Modification of Glassy Carbon Electrode With Single-Walled Carbon Nanotubes and α-Silicomolybdate: Application to Sb(III) Detection

A simple procedure was developed to prepare a glassy carbon (GC) electrode modified with single‐walled carbon nanotubes (SWCNTs) and polyoxometalate. With immersing SWCNTs modified GC electrode in silicon polyoxomolybdate (α‐SiMo12O404−) solution (direct deposition) for a short period of time (2–10 s) oxoanion adsorbed strongly and irreversibly on SWCNTs. Cyclic voltammograms of the α‐SiMo12O404− incorporated‐SWCNTs indicates three well‐defined and reversible redox couples with surface confined characteristic at wide pH range (1–7). The surface coverage (Γ) of α‐SiMo12O404− immobilized on SWCNTs was 2.14 (±0.11)×10−9 mol cm−2 indicating high loading ability of SWCNTs for polyoxometalate. The charge transfer rate constant (ks) of three redox couples of adsorbed α‐SiMo12O404− were 9.20 (±0.20), 8.02 (±0.20), and 3.70 (±0.10) s−1, respectively, indicate great facilitation of the electron transfer between α‐SiMo12O404− and CNTs. In this research the attractive mechanical and electrical characteristics of CNTs and unique properties and reactivity of polyoxometalates were combined. The modified electrode in buffer solution containing Sb(III) shows a new redox system at 0.38 V in pH 1. The voltammetric peak current increased with increasing Sb(III) concentration. The differential pulse voltammetry (DPV) technique was used for detection micromolar concentration of antimony. Furthermore, the interference effects various electroactive compounds on voltammetric response of Sb(III) were negligible. Finally the ability of the modified electrode for antimony detection in real samples was evaluated.