Density Functional Theory Study of Metal and Metal-Oxide Nucleation and Growth on the Anatase TiO<sub>2</sub>(101) Surface
Experimental studies have shown the possible production of hydrogen through photocatalytic water splitting using metal oxide (MO<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><...
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| Autores principales: | , , |
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| Formato: | article |
| Lenguaje: | EN |
| Publicado: |
MDPI AG
2021
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| Materias: | |
| Acceso en línea: | https://doaj.org/article/7f2eac5a04a34fc49d5f9c65fdd9ecd9 |
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| Sumario: | Experimental studies have shown the possible production of hydrogen through photocatalytic water splitting using metal oxide (MO<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi>y</mi></msub></semantics></math></inline-formula>) nanoparticles attached to an anatase TiO<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula> surface. In this work, we performed density functional theory (DFT) calculations to provide a detailed description of the stability and geometry of M<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi>x</mi></msub></semantics></math></inline-formula>O<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi>y</mi></msub></semantics></math></inline-formula> clusters M = Cu, Ni, Co, Fe and Mn, <i>x</i> = 1–5, and <i>y</i> = 0–5 on the anatase TiO<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>2</mn></msub></semantics></math></inline-formula>(101) surface. It is found that unsaturated 2-fold-coordinated O-sites may serve as nucleation centers for the growth of metal clusters. The formation energy of Ni-containing clusters on the anatase surface is larger than for other M clusters. In addition, the Ni<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi>n</mi></msub></semantics></math></inline-formula> adsorption energy increases with cluster size <i>n</i>, which makes the formation of bigger Ni clusters plausible as confirmed by transition electron microscopy images. Another particularity for Ni-containing clusters is that the adsorption energy per atom gets larger when the O-content is reduced, while for other M atoms it remains almost constant or, as for Mn, even decreases. This trend is in line with experimental results. Also provided is a discussion of the oxidation states of M<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mn>5</mn></msub></semantics></math></inline-formula>O<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mrow></mrow><mi>y</mi></msub></semantics></math></inline-formula> clusters based on their magnetic moments and Bader charges and their possible reduction with oxygen depletion. |
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