Engineered CoFe₂O₄@NiFe LDH nanocomposite based electrochemical sensor for the detection of Cr, As, Sb and Tl in various supporting electrolytes

The early detection and timeous monitoring of trace metals within the environment is crucial, especially with the need to develop mitigating strategies that help reduce health challenges. In this context, the electrochemical detection of Cr(VI), Sb(V), As(III), As(V) and Tl(III) has been performed using differential pulse anodic stripping voltammetry (DPASV) on a glassy carbon electrode modified with CoFe₂O₄@NiFe LDH. The anticipated active sites, such as the surface hydroxyl and oxide groups on the highly mesoporous nanoflower-like CoFe₂O₄@NiFe LDH composite that can readily interact with trace metal ions, were identified through physiochemical characterisation. The electrochemical characterisation revealed that the electrical conductivity was improved upon modifying the glassy carbon electrode with the CoFe₂O₄@NiFe LDH modifier. Subsequently, the developed sensor demonstrated a remarkable response on the detection of Cr(VI), Sb(V), As(III), As(V) and Tl(III), with good linearity (0.13–50 µg/L), low limit of detection (0.14, 0.15, 0.09, 0.12 and 0.19, respectively), low limit of quantification and high sensitivity. Significant parameters critical to the sensor's performance, such as type of electrolyte solution, deposition potential, deposition time and pH, were optimised. The DPASV results suggested that the developed sensor was repeatable and reproducible with intra-day and interday precision below 5 %. The proposed electrochemical sensor performed very well in tap and river water samples and could, therefore, open new avenues for the selective detection of trace metals in various matrices.