Fe(II)-based metallo-supramolecular polymer nanostructures: An efficient electrode material for highly sensitive electrochemical detection and abatement of hexavalent chromium

Abstract

Carcinogenic and mutagenic chromium (VI) is a potential hazard to humans and animals. On the contrary, the trivalent Cr(II) counterpart is a nontoxic essential mineral for humans. So, it is always exciting and desirable to develop an agile detection platform that can detect the toxic Cr(VI) with high sensitivity and abate the toxic Cr(VI) to non-toxic Cr(III) in the same platform. We have developed a one-dimensional metallo-supramolecular polymer (MSP), Poly-Fe, consisting of Fe2+ bound bis-terpyridine-based organic ligands to detect and reduce hazard Cr(VI) to non-toxic Cr(III) electrochemically on Poly-Fe modified glassy carbon electrode (GCE) surface. The amperometric response revealed the high efficiency of Poly-Fe modified GCE for detecting Cr(VI) with a wide linear range of 1 μM - 2 mM along with a detection limit of 0.138 μM and sensitivity is 222 μA mM−1 cm−2. The response of detection was also verified using spiked water samples from different sources, and the accuracy and reproducibility of the results were good. Finally, the complete reduction of Cr(VI) to Cr(III) in the sample was observed within 150 complete CV cycles that took around 200 min and were monitored using UV–vis spectroscopy. The Poly-Fe-based electrocatalyst was highly efficient for repeatable electrochemical reduction of Cr(VI) to Cr(III) as it revealed ∼90% retention of reductive current after 5 repeating reduction cycles.