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.