Sol–Gel-Derived ZnO-Doped ZrT Oxide Nanocomposites as Highly Efficient Electrocatalysts for Nonenzymatic Hydrogen Peroxide Detection

Abstract Zr 0.1 Ti 0.9 O 2 nanocomposites containing 0, 1, 2, and 3 mol% ZnO, denoted as ZrT, 1ZnZrT, 2ZnZrT, and 3ZnZrT, respectively, were synthesized via a sol–gel route to investigate the effects of ZnO incorporation on their structural, optical, and electrochemical properties for nonenzymatic hydrogen peroxide sensing. Structural characterization confirmed successful incorporation of Zn into the ZrT oxide matrix and revealed progressive suppression of grain growth, leading to improved morphological uniformity. The average particle size decreased from ~ 89 nm for the undoped sample to ~ 70 nm for the 3 mol% ZnO-doped nanocomposite, indicating effective microstructural refinement. Optical analysis demonstrated enhanced visible–near-infrared absorption and a tunable electronic structure, with the direct band gap varying from 2.95 eV (undoped) to 2.08–2.52 eV in Zn-doped samples, attributed to defect-state formation and band-structure modulation. Electrochemical investigations revealed diffusion-controlled charge transfer and significantly improved interfacial electron-transfer kinetics upon Zn incorporation. Among all compositions, the 3 mol% ZnO-doped sample exhibited the highest electroactive surface area, lowest charge-transfer resistance, and strongest current response, confirming superior electrochemical activity. The synthesized nanocomposites were further evaluated as electrode modifiers for nonenzymatic detection of hydrogen peroxide. The optimized sensor demonstrated high sensitivity, with a linear range of 0.01–200 µM (LOD 0.005 µM) by cyclic voltammetry and 0.02–20 µM (LOD 0.001 µM) by chronoamperometry, excellent selectivity, and good reproducibility and stability. The enhanced sensing performance is attributed to the synergistic interaction between ZnO, ZrO₂, and TiO₂, which facilitates defect engineering, increases active-site density, and promotes efficient electron transport. These findings highlight the effectiveness of Zn incorporation in tailoring mixed-metal oxide nanocomposites and establish ZnO-doped ZrT oxide systems as promising candidates for high-performance, low-cost electrochemical hydrogen peroxide sensors.