From ions to nanoparticles

Exsolution is an advanced catalyst fabrication strategy in which metal nanoparticles emerge from a host oxide under reducing conditions, forming socketed, strongly anchored active sites.
Compared to traditional preparation methods such as impregnation or precipitation, exsolved catalysts exhibit superior resistance to sintering, coking, and metal agglomeration, which make them particularly attractive for heterogeneous and electro-catalysis applications. 

However, exsolution has so far been studied predominantly in sintered matrices, although nanoporosity is clearly beneficial for the performance of heterogeneous catalysts. Moreover, the energy transition calls for sustainable, multifunctional catalysts that can adapt to complex catalytic processes, which requires control not only over the amount of exsolved metal but also over the composition and architecture of the nanoparticles. To this purpose, the solid-state nature of exsolution offers a unique opportunity, as the path from ions to nanoparticles can be steered by the microstructure of the host oxide and by the reduction conditions, and reversed by oxidative regeneration.

In this talk, I will show how these levers can be used to design exsolved perovskite catalysts. First, the exsolution of nickel nanoparticles from nanoporous and sintered perovskite oxides will be compared, showing how nanoporosity enhances metal reduction, influences the nanoparticle formation mechanism and leads to markedly more active, stable and regenerable catalysts for biogas dry reforming.

Particular focus will then be given to shapeshifting bimetallic iron–nickel catalysts for CO2-mediated ethane conversion, in which the reduction temperature determines the nanoparticle architecture and thereby the reaction selectivity. The reversibility of these transformations upon redox cycling will also be discussed.

Speaker:

Simone Mascotto is Professor of Inorganic Chemistry – Functional Ceramics at the University of Koblenz, Germany.
His research focuses on developing nanostructured inorganic materials for catalysis and energy conversion, with particular emphasis on green hydrogen production and CO₂ valorisation. He investigates structure–property relationships to design more efficient, stable and sustainable catalysts.