Trimetallic metal–organic frameworks and derived materials for environmental remediation and electrochemical energy storage and conversion

Nowadays, there is much research focused on advanced technologies for energy storage and conversion in order to mitigate environmental pollution and address concerns on future energy crises. Supercapacitors, batteries, and electrocatalytic splitting of water are some of the very important technologies in this field with a constantly growing attention. The development of an ideal and efficient electrode material made of non-noble metals with good stability and behavior represents the main challenge in these fields. Metal−organic frameworks (MOFs), composed of metal ions and organic linkers, are appealing materials because of their remarkable structural diversity, tunable pore sizes and topologies, tailorable surface chemistry, and multiple functionalities. Engineering structural and electronic states of MOFs through decoration of functional entities is an effective way to advance the design of electrocatalysts and enhance their properties. Compared to mono- and bimetallic metal–organic frameworks, multimetallic MOFs may have several advantages in the context of new energy technologies, namely a significantly enhanced electrochemical activity and electronic conductivity due to possible synergic effect. Addition of other metals to secondary building units (SBUs) of a MOF structure is an effective method for enhancing its electrochemical behavior and electrical conductivity, owing to an increasing number of exposed active sites, superior charge capacity, and charge transfer between different ions. A stability problem of pristine MOFs can also be solved by incorporating second and third metals that are less affected by hydrolysis. In heterotrimetallic MOFs, the ratios of metals can be adjusted and controlled, allowing to tune various physicochemical properties. Moreover, the materials obtained from the calcination of trimetallic MOFs can preserve their porosity, so the morphology of an electrocatalyst prepared in this way can be adjusted during the synthesis of metal–organic framework. In this review, recent developments in heterotrimetallic MOFs and derivatives as extraordinary materials for applications in electrocatalytic water splitting, batteries, supercapacitors, and other environmentally significant uses are discussed. This work extends prior reviews on mono- and bimetallic MOF-based systems with a main goal of creating a roadmap for the introduction of heterotrimetallic MOFs as more advanced materials for electrochemical energy storage and conversion.