Rocking chair-like movement of ex-solved nanoparticles on the Ni-Co doped La_0.6Ca_0.4FeO_3-δ oxygen carrier during chemical looping reforming coupled with CO₂ splitting

Chemical looping reforming coupled with CO₂ splitting is a promising CO₂ utilization method that produces a valuable fuel. Here, we present a novel perovskite oxide with the composition of La_0.6Ca_0.4Fe_0.95M_0.05O_3-δ (M = Ni, Co, Ni-Co) that functions both as an oxygen carrier and as a redox catalyst. Using a multi technique approach with HR-TEM, XRD, XAS, and Mössbauer spectroscopy, we find that alloy nanoparticles spontaneously form on the surface of Ni-Co doped carriers in a CH₄ atmosphere, and as they are repeatedly exposed to CO₂ and CH₄ during the chemical loop, Fe atoms move back and forth between the inside (as Fe cations in the lattice) and the outside (as a part of metallic alloy) of the host scaffold. Eventually, the co-doped samples become highly reactive towards both gases and have excellent coking and redox stability, demonstrating record-level syngas yield (total ∼10 mmol/g) at 850 °C, over 50 redox cycles.