Figure 1: Schematic illustration for evaluating catalysis location and activity.

(a) Bulk CeO2; (b) intact and (c) atomically thin CeO2 sheets with surface-confined pits; P1 and P2 stand for the representative pit-surrounding surface Ce sites, while P3 represents the bottom Ce site of the pit; S stands for the surface Ce site of atomically thin sheet and around the defects of bulk material; A, V and B represent the arris, vertex and surface Ce sites of bulk material, respectively.