Continuous Nanostructure Synthesis via Spatially Varying Precursor Concentrations
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Solution Overview
Problem
Current methods for continuous production of aligned nanostructures on a moving host material, such as carbon nanotubes, face limitations in productivity and cost due to the complexity of synthesis processes and the need for precise control of catalyst lifetime and precursor injection.
Innovation Solution
A process and device that modify synthesis conditions spatially along a moving substrate by varying the concentration of catalytic precursors and carrier gases in different zones, allowing for continuous production of aligned nanostructures with improved catalytic efficiency, growth rate, and purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous production of aligned nanostructures is implemented on a moving substrate, then productivity is improved, but the complexity of synthesis process control increases due to the need for precise catalyst lifetime management and precursor injection timing
Solution Approach 1:
The synthesis chamber is divided into multiple zones along the substrate conveyance direction, with each zone having independent precursor injection systems and heating control. This segmentation allows different regions of the substrate to experience optimized local synthesis conditions simultaneously, enabling continuous production while maintaining precise control over catalyst lifetime and nanostructure quality in each zone
Solution Approach 2:
The system dynamically adjusts precursor injection rates, carrier gas flow rates, and heating temperatures in real-time based on the moving substrate's position and the desired catalyst lifetime. This dynamic control enables the synthesis process to adapt continuously, maintaining optimal conditions for nanostructure growth throughout the entire substrate surface area
2Productivity
If the concentration of catalytic precursors is increased to improve growth rate, then productivity is improved, but the purity of nanostructures deteriorates due to catalyst residue
Solution Approach 1:
Different zones along the substrate conveyance path are assigned different catalytic precursor concentrations optimized for their specific function: upstream zones use higher concentrations to initiate rapid nucleation and growth, while downstream zones use lower concentrations to complete growth with minimal catalyst residue, thereby maintaining both high growth rate and high purity
Solution Approach 2:
The system changes the concentration parameter of catalytic precursors dynamically along the synthesis path, transitioning from high concentration at the initiation stage to low concentration at the completion stage. This parameter evolution enables the growth rate to remain high while the purity is maintained by reducing catalyst contamination in the final product
3Manufacturing precision
If the concentration of catalytic precursors is decreased to improve purity, then manufacturing precision is improved, but the growth rate deteriorates
Solution Approach 1:
The system performs preliminary high-concentration precursor injection in upstream zones to establish rapid nucleation and initial growth phases, ensuring high growth rate is achieved early. Subsequently, low-concentration precursor injection continues in downstream zones to complete growth with high purity, thereby resolving the trade-off between growth rate and purity through sequential action
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 approach enhances productivity and reduces costs by achieving higher yields and purer nanostructures through spatial variation of synthesis conditions, enabling efficient industrial-scale production of aligned nanostructures.
Implementation Method 1
synthesizing, in this space, the nanostructures aligned on the support by catalytic chemical vapor deposition
Implementation Method 2
injection operations are carried out by modifying, in at least two of the n zones, at least one parameter chosen from among the flow rate of the carrier gas, the chemical composition of the carrier gas, and the mass concentration of the catalytic precursor
Implementation Method 3
heating and injection operations, in each of the n zones, of a flow of an aerosol containing a catalytic precursor and a source precursor
Implementation Method 4
synthesizing, in this space, the nanostructures aligned on the support by catalytic chemical vapor deposition
Data Source
Figure 1~2
Figure 3~4a
Figure 4b~4c
AI summary
The invention relates to a method for continuous production of nanostructures aligned on a travelling substrate, which comprises conveying the substrate through a heated space and synthesising, in said space, nanostructures aligned on the substrate by catalytic chemical vapour deposition. The heated space is divided into n consecutive areas in the direction in which the substrate is conveyed (n being an integer > 2) and the synthesis of the nanostructures is the result of heating and injection operations, in each of said n zones, of a stream of an aerosol containing a catalytic precursor and a source precursor of the material of the nanostructures to be formed, carried by a carrier gas. The injection operations are carried out by modifying, in at least two of the n zones, at least one parameter chosen from the flow rate of the stream of carrier gas, the chemical composition of the carrier gas, and the mass concentration of the catalytic precursor in the mixture of the catalytic precursor and the source precursor. The invention also relates to a device for implementing said method.