ZnFe₂O₄/Graphitic Carbon Nitride Nano/Microcomposites for the Enhanced Electrochemical Sensing of H₂O₂

Hydrogen peroxide (H2O2) sensors with high sensitivity and stable detecting ability have been particularly in demand in the charming medical health and environmental monitoring. In this work, spherical ZnFe2O4/g-C3N4 (ZFO/g-C3N4) nano/microcomposites with different contents of g-C3N4 were controllably synthesized through a solvothermal calcination strategy, and the morphologies of their target materials were systematically characterized via scanning electron microscopy, energy dispersive spectroscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction. Subsequently, the as-prepared spherical ZFO/g-C3N4 composites are designed as an outstanding electrochemical sensor for H2O2, and its sensitivity was evaluated using cyclic voltammetry and chronoamperometry techniques. The ZFO/g-C3N4 microspheres exhibited a synergistic catalytic effect with a broad linear detection range between 5 and 200 μM and a detection limit of 1 μM (S/N = 3). The enhanced electrochemical performances of uniform ZFO/g-C3N4 composites with a three-dimensional net structure proved that the combination of a two-dimensional material (C3N4) and spinel-type metal oxide (ZnFe2O4) produces apparent activity, showing broad application potential in nonenzymatic sensors.