Development of MOF-derived Co3O4 microspheres composed of fiber stacks for simultaneous electrochemical detection of Pb2+ and Cu2+

As an ideal transition metal oxide, Co₃O₄ is a P-type semiconductor with excellent electrical conductivity, non-toxicity and low cost. This work reports the successful construction of Co₃O₄ materials derived from metal-organic frameworks (MOFs) using a surfactant micelle template-solvothermal method. The modified electrodes are investigated for their ability to electrochemically detect Pb²⁺ and Cu²⁺ in aqueous environments. By adjusting the mass ratios of alkaline modifiers, the morphological microstructures of Co₃O₄-X exhibit a transition from distinctive microspheres composed of fiber stacks to rods. The results indicate that Co₃O₄-1(NH₄F/CO(NH₂)₂ = 1:0) has a distinctive microsphere structure composed of stacked fibers, unlike the other two materials. Co₃O₄-1/GCE is used as the active material of the modified electrode, it shows the largest peak response currents to Pb²⁺ and Cu²⁺, and efficiently detects Pb²⁺ and Cu²⁺ in the aqueous environment individually and simultaneously. The linear response range of Co₃O₄-1/GCE for the simultaneous detection of Pb²⁺ and Cu²⁺ is 0.5–1.5 μM, with the limits of detection (LOD, S/N = 3) are 9.77 nM and 14.97 nM, respectively. The material exhibits a favorable electrochemical response, via a distinctive Co₃O₄-1 microsphere structure composed of stacked fibers. This structure enhances the number of active adsorption sites on the material, thereby facilitating the adsorption of heavy metal ions (HMIs). The presence of oxygen vacancies (O_V) can also facilitate the adsorption of ions. The Co₃O₄-1/GCE electrode also exhibits excellent anti-interference ability, stability, and repeatability. This is of great practical significance for detecting Pb²⁺ and Cu²⁺ in real water samples and provides a new approach for developing high-performance metal oxide electrochemical sensors derived from MOFs.

Graphical abstract