EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Particles dispersed on the surface of oxide supports have enabled a wealth of applications in electro- photo- and heterogeneous catalysis. Dispersing nanoparticles within the bulk of oxides is, however, synthetically much more challenging and therefore less explored, but could open new dimensions to control material properties. Here we demonstrate such a concept allowing extensive, controlled growth of metallic nanoparticles, at nanoscale proximity, within the bulk of perovskite oxides of 100-150 µm particle size as well as on its surface by employing the exsolution concept outside its conventional use. By employing operando techniques, we show that in the emergent nanostructure, the endoparticles and the perovskite lattice become reciprocally strained and seamlessly connected. In turn, this greatly enhances oxygen exchange across the nanocomposite, seamlessly connecting even the deepest embedded particles to the gas phase environment. We use this concept towards the challenging process of CH4 conversion to syngas via chemical looping partial oxidation. In this process, the oxygen carrier material which reacts cyclically with a reducing and an oxidizing stream also fulfils the catalytic role of CH4 activation producing synthesis gas with high selectivity and minimal carbon deposition at lower temperatures than conventional materials. We demonstrate that the embedded nanoparticles undergo cyclic, redox transformation between metal and metal oxide state, acting as readily accessible nanoscale reservoirs for oxygen storage, maintaining nanocomposite integrity while also being protected against agglomeration or other deactivation processes. Such a concept gives us the ability to tailor materials, through strain engineering, which has been shown to control multiple properties including oxide ion, electron and thermal transport, catalytic reactivity and magnetic properties and thus impact on many other research areas of interest.