Synthesis of S-doped Graphitic Carbon Nitride (g-C3N4)/CuO/ZrO2Based Semiconducting Nanostructures for Sensor and Catalytic Degradation of Pollutant Dyes

Abstract

Due to the presence of basic surface sites, g-C3N4 is utilized for many applications, including catalysis, biosensors, and hydrogen production. However, because of some limitations such as less ability to utilize the visible spectrum of light and low conductivity, g-C3N4 suffers from a low efficiency in many applications. The objective of this study was to synthesize S-doped g-C3N4/ CuO/ZrO2-based semiconducting NCs for sensor and catalytic degradation of pollutant dyes using the chemical precipitation method, as well as to elucidate the position of S in S-doped g-C3N4 applying computational studies. A facile gas-templating method was developed to realize the synchronous S-doped g-C3N4 in one step at 550 oC. The XRD results indicate the average crystallite sizes of S-doped g-C3N4, binary CuO@S-doped g-C3N4(30%), ZrO2@S-doped g-C3N4 (20%) and ternary CuO/ZrO2@S-doped g-C3N4 (30%) to be 13.23,6.50, 6.99 and 3.36 nm respectively. The band gap energy of synthesized samples was determined by UV-vis/DRS studies respectively. The specific surface area of the samples was determined via BET analysis. The position of S in S-doped g-C3N4 was visualized with DFT using optimized structures. The presence of N, C, and S elements, monoclinic shape CuO and ZrO2 in the NCs was confirmed by HRSEM/EDS and XPS study analysis. The morphology and presence of flower-shaped S-doped g C3N4 in the binary and ternary NCs were investigated through HRSEM/EDS/TEM. The electrochemical property for mono, binary and ternary samples was verified by using CV, EIS, and M-S analysis. The ternary NC showed outstanding performance (99.56%) in the reduction study of 4-NP to 4-AP within 300s at the optimized load of 0.01g with pseudo-first-order kinetics. The electrochemical reaction taking place at the modified electrodes was a diffusion-controlled process The sensitivity of the binder-free electrodes for CuO@S-doped g-C3N4 (30%)/FTOE, ZrO2@S doped g-C3N4 (20%)/FTOE, and CuO/ZrO2@S-doped g-C3N4 (30%)/FTOE for 4-NP was determined to be 0.017, 0.007 and 0.004 µAµM −1 cm−2 respectively. In the study of BPA sensing, surprisingly the ZrO2@S-doped g-C3N4 (20%)/CPE present the highest LOD (3.21nM) than the CuO@S-doped g-C3N4 (30%)/CPE and CuO/ZrO2@S-doped g-C3N4 (30%)/CPE. The higher photocatalytic (99.454%) degradation of MB was recorded by CuO/ZrO2@ S-doped g-C3N4(30%). Generally, this study supports the notion that the synthesized binary and ternary NCs have good promise for multifunctional uses as catalysts, sensors, and photocatalysts.