Solutions of dyes (50 mg/L) were prepared via dissolving 5 mg of dyes in 100 mL distilled water. 100 mL of the dye solution was mixed with an appropriate amount ZnO@N-doped C for adsorption alongside four h and under stirring at ambient temperature as illustrated in Figure (Electronic Supporting Information, ESI). The influence of catalyst load was investigated using 5, 10, or 20 mg. At a particular reaction time, 5 mL of the reaction was withdrawn, and the catalyst was removed through filtration using a 0.2 μm cellulose acetate membrane filter (CHMLAB group, Spain). The changes in the concentrations of dyes were recorded using a UV-Vis spectrophotometer. The adsorption efficiency was calculated using Eq. 1.