The effect of cobalt-doped ZnO-g-C3N4 heterostructures on photocatalytic degradation of eosin yellow dye in water under simulated solar light

Abstract

The unrestricted discharge of textile chemicals in natural water sources has posed major ecological and environmental threats to our standard of living. For decades, there has been a continuous search for affordable, and visible-light driven semiconductors with the capability of harnessing the full potential of sunlight to help curb the aforementioned problem. Herein, photocatalysts based on a series of cobalt (Co) and graphitic carbon nitride (g-C3N4) co-doped ZnO were synthesized via the co-precipitation method for eosin yellow dye degradation in water under visible light. The functional groups present in the materials were determined by FTIR. Other techniques such as Ultraviolet–visible (UV–Vis) spectrophotometry, X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were utilized to study the optical properties, structural properties, morphology and elemental composition respectively. The nanomaterials' optical analysis showed a marginal rise in absorbance in the visible region with a corresponding reduction in the forbidden gap energy from 3.10 to 2.52 eV. XRD studies showed that the nanocomposites were polycrystalline in nature and possessed the hexagonal phase of ZnO having an average crystallite size of 42 nm. From the photocatalysis outcomes, the maximum photocatalytic performance was observed for the 0.8 % Co-doped ZnO-g-C3N4 system, which degraded 96 % of the dye in 180 min, with a rate constant of 17.01 x 10−3 min−1. The incorporation of Co enhanced ZnO's outstanding photocatalytic activity in the g- C3N4–ZnO system.

Keywords

• Photocatalysis
• Graphitic carbon nitride
• Zinc oxide
• Cobalt
• Eosin yellow