A research group in Japan has successfully developed a “nanoporous super multi-element catalyst” (1) that contains 14 elements (2) which are mixed uniformly at the atomic level and used as a catalyst. The new catalyst was found to show excellent properties as an electrode material for water electrolysis due to the multi-element superposition effect (cocktail effect). The researchers are expecting it will be developed into an omnipotent and versatile catalyst in the future.

The nanoporous super multi-element catalyst promotes the water splitting from water to hydrogen and oxygen. Image Credit and ©: Takeshi Fujita, Kochi University of Technology. Click image for the largest view.

A high-entropy alloy composed of 10 or more elements may act as a catalyst to exhibit “omnipotency and versatility” because it is able to freely modify its morphology and become active according to the reaction field. However, so far, it has not been easy to produce entropy alloys composed of more than 10 elements. The reason is the existence of combinations of some elements that are hard to be mixed, like water and oil.

The joint research group is led by Research Associate Cai ZeXing and Professor Takeshi Fujita at School of Environmental Science and Engineering, Kochi University of Technology, and Professor Masahiro Miyauchi at School of Materials Science and Engineering, Tokyo Institute of Technology. The team’s research paper has been published in the journal Chemical Science.

The nanoporous super multi-element catalyst can be made from an Al alloy containing 14 elements dealloyed by an alkaline solution such as NaOH. Image Credit and ©: Takeshi Fujita, Kochi University of Technology. Click image for the largest view.

The team has developed a “nanoporous super multi-element catalyst” by a method called de-alloying(3) via the selective corrosion and elusion of a specified element from the alloy. The fabrication method is simple: an aluminum alloy containing 14 elements is prepared, and the nanoporous super multi-element catalyst is manufactured by preferential dissolution of aluminum using an alkaline solution.

The team has found by using this method, while creating a nanoporous structure with a large specific surface area (surface area per unit mass of material) with a pore size of about 5 nanometers, elements other than aluminum that do not dissolve in the alkaline solution are accumulated to be aggregated in the form of a solid solution alloy(4) in which the 14 elements are uniformly distributed at the atomic level.

The nanoporous super multi-element catalyst was also found to show excellent properties as an electrode material for water electrolysis due to the multi-element superposition effect (cocktail effect) (5). As this catalyst contains many different elements, it is expected that in the future, it will be developed into an omnipotent and versatile catalyst.

Notes:
(1) Nanoporous super multi-element catalyst:
A catalyst wherein at least 10 elements are uniformly distributed in a sponge structure (porous structure comprising nanosized pores) in which the nanosized pores are randomly connected.
(2) The 14 elements are:
Aluminum (Al), Silver (Ag), Gold (Au), Cobalt (Co), Copper (Cu), Iron (Fe), Iridium (Ir), Molybdenum (Mo), Nickel (Ni), Palladium (Pd), Platinum (Pt), Rhodium (Rh), Ruthenium (Ru), Titanium (Ti).
(3) De-alloying:
A method of selectively eroding and eluting specific elements from an alloy. It is also called selective corrosion.
(4) Solid solution alloy:
An alloy in which two or more elements are mutually melted in each other to form a uniform solid phase.
(5) Multi-element superposition effect (cocktail effect):
Manifestation of a characteristic feature resulting from nonlinear interaction between various constituent atoms. It is expected to reveal particular and outstanding catalytic properties so far inexistent in conventional alloy catalysts.

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The innovative and creative thinking, learned perhaps from Chindogu, the Japanese art of “unuseless inventions” and Wacky Inventions, may have really paid off with this team. The selective corrosion effect taken up to a “De-alloying” level is quite impressive used as a product creation process. Congratulations, indeed.

The team has also shown that the catalyst field is growing out into new territory and becoming ever more useful in processes today and in ways yet to be thought of tomorrow. More is sure to come. Its a very exciting time in chemistry.


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