Photodeposition of CdS Quantum Dots on TiO2: Preparation, Characterization, and Reaction Mechanism

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• 作者：Masashi Fujii ; Kazuki Nagasuna ; Musashi Fujishima ; Tomoki Akita ; Hiroaki Tada
• 刊名：Journal of Physical Chemistry C
• 出版年：2009
• 出版时间：September 24, 2009
• 年：2009
• 卷：113
• 期：38
• 页码：16711-16716
• 全文大小：275K
• 年卷期：v.113,no.38(September 24, 2009)
• ISSN：1932-7455

文摘

Ultraviolet light irradiation (λ_ex > 300 nm) to a mixed ethanol solution of cadmium perchlorate and elemental sulfur (S₈) under deaerated conditions has led to deposition of CdS quantum dots on the surfaces of TiO₂ particles and films (CdS/TiO₂). High-resolution transmission electron microscopy (HRTEM) confirmed that the hexagonal CdS crystals are in good contact with TiO₂. The loading amount and band gap of CdS can be controlled by irradiation time. Photoelectrochemical measurements using cyclic voltammetry and photochronopotentiometry indicated the photodeposition of CdS on TiO₂ preferentially proceeds via an atomic route (Cd⁰ + S → CdS), whereas that on Au nanoparticle-loaded TiO₂ (Au/TiO₂) follows an ionic route (Cd²⁺ + S²⁻ → CdS). This difference was revealed to result from the predominant adsorption of Cd²⁺ over S₈ on TiO₂ (adsorbent-selective adsorption) in the former system and the selective adsorption of S₈ and Cd²⁺ ions on Au and TiO₂, respectively, (site-selective adsorption) in the latter system.