Dynamic interplay between metal nanoparticles and oxide support under redox conditions

Frey, Hannes; Beck, Arik; Huang, Xing; Bokhoven, Jeroen A. van; Willinger, Marc Georg

doi:10.1126/science.abm3371

Cited by 131 publications

(132 citation statements)

References 77 publications

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“…16 While some authors claim that the encapsulation can also be reversed by O2 annealing 6,17,[18][19][20] , others report an oxidation of the particles and/or thickening of the titania encapsulation layer under such conditions. 7,[21][22][23] In their pioneering work on SMSI, Tauster et al reported that the change in chemisorption behavior of a reduced Pd/TiO2 powder catalyst upon O2 annealing at 773 K is completely reversible. 6 Similarly, different authors found restored H2 chemisorption after annealing reduced TiO2 decorated with noble metal powder catalysts at elevated O2 pressures and temperature (>70 Torr O2, > 573 K).…”

Section: Introductionmentioning

confidence: 99%

Tuning Strong Metal–Support Interaction Kinetics on Pt-Loaded TiO₂(110) by Choosing the Pressure: A Combined Ultrahigh Vacuum/Near-Ambient Pressure XPS Study

Petzoldt¹,

Eder²,

Mackewicz³

et al. 2022

J. Phys. Chem. C

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Pt catalyst particles on reducible oxide supports often change their activity significantly at elevated temperatures due to the strong metal-support interaction (SMSI), which induces the formation of an encapsulation layer around the noble metal particles. However, the impact of oxidizing and reducing treatments at elevated pressures on this encapsulation layer remains controversial, partly due to the 'pressure gap' between surface science studies and applied catalysis. In the present work, we employ synchrotron-based near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) to study the effect of O2 and H2 on the SMSI-state of well-defined Pt/TiO2(110) catalysts at pressures of up to 0.1 Torr. By tuning the O2 pressure, we can either selectively oxidize the TiO2 support or both the support and the Pt particles.Catalyzed by metallic Pt, the encapsulating oxide overlayer grows rapidly in 1x10 -5 Torr O2, but orders of magnitudes less effective at higher O2 pressures, where Pt is in an oxidic state.While the oxidation/reduction of Pt particles is reversible, they remain embedded in the support once encapsulation has occurred.

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Section: Introductionmentioning

confidence: 99%

Tuning Strong Metal–Support Interaction Kinetics on Pt-Loaded TiO₂(110) by Choosing the Pressure: A Combined Ultrahigh Vacuum/Near-Ambient Pressure XPS Study

Petzoldt¹,

Eder²,

Mackewicz³

et al. 2022

J. Phys. Chem. C

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“…The face-centered cubic crystal structure of Au is lost when exposing the gold sample to the hydrogen conditions 38 . Also, platinum particles could be influenced by the redox chemical environment to form twin planes 39 . Furthermore, for the Au/TiO 2 catalyst in the CO oxidation reaction, the reconstruction of Au NPs with the major (111) and (100) facets of the gold NPs exposed by the reactants has been reported 42 .…”

Section: Resultsmentioning

confidence: 99%

Insight into the transient inactivation effect on Au/TiO2 catalyst by in-situ DRIFT and UV–vis spectroscopy

et al. 2022

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Au catalysts have drawn broad attention for catalytic CO oxidation. However, a molecular-level understanding of the reaction mechanism on a fast time-resolved scale is still lacking. Herein, we apply in situ DRIFTS and UV-Vis spectroscopy to monitor the rapid dynamic changes during CO oxidation over Au/TiO2. A pronounced transient inactivation effect likely due to a structural change of Au/TiO2 induced by the reactants (CO and O2) is observed at the beginning of the reaction. The transient inactivation effect is affected by the ratio of CO and O2 concentrations. More importantly, during the unstable state, the electronic properties of the Au particles change, as indicated by the shift of the CO stretching vibration. UV-Vis spectroscopy corroborates the structure change of Au/TiO2 surface induced by the reactants, which leads to a weakening of the Au catalyst’s ability to be oxidized (less O2 adsorption), resulting in the transient inactivation effect.

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“…used in situ TEM to observe the Pt/TiO 2 system under different atmospheres. [ 50 ] Noticeably, it was the first time that the SMSI process was observed under real working conditions, which provides new insights into understanding the SMSI process. First, the classical SMSI with the formation of encapsulation overlayer was constructed in pure H 2 atmosphere at 600 °C, and the overlayer became thicker during this process, accompanied with no apparent change in the shape of Pt NPs.…”

Section: Understandings and Extensions Of Smsimentioning

confidence: 99%

Section: Understandings and Extensions Of Smsimentioning

confidence: 99%

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Strong Metal–Support Interaction in Heterogeneous Catalysts

Luo

Zhao

Pan

et al. 2022

Advanced Energy Materials

122

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too strong of a metal-support interaction would trigger Ostwald ripening, whereas too weak of that would lead to particle migration and coalescence. Therefore, the metal-support binding energy serves as a descriptor to predict the growth rates of supported NPs in this case. [14] Strong metal-support interaction (SMSI) is a special form of interaction that is typically observed between metal NPs and reducible supports. [15][16][17] In 1978, Tauster et al. first discovered that the chemisorption abilities of TiO 2 -supported Group VIII noble metals toward small gas molecules, such as CO and H 2 , suddenly disappeared after a reduction treatment at 500 °C. [15] In this case, the term SMSI was proposed to describe this phenomenon that was once believed to be caused by the electronic perturbation due to the formation of PtTi bond. [16,[18][19][20] Later, subsequent investigations confirmed the encapsulation of metal NPs by migrated support species. [21][22][23][24] In 1986, Sakellson et al. provided direct evidences of the SMSI in Rh-TiO 2 using extended X-ray absorption fine structure spectroscopy (EXAFS)-the RhTi bond formed between Rh NPs and TiO 2 support was apparently shorter than that in RhTi intermetallic compounds due to the cationic nature of Ti n+ in TiO 2 . [25] This highlights the meaning of "strong" in "SMSI". On that occasion, Tauster emphasized that the SMSI should be referred to as the formation of such strong interfacial metalmetal bonds rather than its subsequent consequences. [17] However, considering the difficulty in detecting the relatively small amounts of interfacial bonds in supported metal NPs, SMSI is still identified by the apparent change of physicochemical behaviors including encapsulation, loss of chemisorption ability, etc.Later, similar phenomena were observed when other reducible metal oxides were used as the supports including CeO 2 , [26,27] Nb 2 O 5 , [28,29] etc. Moreover, such a reduction-induced SMSI can be eliminated after oxidation treatment at elevated temperatures. Recently, the SMSI has been observed between some new components beyond the typical Group VIII noble metals and reducible metal oxide supports. [30][31][32] The development of advanced material characterization technologies, in situ high-resolution transmission electron microscopy (HRTEM) for example, [33][34][35][36] has also brought new insights into understanding SMSI behaviors. More importantly, owing to its intriguing behaviors, SMSI brings about new principles for designing and modulating advanced heterogeneous catalysts toward thermocatalysis and electrocatalysis. [27,[37][38][39] Meanwhile, it should also be noted that the concept of SMSI has been usedStrong metal-support interaction (SMSI) in supported metal catalysts, typically accompanied by the formation of encapsulation layers over metal nanoparticles, has drawn intense research attention owing to a variety of intriguing behaviors. In particular, recent years have witnessed enormous progress in constructing SMSI between novel components as well as...

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Dynamic interplay between metal nanoparticles and oxide support under redox conditions

Cited by 131 publications

References 77 publications

Tuning Strong Metal–Support Interaction Kinetics on Pt-Loaded TiO₂(110) by Choosing the Pressure: A Combined Ultrahigh Vacuum/Near-Ambient Pressure XPS Study

Tuning Strong Metal–Support Interaction Kinetics on Pt-Loaded TiO₂(110) by Choosing the Pressure: A Combined Ultrahigh Vacuum/Near-Ambient Pressure XPS Study

Insight into the transient inactivation effect on Au/TiO2 catalyst by in-situ DRIFT and UV–vis spectroscopy

Strong Metal–Support Interaction in Heterogeneous Catalysts

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Dynamic interplay between metal nanoparticles and oxide support under redox conditions

Cited by 131 publications

References 77 publications

Tuning Strong Metal–Support Interaction Kinetics on Pt-Loaded TiO2(110) by Choosing the Pressure: A Combined Ultrahigh Vacuum/Near-Ambient Pressure XPS Study

Tuning Strong Metal–Support Interaction Kinetics on Pt-Loaded TiO2(110) by Choosing the Pressure: A Combined Ultrahigh Vacuum/Near-Ambient Pressure XPS Study

Insight into the transient inactivation effect on Au/TiO2 catalyst by in-situ DRIFT and UV–vis spectroscopy

Strong Metal–Support Interaction in Heterogeneous Catalysts

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Product

Resources

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Tuning Strong Metal–Support Interaction Kinetics on Pt-Loaded TiO₂(110) by Choosing the Pressure: A Combined Ultrahigh Vacuum/Near-Ambient Pressure XPS Study

Tuning Strong Metal–Support Interaction Kinetics on Pt-Loaded TiO₂(110) by Choosing the Pressure: A Combined Ultrahigh Vacuum/Near-Ambient Pressure XPS Study