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-delta catalyst, showed the highest CH4 conversion (81%) at 750 degrees C via the preactivation of the catalyst with H-2 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-delta 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-delta is more exothermic with/without an oxygen vacancy conditin by 1.01 ev/0.43 eV, which suggests the agglomentation of Ir on the surface.