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New dye functionalized polymeric carbon nitrides with increased visible light response were designed and fabricated. In this research, Rose Bengal (RB) was immobilized on g-C3N4 (CN) and carboxylated g-C3N4 (CCN) through the formation of a covalent bond. The covalent bonding of Rose Bengal to the CN or CCN resulted in the transfer of electrons from the dye to the semiconductor and the enhancement of the light harvesting performance, which promoted the photocatalytic efficiency. The photocatalytic activity of CN, CCN, and their hybrids with RB toward selective oxidation of benzyl alcohol was investigated under the visible light irradiation. The results obtained from the GC–MS analyses related to the oxidation reaction displayed the highest percentage of benzyl alcohol conversion and benzaldehyde selectivity for the hybrid structures compared to the bare RB, CN, CCN, or a mixture of RB and CN (or CCN). The effect of several parameters, including the amount of photocatalyst and promoter, irradiation time, and photocatalyst type, was studied and optimized. The recovery of RB-CCN (the most active catalyst) was surveyed in five runs, and the results verify that the activity is mostly maintained. Finally, the optimized structure, energy gap, and frontier orbitals of Rose Bengal/graphitic carbon nitride were investigated by DFT methods. |
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