Surface enhanced Raman scattering in organic thin films covered with silver, indium and magnesium

Salvan, Georgeta; Zahn, Dietrich R. T.; Paez, B. A.

doi:10.1016/j.jlumin.2004.08.024

Cited by 9 publications

(6 citation statements)

References 18 publications

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“…Further evaluation of ion exchange was conducted by Raman spectroscopy on pristine In 2 O 3 , nano_In 2 O 3 /HZSM-5 (1:1), nano_In 2 O 3 /HZSM-5 (1:5), 0.3InZSM-5, 0.7InZSM-5, and 3.5InZSM-5, shown in Figure 10 B. In agreement with XPS and PXRD, no samples exhibited bands for metallic In at 250 and 620 cm –1 (RRUFF ID: R060771.2), 106 , 107 and cubic In(OH) 3 at 137, 204, 356, 390, and 659 cm –1 . 108 , 109 Pure In 2 O 3 exhibited bands at 308, 497, and 632 cm –1 , which is attributed to the InO 6 vibration of the cubic phase of In 2 O 3 , consistent with PXRD patterns.…”

Section: Resultssupporting

confidence: 71%

Intermediate Transfer Rates and Solid-State Ion Exchange are Key Factors Determining the Bifunctionality of In₂O₃/HZSM-5 Tandem CO₂ Hydrogenation Catalyst

Mahnaz,

Mangalindan,

Dharmalingam

et al. 2024

ACS Sustainable Chem. Eng.

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Identifying the descriptors for the synergistic catalytic activity of bifunctional oxide-zeolite catalysts constitutes a formidable challenge in realizing the potential of tandem hydrogenation of CO 2 to hydrocarbons (HC) for sustainable fuel production. Herein, we combined CH 3 OH synthesis from CO 2 and H 2 on In 2 O 3 and methanol-to-hydrocarbons (MTH) conversion on HZSM-5 and discerned the descriptors by leveraging the distance-dependent reactivity of bifunctional In 2 O 3 and HZSM-5 admixtures. We modulated the distance between redox sites of In 2 O 3 and acid sites of HZSM-5 from milliscale (∼10 mm) to microscale (∼300 μm) and observed a 3-fold increase in space-time yield of HC and CH 3 OH (7.5 × 10 −5 mol C g cat −1 min −1 and 2.5 × 10 −5 mol C g cat −1 min −1 , respectively), due to a 10-fold increased rate of CH 3 OH advection (1.43 and 0.143 s −1 at microscale and milliscale, respectively) from redox to acid sites. Intriguingly, despite the potential of a three-order-of-magnitude enhanced CH 3 OH transfer at a nanoscale distance (∼300 nm), the sole product formed was CH 4 . Our reactivity data combined with Raman, Fourier transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS) revealed the occurrence of solid-state-ion-exchange (SSIE) between acid sites and In δ+ ions, likely forming In 2 O moieties, inhibiting C−C coupling and promoting CH 4 formation through CH 3 OH hydrodeoxygenation (HDO). Density functional theory (DFT) calculations further revealed that CH 3 OH adsorption on the In 2 O moiety with preadsorbed and dissociated H 2 forming an H−In−OH−In moiety is the likely reaction mechanism, with the kinetically relevant step appearing to be the hydrogenation of the methyl species. Overall, our study revealed that efficient CH 3 OH transfer and prevention of ion exchange are the key descriptors in achieving catalytic synergy in bifunctional In 2 O 3 /HZSM-5 systems.

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Section: Resultssupporting

confidence: 71%

Intermediate Transfer Rates and Solid-State Ion Exchange are Key Factors Determining the Bifunctionality of In₂O₃/HZSM-5 Tandem CO₂ Hydrogenation Catalyst

Mahnaz,

Mangalindan,

Dharmalingam

et al. 2024

ACS Sustainable Chem. Eng.

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“…All of the pyridine normal modes of the pristine film are still distinguishable and considerably enhanced in intensity in the spectra upon metallization (e.g., ν 16a , ν 6b , ν 1 , ν 12 , ν 9a , and ν 8b ); this enhancement is attributed to SERS from Mg nanoparticles, consistent with previous observations. 59,60 Additionally, several new bands are observed that suggest reaction chemistry. These new bands include those at 276, 334, 475, 522, 599, 659, 813, 1041, 1187, 1240, 1274, 1400, 1500, and 1531 cm −1 that gradually increase in intensity with Mg coverage and those at 544, 690,793, 879, 937, and 1626 cm −1 that appear initially upon Mg deposition but diminish in intensity with higher Mg coverage.…”

Section: ■ Introductionmentioning

confidence: 96%

Reaction Chemistry of Solid-State Pyridine Thin Films with Vapor Deposited Ag, Mg, and Al

Matz

Pemberton

2012

J. Phys. Chem. C

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The reaction of pyridine in thin solid-state films with postdeposited Ag, Mg, and Al is investigated using surface Raman spectroscopy in ultrahigh vacuum. Vapor-deposited Ag forms metallic nanoparticles on the pyridine film, resulting in surface enhancement of the Raman scattering (SERS), with no reaction chemistry evident. Mg and Al react with pyridine by electron transfer to form radical anion intermediates, some of which are stabilized by entrapment in the solid pyridine matrix. With Mg, slight SERS enhancement is observed along with Mg-to-pyridine electron transfer to form pyridyl radical anions, some of which dimerize to 4,4′-bipyridine with loss of MgH 2 and a neutral Mg atom. With Al, the reaction chemistry is initiated by a similar Al-to-pyridine electron transfer, but the radical anions so formed undergo further degradation to amorphous carbon. In total, these results demonstrate the complex reaction chemistry that can occur between heterocycles in the solid state and low work function metal atoms.

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“…Plasmonic resonances have been registered in the 2.8–4.5 eV range for granular In films deposited on NaCl and KCl 51. The SERS has been observed for In as well 52. A plasma peak in the spectrum of inelastic electron loss was found at 5.2 eV in a dielectric zeolite matrix containing as small as 8‐atoms indium clusters 53.…”

Section: Band Structure and Plasmonic Properties Of Indiummentioning

confidence: 92%

Plasmonic effects and optical properties of InN composites with In nanoparticles

Shubina

2010

Physica Status Solidi (a)

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Phone: þ7 812 292 8924, Fax: þ7 812 247 1017Nanocomposites comprising metallic nanoparticles (MNPs) inside a semiconductor matrix are promising materials for plasmonics suggesting a new concept of light manipulation and generation. Optical properties of the nanocomposites are controlled by localized plasmons (Mie resonances) in the MNPs. The basic properties of the nanocomposites have been studied using InN/In with In clusters formed both spontaneously and by the periodic deposition of In insertions. In the specially designed nanocomposites, the spots of intense cathodoluminescence are strongly correlated with the agglomerations of the In MNPs due to plasmon-induced enhancement. Furthermore, a strong difference is discovered between the onsets of thermally detected absorption and photocurrent. This feature is a key to distinguish InN/In from pure InN. To simulate the plasmonic effects in the nanocomposites a model has been proposed, which considers the clusters as spheroids of random shapes and orientations. The calculated dependences are in reasonable agreement with obtained optical data.

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Surface enhanced Raman scattering in organic thin films covered with silver, indium and magnesium

Cited by 9 publications

References 18 publications

Intermediate Transfer Rates and Solid-State Ion Exchange are Key Factors Determining the Bifunctionality of In₂O₃/HZSM-5 Tandem CO₂ Hydrogenation Catalyst

Intermediate Transfer Rates and Solid-State Ion Exchange are Key Factors Determining the Bifunctionality of In₂O₃/HZSM-5 Tandem CO₂ Hydrogenation Catalyst

Reaction Chemistry of Solid-State Pyridine Thin Films with Vapor Deposited Ag, Mg, and Al

Plasmonic effects and optical properties of InN composites with In nanoparticles

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Surface enhanced Raman scattering in organic thin films covered with silver, indium and magnesium

Cited by 9 publications

References 18 publications

Intermediate Transfer Rates and Solid-State Ion Exchange are Key Factors Determining the Bifunctionality of In2O3/HZSM-5 Tandem CO2 Hydrogenation Catalyst

Intermediate Transfer Rates and Solid-State Ion Exchange are Key Factors Determining the Bifunctionality of In2O3/HZSM-5 Tandem CO2 Hydrogenation Catalyst

Reaction Chemistry of Solid-State Pyridine Thin Films with Vapor Deposited Ag, Mg, and Al

Plasmonic effects and optical properties of InN composites with In nanoparticles

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Intermediate Transfer Rates and Solid-State Ion Exchange are Key Factors Determining the Bifunctionality of In₂O₃/HZSM-5 Tandem CO₂ Hydrogenation Catalyst

Intermediate Transfer Rates and Solid-State Ion Exchange are Key Factors Determining the Bifunctionality of In₂O₃/HZSM-5 Tandem CO₂ Hydrogenation Catalyst