## 3 Results
From data in Table 3, it can be clearly seen that the specific surface area of the washcoat, including the pore diameter and the volume, does not undergo significant variations with treatment. \begin{table}
\begin{tabular}{c c} \hline
**SAMPLE** & **Size (nm)** \\ \hline
**Pristine** & \(8\pm 1\) \\
**NSC_8\_Ar** & \(11\pm 2\) \\
**NSC_8\_O2** & \(12\pm 3\) \\
**NSC_24\_Ar** & \(15\pm 5\) \\
**NSC_24\_O2** & \(43\pm 9\) \\ \hline \end{tabular}
\end{table} 
Table 2: Pt NP size distribution \(\pm\) standard deviation as a function of thermal treatment duration and oxygen exposure. Figure 6: TEM images of (**A**) the pristine NSC catalyst and of samples (**B**) NSC_8\_O2, (**C**) NSC_24\_Ar, and (**D**) NSC_24\_O2. Similar conclusions can be drawn on the basis of XRD analyses (Figure 7), for which the crystalline structure of the major oxide components of the washcoat (BaO, \(\gamma\)-alumina, and ceria) does not undergo substantial changes after the treatments. It should be noted that the XRD spectrum seems to be useless for this purpose because of the widening of peaks due to the contributions of the various oxides that drop to 2 theta values that are very close to each other. In addition, due to the small percentages, platinum peaks are not useful for speculating on possible variations in the structure. Therefore, the real changes detected are due to the sintering of platinum nanoparticles, which is well evidenced by TEM analyses of Figure 6.  
In conclusion, we have demonstrated that NSC aging can be studied carefully by means of electronic microscopy (SEM-EDS and TEM techniques) evaluating for the first time on real (commercial) samples the separate effects of thermal and chemical (oxidizing environment) treatment. Besides morphology and size distribution, EDS analyses provide chemical compositions of the catalyst environment, and all these data can provide a precise snapshot of the catalyst life. It should be noted that alternative methods exist, such as the traditional basic I/M (idle) tests or the borescope technique developed by Olympus of America, but these techniques do not yield as accurate a diagnosis of the health state of the catalyst [28]. The information attained with these techniques allowed for the direct observation that Pt nanoparticle sintering is strongly increased by oxygen exposure. This can be considered a very useful preliminary investigation for the studies already present in the literature on the efficiency of NSCs, as it clearly demonstrates, based on quantitative data, that an increased resistance of NSCs to thermal aging is possible if the presence of moisture and oxygen into the exhaust gases is reduced. Thanks to Centro Studi Componenti per Veicoli S.p.A. Societa Unipersonale del gruppo BOSCH, Modugno (BA), Zona Industriale, Via delle Ortensie, 19 for financial support. Thanks are due to Dott. Ing. [PERSON] for helpful discussions. [PERSON] and [PERSON] performed the experiments, [PERSON] and [PERSON] performed the preparation of Metallic sample, [PERSON] and [PERSON] performed the SEM EDS analysis; [PERSON] performed TEM analysis, [PERSON], [PERSON], and [PERSON] performed preliminary analysis on the ceramic NSC catalyst and analyzed the data on the metallic sample. [PERSON] conceived and designed the experiments [PERSON], and [PERSON] wrote the paper. The authors declare no conflict of interest. Figure 7: XRD analyses of NSC samples. Colored points indicate the overlap of peaks due to the different oxides assigned based on the literature [23; 24; 25; 26; 27].