1. Introduction
Silver (Ag) is an incredibly versatile material utilized in numerous applications, both in its ionic and elemental forms. Its exceptional catalytic properties have been demonstrated across a wide range of fields, including gas hydration, medical treatments, sensors, photovoltaics, drug delivery, textiles, paints, and imaging[1–4]. Particularly in organic synthesis, silver has proven to be highly effective as a catalyst, contributing to its extensive application in chemical synthesis[4–7]. Furthermore, silver ions and nanoparticles have shown significant potential in gas separation techniques, particularly when incorporated into membrane systems[8–12]. To ensure precise control over silver nanoparticle size and prevent aggregation, researchers have developed encapsulation and stabilization methods. By utilizing high surface area, porous materials like metal-organic frameworks (MOFs) and zeolites, silver nanoparticles can be effectively encapsulated[13–16]. Moreover, silver has been successfully incorporated as a dopant in diverse porous frameworks, thereby imparting its remarkable catalytic and antimicrobial properties to the porous structure [17–19]. This strategy allows for the synthesis of multifunctional materials with enhanced performance and applications in various industries.
MOF is one of the most studied porous materials due to it being a very versatile material owing to not onlitx exceptional porosity but also high tunability. MOF’s capability to change its respective ligands and metal nodes within its structure allows for tunable pore characteristics to suit different applications.[20] A recent study has shown a new phase of this highly tunable material, at which some species of zeolitic imidazolate frameworks (ZIFs), a family of MOF, can be melted to form a glassy phase.[21,22] This highly processible material has been shown to have good applications in gas separation and has also been shown to be able to form excellent composites with other materials such as perovskite and other MOF for gas separation, photocatalysis and oxygen reduction reaction. The ease of processibility for this material also allows its application in coatings of previously hard-to-coat substrates such as non-functionalized carbon cloth.
One of the widely studied MOF glass is ZIF-62 due to its ultrahigh glass forming capabilities and large melting-to-decomposition temperature difference.[21] Although ZIF-62 thermal behaviour and applications have been studied in the form of composites (with ionic liquid), metal substitution and ligand substitution, not much research has been done on the effect of functional guest molecules within its structure on its thermal and melting behaviour, as well as their gas separation applications.[23–26] In this paper, we aim to understand and explore the effect of silver doping in ZIF-62 glass, its effects on dynamic thermal changes, and the resulting interactions of Ag within the glassy structure towards engineered gas separations.