition metal microparticles comprise a catalytic transition metal selected from the group consisting of nickel (Ni), silver (Ag), gold (Au), platinum (Pt), palladium (Pd), iron (Fe), ruthenium (Ru), osmium (Os), cobalt (Co), rhodium (Rh) and iridium (Ir).

### Claim 74 (depends on 66)

The carbon nanotube material of claim 66, wherein the catalytic transition metal microparticles comprise nickel (Ni).