The phase analysis of all the samples were performed on an X-ray diffractometer (XRD, Shimadzu LabX XRD-6100, CuKα radiation). The isobaric heat capacity (Cp) of all the samples was measured using differential scanning calorimetry (DSC) (Netszch Jupiter STA 449F3, Selb, Germany) at the heating rate of 10 K/min in the purged N2 atmosphere. X-ray photoelectron spectroscopy (XPS) measurements were carried out with an ESCALAB 250Xi spectrometer. Fourier transform infrared (FTIR) spectra were collected by a Thermo Fisher IS10 spectrophotometer (America) with KBr pellet method.