Comparative study of metal (Al, Mg, Ni, Cu and Ag) doped ZnO/g-C3N4 composites: Efficient photocatalysts for the degradation of organic pollutants

In present work comparative photocatalytic activity of M doped ZnO/g-C3N4 (M = Al, Mg, Ni, Cu and Ag) composites synthesized via one-pot pyrolysis technique have been addressed in the degradation of EBT dye. XRD results revealed that metals ions were successfully introduced into the framework of ZnO/g-C3N4. Optical properties of the composites showed red shift in the light absorption and inhibited charge carriers' recombination rate. Cu doped ZnO/g-C3N4 catalyst showed the maximum photocatalytic EBT degradation of 99% after 90 min of visible light illumination. The effect of operational parameters (catalyst dose and initial dye concentration) on the extent of the photocatalytic performance was also been studied. The significant improvement in the photocatalytic EBT degradation efficiency was assigned to decrease in the optical band gap, high surface area and inhibited electron-hole recombination rate, identifying the significance of dopnats into ZnO/g-C3N4. The catalysts revealed excellent photostability of 99% after 15 successive cycles. Photoelectrochemical (PEC) measurements showed that metal doped ZnO/g-C3N4 composites have effectively increased the charge separation and declined the electron-hole recombination rate. A physical mechanism was proposed to explain the observed increase in the photocatalytic activity. At the end, photocatalytic test for the Basic Red 51 degradation was also studied to determine the effectiveness of the synthesized catalysts.