2D assembled ZnO/ZnCo2O4 heterostructures as efficient electrocatalysts for electrochemical detection of ofloxacin in water: experimental and DFT study

Abstract

In this work, assembled ZnO/ZnCo₂O₄ heterostructure nanosheets (ZnO/ZCO) were successfully synthesized through a rapid one-step microwave-assisted hydrothermal method. The ZnO/ZnCo₂O₄ sample features an ordered assembly of nanocrystals with a size of 30 nm forming two dimensional (2D) nanosheets, and ZnO-ZnCo₂O₄ heterojunctions are uniformly distributed. The physicochemical properties of ZnO/ZCO heterostructures were systematically studied by combining experiments and density functional theory (DFT) calculation. The heterojunction configuration of ZnO and ZnCo₂O₄ produced an interfacial charge redistribution and strong electronic interaction, resulting in the enhanced electrocatalytic performance towards ofloxacin (OFL). Consequently, the ZnO/ZnCo₂O₄ heterostructure nanosheet-based electrochemical sensor possessed an outstanding sensing performance in the detection of OFL with a high electrochemical sensitivity of 1.97 µA µM⁻¹ cm⁻². In addition, the proposed sensor was successfully applied for the detection of OFL in tap and lake water with recovery rates of 97.0–99.2%. The study demonstrates the potential of spinel oxide-based electrochemical sensors for rapid and cost-effective detection of antibiotic residues, providing an effective solution for water quality safety monitoring.