Direct electrochemistry of cytochrome c immobilized on titanium nitride/multi-walled carbon nanotube composite for amperometric nitrite biosensor

In this report, titanium nitride (TiN) nanoparticles decorated multi-walled carbon nanotube (MWCNTs) nanocomposite is fabricated via a two-step process. These two steps involve the decoration of titanium dioxide nanoparticles onto the MWCNTs surface and a subsequent thermal nitridation. Transmission electron microscopy shows that TiN nanoparticles with a mean diameter of ≤20nm are homogeneously dispersed onto the MWCNTs surface. Direct electrochemistry and electrocatalysis of cytochrome c immobilized on the MWCNTs–TiN composite modified on a glassy carbon electrode for nitrite sensing are investigated. Under optimum conditions, the current response is linear to its concentration from 1µM to 2000µM with a sensitivity of 121.5µAµM−1cm−2 and a low detection limit of 0.0014µM. The proposed electrode shows good reproducibility and long-term stability. The applicability of the as-prepared biosensor is validated by the successful detection of nitrite in tap and sea water samples. •Direct electrochemistry of cytochrome c immobilized on the MWCNTs–TiN composite.•The low detection limit for nitrite sensing was identified as 0.0014µM.•Detection of wide range (1–2000µM) of nitrite concentrations.•High stability and reproducibility of the composite electrode.•Excellent anti-interference capacity towards various common ions.