A ruthenium(iii) phosphonate complex on polyallylamine functionalized carbon nanotube multilayer films: self-assembly, direct electrochemistry, and electrocatalysis

Abstract

On the basis of the electrostatic and donor–acceptor interactions between carboxylated multiwalled carbon nanotubes (MWCNT-COOH) and polyallylamine hydrochloride (PAH), PAH functionalized MWCNT multilayer films ({PAH/MWCNT-COOH}_n) were readily formed on a glassy carbon (GC) electrode surface through a layer-by-layer (LBL) self-assembly method. Then, the PAH functionalized MWCNT multilayer films were used as a functional interface to effectively immobilize the ruthenium(III) ethylenediamine-tetramethylene phosphonate (EDTMP–Ru^III) complex through the strong electrostatic and/or hydrogen bonding interactions between –NH₂ and –PO₃H₂ groups. Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-vis), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectrum (EDS) mapping, and Raman measurements were used to characterize the self-assembly process, structure, composition and morphology of the EDTMP–Ru^III/{PAH/MWCNT-COOH}_n/GC electrode. In the EDTMP–Ru^III/{PAH/MWCNT-COOH}_n/GC electrode, the immobilized EDTMP–Ru^III complex could directly exchange electrons with the substrate electrode and showed excellent electrocatalytic activity towards iodate reduction. Thus, the fabricated EDTMP–Ru^III/{PAH/MWCNT-COOH}_n/GC electrode could be used as an electrochemical sensor for iodate detection.