The influence of cobalt and graphitic carbon nitride on the efficiency of zirconium oxide for photodegradation of an organic dye in wastewater

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This study synthesized semiconducting cobalt-doped zirconium oxide–graphitic carbon nitride (Co-ZrO 2 /g-C 3 N 4 ) nanocomposites using a simple technique with low production cost and investigated the collective impact of Co and g-C 3 N 4 on the efficiency of ZrO 2 photocatalyst in degrading eosin yellow (EY) dye in synthetic wastewater. The Co-ZrO 2 /g-C 3 N 4 composites were synthesized via the chemical co-precipitation technique. They were systematically analysed using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-vis) spectrophotometry, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDX) and dynamic light scattering (DLS). Structural analysis not only confirmed the successful integration of Co and g-C 3 N 4 into ZrO 2 but also showed the transformation of the monoclinic ZrO 2 into the cubic phase on the addition of the dopant. The UV-vis characterization showed a slight enhancement in light absorption capacity by the Co-ZrO 2 /g-C 3 N 4 composite system on increasing the concentration of cobalt with an associated decrease in the bandgap from 3.82 to 3.11 eV. The addition of Co and g-C 3 N 4 into ZrO 2 nanoparticles improved the performance of the virgin ZrO 2 with degradation efficiencies from 30% up to 98% and rate constants (k) from [Formula: see text] up to [Formula: see text]. The research emphasizes the importance of maintaining a balance in cobalt doping and underscores the potential of ZrO 2 /g-C 3 N 4 nanocomposites as effective catalysts, for water treatment applications.