The 1500 K EEO2 values for the graphene oxide, carbon black, and carbon nano-onion NPs in Figs. S2 -S4 were all in the same range as that for the graphite NP in Fig. 1.0 x 10 -3 , ~7 x 10 -4 , and 1.5 x 10 -3 Da/O2 collision, respectively. The factor of ~two variation in EEO2 reflects differences in the numbers of reactive sites on the NP surfaces, which are expected to vary due to the distributions of shape and surface structure in the NP feedstocks. Fig. shows two other experiments of this type, for different graphene oxide and nano-onion NPs. These also showed similar 1900 K sublimation kinetics, but the subsequent oxidation kinetics were more complex, with order-of-magnitude fluctuations in the oxidative mass loss rates (raw rate numbers given in the insets). As discussed previously for graphitic NPs, unsteady oxidation behavior is attributed to evolution of the NP surface site distributions as the surface is etched away, removing and exposing reactive surface sites. More dramatic examples are presented below.