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Opportunity

Conventional methods for fabricating nanoporous metallic materials, such as dealloying, often face significant limitations that hinder their widespread industrial application and performance. These existing techniques typically produce materials with several inherent drawbacks, including low purity due to incomplete removal of reactive metal components, coarse nanostructures with thick ligaments and low porosity, and poor mechanical strength, which compromises durability in functional applications. Additionally, traditional manufacturing processes can be complicated, requiring precise control systems, vacuum environments, or cleanroom facilities, leading to relatively high production costs and low throughput. These shortcomings restrict the efficiency and scalability of producing high-quality porous metals needed for advanced technologies. There is a clear market and technological need for a more efficient, cost-effective, and controllable fabrication method that can yield nanoporous metals with superior structural, mechanical, and purity characteristics to meet the demands of modern applications in energy, catalysis, and sensing.

Technology

The present invention addresses these challenges through an innovative hybrid fabrication method that combines Surface Mechanical Attrition Treatment (SMAT) with electrochemical dealloying. The process begins with providing a structure made of an alloy material containing at least two metal components, such as a Cu-Zn or Ni-Cu alloy. This alloy structure is first subjected to SMAT, a mechanical pretreatment where the surface is bombarded with small balls to introduce defects like nanotwins, reduce grain size, and increase grain boundaries. This treatment strengthens the material and enhances its chemical reactivity. The SMAT-treated structure is then selectively etched, typically in an electrolyte solution, often under an applied electric field (DC or pulsed), to dissolve and remove the more reactive metal component(s). This dealloying step creates a porous metallic framework. The key innovation lies in the synergistic effect of the SMAT pretreatment. It significantly lowers the dealloying threshold, allowing porosity formation even in alloys with lower reactive metal content. It accelerates the etching rate, enables more thorough removal of the reactive metal for higher purity, and results in a final structure with finer nanostructures—thinner ligaments and larger pores—leading to a higher surface area. Furthermore, the mechanical strengthening from SMAT is retained, yielding a porous material with improved mechanical performance. The method offers great flexibility; parameters like SMAT duration, etching conditions, and applied voltage can be tuned to precisely control pore size, porosity, and composition. Optional post-treatments, such as thermal oxidation or coating application, can further modify the material into metal oxides or composites for expanded functionality.

Advantages

• Produces porous metallic materials with significantly higher purity due to more complete removal of reactive metal components.
• Creates finer nanostructures with thinner ligaments and larger pores, resulting in a substantially increased surface area.
• Enhances mechanical strength and hardness of the porous framework compared to materials made by conventional dealloying.
• Lowers the dealloying threshold, enabling porosity formation in a wider range of alloy compositions.
• Accelerates the etching/dealloying rate, improving production speed.
• Offers excellent controllability and tunability over structural features (pore size, porosity) and material properties through adjustment of SMAT and electrochemical parameters.
• Reduces production costs by simplifying the process, eliminating the need for expensive vacuum systems or ultra-precise cleanroom environments.
• Enables large-area, uniform fabrication compatible with mass production and automation.
• Provides a versatile platform for creating not just pure metals but also metal oxides and composite structures through subsequent treatments.

Applications

• Electrodes for Energy Storage and Conversion: High-surface-area electrodes for supercapacitors, lithium-ion batteries, and fuel cells.
• Catalysts: Efficient catalyst supports or direct catalysts for chemical reactions, including hydrogen evolution and pollutant degradation.
• Sensors: High-sensitivity platforms for chemical and biological sensing, leveraging the large surface area for analyte binding.
• Photonic and Optoelectronic Devices: Photovoltaic electrodes for solar cells, light-emitting devices, and components utilizing surface plasmon resonance.
• Filter and Separation Media: Advanced filters for chemical processing or environmental remediation.
• Biomedical Devices: Porous structures for drug delivery carriers or implant coatings.
• Instrumentation: Metallic sample holders for spectroscopy (e.g., Raman, fluorescence) to enhance signal detection.
• Structural and Functional Foams: Lightweight, strong metallic foams for various engineering applications.