The Au-coated silicon wafers were cleaned with acetone and
dried under nitrogen, then dipped in the ZIF-8 colloidal
solution with a commercial dip-coater (Chemat Technology,
Inc., 180 mm·min−1 withdraw speed, 10 s still time, ambient
conditions). Samples were dipped in fresh ethanol between
each cycle after drying in air. The quantity of adsorbed
nanoparticles is controllable by conducting multiple dip/rinse
cycles. In our study, we investigated samples of 2 and 4 dip-coat
cycles, hereafter referred to as “2-cycle” and “4-cycle”. After
achieving the desired particle loading, the sample was dried
under N2 and set onto a preheated hot plate at 130 °C for 5
min to remove any residual solvent. For ATR-FTIR measurements,
the Au-coated Si sample was left in a ZIF-8 NP solution
overnight to achieve a thicker film for a stronger IR signal. For
all samples studied in UHV (for XPS and TPRS analysis),
before dip-coating, the Au-coated Si wafer was set into a
custom-made tantalum plate with a thin Ta wire wrapped ∼1
mm from the top edge, and a k-type thermocouple was fixed in
a small notch on the top side using UHV compatible glue
(Aremco, Ceramabond 503). The mounted sample along with
the Ta plate was rinsed in acetone and dip-coated in ZIF-8 NP
solution for the desired number of cycles. After drying at 130
°C, a second Ta wire was wrapped on the bottom part of the
sample, about 1 mm from the bottom edge to fix the sample on
the metal plate and ensure good thermal contact. Finally, the
coated sample was mounted in the UHV chamber approximately
2 mm in front of a tungsten heating element.