Infrared spectra were collected on an IFS120HR Fourier trans-
form infrared (FT-IR) spectrometer (Bruker, Germany). Magnetic properties of the materials were
characterized by Lake Shore 7304 vibrating sample magnetometer (VSM) (Lakeshore, USA). X-ray
photoelectron spectroscopy (XPS) analysis was carried out on an ESCALAB 250Xi X-ray
photoelectron spectrometer (Thermo Fisher
Scientific, United States).