Synthesis and photocatalytic activity of zinc oxide/carbon quantum dots and zinc oxide/S-doped carbon quantum dots nanocomposites

Document Type : Research and Reference

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1 Chemistry Department, Faculty of Science, Tanta University, Tanta, Egypt.

2 Chemistry Department, Faculty of Science, Tanta University, Tanta, Egypt

Abstract

   Carbon quantum dots have recently emerged as promising fluorescent nanomaterials due to their wide applications in nanomedicine, bioimaging, biosensing, and photocatalysis. Their unique optical and electrochemical behavior makes them especially attractive for photocatalytic systems. The role of heteroatom-doped CQDs in enhancing the photocatalytic efficiency of ZnO/CQDs nanoparticles is reported. The CQDs, including those doped with heteroatoms, were synthesized via a hydrothermal method, while zinc oxide nanoparticles (ZnO NPs) were produced using a precipitation technique. Composite materials incorporating doped sulfur atoms were fabricated through an impregnation approach at ambient temperature. Structural and morphological characterizations using XRD, FTIR, XPS, TGA, SEM, and TEM confirmed successful fabrication. Photocatalytic experiments revealed that ZnO/S-CQDs achieved a methylene blue (MB) degradation efficiency of up to 79.5%, outperforming other catalysts tested. Furthermore, the band gap energy of pristine ZnO/CQDs (3.01 eV) was reduced to 2.97 eV upon modification with S-CQDs. These findings indicate that although ZnO/CQDs nanocomposite possess a limited photocatalytic response to UV light due to their relatively large band gap, the incorporation of heteroatom-doped CQDs significantly enhances their optical and electronic properties, thereby improving their overall photocatalytic performance.

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