Mechanistic Insights into the Role of CH 4 and CO 2 Activation in Dry Reforming of Methane over Ni/CeO 2 Catalysts with Different Crystal Planes

The activation of CH 4 and CO 2 as well as the formation of carbon deposit are crucial for dry reforming of methane (DRM), and mechanistic insights into the relationship between reactant activation and carbon evolution during the DRM process are expected to provide guidance for the design of high-performance catalysts. Herein, by utilizing carefully defined Ni/CeO 2 model catalysts with different CeO 2 crystal planes, we elucidate at the atomic scale the roles of crystal plane in determining the reactant activation and carbon deposit formation in DRM by a joint experimental–theoretical method. The crystal planes of CeO 2 determine the active sites and activation ability for CH 4 and CO 2 by influencing Ni–CeO 2 interactions and oxygen vacancy (O V ) concentrations. Both the metal and interface active sites of Ni/CeO 2 (111) and Ni/CeO 2 (110) can activate CH 4 and exhibit good DRM activity. In contrast, only the metal site on Ni/CeO 2 (100) can activate CH 4, leading to a reduced DRM activity. The relatively balanced CH 4 and CO 2 activation pathways for Ni/CeO 2 (110) and Ni/CeO 2 (100) catalysts ensured the stability of the catalysts, whereas Ni/CeO 2 (111) was rapidly deactivated due to carbon deposits. This study provides insights into the roles of metal–support interactions and O V sites on catalysts for CH 4 dissociation activity, CO 2 activation, and carbon deposit elimination in the DRM process, which can provide valuable guidance for the design of efficient catalysts with high activity and stability in DRM.