Kinetics of Nitric Oxide Adsorption on Pd(111) Surfaces through Molecular Beam Experiments: A Quantitative Study

Nagarajan, Sankaranarayanan; Thirunavukkarasu, Kandasamy; Gopinath, Chinnakonda S.; Prasad, S.

doi:10.1021/jp203992r

Cited by 7 publications

(7 citation statements)

References 51 publications

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“…Processed data shown in Figure 6 for Ce 0.9 Zr 0.1 O 2 at 600 K demonstrates the rate of adsorption; large extent of adsorption at the time of shutter opening indicating a high s. Similar rate of adsorption was maintained for about 35 s, after shutter opening and this is indicated by similar s observed up to t = 75 s. Indeed, this trend fully supports the precursor mediated adsorption, 79,80 and the same trend was observed at other temperatures too. However, adsorption rate begins to decline at t > 80 s and a gradual decrease was observed till t = 260 s, and no further net adsorption was observed at higher time.…”

Section: Molecular Beam Study Of Oxygen Adsorption On Ce 1 − X Zr X Osupporting

confidence: 65%

Porous thin films toward bridging the material gap in heterogeneous catalysis

Dubey

Kolekar

Gnanakumar

et al. 2016

Catalysis, Structure & Reactivity

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An attempt has been made to bridge the material gap, existing between ideal single crystals and real-world powder nanocatalyst employed in surface science and heterogeneous catalysis, respectively. Simple wet chemical method (sol-gel and spin-coating deposition) has been applied to make continuous Ce 1 − x Zr x O 2 (x = 0-1) (CZ) thin films with uniform thickness (~40 nm) and smooth surface characteristics. Uniform thickness and surface smoothness of the films over a large area was supported by a variety of measurements. Molecular beam (MB) studies of O 2 adsorption on CZ surfaces reveals the oxygen storage capacity (OSC), and sticking coefficient increases from 400 to 800 K. Porous nature of Ce-rich CZ compositions enhances O 2 adsorption and OSC, predominantly due to O-diffusion and redox nature, even at 400 K. A good correlation exists between MB measurements made on CZ films for oxygen adsorption, and OSC, and ambient pressure CO oxidation on powder form of CZ; this demonstrates the large potential to bridge the material gap. CZ was particularly chosen as a model system for the present studies, since it has been well-studied and a correlation between surface science properties made on thin films and catalysis on powder CZ materials could be a litmus test. Graphical abstract Ambient catalysis on ceria-zirconia nanocatalyst correlates well with surface properties measured through molecular beam on thinfilm and close the material gap.

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Section: Molecular Beam Study Of Oxygen Adsorption On Ce 1 − X Zr X Osupporting

confidence: 65%

Porous thin films toward bridging the material gap in heterogeneous catalysis

Dubey

Kolekar

Gnanakumar

et al. 2016

Catalysis, Structure & Reactivity

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“…The latter is mainly to simulate the calcination conditions carried out on supported Pd-based catalysts employed in the literature. − Ultraviolet photoelectron spectroscopy (UVPES), and XPS measurements were carried out with ambient pressure photoelectron spectrometer (APPES) in the presence of O 2 at relevant conditions to explore the electronic structure changes under experimental conditions. The present manuscript is part of our efforts in exploring the TWC reactions, such as CO oxidation and NO reduction with different reductants on Pd surfaces. ,− …”

Section: Introductionmentioning

confidence: 99%

Sustainable and Near Ambient DeNO_x Under Lean Burn Conditions: A Revisit to NO Reduction on Virgin and Modified Pd(111) Surfaces

2014

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Catalytic conversion of NO in the presence of H 2 and O 2 has been studied on Pd(111) surfaces, by using a molecular beam instrument with mass spectrometry detection, as a function of temperature and reactants composition. N 2 and H 2 O are the major products observed, along with NH 3 and N 2 O minor products under all conditions studied. Particular attention has been paid to the influence of O 2 addition toward NO dissociation. Although O 2rich compositions were found to inhibit the deNO x activity of the Pd catalyst, some enhancement in NO reduction to N 2 was also observed up to a certain O 2 content. The reason for this behavior was determined to be the effective consumption of the H 2 in the mixture by the added O 2 and O atoms from NO dissociation. NO was proven to compete favorably against O 2 for the consumption of H 2 , especially ≤550 K, to produce N 2 and H 2 O. Compared with other elementary reaction steps, a slow decay observed with the 2H + O → H 2 O step under SS beam oscillation conditions demonstrates its contribution to the rate-limiting nature of the overall reaction. Pd(111) surfaces modified with O atoms in the subsurface (Md-Pd( 111)) induces steady-state NO reduction at near-ambient temperatures (325 K) and opens up a possibility to achieve room temperature emission control. A 50% increase in the reaction rates was observed at the reaction maximum on Md-Pd(111), as compared with virgin surfaces. Oxygen adsorption is severely limited below 400 K, and effective NO + H 2 reaction occurs on Md-Pd(111) surfaces. Valence band photoemission with a UV light source (He I) under different oxygen pressures with APPES clearly identified the characteristics of the Md-Pd(111) surfaces and PdO. The electron-deficient or cationic nature of Md-Pd(111) surfaces enhances the NO dissociation and inhibits oxygen chemisorption ≤400 K under lean-burn conditions.

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“…The CO-TPD profiles were simulated assuming an early transition state for CO dissociation. A shift in the transition state from a state resembling more the initial state to a state resembling more the product state will affect the energy barrier for CO-dissociation through a change in the difference in the reaction energy incorporating lateral interactions and the reaction energy in the absence of lateral interactions (see Equation (9)). This difference in the reaction energy for CO-dissociation becomes higher if the extent of CO dissociation increases whilst keeping the fraction of surface which is vacant constant, and upon decreasing the fraction of the surface which is vacant keeping the ratio of CO adsorbed to C/O adsorbed constant.…”

Section: Describing Co-tpd Using Mean Field Modelsmentioning

confidence: 99%

“…Hence, the high temperature peak (β) shifts towards lower temperatures upon decreasing α. . Sensitivity analysis of simulated CO-TPD-profile from Fe(100) (ΘCO,initial = 1.00 ML, 10 K•s −1 ) using a mean field approach on the variation in the factor α describing the similarity of the transition state to the initial state (α = 0) or the final state (α = 1) in CO-dissociation (see Equation (9)).…”

Section: Describing Co-tpd Using Mean Field Modelsmentioning

confidence: 99%

“…The heterogeneous catalysis community has obtained a basic understanding of events occurring on surfaces using the Langmuir isotherm (not unlike the understanding the 19 th -century physicists of gases by using the ideal gas law). However, it is well known that adsorbates are affected by the presence of other adsorbates due to lateral interactions [2][3][4][5][6][7][8][9][10], which originate from so-called through-space and through-surface interactions [11]. The classical through-space interactions can be long range interactions, e.g., via induced dipole-dipole interactions [12], whereas the through-surface interactions are mainly influenced by nearby neighbor interactions.…”

Section: Introductionmentioning

confidence: 99%

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Micro-Kinetic Modelling of CO-TPD from Fe(100)—Incorporating Lateral Interactions

2019

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The experimentally determined temperature programmed desorption profile of CO from Fe(100) is characterized by four maxima, i.e., α1-CO, α2-CO, α3-CO, and β-CO (see e.g., Moon et al., Surf. Sci. 1985, 163, 215). The CO-TPD profile is modeled using mean-field techniques and kinetic Monte Carlo to show the importance of lateral interactions in the appearance of the CO-TPD-profile. The inclusion of lateral interactions results in the appearance of a new maximum in the simulated CO-TPD profile if modeled using the mean-field, quasi-chemical approach or kinetic Monte Carlo. It is argued that α2-CO may thus originate from lateral interactions rather than a differently bound CO on Fe(100). A detailed sensitivity analysis of the effect of the strength of the lateral interactions between the species involved (CO, C, and O), and the choice of the transition state, which affects the activation energy for CO dissociation, and the energy barrier for diffusion on the CO-TPD profile is presented.

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Kinetics of Nitric Oxide Adsorption on Pd(111) Surfaces through Molecular Beam Experiments: A Quantitative Study

Cited by 7 publications

References 51 publications

Porous thin films toward bridging the material gap in heterogeneous catalysis

Porous thin films toward bridging the material gap in heterogeneous catalysis

Sustainable and Near Ambient DeNO_x Under Lean Burn Conditions: A Revisit to NO Reduction on Virgin and Modified Pd(111) Surfaces

Micro-Kinetic Modelling of CO-TPD from Fe(100)—Incorporating Lateral Interactions

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Kinetics of Nitric Oxide Adsorption on Pd(111) Surfaces through Molecular Beam Experiments: A Quantitative Study

Cited by 7 publications

References 51 publications

Porous thin films toward bridging the material gap in heterogeneous catalysis

Porous thin films toward bridging the material gap in heterogeneous catalysis

Sustainable and Near Ambient DeNOx Under Lean Burn Conditions: A Revisit to NO Reduction on Virgin and Modified Pd(111) Surfaces

Micro-Kinetic Modelling of CO-TPD from Fe(100)—Incorporating Lateral Interactions

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Sustainable and Near Ambient DeNO_x Under Lean Burn Conditions: A Revisit to NO Reduction on Virgin and Modified Pd(111) Surfaces