Preparation of photosensitized nanocrystalline TiO2 hydrosol by nanosized CdS at low temperature

A new method was developed for the fabrication of CdS–TiO2 semiconductor nanoparticles as visible-light-excitable photocatalyst at low temperatures. Nanosized CdS acting as an effective and stable sensitizer was incorporated into TiO2 by microemulsion-mediated solvothermal hydrolyzation followed by acidic peptization of the precipitate under 70 °C. The new method avoided the calcination or other pyrochemical treatments involved in traditional preparations, and thus eliminated the unwanted agglomeration of nanoparticles or the oxidation of CdS by oxygen. Compared to traditional methods, it was highly simplified, bypassing those miscellaneous steps like filtration, sintering, milling and redispersion in solutions. The crystal structure, configuration, element composition, as well as the light-absorption properties of the obtained CdS–TiO2 hydrosol were characterized in detail. The hydrosol consisting of uniform and small crystalline particles of about 2 nm in diameter was thermodynamically stable and showed good dispersibility. The photocatalytic activity of the ‘coupled’ material was confirmed through the photocatalytic degradation of methylene blue (MB) dye under visible light irradiation, and the cooperative photocatalytic mechanism is discussed.

[1]  S. Bhushan,et al.  Electroluminescence studies of chemically deposited (Zn‐Cd)S:Cu,F films , 2006 .

[2]  R. Mane,et al.  Nanocrystalline TiO2/ZnO thin films: fabrication and application to dye-sensitized solar cells. , 2005, The journal of physical chemistry. B.

[3]  V. Zucolotto,et al.  Layer-by-Layer Hybrid Films Incorporating WO3, TiO2, and Chitosan , 2005 .

[4]  Zhike He,et al.  A simple new way to prepare anatase TiO2 hydrosol with high photocatalytic activity , 2005 .

[5]  Li Wan,et al.  TiO2‐Based Composite Nanotube Arrays Prepared via Layer‐by‐Layer Assembly , 2005 .

[6]  I. Kiricsi,et al.  Photosensitization of ion-exchangeable titanate nanotubes by CdS nanoparticles , 2004 .

[7]  Jiaguo Yu,et al.  Preparation and photocatalytic behavior of MoS2 and WS2 nanocluster sensitized TiO2. , 2004, Langmuir : the ACS journal of surfaces and colloids.

[8]  Chuncheng Chen,et al.  Efficient degradation of toxic organic pollutants with Ni2O3/TiO(2-x)Bx under visible irradiation. , 2004, Journal of the American Chemical Society.

[9]  Mang Wang,et al.  A facile room-temperature chemical reduction method to TiO2@CdS core/sheath heterostructure nanowires , 2004 .

[10]  Jeffrey L. Blackburn,et al.  Electron Transfer Dynamics in Quantum Dot/Titanium Dioxide Composites Formed by in Situ Chemical Bath Deposition , 2003 .

[11]  Quan Li,et al.  Microemulsion-mediated solvothermal synthesis of nanosized CdS-sensitized TiO2 crystalline photocatalystElectronic supplementary information (ESI) available: UV-visible absorption spectra, XRD patterns and EPR spectrum. See http://www.rsc.org/suppdata/cc/b3/b302418k/ , 2003 .

[12]  D. Riley,et al.  Photosensitization of nanocrystalline TiO2 by self-assembled layers of CdS quantum dots. , 2002, Chemical communications.

[13]  P. Kamat,et al.  Interparticle electron transfer between size-quantized CdS and TiO2 semiconductor nanoclustersDedicated to Professor Frank Wilkinson on the occasion of his retirement. , 2002 .

[14]  Jincai Zhao,et al.  Photooxidation Pathway of Sulforhodamine-B. Dependence on the Adsorption Mode on TiO2 Exposed to Visible Light Radiation , 2000 .

[15]  Akira Fujishima,et al.  Titanium dioxide photocatalysis , 2000 .

[16]  Tohru Sekino,et al.  Titania Nanotubes Prepared by Chemical Processing , 1999 .

[17]  H. Tada,et al.  Promoting Effect of MgOx Submonolayer Coverage of TiO2 on the Photoinduced Oxidation of Anionic Surfactants , 1999 .

[18]  Jincai Zhao,et al.  Photoassisted Degradation of Dye Pollutants. V. Self-Photosensitized Oxidative Transformation of Rhodamine B under Visible Light Irradiation in Aqueous TiO2 Dispersions , 1998 .

[19]  K. Eguchi,et al.  Preparation and photocatalytic activities of a semiconductor composite of CdS embedded in a TiO2 gel as a stable oxide semiconducting matrix , 1998 .

[20]  J. Yates,et al.  Photocatalysis on TiO2 Surfaces: Principles, Mechanisms, and Selected Results , 1995 .

[21]  J. Zhang,et al.  Femtosecond studies of interparticle electron transfer in a coupled CdS–TiO2 colloidal system , 1994 .

[22]  Horst Weller,et al.  Quantum-Sized PbS, CdS, Ag2S, Sb2S3, and Bi2S3 Particles as Sensitizers for Various Nanoporous Wide-Bandgap Semiconductors , 1994 .

[23]  Herron,et al.  Quantum size effects on the exciton energy of CdS clusters. , 1990, Physical review. B, Condensed matter.

[24]  P. Kamat,et al.  Photophysical and photochemical aspects of coupled semiconductors: charge-transfer processes in colloidal cadmium sulfide-titania and cadmium sulfide-silver(I) iodide systems , 1990 .

[25]  R. W. Matthews.  Kinetics of photocatalytic oxidation of organic solutes over titanium dioxide , 1988 .

[26]  A. Henglein,et al.  Photochemistry of semiconductor colloids. 22. Electron ejection from illuminated cadmium sulfide into attached titanium and zinc oxide particles , 1987 .

[27]  Masashi Tanaka,et al.  Heterogeneous Photocatalytic Decomposition of Phenol over TiO2 Powder , 1985 .

[28]  Louis E. Brus,et al.  Size effects in the excited electronic states of small colloidal CdS crystallites , 1984 .

[29]  Encai Hao,et al.  Assembly of alternating TiO2/v\CdS nanoparticle composite films , 1998 .

[30]  C. Minero,et al.  Photocatalytic degradation of phenol in aqueous titanium dioxide dispersions , 1988 .