Annealed metal nano-particle decorated nanotubes
Inventors
Iftime, Gabriel • Kim, Beomseok • Smith, Clinton J. • Cocker, Eric D. • Wei, Junhua • SCHWARTZ, DAVID ERIC • Meyyappan, Meyya • Pandey, Rahul • Zhang, Yong
Assignees
Bay Systems Consulting Inc • SRI International Inc • National Aeronautics and Space Administration NASA
Publication Number
US-11958747-B2
Publication Date
2024-04-16
Expiration Date
2037-12-22
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Abstract
Disclosed are methods and systems of providing carbon nanotubes decorated with polymer coated metal nanoparticles. Then, annealing the metal coated carbon nanotubes to reduce a quantity of hydrophilic components of the polymer coating.
Core Innovation
The invention provides methods and systems for preparing carbon nanotubes decorated with polymer-coated metal nanoparticles, with a subsequent annealing process to reduce the quantity of hydrophilic components of the polymer coating. This process results in carbon nanotube materials with reduced adsorption of water vapor by the metal nanoparticles, thereby producing a composition that is more hydrophobic. The annealing step, conducted at temperatures above 300°C (often around 350°C or higher), effectively reduces oxygenated functional groups and further carbonizes the polymer layer on the nanoparticles.
This approach addresses the limitations of existing gas sensor technologies, particularly in environments with ambient water vapor. Conventional compact and low-power gas sensors can be adversely affected by humidity, leading to reduced detection ability and reliability due to saturation from water vapor. By creating a hydrophobic sensor material through annealing, the invention enables improved performance and lifespan for gas sensors used in atmospheric conditions with varying humidity.
The invention not only describes fabrication of the hydrophobic metal nanoparticle-decorated nanotubes, but also their integration into gas sensor devices. These sensors utilize resistivity changes in the carbon nanotube/metal nanoparticle composition to detect gases such as methane. The method enables improved sensitivity, lower detection limits, and longer sensor lifetime in humid environments.
Claims Coverage
There are two independent claims in the patent, each introducing a unique inventive feature.
Composition of matter comprising annealed polymer-coated metal nanoparticle decorated carbon nanotubes
The composition includes a first set of carbon nanotubes decorated with polymer-coated metal nanoparticles, where: - The polymer coating attaches the metal nanoparticles to the carbon nanotubes and reduces adsorption of water vapor by the metal nanoparticles. - The composition has a first amount of oxygenated functional groups, controlled through an annealing process at a temperature above 300 degrees Celsius, with the amount being within twenty percent of the composition weight. - The composition has a first water contact angle, also achieved by the annealing process, which is higher than eighty-two degrees.
Sensor for detecting gas using annealed polymer-coated metal nanoparticle decorated carbon nanotubes
The sensor includes: - An electrode assembly comprising electrodes with a gas-adsorbing material disposed between them. - The gas-adsorbing material is the same annealed composition: a first set of carbon nanotubes decorated with polymer-coated metal nanoparticles, with a reduced amount of oxygenated functional groups (within twenty percent of the composition weight) and a first water contact angle higher than eighty-two degrees, all resulting from the annealing process at a temperature above 300 degrees Celsius. - The sensor is associated with a detection limit achieved based on this annealing process.
The inventive features cover both the specialized annealed composite material and its integration into a gas-detecting sensor device, with specific characteristics imparted by the annealing process to enhance hydrophobicity and sensor performance.
Stated Advantages
The sensors exhibit improved sensitivity due to lower polymer content and more direct contact between metal nanoparticles and carbon nanotube surface.
The annealed composition provides reduced water sensitivity, as removal of hydrophilic functional groups renders the material more hydrophobic.
Sensors produced with the annealed material demonstrate improved detection limits and increased lifetime in humid conditions.
Documented Applications
Use in gas sensors, particularly for monitoring and detecting natural gas or methane leaks.
Application in sensors for detecting hydrocarbons such as methane, ethane, and propane.
Potential for use in printed methane sensors and sensor devices that must operate over a range of relative humidity in ambient environmental conditions.
Use in gas sensors that can be integrated onto substrates with interdigitated electrodes for resistivity-based detection.
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