Two-dimensional metal-organic frameworks: From synthesis to biomedical, environmental, and energy conversion applications

Abstract

Two-dimensional metal-organic frameworks (2D MOFs) are currently intelligent multifunctional nanostructure materials receiving accelerated attention for different applications in biomedical, environmental remediations, and energy conversion. This is due to their exceptional properties and advantages over conventional materials. They have appealing two-dimensionalities, crystallinity, connecting metal ions with organic linkers, ultrahigh surface areas, nanoscale structures, tunable cage/porous sizes, large surface-to-volume ratios, a larger number of active metal ion sites, flexible skeletons, proficiency in electron transports and transfer capability, and reasonable design strategies. Distinctly, the current study presents recent advances in the 2D MOFs for environmental remediations, energy conversion, and biomedical applications. It started with a comprehensive review of the synthesis strategies of the 2D materials, followed by the strategic modification approach for 2D MOFs for different applications. Unlike the available reviews in the field, the study includes detailed discussions in the biomedical (including biosensing, therapeutic delivery, bioimaging, biocatalysis, photodynamic therapy, biocompatibility, and toxicity), environmental remediations of pollutants (focusing on the various organic and inorganic pollutants remediations), and energy conversion (including nitrogen reduction reaction (NRR), oxygen reduction reaction (ORR), CO2 reduction reaction (CO2RR), overall water splitting, oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) with the corresponding performance of 2D MOFs in these fields, fundamental concepts and mechanisms. The new engineering strategic protocols for accelerating the performance of 2D MOF materials for various applications and some insights into future research discussed in the present study were absent in the available literature. To bridge the knowledge gaps, some associated weaknesses and strengths, and the treatment strategies of the past studies were discussed. In addition, some vital outlooks and recommendations for advancing the 2D MOFs and the corresponding applications in biomedical, environmental remediations of organic and inorganic pollutants, NRR, CO2RR, OER, ORR, HER, and overall water splitting toward realistic industrial expectations were discussed. This review will help the scientific community to understand the research hotspot and the necessity for the fabrication of more viable novel 2D MOFs for clean energy, environmental, and biomedical security in a more eco-friendly approach to alleviate greenhouse gas emissions, global energy shortage, biomedical and environmental insecurity challenges.