AgLa(PO3)4 polycrystalline powder has been prepared by flux method and characterized by X-ray powder diffraction and FTIR spectroscopy. The AgLa(PO3)4 structure was crystallized in the monoclinic ...system with space group P21/n and cell parameters: a = 7.300(5)A°, b = 13.211(9)A°, c = 10.079(7)Å, β = 90.47(4)°, V = 971.99 Å3 and Z = 4. Ionic conductivities of the AgLa(PO3)4 powder were carried out by impedance spectroscopy measurements over a temperature range from 300 °C to 650 °C. A simple equivalent circuit model is described and electrical characteristics predicted by the model are compared with those obtained experimentally. The conductivity values obtained from this sample were 1.8 × 10−7 and 6 × 10−6 S.cm−1 at 350 and 650 °C, respectively. The activation energy in the temperature range investigated is Ea = 0.65 eV corresponds to the mobility of Ag+ cations situated in the tunnels cavities. The most probably Ag+ ion transport between defect states may take place by a quantum tunnelling and hopping processes. The conduction and relaxation processes in the studied AgLa(PO3)4 polycrystalline powder are temperature dependent.
•Polyphosphates containing silver and rare-earth cations show promising conduction properties.•The investigated AgLa(PO3)4 demonstrated low activation energy and better conductivity than similar compared materials.•The AgLa(PO3)4 powder showed a no Debye relaxation type.•Conduction pathways are based on either; quantum tunneling and hopping process of Ag + ion between defect states.
The catalytic performance of a series of dendritic mesoporous silica nanoparticles (DMSNs) containing vanadium, featuring a unique central-radial pore structure with large pore size and highly ...accessible surface areas, was investigated for the selective oxidation of propane. The one-pot method allowed to synthesize vanadium-containing dendritic mesoporous silica nanoparticles (V-DMSNs). V/DMSN catalysts with similar V-loading were prepared using the impregnation procedure for comparison. These V-containing DMSNs materials served as catalysts for the selective oxidation of propane, utilizing a mixture of N2O and O2 as a mild oxidant. The nature of vanadium oxide species was characterized using Raman spectroscopy, diffuse reflectance ultraviolet–visible spectroscopy (UV–vis DRS), and temperature-programmed reduction with hydrogen (H2-TPR). Additionally, the acidic sites' nature and strength were estimated based on the Fourier transform infrared spectroscopy (FTIR) of adsorbed CO and pyridine. Spectroscopic measurements revealed that vanadium predominantly exists as an isolated or low-polymeric VOx species in one-pot synthesized catalysts. At the same time, impregnation resulted in more polymerized or bulk forms of vanadia, characterized by lower accessibility. Textural, SEM, and TEM results indicated that the characteristic dendritic features of DMSNs were maintained after vanadium incorporation, regardless of the preparation procedure. Propane oxidation led to a conversion of 64 %, accompanied by a propene selectivity of approximately 60 % and resulting space-time yield of 77 gC3H6 kgcat−1 h−1. Furthermore, propene oxide was identified among the products, with a space-time yield ranging from 3 to 11.5 gPO kgcat−1 h−1. Notably, the maximum turnover frequency (TOF) values for propene and propene oxide formation were 7.5 h−1 and 1.45 h−1, respectively. V-DMSNs catalysts exhibited superior catalytic performance in propane oxidation. The one-pot synthesized catalysts demonstrated higher stability over time on stream and lower selectivity towards COx. This study introduces a novel multifunctional catalyst that presents the potential for co-production of propene and propene oxide while utilizing N2O.
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•V-containing DMSN catalysts were prepared via the one-pot method and impregnation procedure.•Higher concentrations and better-dispersed isolated VO4 species are achieved on the one-pot synthesized V-DMSNs.•One-pot synthesized catalysts are characterized by better stability over time on stream.•The co-production of propene and propene oxide is achieved in propane oxidation using a mixture of N2O and O2.
► Neolamarckia cadamba extracts were first time examined as corrosion inhibitors. ► Cadambine alkaloid (3-β-isodihydrocadambine) was found to be the active ingredient. ► Inhibition mechanism ...supported by FTIR spectra and molecular modeling studies.
The inhibition effect of Neolamarckia cadamba crude extract (bark, leaves) and pure alkaloid (3β-isodihydrocadambine) were investigated for mild steel corrosion in 1M HCl medium. Potentiodynamic polarization, electrochemical impedance, scanning electron microscopy, FTIR spectroscopy and molecular modelling were employed for this study. Results showed that crude extracts and 3β-isodihydrocadambine reduced the corrosion rate significantly at all concentrations. Polarization measurements indicated that these green inhibitors acted through mixed type inhibition. SEM studies evidenced the formation of a protective film over metal surface while FTIR, supported by molecular modelling proved that this shielding effect was caused by alkaloids, particularly 3β-isodihydrocadambine.
A special feature of the small metal‐free electrophilic anion B6X5− is nitrogen activation through π‐backbonding. The π‐backbonding predicted by EDA ETS‐NOCV and detected by IR spectroscopy as a red ...shift of the bound N2 vibrational frequency is shown as a cartoon “boxing match” between N2 (blue glove, σ‐donation) and B6Cl5‐ (red gloves, π‐backdonation). The measured spectrum is shown on the outer surface of the boxing ring. Further information, including interaction with CO and H2O and comparison with B12X11−, can be found in the Research Article by J. Warneke and co‐workers (DOI: 10.1002/chem.202302247).
This paper presents a method for microplastic (MP) mass quantification using a Focal Plane Array-based Fourier Transform Infrared imaging technique. It discusses the issue that particle number is not ...a conserved base quantity and hence less suited than mass to compare independent studies on MP in the environment. It concludes that MP mass should be included when quantifying MP pollution in the environment, supplementing the conventional approach of reporting particle numbers. Applying mass as the unit of MP measurement, the paper presents data showing that Danish wastewater treatment plants discharge around 3 t/year of MP in the size range 10–500 μm. This value corresponds to an annual per capita emission from these plants of 0.56 g MP/(capita year). The distribution of polymer types by mass and particle number differed because the size of MP particles of the different material types varied.
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•98% of MPs are removed from influent wastewater in WWTPs.•The annual MP discharge from WWTPs in Denmark is approx. 0.56 g/(capita year).•MPs are quantified by mass in addition to particle number.•Mass can be estimated using FT-IR imaging.
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•The atomistic nature of Pt single atom catalysts on anatase TiO2 is demonstrated.•The isolated Ptiso species consist of a PtO2 unit.•Metallic, Ptmetal, and oxidized, Ptox, particles ...are also present.•We combined CO probe molecule FTIR and TPD measurements with DFT calculations.
Pt single atom catalysts anchored on the surface of anatase TiO2 have recently been shown to be stable through oxidation and reduction conditions and exhibit higher catalytic activity in CO oxidation than Pt metallic clusters. In this work we unravel the atomistic nature of the isolated Ptiso species on anatase TiO2 thanks to the combination of CO probe molecule Fourier Transform Infrared (FTIR) and temperature programmed desorption (TPD) experiments with an extensive set of Density Functional Theory (DFT) calculations. We used the stretching frequencies and adsorption energies of CO bound to Pt as a fingerprint of the specific structure of the stable Ptiso species. These consist of Pt atoms bound to two excess O atoms on the surface (PtO2). The excess oxygen atoms on the surface arise from the formation of surface hydroxyl groups, and provide a solid anchor to the oxide support, which explains the high thermal stability of the single-atom Pt catalyst through oxidative and reductive treatments. Beside the single atom Pt species, also models of metallic, Ptmetal, and oxidized, Ptox, sub-nanometer clusters have been considered. Comparisons between characteristics of Ptiso species and sub-nanometer Ptmetal and Ptox clusters demonstrate that the combination of CO vibrational frequency and adsorption energy can be an effective approach to differentiate these species.
Trapped inside: A new catalyst was developed where gold nanoparticles are encased inside hollow titania nanospheres (see picture). The new nanoarchitecture prevents the nanoparticles from sintering ...and losing their activity while still providing the reactants free access to the metal surface. The result is a catalyst capable of promoting the oxidation of CO at room temperature while surviving calcination at temperatures above 775 K.
► We present new kinetics data on the radiolytic destruction of amino acids at 15, 100, and 140K. ► The amino acids glycine, alanine, and phenylalanine were studied. ► Destruction of amino acids was ...measured in situ with infrared spectroscopy. ► The half-lives of amino acids were estimated for various extraterrestrial environments.
We present new kinetics data on the radiolytic destruction of amino acids measured in situ with infrared spectroscopy. Samples were irradiated at 15, 100, and 140K with 0.8-MeV protons, and amino-acid decay was followed at each temperature with and without H2O present. Observed radiation products included CO2 and amines, consistent with amino-acid decarboxylation. The half-lives of glycine, alanine, and phenylalanine were estimated for various extraterrestrial environments. Infrared spectral changes demonstrated the conversion from the non-zwitterion structure NH2CH2(R)COOH at 15K to the zwitterion structure +NH3CH2(R)COO− at 140K for each amino acid studied.
This study aims to compare photoacoustic (FTIR–PAS), diffuse reflectance (DRIFT), and attenuated total reflection (ATR) FTIR modalities in the wide wavenumber range from NIR (7500 cm−1) to FIR (150 ...cm−1) for the same silicate soil samples under the same conditions. The possibilities of non-destructive rapid qualitative analysis of soils by these modalities without comprehensive data treatment were compared. The assignment of more than 100 bands for the chernozem and sod-podzolic as common types of silicate types of soil was made. The following groups of bands of organic matter and inorganic matrix were reliably found in spectra of all or at least two modalities: 3690–3680 cm−1 (hydrogen-bonded SiO–H…H2O stretch, not ATR), 2930–2910 cm−1 and 2860–2850 cm−1 (methylene stretch), 1390–1380 cm−1, (symmetric stretch carboxylate, DRIFT and FTIR–PAS); 2000–1990 cm−1, 1885 cm−1, and 1790–1783 cm−1 (SiO2 overtones, DRIFT and FTIR–PAS), 1163–1153 cm−1, SiO2 lattice (not FTIR–PAS), 1037 cm−1 (Si–O or Al–O stretch), 796 cm−1 (lattice symmetrical Si–O–Si stretch); 697 cm−1, SiO2; and 256 cm−1 (not FTIR–PAS). Amide I, II, and III bands appear in DRIFT and FTIR–PAS spectra while not in ATR. Except for methylene and carboxylate groups, CH vibrations (3100–2900 cm−1) are not seen in ATR. Bands at 1640–1630 cm−1, 1620–1610 cm−1, 1600–1598 cm−1 (primary water bands and probably carboxylate) appear in the spectra of all three modalities but are unresolved and require data treatment. It is preferable to use all three modalities to characterize both soil organic matter and mineral composition. DRIFT provides the maximum number of bands in all three modalities and should be selected as a primary technique in the NIR and 4000–2000 cm−1 regions for hydrogen-bonding bands, CHX groups, and the silicate matrix. ATR–FTIR complements DRIFT and provides a good sensitivity for soil water and the matrix in 2000–400 cm−1. FTIR–PAS in 4000–1500 cm−1 reveals more bands than DRIFT and shows the highest sensitivity for absorption bands that do not appear in DRIFT or ATR-IR spectra. Thus, FTIR–PAS is expedient for supporting either DRIFT or ATR–FTIR. This modality comparison can be a basis for methodological support of IR spectroscopy of soils and similar organomineral complexes.
This study investigated the effect of alkali activation process conditions on the IR spectra, on which amount and types of zeolites in the resultant geopolymers influence significantly. Kaolinite was ...used as starting materials. The kaolinitic clay was first calcined to transform into the amorphous aluminosilicate phases (metakaolinite) and then activated with sodium silicate (as water glass) and sodium hydroxide. The effects of reaction systems composition (expressed as SiO2/Al2O3 and Al2O3/Na2O molar ratios) as well as synthesis temperature on the phase composition of obtained products have been determined. In particular, the structures of materials were examined using FT-IR spectroscopy in the middle infrared range. The results were compared to the XRD measurements, as well as SEM observations.
Alkali-activation treatment of the metakaolin yielded bulk materials with different amounts and types of zeolite, which reveal the IR spectra of received materials. With proper selection of the initial conditions (temperature and composition), it is possible to obtain a solid material containing zeolite phase such as zeolite X, zeolite A or sodalite. The presence of zeolite phase was confirmed by the measurement of spectra in the middle infrared. In particular in pseudolattice range of the spectra, i.e. 800–400 cm−1, there are bands associated with the ring vibrations, which are characteristic for secondary building units (SBU) occurred in zeolite structure. IR spectroscopy is also useful in the studies of resulting amorphous phase structure.
•The study investigated the effect of alkali activation conditions on the IR spectra.•Treatment of metakaoline with the use water glass and NaOH was carried out.•It is possible to obtain a sodium zeolites in geopolimeric matrix.•We used the infrared spectra to describe the geopolymerization progress.
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