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Preparation and Characterization of CdS/ZnO Nanoarrays for Solar energy Conversion

Jiefang Zhu

 

Abstract: CdS/ZnO nanocomposites as photoactive materials have their promising applications in solar energy conversion. A combination of electrochemical deposition and chemical bath deposition was used to prepare CdS/ZnO nanomaterials. ZnO nanorods were synthesized on TCO glass by electrochemical deposition. ZnO nanorods grow along the [0001] direction, and they are partially perpendicular to the substrate. The ZnO nanorods deposited by a certain time have smooth walls, high density, and long length of about 1.5 μm and small diameter of around 200 nm (Fig. 1). CdS nanoparticles were coated outside ZnO nanorods by chemical bath deposition to compose CdS/ZnO nanoarrays. During the process of chemical bath deposition of CdS on the substrate with ZnO nanorods, the amount of CdS nanoparticles increases with the deposition time, while the amount of ZnO decreases simultaneously, due to the etching of ZnO. Samples of CdS/ZnO nanoarrays have been characterized by XRD, Raman spectroscopy, SEM, EDS, and UV-Vis spectroscopy. Photoeletrochemical performance of CdS/ZnO nanoarrays has also been investigated by current-potential measurements (Fig. 2). The enhanced solar energy conversion was given by CdS/ZnO nanoarrays with suitable composition, compared with the performance shown by pure ZnO and CdS, which is due to the efficient absorption of visible light by CdS, the photogenerated charge separation by between CdS and ZnO, and the nanorod morphology of ZnO benefiting the fast transfer of electrons to the external circuit.

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