The Design of Cobalt (II)-Porphyrin/Fe2O3-Reduced Graphene Oxide Nanohybrid for Enhanced Electrochemical Sensing of 4-Hydroxybenzoic Acid

Abstract This study presents the synthesis and characterization of a novel electrocatalyst based on cobalt (II)-tetra aminophenyl porphyrin (CoTAPor) conjugated non-covalently with an iron (III) oxide-reduced graphene oxide (Fe 2 O 3 rGO). The synthesized materials were then used to modify a glassy carbon electrode (GCE), with CoTAPor-Fe 2 O 3 rGO identified as the superior electrocatalyst. The electrochemical detection of 4-hydroxybenzoic acid ( p HBA) was performed on the CoTAPor- Fe 2 O 3 rGO-modified GCE using cyclic voltammetry (CV) and chronoamperometry (CA). The CoTAPor-Fe 2 O 3 rGO composite exhibited the best catalytic performance, showing a significantly higher current response compared to bare GCE, CoTAPor, and Fe 2 O 3 rGO individually under CV and CA. This enhanced performance is attributed to the synergistic interactions between CoTAPor and Fe 2 O 3 rGO, resulting in increased sensitivity and a lower limit of detection (LoD). For CoTAPor-Fe 2 O 3 rGO, the sensitivity was 0.761 µA µM −1 , with a LoD of 1.18 µM (S/N = 3). In addition, the electrocatalyst demonstrated good selectivity for p HBA in the presence of potentially interfering substances under controlled experimental conditions. Graphical Abstract