Si‐Doping Switches the Reactivity of Cobalt from Methanation to Reverse Water–Gas Shift in CO ₂ Hydrogenation

Abstract In heterogeneous catalysis, metal oxides are an important group of materials used to support nanoparticle catalysts. These metal oxides, however, are not completely inert and interact with the (transition‐) metal nanoparticle, potentially influencing the overall catalytic properties of the catalyst. This study investigates the influence of the metal oxide support on the catalytic properties of cobalt‐based CO 2 hydrogenation catalysts. A series of cobalt nanoparticles supported on Al 2 O 3 , SiO 2 , CeO 2 , ZrO 2 , and TiO 2 was synthesized using a standardized surface organometallic chemistry approach to provide comparability and characterized by standard microscopy and spectroscopic methods. Catalytic evaluation in CO 2 hydrogenation identifies SiO 2 as a unique support in promoting reverse water–gas shift reactivity in cobalt, while other supports yielded methanation reactivity as commonly observed for cobalt‐based CO 2 hydrogenation. Notably, doping supports with Si, here Al 2 O 3 and TiO 2 , is enough to shift the reactivity of Co toward RWGS, paralleling what is observed when Co is supported on SiO 2 .