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 LaNi0.08Al0.92O3 [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.