SYNTHESIS AND CHARACTERIZATION OF Ta2O5-GRAFTED SiO2 NANOPARTICLES FOR PHOTOCATALYTIC APPLICATIONS

摘要

Some of the challenges facing currently available semiconductor photocatalysts include the high cost of production, low quantum yield, limited reaction selectivity to produce the targeted products and activity that is limited to only UV radiation wavelengths. Greater activity would be possible for a photocatalyst that shows activity within visible wavelengths that make up much of solar energy reaching the Earth. Some attempts to overcome these challenges include the coupling of semiconductors that are mismatched in bandgap widths to increase charge separation and extend the range of photoexcitation wavelengths. Improvements in photocatalyitic activity have been shown to occur when photocatalysts are mixed with inert oxides. In this study we look into the dispersion of photocatalyst nanoparticles onto a high surface area acidic but non-photocatalytic material such as SiO2. These composite materials take advantage of SiO2's higher surface area and acidic surface allowing for a higher photoactivity at lower loadings of Ta2O5 than the pure Ta2O. In a previous study we showed how PVP, 2-methoxyethanol and acetylacetone affect the microstructure evolved from a binder assisted sol-gel synthesis of Ta2O5. In this study we extend these findings to synthesize 2 nm diameter Ta2O5 nanoparticles decorated onto 20 nm diameter SiO2 spheres. The resulting mixed oxide nanoparticles were characterized via transmission electron microscopy (TEM), x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), inductively coupled plasma - mass spectrometry (ICP-MS) and Fourier transform infra red analysis (FTIR).