tailieunhanh - báo cáo hóa học: " Single-step processing of copper-doped titania nanomaterials in a flame aerosol reactor"

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: Single-step processing of copper-doped titania nanomaterials in a flame aerosol reactor | Sahu and Biswas Nanoscale Research Letters 2011 6 441 http content 6 1 441 o Nanoscale Research Letters a SpringerOpen Journal NANO EXPRESS Open Access Single-step processing of copper-doped titania nanomaterials in a flame aerosol reactor Manoranjan Sahu and Pratim Biswas Abstract Synthesis and characterization of long wavelength visible-light absorption Cu-doped TiO2 nanomaterials with well-controlled properties such as size composition morphology and crystal phase have been demonstrated in a single-step flame aerosol reactor. This has been feasible by a detailed understanding of the formation and growth of nanoparticles in the high-temperature flame region. The important process parameters controlled were molar feed ratios of precursors temperature and residence time in the high-temperature flame region. The ability to vary the crystal phase of the doped nanomaterials while keeping the primary particle size constant has been demonstrated. Results indicate that increasing the copper dopant concentration promotes an anatase to rutile phase transformation decreased crystalline nature and primary particle size and better suspension stability. Annealing the Cu-doped TiO2 nanoparticles increased the crystalline nature and changed the morphology from spherical to hexagonal structure. Measurements indicate a band gap narrowing by eV eV was achieved at 15-wt. copper dopant concentration compared to pristine TiO2 eV synthesized under the same flame conditions. The change in the crystal phase size and band gap is attributed to replacement of titanium atoms by copper atoms in the TiO2 crystal. Introduction Nanosized TiO2 has been widely used because of its stability in aqueous environments and low production cost. However its light absorption range is limited to the ultraviolet UV spectrum of light due to its wide band gap approximately eV . To shift the absorption range to the visible spectrum various approaches have been pursued