In Situ Exsolution of Bimetallic Rh-Ni Nanoalloys: a Highly Efficient Catalyst for CO₂ Methanation

Unique CO₂ methanation catalysts comprising bimetallic Ni-Rh nanoalloy/3DOM LaAlO₃ have been successfully prepared via a poly(methyl methacrylate) microsphere colloidal crystal-templating route, followed by the in situ growth of Ni nanoparticles (NPs). Here, we show that unlike traditional Ni particles deposited on a perovskite support, the exsolution of Ni occurs on both the external and internal surface of the porous perovskite substrate, leading to a strong metal-support interaction. Owing to the exsolution of Ni and the formation of Ni-Rh nanoalloys, a 52% enhancement in the methanation turnover frequency was obtained over the Ni-Rh/3DOM LaAlO₃ [13.9 mol/(mol h)] compared to Rh/3DOM LaNi_0.08Al_0.92O₃ [9.16 mol/(mol h)] before reduction treatment. The results show that the low-temperature reducibility, rich surface adsorbed oxygen species, and basic sites of the catalyst greatly improve its activity toward CO₂ methanation. The hierarchically porous structure of the perovskite support provides a high dispersion of bimetallic Ni-Rh NPs.