Electrocatalytic detection of nitrite at NiCo2O4 nanotapes synthesized via microwave-hydrothermal method

Abstract

NiCo 2 O 4 nanotapes were obtained via a facile microwave assisted hydrothermal approach followed by calcination using urea and the metal nitrates without any structure directing agents. The material was characterized by XRD, SEM, FTIR, BET and XPS to ascertain its chemical and physical nature. The NiCo 2 O 4 nanostructures were found to be crystalline with phase purity, composed of nanotapes formed by aggregates of numerous nanoparticles providing high surface area and porosity, chemically pure and with Ni and Co in multiple oxidation states. By virtue of all these properties NiCo 2 O 4 nanotapes were catalytically active towards the oxidation of nitrite in 0.1 M phosphate buffer (PBS) of pH 7.0. The kinetic and heterogeneous rate constants are relatively higher and indicate facile electron transfer between the NiCo 2 O 4 electrode surface and nitrite ions. Experiments on electrochemical detection of nitrite with the proposed catalyst displayed a linear range of detection between 10 and 300 μM with detection limit of 1.04 μM and a sensitivity of 1.03 μAμM −1 cm −2 . • NiCo 2 O 4 nanotapes were synthesized without any structure directing agent in a domestic microwave oven. • The NiCo 2 O 4 nanotapes were found to be electrocatalytically more active towards oxidation of nitrite compared to NiO and Co 3 O 4 . • The rate constant for oxidation of nitrite at NiCo 2 O 4 is higher compared to literature. • NiCo 2 O 4 nanotapes show a linear range between 10-300 μM, sensitivity of 1.03 μAμM 1 cm 2 and 1.04 μM LOD for nitrite.