A Sensitive and Selective Non-Enzymatic Dopamine Sensor Based on Nanostructured Co₃O₄-Fe₂O₃ Heterojunctions

In the present work, a study was carried out with the aim of enhancing the performance of electrochemical biosensors based on Co3O4:Fe2O3 heterojunctions. Specifically, the redox behavior of screen-printed carbon electrodes (SPCEs) modified with Co3O4:Fe2O3 (0.5 wt%:x wt%) nanocomposites, where x ranged from 0.1 to 0.5 wt%, was examined in detail. The hybrid nanocomposites were synthesized using the sol-gel auto-combustion method. Several characterization methods were performed to investigate the morphology, microstructure, and surface area of the pure Co3O4, pure Fe2O3, and the synthesized Co3O4:Fe2O3 nanocomposites. Using cyclic voltammetry (CV) tests, the electrochemical behavior of the modified electrodes toward the dopamine (DA) molecules was investigated. The modified Co3O4:Fe2O3, (0.5 wt%, x = 0.4 wt%)/SPCE resulted in a sensor with the best electrochemical performance toward DA. A high linear relationship between DA concentrations and the faradic current variation (i(pa) (& mu;A) = 0.0736 + 0.1031 C-DA (& mu;A) and R-2 = 0.99) was found in the range of 10-100 & mu;M. The sensitivity value was computed to be 0.604 & mu;A & mu;M(-1)cm(-2) and the limit of detection (LOD) 0.24 & mu;M. Based on the characterization and electrochemical results, it can be suggested that the formation of Co3O4:Fe2O3 heterostructures provides a large specific surface area, an increased number of electroactive sites at the metal oxide interface and a p-n heterojunction, thus ensuring a remarkable enhancement in the electrochemical response towards DA.