A laminar nanocomposite constructed by self-assembly of exfoliated α-ZrP nanosheets and manganese porphyrin for use in the electrocatalytic oxidation of nitrite

Laminar nanocomposite of α-ZrP/MnTMPyP, [5, 10, 15, 20-tetrakis (N-methylpyridinium-4-yl) porphyrinato manganese (III)], was obtained through the self-assembly of α-ZrP nanosheets and manganese porphyrin molecules, namely the exfoliation/restacking route. The final products were characterized by several analytic techniques such as XRD, IR, UV–Vis, and SEM. Meanwhile, the surface charge change of layered zirconium phosphate during the restacking process was monitored by a Zetasizer Nano instrument. The zeta potential value of α-ZrP colloidal dispersion is −40.1 mV, indicating that the colloidal dispersion was stable and well dispersed. The cyclic voltammetry measurements of α-ZrP/MnTMPyP film-modified glass carbon electrode displayed a pair of well-defined oxidation/reduction peaks with redox potentials at −0.256 and −0.197 V with an increase in the peak current compared to MnTMPyP aqueous solution. Furthermore, α-ZrP/MnTMPyP hybrid thin film exhibited excellent electrocatalytic activities toward oxidation of nitrite. The oxidation peak current increased linearly with the square root of scan rate, suggesting that the electrocatalytic process was controlled by nitrite diffusion. Finally, a detection limit of 5.3 × 10⁻⁵ M was estimated at a signal-to-noise ratio of 3.0 with a concentration range of 1.5 × 10⁻⁴ to 4.76 × 10⁻³ M.