Wang et al. reported in their Article on pages 462-467 a theoretical study on the mechanism of methane activation on spinel Co3O4 nanocrystals. The results suggest that the activity of methane oxidation on Co3O4 surface exhibits a strong crystal-plane effect and structure sensitivity. They found that Coδ+-Oδ– ion-pair active centers played a significant role in activating the inert and robust C-H bonds in methane.