*3.1. Characterization of nCeO2*

*n*CeO2 characterization data are showed in Table S1, Supplementary Materials. The Hd distribution of both the materials is in agreement with the value provided by the supplier. The *n*CeO2 exhibited a monodisperse size particle distribution with relatively low PDI. The highest particle size was 62.0 nm (Figure 2A). The relative Z-averages were much larger than that value due to particle aggregation (Figure 2B).

**Figure 2.** (**A**) Particle size distribution obtained by dynamic light scattering (DLS). (**B**) Transmission electron microscopy (TEM) image of *n*CeO2 25 nm suspension.
