Nano-sized Ag rather than single-atom Ag determines CO oxidation activity and stability
Single-atom catalysis recently attracts great attentions, however, whether single atom or their nanoparticle (NP) has the advantage in its intrinsic activity remains under heated debate. Ag/Al 2 O 3 is a widely used catalyst for many catalytic reactions, while the effect of Ag particle size on the a...
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Veröffentlicht in: | Nano research 2022, Vol.15 (1), p.452-456 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Single-atom catalysis recently attracts great attentions, however, whether single atom or their nanoparticle (NP) has the advantage in its intrinsic activity remains under heated debate. Ag/Al
2
O
3
is a widely used catalyst for many catalytic reactions, while the effect of Ag particle size on the activity is seldom investigated due to the great difficulty in synthesizing single atom Ag and Ag clusters/particles with different sizes. Herein, we firstly prepared an atomically dispersed Ag/Al
2
O
3
catalyst using a nano-sized γ-Al
2
O
3
as the support, subsequently obtained a series of Ag
0
/Al
2
O
3
catalysts with different Ag particle sizes by H
2
reducing single-atom Ag/Al
2
O
3
catalyst at various temperatures. The Ag
0
/Al
2
O
3
treated at 600 °C demonstrated superior CO oxidation performance over single-atom Ag/Al
2
O
3
and the Ag/Al
2
O
3
treated at 400 and 800 °C. Based on experimental data and density functional theory (DFT) calculation results, we reveal that the larger Ag
0
particle is beneficial to oxygen activation and improves the valence stability during oxidation reaction, while the aggregation of Ag
0
particle also accordingly decreases the concentration of surface active sites, hence, there is an optimum Ag
0
particle size. Our findings clearly confirm that Ag
0
nanoparticle has the advantage over single-atom Ag species in its intrinsic activity for CO oxidation. |
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ISSN: | 1998-0124 1998-0000 |
DOI: | 10.1007/s12274-021-3501-1 |