Composite Catalyst Layer for Long Carbon Nanotube Arrays
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The short length of carbon nanotubes has limited their applications, as they are difficult to grow with controlled morphology over large surfaces, hindering their use in structural and sensing applications.
Innovation Solution
A composite catalyst layer comprising a group VIII element, such as iron, combined with a non-catalytic lanthanide metal like gadolinium, is used for vapor deposition to grow carbon nanotube arrays exceeding 1 millimeter in length, allowing for multiple growth cycles without reprocessing the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If traditional catalytic substrates (iron, nickel, cobalt) are used for carbon nanotube growth, then nanotubes can be formed, but the nanotube length remains short and controlled morphology over large surfaces is difficult to achieve
Solution Approach 1:
The patent applies composite catalysts combining group VIII elements (Fe, Ni, Co) with lanthanide elements (Gd, La, Eu) to achieve both long nanotube growth and controlled morphology. The composite catalyst layer deposited on substrate enables homogeneous nanotube arrays with lengths exceeding 1 millimeter while maintaining uniform structure over large surface areas greater than one square centimeter.
2Length of moving object
If longer carbon nanotube arrays are formed, then applications in structural reinforcement and sensing are enabled, but traditional methods cannot achieve lengths greater than 1 millimeter
Solution Approach 1:
The patent changes the chemical composition parameters of the catalyst by introducing lanthanide elements in specific ratios (e.g., 1:4 to 4:1 atomic ratios of group VIII to lanthanide elements). This parameter change enables nanotube lengths up to 12 millimeters while simplifying the manufacturing process through vapor deposition methods that can be applied to large substrates without complex processing steps.
3Productivity
If carbon nanotubes are grown on substrate surfaces, then arrays can be formed for applications, but the substrate requires reprocessing for each growth cycle
Solution Approach 1:
The composite catalyst layer on the substrate maintains its catalytic activity and structural integrity after nanotube growth, enabling the substrate to serve itself for multiple growth cycles without reprocessing. The substrate with composite catalyst can be reused repeatedly to grow additional nanotube arrays, eliminating time-consuming reprocessing steps and significantly improving productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method enables the production of longer carbon nanotube arrays, facilitating their use in structural and sensing applications by achieving lengths up to 12 millimeters and allowing for repeated growth without additional substrate processing.
Implementation Method 1
carbon nanotube arrays with carbon nanotubes having lengths greater than 1 millimeter up to and exceeding 2 centimeters can be obtained by vapor deposition of carbon onto a catalyst coated substrate
Implementation Method 2
The oxidized composite catalyst layer is then reduced to the elemental form prior to introducing reactant gases to grow a carbon nanotube array
Implementation Method 3
Carbon nanotubes have been traditionally formed by chemical vapor deposition of carbon on a catalytic substrate
Data Source
AI summary
A method of forming a carbon nanotube array substrate is disclosed. One embodiment comprises depositing a composite catalyst layer on the substrate, oxidizing the composite catalyst layer, reducing the oxidized composite catalyst layer, and growing the array on the composite catalyst layer. The composite catalyst layer may comprise a group VIII element and a non-catalytic element deposited onto the substrate from an alloy. In another embodiment, the composite catalyst layer comprises alternating layers of iron and a lanthanide, preferably gadolinium or lanthanum. The composite catalyst layer may be reused to grow multiple carbon nanotube arrays without additional processing of the substrate. The method may comprise bulk synthesis by forming carbon nanotubes on a plurality of particulate substrates having a composite catalyst layer comprising the group VIII element and the non-catalytic element. In another embodiment, the composite catalyst layer is deposited on both sides of the substrate.