Ceria crystal facet impact for methane C–H activation in Pd/CeO2 catalysts

The exposed facets of ceria crystals have a profound effect on the reactivity of ceria-supported catalysts owing to the intricate metal-support interactions. In this work, ceria nanorods, nanocubes, and polyhedra, with corresponding exposed (110)/(100), (100), and (111) terminations, were hydrothermally synthesized to support Pd species, with the aim of investigating the in-depth impacts of ceria crystal facets for methane combustion over ceria-supported palladium catalysts. The nanorod sample delivered the highest methane conversion (T50 = 277 & DEG;C, GHSV = 200 000 mL h^-1 gcat^-1) and greater reaction rate (9.59 x 10^-4 molCH4 h^-1 gcat^-1), 1.23 times that of nanocubes and 3.14 times that of polyhedra. Further characterizations revealed that on the (110)/(100) surface planes, PdOx exhibited stronger interactions with CeO2. This led to enhanced formation of Pd⁴⁺ and higher reducibility of PdOx species, thus promoting methane activation. This work would supply experimental insights into the relationship between exposed facets and reactivity, as well as guidance for rational catalyst design.