Strong Activity Enhancement of the Photocatalytic Degradation of an Azo Dye on Au/TiO<sub>2</sub> Doped with FeO<sub>x</sub>
The doping of Au/TiO<sub>2</sub> with FeO<sub>x</sub> is shown to result in a strong enhancement of its photocatalytic activity in the degradation of the azo dye Orange II. In order to examine the source of this enhancement, Au-FeO<sub>x</sub>/TiO<sub>2</...
| Main Authors: | , , , , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2020-08-01
|
| Series: | Catalysts |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2073-4344/10/8/933 |
| _version_ | 1797558376692973568 |
|---|---|
| author | Ammara Waheed Quanquan Shi Nobutaka Maeda Daniel M. Meier Zhaoxian Qin Gao Li Alfons Baiker |
| author_facet | Ammara Waheed Quanquan Shi Nobutaka Maeda Daniel M. Meier Zhaoxian Qin Gao Li Alfons Baiker |
| author_sort | Ammara Waheed |
| collection | DOAJ |
| description | The doping of Au/TiO<sub>2</sub> with FeO<sub>x</sub> is shown to result in a strong enhancement of its photocatalytic activity in the degradation of the azo dye Orange II. In order to examine the source of this enhancement, Au-FeO<sub>x</sub>/TiO<sub>2</sub> nanocomposites containing different molar ratios of Au:Fe were synthesized, and X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), and high-resolution transmission electron microscope (HRTEM) analyses indicated that the TiO<sub>2</sub>-supported Au nanoparticles were partially covered with an amorphous layer of FeO<sub>x</sub> species, in which the iron was present as Fe<sup>2+</sup> and Fe<sup>3+</sup>. The metal-semiconductor system, i.e., Au/TiO<sub>2</sub>, showed only a moderate degradation rate, whereas doping with FeO<sub>x</sub> strongly enhanced the degradation activity. The bandgap energy decreased gradually from Au/TiO<sub>2</sub> (3.13 eV) to the catalyst with the highest FeO<sub>x</sub> loading Au-FeO<sub>x</sub> (1:2)/TiO<sub>2</sub> (2.23 eV), and this decrease was accompanied by a steady increase in the degradation activity of the catalysts. XPS analyses revealed that compared to Au/TiO<sub>2</sub>, on Au-FeO<sub>x</sub>/TiO<sub>2</sub> a much higher population density of chemisorbed and/or dissociated oxygen species was generated, which together with the decreased bandgap resulted in the highest photocatalytic activity observed with Au-FeO<sub>x</sub> (1:2)/TiO<sub>2</sub>. The processes occurring during reaction on the catalyst surface and in the bulk liquid phase were investigated using operando attenuated total reflection IR spectroscopy (ATR-IR) combined with modulation excitation spectroscopy (MES), which showed that the doping of Au/TiO<sub>2</sub> with FeO<sub>x</sub> weakens the interaction of the dye with the catalyst surface and strongly enhances the cleavage of the azo bond. |
| first_indexed | 2024-03-10T17:29:40Z |
| format | Article |
| id | doaj.art-60e7c04f3b584d0fb7a45c4f880da84d |
| institution | Directory Open Access Journal |
| issn | 2073-4344 |
| language | English |
| last_indexed | 2024-03-10T17:29:40Z |
| publishDate | 2020-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Catalysts |
| spelling | doaj.art-60e7c04f3b584d0fb7a45c4f880da84d2023-11-20T10:03:01ZengMDPI AGCatalysts2073-43442020-08-0110893310.3390/catal10080933Strong Activity Enhancement of the Photocatalytic Degradation of an Azo Dye on Au/TiO<sub>2</sub> Doped with FeO<sub>x</sub>Ammara Waheed0Quanquan Shi1Nobutaka Maeda2Daniel M. Meier3Zhaoxian Qin4Gao Li5Alfons Baiker6State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, ChinaState Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, ChinaInstitute of Materials and Process Engineering, Zurich University of Applied Sciences (ZHAW), Technikumstrasse 9, CH-8400 Winterthur, SwitzerlandInstitute of Materials and Process Engineering, Zurich University of Applied Sciences (ZHAW), Technikumstrasse 9, CH-8400 Winterthur, SwitzerlandState Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, ChinaState Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, ChinaDepartment of Chemistry and Applied Biosciences, Institute for Chemical and Bioengineering, ETH Zurich, Hönggerberg, HCl, CH-8093 Zurich, SwitzerlandThe doping of Au/TiO<sub>2</sub> with FeO<sub>x</sub> is shown to result in a strong enhancement of its photocatalytic activity in the degradation of the azo dye Orange II. In order to examine the source of this enhancement, Au-FeO<sub>x</sub>/TiO<sub>2</sub> nanocomposites containing different molar ratios of Au:Fe were synthesized, and X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), and high-resolution transmission electron microscope (HRTEM) analyses indicated that the TiO<sub>2</sub>-supported Au nanoparticles were partially covered with an amorphous layer of FeO<sub>x</sub> species, in which the iron was present as Fe<sup>2+</sup> and Fe<sup>3+</sup>. The metal-semiconductor system, i.e., Au/TiO<sub>2</sub>, showed only a moderate degradation rate, whereas doping with FeO<sub>x</sub> strongly enhanced the degradation activity. The bandgap energy decreased gradually from Au/TiO<sub>2</sub> (3.13 eV) to the catalyst with the highest FeO<sub>x</sub> loading Au-FeO<sub>x</sub> (1:2)/TiO<sub>2</sub> (2.23 eV), and this decrease was accompanied by a steady increase in the degradation activity of the catalysts. XPS analyses revealed that compared to Au/TiO<sub>2</sub>, on Au-FeO<sub>x</sub>/TiO<sub>2</sub> a much higher population density of chemisorbed and/or dissociated oxygen species was generated, which together with the decreased bandgap resulted in the highest photocatalytic activity observed with Au-FeO<sub>x</sub> (1:2)/TiO<sub>2</sub>. The processes occurring during reaction on the catalyst surface and in the bulk liquid phase were investigated using operando attenuated total reflection IR spectroscopy (ATR-IR) combined with modulation excitation spectroscopy (MES), which showed that the doping of Au/TiO<sub>2</sub> with FeO<sub>x</sub> weakens the interaction of the dye with the catalyst surface and strongly enhances the cleavage of the azo bond.https://www.mdpi.com/2073-4344/10/8/933Orange II degradationphotocatalysisAu-FeO<sub>x</sub>/TiO<sub>2</sub>operando modulation excitation spectroscopy |
| spellingShingle | Ammara Waheed Quanquan Shi Nobutaka Maeda Daniel M. Meier Zhaoxian Qin Gao Li Alfons Baiker Strong Activity Enhancement of the Photocatalytic Degradation of an Azo Dye on Au/TiO<sub>2</sub> Doped with FeO<sub>x</sub> Catalysts Orange II degradation photocatalysis Au-FeO<sub>x</sub>/TiO<sub>2</sub> operando modulation excitation spectroscopy |
| title | Strong Activity Enhancement of the Photocatalytic Degradation of an Azo Dye on Au/TiO<sub>2</sub> Doped with FeO<sub>x</sub> |
| title_full | Strong Activity Enhancement of the Photocatalytic Degradation of an Azo Dye on Au/TiO<sub>2</sub> Doped with FeO<sub>x</sub> |
| title_fullStr | Strong Activity Enhancement of the Photocatalytic Degradation of an Azo Dye on Au/TiO<sub>2</sub> Doped with FeO<sub>x</sub> |
| title_full_unstemmed | Strong Activity Enhancement of the Photocatalytic Degradation of an Azo Dye on Au/TiO<sub>2</sub> Doped with FeO<sub>x</sub> |
| title_short | Strong Activity Enhancement of the Photocatalytic Degradation of an Azo Dye on Au/TiO<sub>2</sub> Doped with FeO<sub>x</sub> |
| title_sort | strong activity enhancement of the photocatalytic degradation of an azo dye on au tio sub 2 sub doped with feo sub x sub |
| topic | Orange II degradation photocatalysis Au-FeO<sub>x</sub>/TiO<sub>2</sub> operando modulation excitation spectroscopy |
| url | https://www.mdpi.com/2073-4344/10/8/933 |
| work_keys_str_mv | AT ammarawaheed strongactivityenhancementofthephotocatalyticdegradationofanazodyeonautiosub2subdopedwithfeosubxsub AT quanquanshi strongactivityenhancementofthephotocatalyticdegradationofanazodyeonautiosub2subdopedwithfeosubxsub AT nobutakamaeda strongactivityenhancementofthephotocatalyticdegradationofanazodyeonautiosub2subdopedwithfeosubxsub AT danielmmeier strongactivityenhancementofthephotocatalyticdegradationofanazodyeonautiosub2subdopedwithfeosubxsub AT zhaoxianqin strongactivityenhancementofthephotocatalyticdegradationofanazodyeonautiosub2subdopedwithfeosubxsub AT gaoli strongactivityenhancementofthephotocatalyticdegradationofanazodyeonautiosub2subdopedwithfeosubxsub AT alfonsbaiker strongactivityenhancementofthephotocatalyticdegradationofanazodyeonautiosub2subdopedwithfeosubxsub |