ZIF-8 and IG were synthesised according to published reports (see Supplementary Material). ZIF-8 was carefully characterised through powder X-ray diffraction (PXRD) to determine the phase purity and thermogravimetric-analysis (TGA) to obtain the decomposition temperature (Td) value. This indicates the maximum value of the working temperature (Tw) in the preparation of the composite (Fig. ). Scanning electron microscopy (SEM) images were collected to analyse the size and morphology of the ZIF sample (Fig. ). The inorganic glass was characterised by PXRD (Fig. ) and SEM-energy dispersive spectroscopy (SEM-EDS). This confirmed the lack of crystallinity in the sample, and the phosphorous and sodium contents, respectively (Table ). SEM images were used to analyse the size and morphology of the glass (Fig. ). Differential scanning calorimetry (DSC) showed a glass transition temperature (Tg) value of 300 °C, coincident with the literature value (Fig. ). Tg is the temperature where the reversible transition between glassy and viscoelastic states behaviour in glasses occurs. Additionally, the DSC of the material also contains an exothermic peak, at ca. 350 °C. This is ascribed to the temperature of glass recrystallisation (Tr), in this case to a known crystalline Na3P3O9 structure (Fig. ). A physical mixture with a weight percentage incorporation of 20% ZIF-8 and 80% IG, termed (ZIF-8)0.2/(IG)0.8, was employed as a standard to determine the optimum conditions for the preparation of the physical mixtures ((ZIF-8)x/(IG)1-x) and MOF-CIGC materials [(ZIF-8)x(IG)1-x], where x is the proportion by weight of the ZIF-8 compound in the composite (see Supplementary Material). To facilitate the homogenisation of the physical mixture, the IG was previously ball milled for 30 After that the obtained physical mixture was pelletised at an optimised pressure followed by a thermal treatment at the chosen working temperature. min at 30 Hz to obtain a particle size of ~5 µm (Fig. ). However, the glass was observed to adsorb water on its surface, due to the hygroscopic nature of these phosphate-based glasses. These water molecules are able to disrupt the glass network upon heating and, consequently, decrease both Tg and Tr values of the glass from 297 °C and 362 °C to 250 °C and 312 °C, respectively (Fig. ).