Nitrite electrochemical sensing using Cu centred porphyrin functionalized TiO2 nanoparticles modified glassy carbon electrode

Abstract

Free base and Cu(II)5-(4-carboxyphenyl)-10,15,20-tris(4-bromophenyl)porphyrin were synthesized and used to functionalize TiO2 nanoparticles. The porphyrins and conjugates were used to modify glassy carbon electrode for use as electrocatalysts for the electrochemical sensing of nitrite. The nanoparticles were synthesized via sol–gel procedure. The free base porphyrin was synthesized via a modified Adler-Longo method followed by metallation with Cu(II). The functionalization was done by directly linking the metallated porphyrin and nanoparticles via an ester bond. The synthesized porphyrins were characterized with ultraviolet–visible spectrophotometry which showed the expected bands; metallated (B band at 418 nm and Q band at 538 nm) and unmetallated (B band at 417 nm and Q bands at 511, 549, 587 and 645 nm). The limit of detection and catalytic rate constant of the electrocatalyst for nitrite sensing when using Cu-porphyrin linked to TiO2 nanoparticles were 1.41×10-3 μM and 7.46 ×102 M−1 s-1, respectively and comparably better than some of the previously reported nitrite electrocatalysts.