High-entropy oxides, or so-called disordered crystals, are a very young field of research in which there is still much to discover. Young researcher Amy Knorpp sees enormous potential in these materials for catalytic systems, especially in the conversion of CO2 and hydrogen to methanol. This is because methanol is an important basic chemical substance that can be used in many forms in our society - for fuels, for example. However, to produce synthetic methanol at large scale, more robust and efficient catalysts than currently exist are needed. "Disordered crystals pose as a potential material for these sought-after catalysts. On one hand, their extreme disorder can bring new dimensions of stability in catalytic processes, leading to a longer lifetime of the catalyst. On the other hand, their chemistry is highly tailorable to create both defects and synergies between different elements", explains Amy Knorpp. Specifically, in high-entropy oxides, individual positions within the precisely ordered structures of a crystal are replaced by foreign elements. With a mix of at least five different elements, exceptional properties can be expected. Scientists then like to speak of the so-called cocktail effect. A crucial property of a successful catalyst is to allow for preference to the making of methanol instead to other hydrocarbons. The specific alteration of certain sites in a crystal, as in high-entropy oxides, benefits exactly that, through efficient activation of the CO2 and dissociation of H2 in a favorable arrangement.
"Empa Young Scientist Fellow" Amy Knorpp and Michael Stuer produce different crystal mixtures. (Image: Empa)
Bringing light into the dark
But there are still many unanswered questions along the way. Amy Knorpp and the "Nanopowers and ceramics" project group, led by Michael Stuer, are now systematically investigating in this various changes leading to a new variety of high-entropy oxides. In doing so, they hope to answer questions such as how efficiently this new materials work as catalysts and what their lifespans are. "This will result in a kind of map for the sys-tematic modification of crystals with the goal of creating the "ideal disorder" in a crystal for methanol synthesis. This project serves as basic research and will shed light on the darkness," explains "Empa Young Scientist Fellow" Amy Knorpp.
Talent promotion at Empa
The Empa Young Scientist Fellowship is a funding instrument for exceptionally talented young scientists. The Fellow receives the financial means to carry out an independent research project for a period of two years. Fellowships are awarded by Empa
in a competitive process to ensure that applications with the highest potential are being selected.