Syntheses and Functional Studies of Advanced Porous Materials (APMs): A Promising Platform for Aquatic Pollutant Remediation and Energy Applications

Abstract

Development of advanced porous materials (APMs) including Metal-organic Frameworks (MOFs), Metal-organic Polyhedra (MOP), and others, has progressed fast during recent two decades, particularly in the fields of energy and environmental applications. MOFs, being crystalline solids made up of organic ligands held together in an ordered manner by metal nodes, have evolved as a distinct class of porous materials, and are being explored for a variety of applications including gas storage, separation, hazardous oxo-ion remediation, ion-conduction, catalysis, and so on. This diverse applicability is attributed to features that enable tunable architectures and altering chemical/physical properties on demand at the molecular level. Recently, MOFs drew attention as functionally interesting materials for the challenging task of selective, efficient remediation of environmentally hazardous contaminants including hazardous oxo-ions, organic medical and pharmaceutical pollutants, as well as separation of important light hydrocarbons and greenhouse gases. This work has sparked widespread global interest and invites further comprehensive explorations. Hereof we sought to elucidate the design principles influencing formation of stable ‘O and N-donor’ linker based MOFs by deploying linker with higher denticity. Polydentate linkers; carboxylate-based linker’s additionally bearing N-donor sites have been used in the synthesis offering diverse alternatives to build functional MOFs are explored. Such linkers facilitate formation of anionic frameworks coupled with extra functionality through exchangeable uncoordinated cations within the porous cavity of the framework. Design strategies were centered on building compounds that were specifically targeted for the remediation of hazardous pollutants including heavy metal oxo-cations, radioactive species (via surrogate cations), antibiotics and pesticides via ion-exchange pathway and compounds with polar sites for the adsorption of hydrocarbon and greenhouse gas. Separately, addressing the emergent demand for wearable electronics, fast developments are currently occurring in the field of self-powered sensors, e-skin with sustainable and flexible devices. This has led to Triboelectric Nanogenerators (TENG) related technologies exploiting MOFs as a versatile platform. MOFs acquired prominence in recent years as low, medium to high power mechanical energy harvesting devices and are explored recently for the conversion of mechanical energy into electricity by means of Nanogenerators (NG) utilizing the virtue of being a multifunctional, tunable platform thereby extending the application domain of the TENG device.5 In this respect, we sought to comprehend the in-depth design concepts affecting NG and developed a facile, unique, reusable, and flexible NG composed of MOFs and MOPs capable of successfully harvesting irregular mechanical energy. The mechanics of the TENG was thoroughly explored and demonstrated. Advanced tunability and stabilization strategies enabled outcomes to validate the advantages of APMs in a diverse range of applications.