Importance of Exsolution in Transition-Metal (Co, Rh, and Ir)-Doped LaCrO₃ Perovskite Catalysts for Boosting Dry Reforming of CH₄ Using CO₂ for Hydrogen Production

LaCrO3 perovskite and transition-metal (Co, Rh, Ir)-doped perovskite-based catalysts were fabricated using the Pechini method and applied to the dry reforming reaction of CH4 using CO2. One of the prepared perovskite-based catalysts, the LaCr0.95Ir0.05O3−δ catalyst, showed the highest CH4 conversion (81%) at 750 °C via the preactivation of the catalyst with H2 gas. It also showed highly stable catalytic activity for 72 h without coke formation on the catalyst surface. Through X-ray photoelectron spectroscopy and transmission electron microscopy analyses, it is confirmed that the improved catalytic activity of the LaCr0.95Ir0.05O3−δ perovskite-based catalyst was based on the exsolution of Ir nanoparticles on the catalyst surface, which catalyzes the cleavage of the C–H bond for CH4. Density functional theory calculations revealed that the exsolution of a dopant Ir in LaCr0.95Ir0.05O3−δ is more exothermic with/without an oxygen vacancy condition by 1.01 eV/0.43 eV, which suggests the agglomeration of Ir on the surface