Work

Simultaneous Electrochemical Sensing of Ultra-Trace Multiple Heavy Metals Using Metal–Organic Frameworks-Graphene Oxide Nanocomposite-Modified Electrodes

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide The relentless pace of industrialization has significantly exacerbated environmental pollution, with heavy-metal ions (HMIs) emerging as some of the most persistent and toxic pollutants in natural ecosystems. Growing concerns over environmental pollution have created a need for advanced sensing technologies that offer superior sensing sensitivity, selectivity, and reliability. This work reports the development of an electrochemical sensor based on a UiO-66-NH 2 (Zr) metal–organic framework (MOF)/graphene oxide (GO) nanocomposite for the simultaneous detection of HMIs in aqueous environments. Using one-pot hydrothermal synthesis, MOFs and conductive GO materials were integrated into a single nanostructure via in situ growth of the UiO-66-NH 2 (Zr) MOF on the GO matrix, resulting in the formation of a stable MOF/GO nanocomposite with enhanced conductivity and increased number of effective reaction sites. The amino groups (−NH 2 ) on UiO-66-NH 2 (Zr) porous materials serve as adsorption sites to capture HMIs. The morphological, structural, and electrochemical properties of the UiO-66-NH 2 (Zr)-GO nanocomposite were examined by using scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDS), powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). Differential pulse anodic stripping voltammetry (DPASV) was subsequently employed for the detection of heavy-metal ions over nanomolar to micromolar concentration ranges using a UiO-66-NH 2 (Zr)-GO-modified glassy carbon (GC) electrode. The electrochemical sensor developed in this study was successfully utilized for the selective and concurrent detection of multiple HMIs, namely, copper ion (Cu 2+ ), cadmium ion (Cd 2+ ), and lead ion (Pb 2+ ) in electrolyte solution. The sensor demonstrated achieving high selectivity and sensitivity (1.30 μA μM –1 for Cu 2+, 0.50 μA μM –1 for Cd 2+, and 12.38 μA μM –1 for Pb 2+ ) with low limit of detection (LOD) (0.59 ng/mL for Cu 2+, 0.84 ng/mL for Cd 2+, and 2.9 ng/mL for Pb 2+ ), and observed ≥85% reproducibility. The sensor demonstrated excellent long-term stability and operated effectively within a temperature range of 283–313 K, enabling the simultaneous detection of multiple heavy-metal ions from small sample volumes. The developed electrochemical method can equally be employed to detect HMIs at trace (parts-per-billion (ppb)) levels in diverse environmental matrices such as lake, river, tap water, river sediments, and wastewater.

Source: ACS Omega

DOI: 10.1021/acsomega.5c07592