The Preparation of Mesoporous Silica Confined Photoactive CuxS Nanoparticles G. Wang Background Copper sulfide is a family of chemical compounds with the formula CuxSy, which can form a variety of stoichiometric compounds including covellite (CuS), anilite (Cu7S4), geerite (Cu8S5), digenite (Cu9S5), djurleite (Cu31S16) and chalcocite (Cu2S). They are p-type semiconductors with unusual electrical, optical, and catalytic prosperities. Unlike copper oxide (CuxOy), CuxSy is intrinsically stable in aqueous solution. CuS and Cu2S are promising materials with potential applications in many ﬁelds such as electrode material, semiconductor, solar cells, light-emitting diodes.1 Both CuS and Cu2S are also potential photocatalysts with activity under visible illumination. The photocatalytic activity of CuxS can be improved by tuning the nanostructure and particle size.2 Recent research in our group has shown a great progress in the control over size and location of Cu-based nano-particles in mesoporous silica.3 It has shown that the stability of nanostructured materials could be improved by tuning their distribution in support materials.4,5 Aim In this project we aim to investigate whether CuS and Cu2S nanoparticles on mesoporous silica can be obtained, how to control size and distribution, and if time allows the stability and photocatalytic activity of supported CuxS nanoparticles. Approach 1. The direct preparation of MCF supported CuS nanoparticles 1.1 CuS nanoparticles with different morphologies will be synthesized from a mixture of copper chloride aqueous solution (100 ml, 0.05 M) and thioacetamide by refluxing at 130 °C for 1.5 – 6 h.6 The as-synthesized nanoparticles will be dispersed in water, and MCF will be impregnated by the suspension. 1.2 Cetyltrimethylammonium bromide (CTAB) capped CuS will be prepared from a mixture of copper acetate aqueous solution (10 ml, 2.5 mM) and thioacetamide (0.0020 g) in the existence of CTAB (0.2 g) by stirring at 30 °C for 12 h.7 The as-synthesized nanoparticles will be dispersed in water, and MCF will be impregnated by the suspension. 2. The direct preparation of MCF supported Cu2S nanoparticles Cu2S nanoparticles will be synthesized through a water-oil interface confined reaction.8 Cu(NO3)2•3H2O (0.24 g, 0.001 M) was dissolved in DI water (20 ml). Then sodium acetate (0.82 g, 0.010M) and acetic acid (0.60 ml) were also introduced into the solution. After keeping stirring for 15 min, the solution was transferred into a 40 ml Teflon-lined autoclave and dodecanethiol (3 ml) was added into the solution. The autoclave was sealed and heated at 200 ºC for 6 h. After the autoclave was cooled to room temperature, the product was collected and the water in the autoclave was discarded. Then 20 ml ethanol was introduced and the product was washed and precipitated. The mixture was centrifuged for 5 min at 4800 rpm, and the precipitate was collected. The as-synthesized nanoparticles will be dispersed in water, and MCF will be impregnated by the suspension. 3. The preparation of CuxS from the sulfidation of MCF supported CuxO nanoparticles The sulfidation step will be processed by dispersing CuxO nanoparticles into soluble sulfide (HS-) solution.9 CuxO powder and 0.5 mL of 125 mM Na2S solution will be added to 4.5 mL of DI water, After rotating the mixture for 48 h, the precipitate will be separated by centrifugation. During this project, the student will get acquainted with the following methods and techniques: - The synthesis of CuS and Cu2S by wet chemical synthesis - Incipient wetness impregnation - X-ray diffraction and UV-Vis spectroscopy - Interpretation of TEM images - Photocatalytic and photoelectrochemical measurements (if time allows) References 1. P. Kumar et al., Inorg. Chem. 50 (2011) 3065 2. Z. Hai et al., Mater. Lett. 108 (2013) 304 3. P. Munnik et al., J. Phys. Chem. C 115 (2011) 14698 4. G. Prieto et al., Nature Mater. 12 (2013) 34 5. R. Becker et al., Angew. Chem. Int. Ed. 43 (2004) 2839 6. A. Phuruangrat et al., Chalcogenide Lett. 9 (2012) 421 7. U. Gautam et al., Bull. Mater. Sci. 29 (2006) 1 8. Z. Zhuang et al., JACS, 130 (2008) 10482 9. Z. Wang et al., ACS Nano. 7 (2013) 8715