Palladium and platinum-based nanoparticle functional sensor layers for selective H2 sensing
Inventors
Ohodnicki, JR., Paul R. • Baltrus, John P. • Brown, Thomas D.
Assignees
Publication Number
US-9696256-B1
Publication Date
2017-07-04
Expiration Date
2035-10-20
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Abstract
The disclosure relates to a plasmon resonance-based method for H2 sensing in a gas stream utilizing a hydrogen sensing material. The hydrogen sensing material is comprises Pd-based or Pt-based nanoparticles having an average nanoparticle diameter of less than about 100 nanometers dispersed in an inert matrix having a bandgap greater than or equal to 5 eV, and an oxygen ion conductivity less than approximately 10−7 S/cm at a temperature of 700° C. Exemplary inert matrix materials include SiO2, Al2O3, and Si3N4 as well as modifications to modify the effective refractive indices through combinations and/or doping of such materials. The hydrogen sensing material utilized in the method of this disclosure may be prepared using means known in the art for the production of nanoparticles dispersed within a supporting matrix including sol-gel based wet chemistry techniques, impregnation techniques, implantation techniques, sputtering techniques, and others.
Core Innovation
The disclosure provides a method for sensing hydrogen (H2) concentration in a gas stream through the evaluation of an optical signal generated by a hydrogen sensing material comprised of palladium (Pd)-based nanoparticles, platinum (Pt)-based nanoparticles, or combinations thereof dispersed in an inert matrix. The hydrogen sensing material interacts with the gas stream containing varying concentrations of diatomic hydrogen, and the method measures changes in the optical signal caused by transmission, reflection, or scattering of incident light by the sensing material. The inert matrix has a wide bandgap (greater than or equal to 5 eV) and low oxygen ion conductivity (less than approximately 10^(-7) S/cm at 700° C.), with exemplary materials being SiO2, Al2O3, Si3N4, or doped/mixed variants thereof. The average diameter of the Pd or Pt-based nanoparticles is less than about 100 nanometers, with specific embodiments having diameters less than 10 nanometers.
The method addresses the problem of selectively sensing hydrogen with sensors that operate effectively and safely in harsh environments, elevated temperatures, and explosive atmospheres. Existing hydrogen sensors, including resistive, electrochemical, catalytic, and optical types, often face challenges related to sensitivity, stability, selectivity, and interference from other gases. Pd thin films and alloys have been widely used but have limitations, especially regarding microstructural stability and sensing responses at elevated temperatures. Nanoparticles of Pd or Pd-based alloys on silica or optical fiber substrates have shown promise in addressing some issues, but further work is needed to understand sensing mechanisms and improve performance in the presence of other gases.
This disclosure introduces an improved hydrogen sensing material that utilizes Pd and/or Pt-based nanoparticles dispersed in an inert matrix that serves multiple roles: it acts as a chemically inert protective host for nanoparticles, provides inherent filtering to improve H2 selectivity by minimizing interference from other gases such as CO, and allows tuning of optical properties for compatibility with waveguide-based sensing platforms. The nanoparticles within the matrix maintain stability under high-temperature and repeated H2 loading/unloading conditions, and the matrix mitigates coarsening of nanoparticles. The method and material can be integrated into optical fiber sensors or waveguide sensors, where the optical signal shifts correlate directly with hydrogen concentrations across a broad range, including levels up to the lower explosive limit.
Claims Coverage
The patent includes four claims with inventive features related to a hydrogen sensing method employing a hydrogen sensing material comprising nanoparticles dispersed in an inert matrix. Key inventive features are extracted from the independent claims.
Hydrogen sensing material composition and preparation
A hydrogen sensing material comprising an inert matrix stable at gas stream temperature, optically transparent over a relevant light wavelength range, having a bandgap greater than or equal to 5 eV, and oxygen ion conductivity less than 10^-7 S/cm at 700°C. The material includes a plurality of nanoparticles dispersed within the matrix, with a metallic component of at least 50 wt.% consisting of palladium, platinum, their alloys, or combinations thereof. The nanoparticles have an average diameter less than about 10 nanometers.
Illumination and optical signal monitoring for hydrogen evaluation
Illuminating the hydrogen sensing material with incident light from a light source, collecting exiting light that is transmitted, reflected, scattered, or a combination thereof by the material, and monitoring an optical signal based on comparison of incident and exiting light through optical spectroscopy to evaluate the hydrogen concentration of the gas stream.
Specific matrix composition with palladium metallic component
In configurations where the metallic component comprises palladium, the inert matrix consists of at least 50 wt.% of an inorganic metal oxide with formula MaOb.
Use of platinum metallic component with inorganic metal oxide matrix
Where the metallic component comprises platinum, the inert matrix also comprises at least 50 wt.% of an inorganic metal oxide with formula MaOb.
Integration with a waveguide and evanescent wave illumination
Providing a waveguide composed of a core material; placing the hydrogen sensing material in contact with the core; emitting incident light into the core generating an evanescent wave; and illuminating the hydrogen sensing material with the evanescent wave to effect hydrogen sensing.
The claims collectively cover a hydrogen sensing method based on optical spectroscopy employing Pd and/or Pt-based nanoparticles dispersed in a wide bandgap, low oxygen ion conductivity inert matrix. The method includes specific compositions, optical interrogation techniques, and integration with waveguide sensors to enable evaluation of hydrogen concentration in a gas stream.
Stated Advantages
Improved thermal stability of the sensing material under high-temperature conditions.
Enhanced selectivity to hydrogen by minimizing cross-sensitivity to other chemical species such as carbon monoxide (CO).
Increased stability of nanoparticle size and microstructure during hydrogen loading and unloading cycles.
Tunability of the effective refractive index of the nanocomposite sensing material for compatibility and optimization in optical waveguide-based sensors.
Chemical inertness of the matrix providing protection for embedded nanoparticles suitable for harsh environments.
Documented Applications
Detecting hydrogen leak concentrations up to the lower explosive limit (~4% in ambient air) for safety applications.
Monitoring hydrogen in metallurgical processes at elevated temperatures.
Monitoring fuel gas compositions in power generation technologies such as gas turbines and solid oxide fuel cells.
Measurement of dissolved hydrogen in transformer oil for condition-based monitoring of potential failures.
Optical fiber sensor implementations and waveguide-based sensors integrating the hydrogen sensing material.
Interested in licensing this patent?