Key Role of a‐Top CO on Terrace Sites of Metallic Pd Clusters for CO Oxidation

Oh, Dong Gun; Aleksandrov, Hristiyan A.; Kim, Haneul; Koleva, Iskra Z.; Khivantsev, Konstantin; Vayssilov, Georgi N.; Kwak, Ja Hun

doi:10.1002/chem.202200684

Cited by 8 publications

(9 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Also, Kale and Christopher reported the terrace sites of Pt clusters, which have the lowest activation barrier of the reaction predominantly affected the CO oxidation activity . In addition, the results are consistent with our previous study, which indicated that the linearly adsorbed CO on the terrace sites of Pd clusters initiated CO oxidation on Pd/Al 2 O 3 catalysts . Based on DRIFTS and CO-TPD, it can be concluded that Pt/rutile exhibits weaker CO adsorption under the CO oxidation and reacts with O 2 readily.…”

Section: Resultssupporting

confidence: 89%

“…47 In addition, the results are consistent with our previous study, which indicated that the linearly adsorbed CO on the terrace sites of Pd clusters initiated CO oxidation on Pd/Al 2 O 3 catalysts. 14 Based on DRIFTS and CO-TPD, it can be concluded that Pt/rutile exhibits weaker CO adsorption under the CO oxidation and reacts with O 2 readily. On the contrary, there is no change in the strength of CO adsorbed on Pt/anatase.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…Particularly, their low-temperature activity is of substantial interest for practical usage in exhaust gas treatment systems. ,− However, there is a strong need to develop noble metal catalysts for CO oxidation that can function under practical operating conditions, such as high sulfur conditions. Pt-based catalysts exhibit low CO oxidation activity at low temperatures because of CO poisoning. , Hence, the low-temperature activity of Pt-based catalysts also needs to be improved. CO poisoning is generally due to the strong interaction between CO and metallic Pt, especially on Pt/Al 2 O 3 . , …”

Section: Introductionmentioning

confidence: 99%

“…Pt-based catalysts exhibit low CO oxidation activity at low temperatures because of CO poisoning. 13,14 Hence, the low-temperature activity of Pt-based catalysts also needs to be improved. CO poisoning is generally due to the strong interaction between CO and metallic Pt, especially on Pt/Al 2 O 3 .…”

Section: ■ Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Origin of Higher CO Oxidation Activity of Pt/Rutile than That of Pt/Anatase

Kim

Kwak

2023

J. Phys. Chem. C

Self Cite

View full text Add to dashboard Cite

Herein, we show that the weak interaction of CO with Pt/TiO 2 under the CO oxidation condition is the origin of higher CO oxidation activity of Pt/rutile than that of Pt/anatase. The results of CO temperature-programmed desorption (TPD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) indicate that the onset temperatures of CO desorption on freshly prepared Pt/rutile and Pt/anatase are the same. However, the CO-TPD curves of Pt/rutile after the reaction test show that the desorption temperature of CO shifts to a lower temperature, while that for Pt/anatase does not change. The in situ pulse reaction using DRIFTS reveals that CO on Pt/rutile reacted with oxygen faster than CO on Pt/anatase. IR spectra with peak deconvolution of adsorbed CO on Pt/rutile exhibit that CO adsorbed on the terrace sites of Pt clusters on rutile (2089 cm −1 ) reacts readily with O 2 . These results indicate that the higher lowtemperature activity of Pt/rutile is related to its weaker interaction with CO compared with Pt/anatase under the reaction conditions. Our findings deepen the fundamental understanding of metal−support interaction and CO oxidation on Pt/TiO 2 catalysts.

show abstract

Section: Resultssupporting

confidence: 89%

Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Origin of Higher CO Oxidation Activity of Pt/Rutile than That of Pt/Anatase

Kim

Kwak

2023

J. Phys. Chem. C

Self Cite

View full text Add to dashboard Cite

show abstract

“…In our previous study, we modeled CO adsorption at various surface sites of pristine Pd 79 NP [ 34 ]. Our results have shown that, when CO is at the top coordination (top-cen, top-edg, and top-cor), the calculated C-O vibrational frequencies, 2013–2023 cm −1 (presented also in Table 3 ), are systematically shifted to lower frequencies by ~60 cm −1 than the experimental bands.…”

Section: Resultsmentioning

confidence: 99%

Understanding of Active Sites and Interconversion of Pd and PdO during CH4 Oxidation

Aleksandrov

Kim

et al. 2023

Molecules

View full text Add to dashboard Cite

Pd-based catalysts are widely used in the oxidation of CH4 and have a significant impact on global warming. However, understanding their active sites remains controversial, because interconversion between Pd and PdO occurs consecutively during the reaction. Understanding the intrinsic active sites under reaction conditions is critical for developing highly active and selective catalysts. In this study, we demonstrated that partially oxidized palladium (PdOx) on the surface plays an important role for CH4 oxidation. Regardless of whether the initial state of Pd corresponds to oxides or metallic clusters, the topmost surface is PdOx, which is formed during CH4 oxidation. A quantitative analysis using CO titration, diffuse reflectance infrared Fourier-transform spectroscopy, X-ray diffraction, and scanning transmission electron microscopy demonstrated that a surface PdO layer was formed on top of the metallic Pd clusters during the CH4 oxidation reaction. Furthermore, the time-on-stream test of CH4 oxidation revealed that the presence of the PdO layer on top of the metallic Pd clusters improves the catalytic activity. Our periodic density functional theory (DFT) calculations with a PdOx slab and nanoparticle models aided the elucidation of the structure of the experimental PdO particles, as well as the experimental C-O bands. The DFT results also revealed the formation of a PdO layer on the metallic Pd clusters. This study helps achieve a fundamental understanding of the active sites of Pd and PdO for CH4 oxidation and provides insights into the development of active and durable Pd-based catalysts through molecular-level design.

show abstract

Identifying the Structure of Supported Metal Catalysts Using Vibrational Fingerprints from Ab Initio Nanoscale Models

Salcedo

Zengel

Maurer

et al. 2023

Small

View full text Add to dashboard Cite

Identifying active sites of supported noble metal nanocatalysts remains challenging, since their size and shape undergo changes depending on the support, temperature, and gas mixture composition. Herein, the anharmonic infrared spectrum of adsorbed CO is simulated using density functional theory (DFT) to gain insight into the nature of Pd nanoparticles (NPs) supported on ceria. The authors systematically determine how the simulated infrared spectra are affected by CO coverage, NP size (0.5–1.5 nm), NP morphology (octahedral, icosahedral), and metal‐support contact angle, by exploring a diversity of realistic models inspired by ab initio molecular dynamics. The simulated spectra are then used as a spectroscopic fingerprint to characterize nanoparticles in a real catalyst, by comparison with in‐situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments. Truncated octahedral NPs with an acute Pd‐ceria angle reproduce most of the measurements. In particular, the authors isolate features characteristic of CO adsorbed at the metal‐support interface appearing at low frequencies, both seen in simulation and experiment. This work illustrates the strong need for realistic models to provide a robust description of the active sites, especially at the interface of supported metal nanocatalysts, which can be highly dynamic and evolve considerably during reaction.

show abstract

Key Role of a‐Top CO on Terrace Sites of Metallic Pd Clusters for CO Oxidation

Cited by 8 publications

References 50 publications

Origin of Higher CO Oxidation Activity of Pt/Rutile than That of Pt/Anatase

Origin of Higher CO Oxidation Activity of Pt/Rutile than That of Pt/Anatase

Understanding of Active Sites and Interconversion of Pd and PdO during CH4 Oxidation

Identifying the Structure of Supported Metal Catalysts Using Vibrational Fingerprints from Ab Initio Nanoscale Models

Contact Info

Product

Resources

About