NiFe₂O₄ Nanoparticles as Highly Sensitive Electrochemical Sensor for Nitrite Determination

ABSTRACT Taking into account the harmful influence of superfluous nitrite content onto the ecosystem and human health, sensitive and real‐time estimation of its concentration by developing reduced cost and efficient catalytic surfaces seems as a vital problem to be solved. Herein, a sensing platform for nitrite ions in water samples was designated based on mixed transition metal oxides. NiFe 2 O 4 nanoparticles were fabricated using a simple and straightforward sol–gel protocol followed by calcination at 900°C. Convenient physical characterization tools were employed to investigate the crystal structure, morphological, chemical composition, and the elemental mapping distribution of this formed nanocomposite. The cubic spinel crystal structure of NiFe 2 O 4 was confirmed using XRD and TEM analyses. The average crystallite size was estimated as 25.70 nm for a wide particle size distribution range between 10 and 50 nm. Cyclic voltammetric study revealed pronounced oxidation current density at NiFe 2 O 4 nanomaterial when contrasted to that of Fe 3 O 4 by 1.283 times. The influence of altering the scan rate and electrolyte pH during the relevant electrochemical measurements onto the electroactivity of this mixed oxide nanostructure was evaluated. Some kinetic parameters for nitrite ions oxidation reaction at NiFe 2 O 4 nanocomposite were estimated including Tafel slope (59.96 mV dec −1 ), exchange current density (2.13 × 10 −7 A cm −2 ), diffusion coefficient (1.178 × 10 −3 cm 2 s −1 ), and electron transfer rate constant (2.074 × 10 −3 cm s −1 ) values. A wide linear concentration range towards nitrite ions with outstanding sensitivity of 70.57 nA μM −1 cm −2 and lowered detection limit of 23.9 nM could be monitored using NiFe 2 O 4 nanopowder. These encouraging results might focus further efforts for synthesizing binary transition metal oxides with surprising activity towards numerous analytes determination.