Figure 11. The regional scans of
Ag(a), I(b) and the curve fits of the 104 ppbv/ 200 ℃
CH3I adsorbed Ag0-Aerogel.
Reported in multiple studies,43-47 the Ag BE tends to
decrease as the oxidation state increases. For example, the
Ag3d5/2 BE of metallic Ag is approximately 368.1, and
this value decreases to 367.7-367.9 eV for Ag+ and
367.3-367.6 eV for Ag2+. Admittedly, the instrument
deviations and data calibration standards may vary the BE measured, but
the trend indicates that a certain amount of Ag2+ may
be formed in 104 ppbv CH3I adsorption at 200 ℃, whereas
the peak group 3 remains questionable.
The Ag and I concentrations can be interpreted from the XPS and SEM-EDX
spectra, where the results are listed in Table 3. To compare the iodine
concentrations between samples, the iodine compositions have been
calibrated as additional mass, which the summations of all other
elements are 100%. It is important to noticed that the
Ag0-Aerogel is a highly heterogeneous material; the Ag
coverage on the pellets is uneven, and the values measured by SEM-EDX
and XPS may vary based on the specific location scanned.