Consequences of nitrogen doping and oxygen enrichment on titanium local order and photocatalytic performance of TiO2 anatase
Extended X-ray absorption fine structure (EXAFS) investigation of the oxygen-rich titania formed via the thermal treatment of N-doped TiO has revealed that the removal of N-dopants is responsible for the creation of defect sites in the titanium environment, thus triggering at high temperatures (500-800 °C) the capture of atmospheric oxygen followed by its diffusion toward the vacant sites and formation of interstitial oxygen species. The effect of the dopants on Ti coordination number and Ti-O and Ti-N bond distances has been estimated. The photocatalytic p-cresol degradation tests have demonstrated that the interband states formed by the N-dopants contribute to a greater extent to the visible-light activity than the oxygen interstitials do. However, under the UV irradiation the oxygen-rich titania shows higher efficiency in the pollutant degradation, while the N-dopants in N-TiO play the role of recombination sites. The presence of the surface nitrogen species in TiO is highly beneficial for the application in partial photooxidation reactions, where N-TiO demonstrates a superior selectivity of 5-hydroxymethyl furfural (HMF) oxidation to 2,5-furandicarboxaldehyde (FDC). Thus, this work underlines the importance of a rational design of nonmetal doped titania for photocatalytic degradation and partial oxidation applications, and it establishes the role of bulk defects and surface dopants on the TiO photooxidation performance.
| Main Authors: | , , , , , , , |
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| Other Authors: | |
| Format: | artículo biblioteca |
| Published: |
American Chemical Society
2017
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| Online Access: | http://hdl.handle.net/10261/173473 http://dx.doi.org/10.13039/501100003329 http://dx.doi.org/10.13039/501100003443 http://dx.doi.org/10.13039/501100000780 http://dx.doi.org/10.13039/100011941 |
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| Summary: | Extended X-ray absorption fine structure (EXAFS) investigation of the oxygen-rich titania formed via the thermal treatment of N-doped TiO has revealed that the removal of N-dopants is responsible for the creation of defect sites in the titanium environment, thus triggering at high temperatures (500-800 °C) the capture of atmospheric oxygen followed by its diffusion toward the vacant sites and formation of interstitial oxygen species. The effect of the dopants on Ti coordination number and Ti-O and Ti-N bond distances has been estimated. The photocatalytic p-cresol degradation tests have demonstrated that the interband states formed by the N-dopants contribute to a greater extent to the visible-light activity than the oxygen interstitials do. However, under the UV irradiation the oxygen-rich titania shows higher efficiency in the pollutant degradation, while the N-dopants in N-TiO play the role of recombination sites. The presence of the surface nitrogen species in TiO is highly beneficial for the application in partial photooxidation reactions, where N-TiO demonstrates a superior selectivity of 5-hydroxymethyl furfural (HMF) oxidation to 2,5-furandicarboxaldehyde (FDC). Thus, this work underlines the importance of a rational design of nonmetal doped titania for photocatalytic degradation and partial oxidation applications, and it establishes the role of bulk defects and surface dopants on the TiO photooxidation performance. |
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