Characterization
The crystallinity and phase purity of the materials were measured by powder X-ray diffraction (PXRD) on a Bruker D8 ADVANCE X-ray diffractometer with Cu-Kα (λ = 1.5418 Å) radiation operated at 40 kV and 40 mA. Scanning was performed over the 2θ range of 5-50° at 4 °/min. Scanning electron microscopy (SEM) images were obtained using a Hitachi SEM (SU8010, Hitachi, Japan) equipped with a Horiba X-Max 50 EDX system. The TGA of the samples was collected on a thermal analyzer (NETZSCH, STA 449 F5) at a heating rate of 5 °C/min under air atmosphere. CO2 adsorption/desorption isotherms were obtained using an ASAP 2460 Surface Area and Porosity Analyzer at 273 K.