Inorganic approach to rendering metal-organic frameworks electrically conductive
Inventors
Kung, Chung-Wei • Wang, Timothy Chiaan • Hupp, Joseph T.
Assignees
Publication Number
US-12297216-B2
Publication Date
2025-05-13
Expiration Date
2039-07-18
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Abstract
Electrically conductive, metal-organic framework (MOF) materials, methods of making the materials, and chemical sensors incorporating the materials are provided. The electrically conductive MOF materials are formed from mesoporous MOF crystals having continuous strands of electrically conductive inorganic oxides within their porous structures. The inorganic strands are formed by the condensed-phase grafting of molecular metal species onto MOF nodes.
Core Innovation
The invention provides electrically conductive metal-organic framework (MOF) materials, methods of making these materials, and chemical sensors incorporating them. The electrically conductive MOF materials are formed from mesoporous MOF crystals featuring continuous strands of electrically conductive inorganic oxides, such as tin oxide, within their porous structures. These inorganic strands are created by condensed-phase grafting of molecular metal species onto the MOF nodes, preserving the material’s crystallinity and porosity.
This approach addresses the key problem that most MOFs are effectively insulating under low bias, hindering their application in electrochemical, molecular electronic, or resistive chemical sensing. Previous techniques to impart conductivity often relied on organic species, resulting in stability issues. The present inorganic approach avoids these problems by using conductive inorganic oxide strands, thereby providing robust conductivity while maintaining the MOF’s beneficial high surface area and structural properties.
The process involves reacting hydroxo, aquo, or oxo ligands on the MOF nodes with organometallic complexes in a condensed liquid phase. Through iterative cycles including grafting and steam exposure, continuous electrically conductive strands are built up within the framework. This method has been exemplified using zirconium-based MOFs, such as NU-1000, with continuous tin oxide strands installed along the c-axis, yielding materials suitable for applications such as hydrogen sensing.
Claims Coverage
There are two independent claims providing two main inventive features covered by this patent.
Porous metal-organic framework material with continuous metal oxide strands
The inventive feature is a metal-organic framework material comprising: - A porous metal-organic framework having zirconium nodes connected by 1,3,6,8-tetrakis(p-benzoic acid)pyrene units, with the zirconium nodes capped by hydroxyl ligands. - A plurality of continuous strands of tin oxide running through the framework, with the continuous strands grafted to oxygen atoms on the zirconium nodes. - The material retains its porous nature.
Hydrogen detection method using conductive MOF material
This inventive feature describes a method for detecting hydrogen using the electrically conductive metal-organic framework material, specifically: 1. Providing a MOF material with the characteristics defined above, including continuous strands of electrically conductive tin oxide. 2. Exposing the material to an environment containing hydrogen. 3. Measuring an increase in the conductance of the MOF material, which indicates hydrogen presence.
The patent claims cover a specially structured MOF material with continuous tin oxide strands for conductivity, and a method of hydrogen sensing utilizing the change in electrical conductance of the material upon exposure to hydrogen.
Stated Advantages
Provides a robust inorganic approach that engenders electrical conductivity in MOFs while retaining crystallinity and porosity.
Allows high-density installation of continuous, electrically conductive oxide strands within porous MOF structures.
Reduces dependency on organic components for charge transport, thus improving chemical stability.
Maintains mesoporosity and high internal surface area even after installation of conductive strands.
Enables the MOF to be functional as a rapidly responding, resistive sensor for hydrogen gas.
Documented Applications
Hydrogen sensing, using the electrically conductive MOFs to detect hydrogen based on reversible changes in conductance.
Use in chemical sensors that incorporate the conductive MOF materials.
Potential for aqueous electrocatalysis and applications requiring both electrical conductivity and high surface area.
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