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 analogous to substitutional doping of ions in crystal lattices.Here we demonstrate such a concept allowing extensive, controlled growth of metallic nanoparticles, at nanoscale proximity, within a perovskite oxide lattice as well as on its surface. By employing operando techniques, we show that in the emergent nanostructure, the endogenous nanoparticles and the perovskite lattice become reciprocally strained and seamlessly connected, enabling enhanced oxygen exchange. Additionally, even deeply embedded nanoparticles can reversibly exchange oxygen with a methane stream, driving its redox conversion to syngas with remarkable selectivity and long term cyclability while surface particles are present. These results not only exemplify the means to create extensive, self-strained nanoarchitectures with enhanced oxygen transport and storage capabilities, but also demonstrate that deeply submerged, redoxactive nanoparticles could be entirely accessible to reaction environments, driving redox transformations and thus offering intriguing new alternatives to design materials underpinning several energy conversion technologies.

The growing demand for H2 and syngas requires the development of new, more efficient processes and materials for their production, especially from CH4 that is a widely available resource. One process that has recently received increased attention is chemical looping CH4 partial oxidation, which however, poses stringent requirements on material design, including fast oxygen exchange and high storage capacity, high reactivity towards CH4 activation and resistance to carbon deposition, often only met by composite materials. Here we design a catalytically active material for this process, based on exsolution from a porous titanate. The exsolved Ni particles act as both 2 oxygen storage centres and as active sites for CH4 conversion under redox conditions. We control the extent of exsolution, particle size and population of Ni particles in order to tune the oxygen capacity, reactivity and stability of the system and, at the same time, obtain insights in parameters affecting and controlling exsolution.

Lowering methane conversion temperature has been long-sought in energy conversion applications and is now being realised via exo/endo-particle perovskites.

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 analogous to substitutional doping of ions in crystal lattices.Here we demonstrate such a concept allowing extensive, controlled growth of metallic nanoparticles, at nanoscale proximity, within a perovskite oxide lattice as well as on its surface. By employing operando techniques, we show that in the emergent nanostructure, the endogenous nanoparticles and the perovskite lattice become reciprocally strained and seamlessly connected, enabling enhanced oxygen exchange. Additionally, even deeply embedded nanoparticles can reversibly exchange oxygen with a methane stream, driving its redox conversion to syngas with remarkable selectivity and long term cyclability while surface particles are present. These results not only exemplify the means to create extensive, self-strained nanoarchitectures with enhanced oxygen transport and storage capabilities, but also demonstrate that deeply submerged, redoxactive nanoparticles could be entirely accessible to reaction environments, driving redox transformations and thus offering intriguing new alternatives to design materials underpinning several energy conversion technologies.

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