Control Synthesis of Metallic Gold Decorated ZnO Nanoparticles for Photocatalytic Degradation of Rhodamine B, Methylene Blue and Eriochrome Black T Dyes

Abstract

AbstractPure ZnO and metallic gold (Au) decorated ZnO (Au‐ZnO) nanoparticles were prepared by a modified sol‐gel method employing (CTAB, C19H42BrN) as a cationic surfactant. XRD analysis shows the wurtzite hexagonal structure of pure ZnO and confirms the modification in the structure with the decoration of Au metal in ZnO. TEM characterization illustrates the dispersion of metallic gold on the hexagonal surface of ZnO which confirms the result obtained by XRD. The ZnO and Au‐ZnO nanoparticles had negative charge surface values (−16.7 eV) and (−36.6 eV) which enhance an excellent degradation for cationic dyes. Optical studies show that gap energy decreases from 3.19 eV to 3.11 eV upon the decoration of Au on ZnO surface. The decrease in photoluminescence intensity reflects the positive effects of the role of metallic Au on the photodegradation capacity of Au‐ZnO. Photocatalytic results show that Au‐ZnO exhibits a higher efficiencies degradation of 93 % (k=0.016 min−1) in the case of Rhodamine B and 73 % (k=0.001 min−1) of Methylene blue compared to pure ZnO. In the case of Eriochrome Black T, Au‐ZnO presents low degradation efficiency.