What is it about?
Photoacoustic spectroscopy (PAS) analyses showed that increasing the calcination temperature promoted changes in the chemical structures and an apparent decrease in the band gap energy in TiO2, Nb2O5, Ti:Nb, and Ru-modified oxides.
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Why is it important?
In this work, it was developed and morphological/chemical, spectroscopic, and structural characterized the titanium dioxide, niobium pentoxide, and titanium:niobium (Ti:Nb) oxides, as well as materials modified with ruthenium (Ru) to provide improvement in photoactivation capacity with visible sunlight radiation. The nondestructive characterization of PAS in the ultraviolet visible region suggested that increasing calcination temperature promoted changes in chemical structures and an apparent decrease in gap energy. Through the XRD analysis, the formation of stable phases such as T-Nb16.8O42, o-Nb12O29, and rutile was observed at a lower temperature level, suggesting pore induction and an increase in surface area for the oxides studied, at a calcination temperature below that expected by the related literature. In addition, the synthesis with a higher temperature level altered the previously existing morphologies of the Ti:Nb, base and modified with Ru, forming the new mixed crystallographic phases Ti2Nb10O29 and TiNb2O7, respectively.
Perspectives
As several semiconductor oxide applications aim to reduce costs with photoexcitation under visible light, the modified Ti:Ru oxide calcined at a temperature of 800 °C and synthesized according to the sol-gel methodology used in this work is expected as the optimum preparation point. According to this study, under these conditions, it is suggested the formation of a stable crystallographic phase (rutile), a significant decrease in gap energy (2.01 eV), and a visible absorption threshold (620 nm). Furthermore, the synthesis at a higher temperature level altered the previously existing morphologies of the Ti: Nb, base, and Ru-modified mixed oxides, forming new mixed crystallographic phases. The present work does not intend to rule out that for an efficient application of photocatalysis, for example, there are other processes involved, in addition to photoactivation and generation of charge carriers, such as separation and transport of carriers, and reactions on the surface of the photocatalyst. However, the results are promising in the production of oxides with visible photoexcitation and at calcination temperatures lower than those reported in the literature.
Professor Daniele T Dias
Federal University of Technology - Paraná
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This page is a summary of: Photoacoustic Spectroscopy of Titanium Dioxide, Niobium Pentoxide, Titanium:Niobium, and Ruthenium-Modified Oxides Synthesized Using Sol–Gel Methodology, Applied Spectroscopy, August 2024, SAGE Publications,
DOI: 10.1177/00037028241268158.
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