Rahadian Zainul, Alwi Nofriandi, Norhayati Hashim, Mohamad Idris Saidin, Mohamad Syahrizal Ahmad, Siti Nur Akmar Mohd Yazid, Sharifah Norain Mohd Sharif, Wan Rusmawati Wan Mahamod, Illyas Md Isa
This study presents the fabrication of a ferrocenium tetrachloromagnesate (FTM) modified multi-walled carbon nanotubes (MWCNTs) electrode for the voltammetric determination of bismuth ions (Bi3+) in aquatic environments. The FTM was synthesized from the reaction of magnesium chloride with ferrocene. The incorporation of FTM, a redox-active species, was shown to markedly improve electron transfer kinetics and overall electrochemical conductivity. Structural and morphological characterizations via Fourier transform infrared spectroscopy, transmission electron microscopy, energy dispersive x-ray, field emission scanning electron microscopy and X-ray diffraction confirmed the successful embedding of FTM within the electrode matrix. Electrochemical assessments using cyclic voltammetry, electrochemical impedance spectro-scopy, and chronocoulometry revealed that a 10 wt.% FTM loading provided the most optimal charge transfer and interfacial behaviour. Differential pulse stripping voltammetry further demonstrated the high sensitivity of the developed electrode, achieving an ultralow detection limit of 0.543 nM with two broad linear ranges of 1.0 nM to 0.1 and 1.0 µM to 0.1 mM for Bi3+. The sensor also exhibited remarkable reproducibility (RSD 8.67 %) and stability (RSD 7.77 %). Furthermore, excellent selectivity toward Bi3+ was maintained in the presence of potentially interfering ions such as Mn2+, La3+, Ni2+, Li+, Zn2+, Fe2+, Cd2+, Cu2+, Er2+ and Pb2+. Real water-sample analyses yielded recoveries of 89 to 104 %, confirming the practical feasibility of the electrode for environmental monitoring. © 2026, International Association of Physical Chemists. All rights reserved.
Department of Chemistry, Faculty of Natural Science and Mathematics, Universitas Negeri Padang, Air Tawar, Padang, 25132, Indonesia; Doctoral Program of Environmental Science, Postgraduate Program, Universitas Negeri Padang, Air Tawar, Padang, 25132, Indonesia; Department of Chemistry, Faculty of Science and Mathematics, Universiti Pendidikan Sultan Idris, Perak, Tanjong Malim, 35900, Malaysia
