Synthesis, characterization, and electrochemical application of phosphorus-doped multi-walled carbon nanotubes

Phosphorus-doped multi-walled carbon nanotubes (P-MWCNTs) were grown onto oxidized silicon substrate with decomposition of cyclohexane (CyH) and triphenylphosphine (TPP) in the presence of ferrocene (FeCp2) by means of chemical vapor deposition technique. For the fabrication, the mass percent of TPP in CyH/TPP/FeCp2 ternary mixture was varied from 0.5 % to 2.0 % wt., while the mass percent of FeCp2 was fixed to either 2.0 % or 5.0 % wt. The P-MWCNTs were characterized using scanning and transmission electron microscopy in combination with energy-dispersive X-ray spectroscopy as well as using Raman spectroscopy. The electrochemical response of P-MWCNTs towards ferrocyanide/ferricyanide [Fe(CN)(6)](3-/4-) was studied by means of cyclic voltammetry and electrochemical impedance spectroscopy. Application of P-MWCNTs for electrochemical analysis of ascorbic acid (AA), dopamine (DA), and uric acid (UA) was successfully carried out, and limits of detection of 1.12 mu M, 0.19 mu M, and 0.80 mu M were estimated, respectively. The findings demonstrate that P-MWCNTs are a quite promising material for applications in electrochemical sensing.