Three-dimensional graphene/amino-functionalized metal–organic framework for simultaneous electrochemical detection of Cd(II), Pb(II), Cu(II), and Hg(II)

Recent advances in the modification of electrodes for trace metal analysis: a review

“…303,304 However, two of the main drawbacks of MOFs and COFs in trace heavy metal determination are their low conductivity and low stability in water. To increase the charge transfer (i.e., to facilitate the electron transfer through the electrode surface to or from the electroactive species in solution) and to improve their mechanical strength, MOFs have been combined with carbon-containing materials, such as graphene (mainly rGO), 42,53,285 MWCNTs, 150,[152][153][154] mesoporous carbon, 282 carbon black, 236 and expanded graphite. 286 The addition of conducting polymers (mainly PANI and PPy) 208,209,212,213,216 to MOFs has resulted in higher conductivity and stability in water.…”

“…Few studies reported on the use of newly synthesized MOFs and COFs as sole electrode modifiers. 284,288,291,302 Zeolitic imidazolate frameworks (ZIFs), 154,177,201,236,279,284,286 amino-functionalized Zr-based MOFs (Universitet i Oslo (UiO) type, i.e., NH 2 -UiO-66), 42,53,151,152,209,216,283,285 and Materials of Institute Lavoisier (MILs), 164,212,295 are among the main types of MOFs used as electrode modifiers. The presence of amino groups or imidazole in MOFs facilitates the formation of coordination bonds with heavy metals, improving the adsorption ability of the analytes and thus improving the analytical performance of the electrodes.…”

“…177 Dropcasting dispersions of the MOFs in various solvents (including ethanol, N,N-dimethylformamide, and isopropanol) on the pretreated surfaces of the electrodes, followed by drying at room temperatures, is generally the main mechanism for applying these frameworks. Although GCEs are by far the most commonly used substrates for the application of different types of MOFs and COFs, 53,116,150,[152][153][154]177,198,201,216,236,237,[279][280][281][282][283][284][285][286][287][288][289][290]298,299 several other types of electrodes have also been modified, including CPEs, 291,292,301 SPCEs, 42,209 gold electrodes, 212,293 as well as PGEs, SPEs, and carbon cloth electrodes (CCEs). 208,294,295,298 In addition, Yang et al 296 and Han et al 300 reported on the attachment of a mercaptan functionalized Zr-based MOF as well as a 1,4-benzenedithiol-2,5-diaminohydrochloride and 1,3,5-triformylbenzene condensed COF to a 3D-structure kenaf stem derived carbon.…”

“…The authors reported that the integrated electrode has better analytical performance compared with the GCE modified electrode. 296 In addition to different real water samples, modified electrodes have also been successfully employed in the determination of heavy metals in food, 42,53,116,151,236,293 spices, 198,302 and body fluid 208,209 samples.…”

“…Five main types of NMs, i.e. , graphene, graphene oxide (GO) and reduced graphene oxide (rGO), 22–92 NPs, 23–25,27,31,56,57,59,64,67,70,83,86,87,93–138 single and multiwalled carbon nanotubes (SWCNTs and MWCNTs), 32,83,89,98,99,101,113,129,133,139–162 nanosheets, 34,85,107,111,139,162–166 and nanofibers, 167–169 have been employed in the modification of the electrodes used in the determination of heavy metals. Nanocubes, nanoflakes, nanospheres, and nanodiamonds 75,170–175 are among the other types of NMs used in the modification of the electrodes.…”