Shape-controlled LaNiO3 nanoparticles were prepared by modified hydrothermal and precipitation routes resulting in cubes, spheres, and rods. The solid-phase crystallization of LaNiO3 into its active catalyst form, Ni/La2O3, was found to be highly dependent on the shape and structure of the parent nanoparticle. Factors such as the crystallization pathway and Ni2+-ion depletion are considered as key factors influencing the final material. Catalysts derived from LaNiO3 spheres and rods were found to be free of carbon accumulation after 100 h of reforming, while those derived from cubes showed excessive carbon accumulation and signs of sintering. All three catalysts are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), temperature-programmed reduction (TPR), and thermogravimetric analyses (TGA). The presence of defects, particularly stacking faults within the perovskite, may impact the reduction pathway and subsequent catalytic properties. Stable and active catalysts can therefore be designed and tuned by controlling the shape and structure of perovskite precursors.

The valorization of natural gas is a highly important process which could enable the production of hydrogen or clean synthetic fuels. Methane reforming with carbon dioxide provides an environmentally friendly route for methane conversion to synthesis gas while consuming two greenhouse gasses. Large-scale implementation of this process has been stalled by the lack of stable catalysts owing to variety of deactivation mechanisms such as carbon accumulation (coking) and sintering. We created doped perovskite precursors based on lanthanum ferrite (LaFeO 3) and subsequently doped them with Ni and Re phases. Under reducing conditions, these composite precursors exsolved Re-alloy nanoparticles which were found to be active and stable under dry reforming conditions. The solid-phase crystallization process was studied by in-situ synchrotron XRD, and compared to the temperature programmed reduction of each precursor. No carbon accumulation or nanoparticle sintering was observed after 70 hours of operation. Furthermore, the evaporation of catalytic Re phases, a major problem under reforming conditions, was shown to be completely blocked due to strong catalyst-support interactions imbued by this synthesis technique.