2.2. TGA. A SHIMADZU TGA-50 was used for the
thermogravimetry (TG) study. A sample of several (5−20)
milligrams for each TG experiment was put into a platinum
sample cell, which was then located on a sample pan hanging
inside a furnace tube under a nitrogen flow rate of 50 mL
(STP) min−1
. The thermocouple is located next to the bottom
of the platinum sample cell exposed to the nitrogen flow. The
instrument continuously monitored the change of sample
weight as well as the temperature. The temperature was ramped
from room temperature to 1073 K with the heating rate varied
from 1 to 50 K min−1
.