Facile Fabrication of Co3O4–Fe3O4/ITO Composite Electrode for Simultaneous Electrochemical Detection of Heavy Metals: Insights into Adsorption-Controlled Accumulation
Journal
Journal of The Electrochemical Society
Journal Volume
173
Journal Issue
14
Start Page
147502
ISSN
0013-4651
1945-7111
Date Issued
2026-07-24
Author(s)
Dung, Nguyen Quoc
Toan, Tran Quoc
Hue, Tran Thi
Chuyen, Dam Hong
Keochaidy, Siphachanh
Nguyen, Duc Dung
Nang, Lam Van
Hoa, Nguyen Xuan
Dung, Dang Duc
Thanh, Dang Van
Abstract
A Co3O4–Fe3O4/ITO electrochemical sensor was fabricated via in situ formation of metal hydroxide precursors assisted by electrochemical nitrate reduction, enabling uniform film growth and strong interfacial adhesion. The composite electrode was applied for the simultaneous determination of Cd(II), Pb(II), Cu(II), and Hg(II) using differential pulse anodic stripping voltammetry (DP-ASV). Under optimized conditions (pH 5.25), the sensor exhibited well-defined stripping responses with detection limits of 1.40 nM for Cd(II), 1.33 nM for Pb(II), 0.44 nM for Cu(II), and 3.2 nM for Hg(II). Linear ranges were statistically determined using F-test and RMSE criteria, with correlation coefficients (R2) exceeding 0.99 in most segments. To describe concentration-dependent behavior beyond linear regions, adsorption-based models were employed. Cd(II), Cu(II), and Hg(II) were well fitted by a Sips-offset model, while Pb(II) followed a Henry–Sips hybrid model. Speciation analysis using Visual MINTEQ indicated that Cd(II), Pb(II), and Cu(II) mainly exist as acetate complexes, whereas Hg(II) undergoes significant hydrolysis at higher pH. These findings highlight the effectiveness of the proposed electrode for sensitive multimetal detection and provide insight into adsorption-controlled accumulation in DP-ASV systems.
Publisher
The Electrochemical Society
Type
journal article