tailieunhanh - Báo cáo hóa học: "Synthesis and characterization of Nb2O5@C core-shell nanorods and Nb2O5 nanorods by reacting Nb(OEt)5 via RAPET (reaction under autogenic pressure at elevated temperatures) technique"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Synthesis and characterization of Nb2O5@C core-shell nanorods and Nb2O5 nanorods by reacting Nb(OEt)5 via RAPET (reaction under autogenic pressure at elevated temperatures) technique | Nanoscale Res Lett 2007 2 17-23 DOI S11671-006-9023-7 NANO EXPRESS Synthesis and characterization of Nb2O5@C core-shell nanorods and Nb2O5 nanorods by reacting Nb OEt 5 via RAPET reaction under autogenic pressure at elevated temperatures technique P. P. George V. G. Pol A. Gedanken Published online 27 October 2006 to the authors 2006 Abstract The reaction of pentaethoxy niobate Nb OEt 5 at elevated temperature 800 C under autogenic pressure provides a chemical route to niobium oxide nanorods coated with amorphous carbon. This synthetic approach yielded nanocrystalline particles of Nb2O5@C. As prepared Nb2O5@C core-shell nanorods is annealed under air at 500 C for 3 h removing the carbon coating results in neat Nb2O5 nanorods. According to the TEM measurements the Nb2O5 crystals exhibit particle sizes between 25 nm and 100 nm and the Nb2O5 crystals display rod-like shapes without any indication of an amorphous character. The optical band gap of the Nb2O5 nanorods was determined by diffuse reflectance spectroscopy DRS and was found to be eV. Keywords Niobia Nanoparticles Core-shell structure Diffused reflection spectroscopy Introduction Inorganic nanoparticles with controlled size and shape are technologically important due to the strong correlation between these parameters and their magnetic opto-electrical and catalytic properties 1 2 . Niobium materials have been of special interest due to their opto-electronic properties 3 . In addition they are P. P. George V. G. Pol A. Gedanken El Department of Chemistry and Kanbar Laboratory for Nanomaterials Bar-Ilan University Center for Advanced Materials Nanotechnology Bar-Ilan University Ramat-Gan 52900 Israel e-mail gedanken@ used for various important catalytic reactions. The important features of niobium compounds are the promoter effect and the support effect. Niobium oxides remarkably enhance catalytic activity and prolong catalyst life when small amounts are added to known catalysts. .