Fabrication of Semiconductor and Metal Fine Particles in Nanopores

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New type of mesostructured materials of vanadium-phosphorus oxide, VP,have been hydrothermally synthesized. The optimum conditions for the synthesis of VP were 1.00 VOSO_4・nH_2O : 0.52 H_3PO_4 : 1.10 C_<12>TMAC1 : 1.20 NaOH : 92.80 H_2O,403K,pH2.6,4h. The XRD and TEM measurements revealed that VP has a regular hexagonal superstructure.A new mesostructured material, WP,constructed from lacunary Keggin anions PW_<11>O_<39>^<7-> and surfactant cations CH_3 (CH_2) _<11>N (CH_3) _3^+ has been hydrothermally synthesized. The optimum conditions for the synthesis of WP were 1.0 Na_2WO_4・2H_2O : 0.5H_3PO_4 : 1.0 CH_3 (CH_2) _<11>N (CH_3) _3Br : 83.3 H_2O,pH8.0-8.5,403 K,and 6h. The XRD and TEM measurements revealed that WP has a regular hexagonal superstructure. The dimensions of the unit cell determined by XRD were a=b=3.85 and c=1.57nm. On the basis of FT-IR,^<31>P MAS NMR,TG-DTA,ICP,and elemental analysis studies, the chemical formula of WP was determined to be [CH_3 (CH_2) _<11>N (CH_3) _3] _6NaPW_<11>O_<39>・5.7H_2O.The formation of CdS nanoparticles has been encapsulated into the uniform pores of MCM-41 (2.2 nm pore diameter). The bandgap of the resulting particles was widened to 3.5 eV from 2.3 eV (bulk CdS) and at least two exciton peaks were clearly observed at 425 and 360 nm. These are attributable to quantum size effect with monodispersive distribution of CdS nanoparticles inside the MCM-41 pores. H_2O photodecomposition was performed by using the resulting particles (0.4 g) with TMA as a scavenger. The production of H_2 increased by 0.43mmol g_<CdS>^<-1>h^<-1> with the irradiation time.