Novel templating fabrication of nano-structured Pt clusters and wires in the ordered cylindrical mesopores of FSM-16 and their unique properties in catalysis and magnetism

The robust trigonal prismatic cluster anions such as [Pt-3(CO)(6)](5)(2-) and [Pt-3(CO)(6)](6)(2-) were selectively synthesized in the ordered hexagonal channels (2.8 and 4.7 nm diameter) of FSM-16 and ZrO2-modified FSM-16 by a 'ship-in-bottle' technique in the reductive carbonylation of H2PtCl6 with CO+H2O at 323 K. The cluster anions were characterized by FTIR, UV-visible, TEM and EXAFS spectroscopy. The Zr oxide-modified FSM-16 was prepared by CVD method using Zr(2-propoxyl)(4) impregnated with FSM-16, followed by calcination at 723 K. The controlled removal of CO from [Pt-3(CO)(6)](5)(2-) and [Pt-3(CO)(6)](6)(2-) in FSM-16 by thermal evacuation at 300-423 K yields nanostructured Pt clusters of 1.5-2 nm diameter highly dispersed in the channels of FSM-16. By contrast, Pt nano-wires were prepared by a templating reduction of Pt salts impregnated in FSM-16 (2.8 and 4.7 nm) under photo- and gamma-ray irradiation (see Scheme 1). They exhibited unique properties in CO chemisorption and magnetism due to their anisotropic morphology of Pt nano-wires aligned in the ordered mesoporous channels of FSM-16, which were quite different from those of Pt nano-particles. (C) 1998 Elsevier Science B.V. All rights reserved.