Metal–Organic Frameworks (MOFs)-Based Sensors for the Detection of Heavy Metals: A Review

Metal-organic-frameworks (MOFs) have emerged as promising candidates in different scientific disciplines owing to their intriguing characteristics. Their unique structural properties, including large surface area to volume ratio with multi-functionalities and ultra-high porosity, tunability, uniformity, and easy derivation and fabrication, render them effective materials for sensing applications. The detection of heavy metals in different environmental matrices using various MOF-based sensors is in practice. They include luminescent, electrochemical, electrochemiluminescent, colorimetric, and surface-enhanced Raman scattering, are of great interest. This review elaborates on selected synthetic methods for the fabrication of MOF-based sensors, modification routes for tailoring and enhancing the desired properties, basic characterization techniques, and their limitations in the detection of heavy metals. Also, it emphasizes the use of various types of MOF-based sensors alternatively for the detection of different heavy metals such as Fe(III), Cr(III), Hg(II), Cd(II), and Pb(II) in addition to a normal metal Al(III). A collection of recent references is provided for researchers interested in such applications. Results from the literature have been summarized in tables which give an easy comparison and will help to develop efficient materials.