An incredible nanoporous alloy that contains the 14 major metals

Its chemical formula is Al₈₇Ag₁At₁Co₁With₁Fe₁Ir₁Mo₁Ni₁Pd₁Pt₁Rh₁Ru₁You₁. A team of Japanese researchers has synthesized an alloy containing no less than 14 elements, namelyaluminium, l’money, l’or, le cobalt, the copper, the do, l’iridium, molybdenum, nickel, the palladium, platinum, rhodium, the ruthenium and the titanium. This new material belongs to the class of high entropy alloys, consisting of five or more elements in almost equimolar proportions. Thanks to their extremely stable structure and their microstructured richness, these materials have exceptional mechanical properties from resistance and tenacity. Discovered fortuitously in the 2000s, they have since been the subject of much attention and scientists are testing new “recipes” every day.

An original composition

The interest of the new 14 alloy metals is however less on the side of the mechanical properties than of its power of catalyst. « Most conventional alloy catalysts contain a primary metal component with a high atomic percentage, such as platinum, and one or two types of minor metal components with a relatively low atomic percentage., explique Guofeng Wang, materials scientist at the University of Pittsburgh – who was not involved in the study. Minor constituents normally provide the beneficial effects of ligands or deformation which improves the catalytic performance of the primary metal component “. But, with this new formula, more major and minor constituents, since all the elements are in equimolar proportion. ” We thus obtain millions of possible atomic arrangements Says Takeshi Fujita, researcher at Kochi University of Technology and lead author of the journal study. Chemical Science. This deformation capacity makes it possible to create many “hollows” which make the material very porous, one of the properties sought for catalysis in order to produce an efficient filter – the larger the contact area, the faster the reaction.

The cocktail effect

However, the manufacture of alloys with more than 10 elements is very complex. ” Like water and oil, it is not easy to mix many elements evenly », Explains Takeshi Fujita. The researchers therefore used a method called “desalloying”, which consists of selectively corroding an element. The 14 elements are mixed in a solution alkaline, which will degrade the aluminum. Materials other than aluminum, undissolved, aggregate into a shape solid with a uniform distribution at the atomic level. A nanoporous surface is thus obtained with pores of approximately 5 nanometers, which gives the alloy its exceptional catalytic properties. Fujita describes his new material as ” cocktail effect », The mixture of different metals modifying their behavior. ” A cocktail is tasty not because of the sum of each element, but because of the unexpected tastes of the combination of ingredients », He illustrates. The advantage compared to conventional catalysts is, of course, that there is a need here for a smaller quantity of rare and expensive metals such as platinum or palladium.

Electrodes for the production of hydrogen

The team evaluated the performance of the alloy in the electrocatalysis reaction ofhydrogen andoxygen in condition acid. The new alloy showed excellent electrochemical stability, rapid transport of electrons and high kinetics. He has, moreover, kept his morphology and its porous structure, even after spending ten hours in an acidic environment. This proves that it could be an excellent candidate for electrodes in water catalysis. A huge outlet, since it is neither more nor less produce hydrogen, presented as the fuel of the future.