Catalyst-free fabrication of one-dimensional N-doped carbon coated TiO2 nanotube arrays by template carbonization of polydopamine for high performance electrochemical sensors

Abstract One-dimensional (1D) carbon nanomaterials have extensively explored to fabricate high performance electrochemical sensors for the merits such as high surface area and fast electron transfer kinetics. However, catalytic production of carbon nanomaterials often suffers from misinterpretations of electrochemical signals from the catalyst residue and complicated production steps. Herein, we reported a catalyst-free method to produce 1D N-doped carbon coated TiO2 nanotube arrays (N-doped C/TiO2 NTAs) by template carbonization of polydopamine nanofilm coated anodized TiO2 NTAs. The N-doped C/TiO2 NTAs possesses a uniform structure with an inner diameter for an individual nanotube of about 80 nm and a length of about 8 µm. The carbon coating is about 10 nm in thickness and is doped by nitrogen from the polydopamine precursor. The N-doped C/TiO2 NTAs electrode exhibits an extremely high electrochemical activity with the heterogeneous charge transfer rate constants k0 greater than 0.5 cm/s for Fe(CN)63−/4− redox couple. Simultaneous determination of ascorbic acid, dopamine and uric acid has been demonstrated with the linear ranges of 100–3000 μM, 5–50 μM and 0.1–150 μM, respectively and detection limits (S/N = 3) of 1.8 μM, 0.015 μM and 0.11 μM, respectively.