Raman Spectroscopy Techniques Research Articles

Microwave-assisted conversion of fructose to 5-HMF using carbonaceous acidic catalysts

Recently, the catalytic conversion of fructose to 5-hydroxymethylfurfural (5-HMF) has attracted much interest. The idea of a low-cost, sustainable, energy-efficient method is critical to obtain excellent yield and selectivity for the target product 5-HMF. In this work, microwave (MW) irradiation was chosen as a heating source for the conversion of fructose to 5-HMF with the presence of various amorphous carbons containing Brønsted acid sites as catalysts in dimethyl sulfoxide (DMSO) as a solvent. The catalysts’ morphology, surface functional groups, thermal stability, and compositions of the obtained solids were examined by scanning electron microscope (SEM), elemental mapping, thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FT-IR), energy dispersive X-Ray spectroscopy (EDX), Raman spectroscopy and X-ray diffraction (XRD) techniques. The effect of solvent, heating technique, MW power, time, and catalytic loading on the reaction was studied thoroughly. The highest 5-HMF yield of 79.9% and 5-HMF selectivity of 79.7% were achieved with the optimal condition. 5-HMF was easily separated using a liquid-liquid extraction procedure with high purity. Moreover, the catalyst can be quickly recovered and reused. MW irradiation has proved to selectively and efficiently promote the formation of 5-HMF with high yield in a short reaction time. A mechanism for the formation 5-HMF from fructose was also proposed.

Carbon-slurry optimization for lithium-ion batteries customization

The technological application of lithium-ion batteries (LIB) grows constantly, making customization of the batteries a current necessity and sometimes a challenge. In this paper we described carbon-slurry optimization process for anodes of lithium-ion batteries customization by using a surface response statistical experiment with four response variables such specific discharge capacity, coulombic efficiency, anodes mass deviation, and capacity retention. We studied two commercial graphite active materials by characterizing the materials via Raman spectroscopy, SEM, and electrochemical techniques. We corroborate the graphite structure for both materials but with morphological differences such as shape and particle size. The binder composition seems to interfere with the active carbon materials capabilities while it generates better performance for one of them. Although the chemical structure of both materials was confirmed to be the same via Raman experiments, SEM images shows critical morphological differences that interferes with the final slurry thus, affecting the electrochemical performance of the anodes. Further studies are required to understand ECSA and its possible effect on the charge/discharge capacities of the anodes.

A new fabrication strategy of Ag2O doped PANI as a highly stable and room temperature operable carbon monoxide gas sensor

A new fabrication strategy for a highly stable and room temperature operable CO gas sensor based on Ag2O-doped PANI was successfully introduced here. Ag2O-doped PANI was prepared through the straightforward and inexpensive in-situ polymerization technique of PANI in the presence of Ag2O nanoparticles. The fabricated sensors were characterized using XRD, FTIR, UV–vis spectroscopy, Raman spectroscopy, and AFM techniques. The PANI/Ag2O sensor performed remarkably when subjected to a broad range of CO concentrations, between 5 and 500 ppm. The results of the experiments showed that incorporating Ag2O nanoparticles into PANI greatly enhanced the sensor's response rate (97%) and quickened its response and recovery times (37 s/41 s). Additionally, the sensor maintained its stability for 60 days without any degradation and demonstrated exceptional selectivity. The PANI/Ag2O sensor also demonstrated a remarkable recovery of over 98% and a low CO detection limit of 2 ppm. Based on the comparison between the current work and previously published work, it was found that the proposed sensor is highly effective. The results of this study indicate that the fabricated sensor, due to its reasonable and straightforward construction process and exceptional performance towards CO, could be an excellent choice for real-time CO detection.

Studying the Interaction between Bendamustine and DNA Molecule with SERS Based on AuNPs/ZnCl2/NpAA Solid-State Substrate.

Bendamustine (BENDA) is a bifunctional alkylating agent with alkylating and purinergic antitumor activity, which exerts its anticancer effects by direct binding to DNA, but the detailed mechanism of BENDA-DNA interaction is poorly understood. In this paper, the interaction properties of the anticancer drug BENDA with calf thymus DNA (ctDNA) were systematically investigated based on surface-enhanced Raman spectroscopy (SERS) technique mainly using a novel homemade AuNPs/ZnCl2/NpAA (NpAA: nano porous anodic alumina) solid-state substrate and combined with ultraviolet-visible spectroscopy and molecular docking simulation to reveal the mechanism of their interactions. We experimentally compared and studied the SERS spectra of ctDNA, BENDA, and BENDA-ctDNA complexes with different molar concentrations (1:1, 2:1, 3:1), and summarized their important characteristic peak positions, their peak position differences, and hyperchromic/hypochromic effects. The results showed that the binding modes include covalent binding and hydrogen bonding, and the binding site of BENDA to DNA molecules is mainly the N7 atom of G base. The results of this study help to understand and elucidate the mechanism of BENDA at the single-molecule level, and provide guidance for the further development of effective new drugs with low toxicity and side effects.

Effect of Drying Control Agent on Physicochemical and Thermal Properties of Silica Aerogel Derived via Ambient Pressure Drying Process

This paper presents the effect of drying control agents on the physicochemical and thermal properties of hydrophobic silica aerogels derived via the ambient pressure drying (APD) method by a surface silylation using a TMCS/n-hexane mixture. The structural and physicochemical properties of synthesized DMF-modified and unmodified hydrophobic silica aerogels were characterized using Brunauer–Emmett–Teller (BET) analysis, thermo-gravimetric analysis, FT-IR, and Raman spectroscopic techniques. Based on the obtained results, the differences in structure between samples before and after a surface silylation and the effect of drying control agents were documented. The structural measurements confirmed the efficient silylation process (TMCS/n-hexane), as well as the presence of DMF residues of hydrogen bonded with unreacted Si-OH silanol groups within the silica backbone after surface modification. Based on TG analysis, it was found that DMF addition improves thermal resistance (up to 320 °C) and hydrophobic character of prepared aerogel. Modification of the silica aerogel synthesis process by DMF also resulted in a significant increase in BET—the specific surface area, for the unmodified aerogel was ~828 m2/g, and for the DMF-modified aerogel more than 1200 m2/g—much higher than the value of silica aerogels available on the market.

Processing of PtSe2 ultra-thin layers using Ar plasma

This paper contains a detailed analysis of the Ar plasma treatment dynamics of the PtSe2/Al2O3 system comprising ultrathin PtSe2 layers with a thickness of 1–3 monomolecular layers. The impact of the etching process on the physical properties of the ultrathin PtSe2 layers was analysed using Raman spectroscopy and atomic force microscopy techniques in time intervals up to the complete decomposition of the PtSe2 layers. The processing duration that allowed the complete removal of the PtSe2 layer was determined for the investigated systems. The results, in combination with the optimised photolithography, were used for the active PtSe2 channel formation in the 3 ML PtSe2-based transfer line measurement structure using electrodes consisting of Ni and Au layers (with thicknesses of 20 and 40 nm, respectively). The electrical properties of the fabricated system confirm the effectiveness of commercially available PtSe2/Al2O3 samples in the fabrication of simple electronic devices utilising planar architecture, i.e. micro- and nanosensors.

Electrochemical Analysis of Anion Exchange Membrane Water Electrolyzers (AEMWE)

The increase in deployment of renewable electricity has made green hydrogen production an attractive solution for decarbonizing energy systems. The prominent technologies currently deployed are the proton exchange membrane water electrolyzers (PEMWE) and alkaline water electrolyzers (AWE). The PEMWE technology uses platinum group material (PGM) catalysts, coated onto fluorinated Nafion® polymer membranes and needs specially treated titanium bipolar plates, reaching current densities of greater than 2 A cm-2. The AWE technology, in contrast, uses cheaper materials with a porous diaphragm separator, but the operating current density reaches only <0.5 Acm-2. The anion exchange membrane water electrolyzers (AEMWE) combine the advantages of both the PEMWE and AWE by using hydroxide (OH-) conducting, functionalized styrene-based membranes with non-PGM electrocatalysts, reaching current densities of >1 Acm-2.In this study, a membrane electrode assembly (MEA) consisting of Sustainion® X37-50 Grade RT membranes and non-PGM hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts are fabricated and analyzed for performance. NiFe2O4 (Merk) was chosen as the OER electrocatalyst and spray-coated on the sintered 316L stainless steel fibre (dioxide materials). On the counter side, NiFeCo (USnano) as HER electrocatalyst was spray coated on the molded graphite layer 370 (MGL370- fuelcellstore) porous transport layer. A catalyst loading of 3 mg cm-2 is obtained for both HER and OER electrodes. The fabricated MEA of 1x1cm2 is firstly tested for performance in a inhouse setup, using current density-voltage scans (j-V) using Zahner Zennium X electrochemical workstation. Consequently, electrochemical impedance spectroscopy (EIS) is performed in pseudo-galvanostatic mode. The perturbation amplitude is adjusted such that a linear region of the j-V curve is probed. The fuel electrode and air electrode contributions to the overall MEA performance are distinguishable due to the twin reference electrode configuration. The half cell-MEA contributions are further analyzed by performing parallel impedance measurements between the i) Reference electrode – cathode, ii) Reference electrode - Anode and iii) full-cell operation at predetermined current-density biases. These type of investigation gives deeper insight to the fuel electrode and the air electrode processes. The quality of the EIS spectra is analyzed using Kramers Krönig residual tests.A sensitivity analysis on the MEA is performed by changing impedance-effecting parameters such as temperature, operating current density and potassium hydroxide (KOH) concentration. Further, post-test characterization of the electrode substrates is performed to identify affected parameters through XPS, Raman spectroscopy, SEM-EDX and XRD techniques. The parallel impedance measurements confirms the presence of anodic, cathodic and low-frequency diffusion processes in real time.

Understanding the lithiation intermediates of a silicon-based alloying anode by using operando diffraction and Raman spectroscopic techniques

In the present study, the effect of lithiation on a chalcopyrite phase, cadmium silicon phosphide (CdSiP2) anode is studied. This silicon-based phosphide anode helps in overcoming certain challenges encountered towards the application of elemental silicon anode for lithium-ion battery. Despite of having a fairly high band gap, this material represents outstanding cycling stability for lithium storage. Half-cell configuration results in a capacity of 970 mAh g−1 towards the end of 500 cycles at an applicable rate of 300 mA g−1, whereas a capacity of 645 mAh g−1 is obtained at a rate of 5000 mA g−1 for about 1800 cycles. The rate capability studies suggest highly reversible storage processes when switching from extremely high current rates such as 30 A g−1. Full-cell studies indicate highly stable charge-discharge voltage profiles with an appreciable capacity of around 400 mAh g−1 towards the end of 1400 cycles. Further, in-situ X-ray diffraction (XRD) analysis indicates conversion processes and confirms the formation of phases such as Li3P, LiCdP, Li5SiP3, Li13Si4, Li22Si5 and CdLi at various stages of charge-discharge cycling.

Influence of Alkali Metal Ions on the Structural and Spectroscopic Properties of Sm3+-Doped Silicate Glasses

In the present work, the influence of alkali ions (Li, Na, K) on the structural and spectroscopic properties of silica glasses doped with Sm3+ was investigated. Infrared and Raman spectroscopy techniques were used to investigate the structural properties of the alkali silicate glasses. The optical absorption showed bands characteristic of Sm3+ ions in alkali silicate glasses, and this was investigated. The Judd–Ofelt theory was applied to evaluate the phenomenological intensity parameters (Ω2, Ω4, and Ω6) of the optical absorption measurements. The multi-channel visible and near infrared emission transitions originating from the 4G5/2-emitting state of the Sm3+ in alkali silicate glasses with a maximum phonon energy of ~1050 cm−1 were investigated. From the evaluated Judd–Ofelt parameters, radiative parameters such as spontaneous emission probabilities, radiative lifetimes, branching ratios, and stimulated emission cross-sections were calculated. The recorded luminescence spectra regions revealed intense green, orange, red, and near-infrared emission bands, providing new traces for developing tunable laser and optoelectronic devices.

A magnetic field augmented ultra-thin layer chromatography coupled surface enhanced Raman spectroscopy separation of hemozoin from bacterial mixture

Malaria is considered as one the most widespread disease with highest possibility of co-infection at all levels of the disease prognosis. Rapid detection and discrimination of malaria from other co-infections remains a challenge. Hemozoin is a metabolic biproduct of malaraia possessing paramagnetic property due to presence of iron at its centre. Here, we report a label free, rapid and highly sensitive magnetic field based ultra-thin layer chromatography (UTLC) coupled with surface enhanced Raman spectroscopy (SERS) technique for detection and separation of hemozoin from a bacterial mixture. Highly optimized silver nanorods chip fabricated using glancing angle deposition (GLAD) is explored for the UTLC-SERS separation. These chips possessing channel like characteristic and high surface to the volume ratio serve as excellent UTLC plates. The magnetic nature of hemozoin has been exploited for its separation from the mixture of P. aeruginosa (Gram-negative) and S. aureus (Gram-positive) by allocating a 0.6 T magnet over the UTLC flow setup. The solvent front migrated approximately to a distance of 13 mm from the sample point due to the magnetic environment. Spatially resolved SERS data was collected along the mobile phase and separation of mixture was confirmed. Further, staining of hemozoin, P. aeruginosa and S. aureus was done using methylene blue, acridine orange and rhodamine 6 G respectively. The separation was confirmed for the stained analytes. The present developed method provides plate height as low as 18 µm and hemozoin detection limit as <10 parasites/mL. Therefore, we establish a highly specific and sensitive technique capable of separating small amounts of bioanalytes, aiding in the removal of co-infections from the disease at a very early stage of infection.

Development of a multi-needle fiberoptic Raman spectroscopy technique for simultaneous multi-site deep tissue Raman measurements in the brain.

We report on the development of a multi-needle fiberoptic Raman spectroscopy (MNF-RS) technique for simultaneous multi-site deep Raman measurements in brain tissue. The multi-needle fiberoptic Raman probe is designed and fabricated using a number of 100 µm core diameter, aluminum-coated fibers under a coaxial laser excitation and Raman collection scheme, enabling simultaneous collection of deep tissue Raman spectra from a number of tissue sites. We have also developed a Raman retrieval algorithm based on the transformation matrix of each individual needle fiber probe projected to different pixels of a charge-coupled device (CCD) for recovering the tissue Raman spectra collected by each needle fiber probe, allowing simultaneous multi-channel detection by a single Raman spectrometer. High-quality tissue Raman spectra of different tissue types (e.g., muscle, fat, gray matter, and white matter in porcine brain) can be acquired in both the fingerprint (900-1800 cm-1) and high-wavenumber (2800-3300 cm-1) regions within sub-second times using the MNF-RS technique. We also demonstrate that by advancing the multi-needle fiberoptic Raman probe into deep porcine brain, tissue Raman spectra can be acquired simultaneously from different brain regions (e.g., cortex, thalamus, midbrain, and cerebellum). The significant biochemical differences across different brain tissues can also be distinguished, suggesting the promising potential of the MNF-RS technique for label-free neuroscience study at the molecular level.

Amine-functionalized reduced graphene oxide-supported silver nanoparticles for superior catalytic reduction of organic pollutants.

In this work, a simple and environmentally friendly approach has been followed to synthesize amine-functionalized reduced graphene oxide (RGO)-supported silver nanoparticle (AgNPs) having superior catalytic efficiency towards the reduction of organic pollutants. RGO/AgNPs nanohybrid was synthesized by a one-pot hydrothermal reduction of silver nitrate in the presence of amino-propyl trimethoxy silane (APTMS)-functionalized graphene oxide (GO) nanosheets. The structural and morphological characterization of as-synthesized RGO/AgNPs nanohybrid was done by using XRD, SEM, TEM, FT-IR, and Raman spectroscopy techniques. APTMS plays an important role in controlling the size of anchored AgNPs on the nanohybrid in the present study. The -NH2 groups on the surface of APTMS-modified GO function as effective and well-organized nucleation centers facilitating uniform growth of discrete and smaller-sized spherical AgNPs on the surface of RGO nanosheets. In the absence of APTMS, the nanohybrid comprised of bigger-sized AgNPs with few hundred of nanometers in dimension. The catalytic efficiency of RGO/AgNPs nanohybrid was evaluated for the reduction of two model organic pollutants: 4-nitrophenol (4-NP) and methylene blue (MB). Due to the synergistic effects of RGO, APTMS, and Ag components, RGO/AgNPs nanohybrid developed in the present study exhibited superior catalytic activity towards the reduction of 4-NP and MB in comparison with previously reported graphene/graphene oxide/reduced graphene oxide-supported AgNPs catalysts. The catalytic reduction of 4-NP and MB followed pseudo-unimolecular kinetics and the rate constants were found to be 18.83 × 10-3 s-1 and 131.5 ×10-3 s-1 respectively for 4-NP and MB. Furthermore, RGO/AgNPs nanohybrid showed admirable recyclability with negligible loss in its activity until five recycle runs. The superior catalytic activity, favorable kinetic parameters, and sustained catalytic efficiency after recycling make RGO/AgNPs nanohybrid a promising catalyst for the reduction of organic pollutants in environmental remediation.

Development of phosphotungstic acid immobilized amine-grafted graphene oxide as heterogeneous catalyst for synthesis of bis(indolyl)methane derivatives

Phosphotungstic acid was immobilized hydrothermally on the surface of 3-aminopropyltriethoxysilane-grafted graphene oxide (GO-N-PTA) and used as a heterogeneous solid acid catalyst for the synthesis of bis(indolyl)methane derivatives. X-ray diffraction (XRD), fourier transform infrared (FTIR) spectroscopy, BET isotherm, FESEM with EDS and elemental mapping, FETEM, X-Ray photoelectron spectroscopy (XPS), Raman spectroscopy techniques were used to characterize the synthesized catalyst. The catalyst was found to be highly effective for the synthesis of bis(indolyl)methane derivative compounds with yields in the ranges of 94–96.5 % under the optimized reaction conditions. The catalyst was recycled upto 3rd cycle for a specific reaction, that produced 94.5% yield with marginal loss in yield compared to the fresh catalyst (96.5%) depicting the hetreogneiety and sustainability of the present GO-N-PTA catalyst. This study provides the development of sustainable heterogeneous GO-N-PTA catalyst towards the synthesis of highly pharmaceutically important bis(indolyl)methanes derivative compounds.

Dynamic Study of Intercalation/Deintercalation of Ionic Liquids in Multilayer Graphene Using an Alternating Current Raman Spectroscopy Technique.

We report Raman spectra and infrared (IR) imaging collected during the intercalation-deintercalation half cycles in a multilayer graphene (MLG) device (∼100 layers) operating at 0.2-10 Hz. The device consists of a MLG/alumina membrane/copper stack, in which the alumina membrane is filled with ionic liquid [DEME][TFSI], forming an electrochemical cell. Upon the application of a positive voltage, the TFSI- anions intercalate into the interstitial spaces in the MLG. The incident laser light is modulated using an optical chopper wheel that is synchronized with (and delayed with respect to) a 0.2-10 Hz alternating current (AC) voltage signal. Raman spectra taken just 200 ms apart show the emergence and disappearance of the intercalated G band mode at around 1610 cm-1. By integration of over hundreds of cycles, a significant Raman signal can be obtained. The intercalation/deintercalation is also monitored with thermal imaging via voltage-induced changes in the carrier density, complex dielectric function ε(ω), and thermal emissivity of the device.

Characterization of nanocrystalline CdO prepared by solution combustion method for photocatalytic and fluorescence sensing applications

Here we report the characterization of pure CdO nanoparticles prepared by solution combustion method and annealed in air at 285, 385 and 485 °C. XRD study reveals their high crystallinity, face centred cubic (FCC) structure, and crystallite size as 43, 44 and 45 nm respectively. Cd and CdO2 impurity phases are detected in 285 and 485 °C annealed samples, while no impurity phase appeared in 385 °C annealed sample. Change in surface morphology of CdO in response of annealing treatment and typical grain-size ranging from 30 to 120 nm have been obtained from FESEM and TEM images. XPS, FTIR and Raman spectroscopy techniques provide strong evidence of the chemistry of these materials. Optical studies indicate a blue-shift in energy bandgap by ∼19, 26 and 27% for 285, 385 and 485 °C annealed samples when compared with the bulk CdO (2.2 eV). These materials when studied for the photocatalytic degradation of methyl orange (MO), methylene blue (MB) and picric acid (PA) under UV illumination and for fluorescence quenching of PA indicate that 385 °C annealed sample is the most effective towards these applications, despite increase in the optical bandgap. Degradation of MO, MB and PA, with rate constant: 31.6 × 10−3, 24.54 × 10−3 and 22.68 × 10−3 min−1 respectively, and detection of PA with limit of detection (LOD): 1.85, 1.44, and 1.64 μM for 285, 385 and 485 °C annealed samples were obtained. This work demonstrates that increase in electron degeneracy and improved crystallinity in 385 °C annealed oxygen-deficient nanostructured CdO both are contributing factors for the observed enhanced performances. To be more specific, this is possible contribution of charge carrier separation in consequence of UV light excitation that presumably occurred due to Burstein – Moss effect.

SERS study of classical and newly β-lactams-metal complexation based on in situ laser-induced coral reefs-like silver photomicroclusters: In vitro study of antibacterial activity

The influence of metal complexation of two polar β-lactam antibiotics was investigated using surface enhanced Raman spectroscopy (SERS) technique. SERS method was applied to track the structural changes and the degradation behaviour of the studied compounds upon Zinc (II) ions-complexation. In situ laser-induced coral reefs-like photomicroclusters have been utilized as a SERS platform. The produced coral reefs-like photomicroclusters were characterized using scanning electron microscopy (SEM) and transmission electron microscope (TEM). The antibacterial efficiency of the antibiotics was investigated and compared before and after metal complexation using two techniques; agar well diffusion and growth curve. To provide a detailed elucidation of the complexation reaction, mass fragmentation of metal- antibiotics complexes was investigated using liquid chromatography/mass spectrometric (LC/MS) technique. It was found that metal complexation of classical β-lactam antibiotic (Ticarcillin) promoted the rate of its degradation, leading to a decrease of the antibacterial efficiency. On the other side, the antibacterial activity of the newly developed β-lactam (Faropenem) has been greatly enhanced via metal-complexation reaction.

A new route for the fabrication of SBA-15 supported Co3O4 and its catalytic application in the epoxidation of styrene

Cobalt isonicotinate tetrahydrate has been explored as the molecular precursor for the fabrication of both the bare and SBA-15 supported Co3O4. This method appears to be effective in minimizing the formation of oxide particles outside the mesopore volumes of SBA-15. Microstructural properties of the synthesized materials have been investigated by the PXRD, SEM, TEM, H2-TPR, N2-Physisorption, and DR. UV–Visible and Raman spectroscopic techniques. The SBA-15 supported nanocomposite has shown excellent catalytic activity giving 95% conversion in the epoxidation of styrene using TBHP as the oxidant. Deposition of trace amount of gold significantly enhances the epoxide selectivity of the catalysts up to 85%. The catalysts have shown excellent reusability.

In-situ redox conditions in hydrothermal diamond-anvil cell experiments using various metal gaskets

Hydrothermal diamond-anvil cells (HDACs) have been widely used in various research fields since they were introduced in 1993. Unlike temperature (T) and pressure (P), the redox states of the samples in HDAC experiments were poorly controlled or measured; they were usually estimated by observing the reduction/disappearance of redox-sensitive mineral(s) (e.g., Mo metal) and corresponding formation and growth of such mineral(s) (e.g., MoO2) without in-situ redox measurement. In this study, we demonstrated the generation of H2 during experiments using various metal gaskets, including inert (Re) and chemically more reactive metals (Ni, Co, Mo, and W), in the pure H2O system under various P-T conditions. A technique for quantitative Raman spectroscopic analysis of H2 in HDAC is designed. Based on this technique, the oxygen fugacity (fO2) values of Mo-MoO2 buffer at the experimental P-T conditions were then calculated from these measured H2 pressures. We demonstrated that steady-state redox control can be maintained at a fixed T between 400 and 500 °C in HDAC experiments using a Mo gasket for durations of up to two hours and for those using a Re gasket with an additional Mo rod in the sample between 400 and 800 °C for durations of up to 90 min, regardless of the considerable changes in sample pressure. This demonstration was established by the balance between the rates of H2 generation and H2 loss from the sample chamber. The loss of H2 enhanced the consumption of H2O and therefore reduced the sample pressures during the experiments.We believe that hydrogen contents in every HDAC experiment, which attempt to control the redox state, need in situ measurement, then estimate the real redox state and compare it to thermodynamic equilibrium prediction. To enhance in situ redox control and measurements, modifications of HDAC are required for improving the quantitative Raman spectroscopic analysis technique in both sensitivity and accuracy.

Characterization and discrimination of some gem silicate minerals adopting LIBS, FTIR, and Raman spectroscopic techniques

In this paper, characterization and discrimination of some silicate gems (gemstones and low-gem quality varieties) from ancient Egyptian mines have been performed for the first time adopting molecular and elemental spectroscopic techniques. The selected gem groups are peridot, beryl/emerald, amazonite, and amethyst. In this sense, characterization of the genuine Egyptian gems and the importance of mineralogical and chemical signatures in a historical context as well as the scope of geoheritage can be achieved for the first time. Laser induced breakdown spectroscopy (LIBS) analysis has been found to be an effective method for the discrimination among different gems groups where a characterizing element for each group in a specific spectral window has been found. Raman and Fourier transform infrared (FTIR) spectroscopy spectra have proven to be fingerprints with the ability to distinguish future alteration of the gemstone depending on the molecular vibrational spectroscopy. FTIR provides the functional group that can absorb the infrared radiation and be responsible for the coloring of the gemstones.

Micelles self-degraded template based 2D graphitic carbon nitride-polypyrrole nanotube composite electrode for high supercapacitor performance

In this present work, Graphitic Carbon Nitride (gCN) is synthesized via simple pyrolysis method. The Graphitic Carbon Nitride-Polypyrrole nanotubes composite (gCNPNT) was prepared through micelles self-degraded template method by altering the amount of gCN. The structural, chemical, and morphology of the composite were characterized by X-Ray Diffraction, Fourier transform infrared spectra (FT-IR), Raman spectroscopy, and Field emission scanning electron microscopy (FESEM) techniques. Thermal stability was examined by thermal gravimetric analysis (TGA). The Electrochemical analysis of the Galvano charging-discharging (GCD) curves was achieved a high specific capacitance (Csp) of 514.28 F g−1 at a current density (CD) of 1.2 A g−1. The cyclic voltammetry (CV) curve for the gCNPNT electrode shows pseudocapacitive behavior with effective reduction and oxidation rate and exhibits a high Csp of 325 F g−1 at scan rate of 10 mV s−1. These results demonstrate gCNPNT-2 is a prominent candidate in energy and conversion device applications.