Highly sensitive voltammetric detection of 4-nitrobenzoic acid using Zn2SnO4/porous graphene oxide nanosheets composite electrode

Abstract

Detecting 4-nitrobenzoic acid (4-NBA) is crucial due to its prevalence as an industrial pollutant and associated health hazards. In this study, we synthesized a novel stannate-based nanocomposite, Zn₂SnO₄/porous graphene oxide nanosheets (Zn₂SnO₄/PGO), through a facile hydrothermal method followed by ultrasonication-assisted dispersion. For the first time, this Zn₂SnO₄/PGO nanocomposite was employed as an electrode modifier for 4-NBA detection. The structural and physicochemical properties of the synthesized Zn₂SnO₄/PGO nanocomposite were systematically characterized using various spectroscopic techniques. Electrochemical studies, including electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and differential pulse voltammetry (DPV), demonstrated that the Zn₂SnO₄/PGO-modified electrode has a significantly enhanced electroactive surface area and efficient electron transport, resulting in superior electrocatalytic activity for 4-NBA detection. From the DPV quantification experiments, the limit of detection was calculated as 3.3 nM within the linear detection range of 0.1–231 μM. The sensor demonstrated high accuracy, repeatability, reproducibility, and long-term stability. Anti-interference studies indicated no significant cathodic potential shifts in the presence of common interfering species. Finally, the Zn₂SnO₄/PGO-modified sensor was successfully applied to detect 4-NBA in real samples, including human urine, river water, and wastewater, showing excellent recovery rates. These findings confirm the sensor's potential for reliable and sensitive electrochemical monitoring of 4-NBA in different matrices, underscoring the importance of environmental safety and public health protections.