Nanocomposites with ZrO@S-Doped g-CN as an Enhanced Binder-Free Sensor: Synthesis and Characterization.

This study describes new electrocatalyst materials that can detect and reduce environmental pollutants. The synthesis and characterization of semiconductor nanocomposites (NCs) made from active ZrO@S-doped g-CN is presented. Electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) measurements were used to examine electron transfer characteristics of the synthesized samples. Using X-ray diffraction (XRD) and high-resolution scanning electron microscopy (HR-SEM) techniques, inclusion of monoclinic ZrO on flower-shaped S-doped-g-CN was visualized. High-resolution X-ray photoelectron spectroscopy (XPS) revealed successful doping of ZrO into the lattice of S-doped g-CN. The electron transport mechanism between the electrolyte and the fluorine tin-oxide electrode (FTOE) was enhanced by the synergistic interaction between ZrO and S-doped g-CN as co-modifiers. Development of a platform with improved conductivity based on an FTOE modified with ZrO@S-doped g-CN NCs resulted in an ideal platform for the detection of 4-nitrophenol (4-NP) in water. The electrocatalytic activity of the modified electrode was evaluated through determination of 4-NP by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) under optimum conditions (pH 5). ZrO@S-doped g-CN (20%)/FTOE exhibited good electrocatalytic activity with a linear range from 10 to 100 μM and a low limit of detection (LOD) of 6.65 μM. Typical p-type semiconductor ZrO@S-doped g-CN NCs significantly impact the superior detection of 4-NP due to its size, shape, optical properties, specific surface area and effective separation of electron-hole pairs. We conclude that the superior electrochemical sensor behavior of the ZrO@S-doped g-CN (20%)/FTOE surfaces results from the synergistic interaction between S-doped g-CN and ZrO surfaces that produce an active NC interface.