Tuning the CO2 Hydrogenation Activity via Regulating the Strong Metal–Support Interactions of the Ni/Sm2O3 Catalyst

Strong metal–support interactions (SMSIs), characterized by the encapsulation of metal nanoparticles by the support oxide, have a significant impact on various heterogeneous catalytic reactions. In this study, we present our investigations on tuning the catalytic performance of CO2 hydrogenation through regulating the SMSI in a Ni/Sm2O3 catalyst. Our results demonstrate that the complete encapsulation of Ni nanoparticles with amorphous Sm2O3, achieved through H2 reduction, leads to nearly full selectivity to CO. In contrast, with controlled in situ thermal postannealing in an H2/CO2/N2 mixture, the encapsulated Sm2O3 layer can be partially removed and crystallized, as revealed by atomic-resolution transmission electron microscopy analyses, which results in enhanced activity and a full selectivity toward CH4. In addition, the prolonged postannealing durations completely remove the Sm2O3 overlayer, causing a decline in CO2 methanation activity. These findings underscore the critical role of the SMSI effect in CO2 hydrogenation activity and offer valuable insights for regulating SMSI to produce targeted value-added chemicals.