Electrochemical deposition of PANI/Co-MOF for highly sensitive electrochemical detection of copper(II) ions

Abstract

Polyaniline (PANI) nanoparticles/Co-based metal-organic framework (Co-MOF) was in situ prepared on a glassy carbon electrode (GCE) via electrochemical deposition and employed for the highly sensitive detection of copper(II) ions (Cu²⁺). The as-synthesized PANI/Co-MOF/GCE electrode exhibited an enlarged electroactive surface area and reduced charge transfer resistance, which remarkably enhanced the electroanalytical performance. Cyclic voltammetry (CV) measurements conducted at the various scan rates revealed the redox process of Cu²⁺ on the PANI/MOF/GCE surface was dominated by a diffusion-controlled process. Differential pulse voltammetry (DPV) was utilized to investigate the electrochemical detection property of PANI/Co-MOF/GCE after Cu²⁺ pre-concentration. The results showed that the detection current increased markedly with the increase of Cu²⁺ concentration in the range of 0.03 mM to 11.1 mM. Within the Cu²⁺ concentration from 0.03 mM to 0.10 mM, the electrochemical sensor constructed on the basis of PANI/Co-MOF/GCE achieved a high sensitivity of 8610.16 µA⋅cm⁻²⋅mM^− 1 and a low limit of detection (LOD) of 0.29 µM. Moreover, the sensor displayed excellent repeatability, good stability, and strong anti-interference ability. For actual sample detection, the sensor yielded satisfactory recoveries ranging from 98.34% to 101.54%, indicating its great potential for the Cu²⁺ detection in the practical applications.