Creating a 3D Nanoporous Alloy with an Environmentally Friendly Vapor Phase Dealloying Technique

– A new recycling-compatible method that does not use chemical etching –

Researcher: Akihiko Hirata, AIST-Tohoku Mathematics for Advanced Materials Open Innovation Laboratory


  • A new nanoporous alloy manufacturing method that does not use chemical etching was developed.
  • Metal that evaporates during the manufacturing process can be recovered.
  • This is an environmentally friendly method because the materials are recyclable and it does not generate waste.
(a) Schematic of a high vacuum furnace. (b) Method of manufacturing cobalt-zinc alloy. (c) X-ray diffraction results of cobalt-zinc alloy. (d) Relationship between saturated vapor pressure and temperature of cobalt and zinc.

Societal Background of Research

Conventionally, electrochemical dealloying has been used to make nanoporous alloys. However, this method poses problems, as it produces chemical waste during the etching process, and it is very difficult to recover etched metal. These issues have the potential to cause environmental pollution, so the method is not suitable for large-scale commercial applications.


The researcher has developed a new method for manufacturing nanoporous alloys using a vapor phase dealloying method in collaboration with Tohoku University.

Because the vapor pressure of each element in an alloy is different, when that alloy is heated in a vacuum, elements with higher vapor pressure easily evaporate from the alloy, and elements with lower vapor pressure form nanoporous structures by atomic diffusion. Compared to conventional electrochemical dealloying methods, this method has the advantage of producing nanoporous alloys without the use of chemical etching, and evaporated elements can be recovered completely. Therefore, this method is harmless, so it is environmentally friendly. The method is expected to widen the application range of nanoporous alloys.

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