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Abstract In recent years, there has been a surge in interest in developing new polymeric materials with high performance and low cost. With increased environmental awareness, research has focused on eco-friendly materials, with terms like “renewable,” “recyclable,” “sustainable,” and “biodegradable” becoming important features of the materials, Polymer blends can provide products with a wider range of useful qualities than single polymer equivalents. In this study, Polymer blend films were prepared using dextrin at different compositions of (PVA- PMMA-PAAm) by solvent casting method. The prepared blend films were flexible and transparent and characterized using was examined by scanning electron microscopy to examine the surface morphology of the samples that show the good distribution of starch in the blend, while FT-IR was used to identify the active groups, which refer to the interaction among the materials. Also, we have studied the optical properties and recording the absorption spectrum with a visible ultraviolet spectrophotometer. Absorption spectra were recorded in the wavelength range of 200–1100 nm. The absorbance and optical conductivity were increased by dextrin additive, while the transmittance and energy gap decreased. Based on the overall results, the prepared films can be used in drug delivery and optical devices.

A new NLO crystal of L-Arginine doped with potassium iodide were harvested from solution growth technique with slow evaporation method. Powder X-ray diffraction analysis exposes the structure. Presence of vibration functional groups in the grown crystal was confirmed by FTIR spectroscopy. Using the spectrum of UV–Vis-NIR the optical transmission and absorption spectra were studied. TGA-DSC studies reveal the decomposition and thermal stabilities of the grown crystals. Kurtz Perry Powder technique determines the second harmonic generation NLO behavior.

The effect of Dysprosium concentration has been studied in glasses of the system 30 SiO2 + 30 Li2O + (40−x) B2O3 + x Dy2O3 glass system where x = 0.5, 1, 2.5, 5 and 10 mol%. FT-IR studies were performed to understand the functional groups of the network involved in the host glass. The optical band gap is found in the range of 3.84–3.5 eV. From the absorption spectra, the experimental data were compared with the theoretical data computed by Judd–Ofelt theory. Nephelauxetic ratio (β) and bonding parameters (δ) computed using the absorption spectrum. The Judd–Ofelt parameters (Ω2, Ω4, and Ω6) obtained demonstrates the covalent and asymmetric nature of dysprosium ions. From the visible emission spectra, the intensity ratios were calculated from yellow to blue and the relative differences were discussed based on the concentration of Dy3+ ions. CIE chromaticity coordinates were calculated for all glass samples. A CIE chromatogram shows a glass containing 0.5 mol% Dy2O3 with color coordinates X = 0.32 and Y = 0.33 with the highest emission intensity. These glasses have great potentials for lasers and white LEDs (Light-Emitting Diode) applications.

The obtaining of monocrystalline TiO2 nanofibers with high specific surface area synthesized by the electrospinning technique with controlled crystalline structure and morphology is reported. The nanofibers were annealed at 500, 700 and 900 °C in a controlled atmosphere in the presence of air for two hours to achieve crystalline phase transformation. By means of TEM, it was possible to clearly corroborate the presence of solid nanofibers with a well-defined shape, a smooth surface and without the presence of interconnections and defects called beads. The chemical stoichiometry of electrospun TiO2 nanofibers was estimated by EDS, finding that at low annealing temperatures excess of oxygen was detected and at high temperatures excess of titanium that originates oxygen vacancies. By Raman scattering was found that the TiO2 nanofibers showed a crystalline phase transformation from pure anatase, mixed anatase-rutile and pure rutile as the annealing temperature is increased, caused by the generation of oxygen vacancies, which was corroborated by X-ray diffraction. The band gap energy (Eg), obtained from optical absorption spectra, decreases as the temperature is increased, which is ranged in 2.42 ≤ Eg ≤ 3.27 eV, caused by the anatase→rutile crystalline phase transformation. Photoluminescence shows that the radiative bands -present a gradual red shift as the temperature increases due to the Eg reduction. In addition, the photocatalytic properties of the annealed TiO2 nanofibers were evaluated in the decolouration of the Remazol Black B azo dye. Changes in absorption spectra were noticeable as the measurement time increases. Absorbance spectra showed a decrease in the intensity of the main absorption band at 589 nm, which gradually decreases until it completely disappears, indicating that the decomposition of the organic compound is complete, while physically there is an absence of color from the solution. The anatase crystalline phase was the one with the highest specific surface area and the highest photocatalytic activity.

Owing to the unique electromagnetic response ability, artificial electromagnetic metasurfaces have potential applications in medical, imaging, sensing, and other fields. In this paper, a novel composite THz metasurface integrated by carbon nanotubes (CNTs) resonant metasurface and silicon microfluidic channel has been proposed, which combines the advantages of semiconductor and carbon nanotubes film materials. The absorption characteristics and the refractive index sensing capabilities are investigated comprehensively. Calculation results show that two obvious resonant absorption peaks located at 1.20 THz and 1.85 THz and the absorption is nearly 99.6% and 89.8%, respectively; the device performs a good linear relationship between the position of resonant absorption peaks and the refractive index, and the frequency sensitivity can achieve 492 GHz/RIU. The influence of structural parameters and the offset of the center of the CNTs metasurface on the absorption spectrum demonstrate that the novel composite metasurface has a good reliability and stability and can be used for sensing various materials in other frequency regions range from radio frequency through THz and to the infrared regime. This novel composite metasurface has good biocompatibility and low cost, which widens the application range of terahertz functional devices.

Two Bi–Mo–Co–Fe–O catalysts were synthesized by flame spray pyrolysis and tested for their catalytic performance in selective oxidation of propylene to acrolein. Pronounced structural changes during temperature–programmed oxidation and reaction were observed by operando X–ray absorption spectroscopy, X–ray diffraction, Raman spectroscopy, and thermogravimetric analysis. During oxidative treatment, mainly binary oxide phases (α–Bi$^{2}$Mo$^{3}$O$^{12}$, β–CoMoO$^{4}$, Fe$^{2}$ (MoO$^{4}$)$^{3}$) were observed, but single (MoO$^{3}$) or ternary (Bi$^{3}$ (FeO$^{4}$)(MoO$^{4}$)$^{2}$) oxides also formed depending on the relative elemental catalyst composition. During propylene oxidation, the reduction of Fe$^{3+}$ to Fe$^{2+}$ led to a strong rise in activity and induced further phase transformations. MoO$^{3}$ was found to be unselective towards acrolein but was essential in binding other single oxides. The formation of β–Co$^{0.7}$Fe$^{0.3}$MoO$^{4}$ and Bi$^{3}$ (FeO$^{4}$)(MoO$^{4}$)$^{2}$ as well as their synergistic interplay with α–Bi$^{2}$Mo$^{3}$O$^{12}$ are key factors for high performance. The combination of complementary operando methods was crucial to reveal new structure–activity/selectivity correlations, therefore bridging the knowledge gap between simplified model systems and complex applied catalysts.

The efficacy of treatment with hydrogen and Ag-Cu co-deposition on TiO2 photocatalysts has been investigated computationally and experimentally. The hydrogenated Ag-Cu with co-loaded TiO2 (H:(Ag-Cu/TiO2)) achieved a photoactivity about 110 times that of pristine TiO2, which corresponds to a rate of 1.16 mmol h−1 g−1 for hydrogen generation. Soft X-ray spectra and quantum-chemical calculations indicate that the notable promotion of photoactivity on H:(Ag-Cu/TiO2) is ascribable to the synergy between new electronic states and a lattice distortion. The soft X-ray absorption spectra (XAS) indicated that the TiO6 octahedral symmetry and the Ti 3d- orbital orientation are significantly affected by the Ag-Cu decoration and the hydrogenation treatment. The mechanisms involved in this photocatalysis were studied with soft XAS in situ, which showed that the photoexcited electrons transfer from the bimetallic Ag-Cu to the TiO2 conduction band as the photoresponse of this composite photocatalyst. The strategy of coupling hydrogenation with bimetallic Ag-Cu onto TiO2-based photocatalysis provides a facile and promising solution to other environmental and energy applications.

Electrochemistry and X-ray absorption spectroscopy (XAS) of MnO2/reduced graphene oxide (RGO) were made to evaluate capacitive performance and electronic structure as a supercapacitor. MnO2 was deposited on the surface of RGO by a spontaneous redox reaction. At low current density (1 A g−1), the specific capacitance of MnO2/RGO (MRGO) greatly increased with increasing growth time from 281 to 462 F g−1. Electrochemical results show that the specific capacitance of RGO and MRGO arises from the combined contributions of electrochemical double-layer capacitance (EDLC) and pseudo-capacitance. To gain insights into the charge storage mechanism of RGO and MRGO, it was characterized using ex-situ soft XAS techniques at Mn L-edge and C, O K-edges in the charging/discharging process. The ex-situ soft XAS results provide evidence that the contribution of RGO to specific capacitance involves an oxygen-functionality-related contribution of pseudocapacitance and EDLC. In addition, the specific capacitance of MRGO reveals pseudocapacitive contributions from the redox processes that involve the Mn(III)/Mn(IV) redox reaction in MnO2. This work utilizes electrochemical and ex-situ XAS techniques to elucidate charge storage mechanism for supercapacitor applications.

3 at.% Er3+, x at.% Ho3+: SrF2 (x = 0, 0.05, 0.1, 0.5, 1, 2) transparent ceramics, as the potential material for the 2.7 μm solid-state laser, were fabricated by hot-pressed sintering. XRD, TEM, SEM, and EDS measurements were used to investigate the phase composition, morphology, microstructure, and distribution of the elements of the nanoparticles and transparent ceramics. Results showed that the Er3+ ions and Ho3+ ions do not alter the SrF2 crystal structure, and they are distributed uniformly in the sample. With the increase of the Ho3+ doping concentration, the lattice parameter decreased from 5.799 A to 5.784 A, and the average grain size decreased gradually. The maximum transmittance of as-obtained ceramics is approximately 93 % which is close to the theoretical transmittance of SrF2. Moreover, the absorption spectra, emission spectra, and the lifetime of Er3+ and Ho3+ were investigated. The energy transfer processes between Er3+ and Ho3+ were discussed. After co-doping Ho3+, the lifetime difference between Er3+:4I11/2 and Er3+:4I13/2 levels was shortened from 8.50 ms to 1.12 ms. All the results show that the incorporation of Ho3+ with proper doping concentration is beneficial for achieving 2.7 μm laser output in Er3+: SrF2 transparent ceramics.

In the present communication, pure and stable α-Bismuth Oxide (Bi2O3) nanoparticles (NPs) were synthesized by low temperature solution combustion method using urea as a fuel and calcined at 500oC. The synthesized sample was characterized by using powder X-ray Diffraction (PXRD), Scanning Electron Microscopy (SEM), Energy dispersive X-ray analysis (EDAX), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and UV–Visible absorption spectroscopy. The PXRD pattern confirms the formation of mono-clinic, stable and low temperature phase α-Bi2O3. The direct optical energy band gap was estimated by using Wood and Tauc's relation which was found to be 2.81 eV. The characterized sample was studied for X-ray/gamma ray shielding properties in the energy range 0.081–1.332 MeV using NaI (Tl) detector and multi channel analyzer (MCA). The measured shielding parameters agrees well with the theory, whereas, slight deviation up to 20% is observed below 356 keV. This deviation is mainly due to the influence of atomic size of the target medium. Furthermore an accurate theory is necessary to explain the interaction of X-ray/gamma ray with the NPs.The present work opens new window to use this facile, economical, efficient, low temperature method to synthesize nanomaterials for X-ray/gamma ray shielding purpose.

The synthesis of silver doped cobalt oxide nanoparticles by microwave-assisted method and their structural, optical, antibacterial activities are presented in this study. The doping concentrations were chosen as 5, 10, 15, and 20 wt percentages. The sample was undergone powder X-ray diffraction studies and the result shows the good crystalline nature of the sample. Also, the average crystallite size increases from 13.95 nm, 21.26 nm, 26.13 nm, and 28.35 nm with different doping concentrations. The transmission electron microscopy image shows cubic and spherical morphology. The optical properties were tested by UV–vis–NIR absorption spectrum. It indicates the decrease of band gap value. From the antibacterial activity studies, the 20 wt % Ag doped nanoparticles exhibit better activity.

Energetic materials have extremely high volumetric and specific energy densities, making them attractive and important in combustion systems. To improve their combustion performance, reliable temperature acquirement method is highly demanded. A laser sensor was developed for in situ and quantitative measurements of gas temperature. Scanned-wavelength direct absorption spectroscopy was used for line-of-sight temperature measurements. Multiple absorption features in the near-infrared combination band (v1+v3) and mid-infrared fundamental band (v3) were selected to establish four absorption line pairs with good temperature sensitivity. Three infrared distributed feedback lasers (DFB) were used to cover the selected absorption lines. The accuracy and uncertainty of the sensor were first numerically evaluated in a wide temperature range of 1000–3000 K under different Gaussian white noise levels (5–20%). A free-space optical setup was established to experimentally evaluate the sensor performance by measuring benchmark laminar premixed flames, which were compared with additional thermocouple measurements, chemical kinetic modeling and computational fluid dynamics simulations. The good performance of the current sensor indicates the potential of being used in non-intrusive, in-situ and quantitative diagnostics of the energetic materials combustion.

In this paper, polymer composite (PC) film based on Methylcellulose (MC) has been prepared by solution cast technique and its optical bandgap was discussed in detail. X-ray diffraction (XRD) method , UV–Vis absorption spectroscopy and Fourier transforms infrared spectroscopy (FTIR) technique were used to study the effect of different concentrations of copper chloride (CuCl2) salt on the structural and optical properties of the MC polymer. Scanning electron microscopy (FESEM) is used to examine the effect of CuCl2 on films morphology. The fundamental optical parameters, such as optical energy gap (Eg), optical dielectric constant (er) and dielectric loss (ei) have been measured in which the amount of CuCl2 has significant effectiveness. Tauc’s relation was used to specifying the direct and indirect bandgap energy. The Eg of pure MC was considerably reduced from 6.21 to 2.68 eV by the addition of 20 wt% of CuCl2 salts. To specify the optical transition type, the exponent value of Tauc's law (γ) was identified by using the plot of ei against photon energy (hυ) to estimate the Eg value and specify the electronic transition type. For the composite samples, the Urbach energy (E0) increased, which can be evidence for a large possible number of tail-to-tail transitions. There is an increasing the refractive index (n) from 1.44 for pure MC to 2.04 upon the addition of 20wt.%CuCl2, indicating the occurrence of interaction between electrons and photons.

Na0.5(Bi3/4RE1/4)0.5TiO3 (RENBT, RE = Nd, Gd, Dy, and Ho) compounds were investigated in the framework of first-principles calculations using the full potential linearized augmented plane wave (FP-LAPW) method based on the spin-polarized density functional theory implemented in the WIEN2k code. Combined charge density distribution and Ti K-edge X-ray absorption spectra revealed that the RENBT compositions with high polarization values were accompanied by a higher TiO6 distortion, DyNBT, and NdNBT compounds. The effect of the rare-earth elements on the polarization were confirmed experimentally with the collection of the hysteresis loops. The investigation of the electronic properties of the compounds highlighted the emergence of a magnetization owing to the 4f orbital effect of the rare-earth elements. Besides, the investigation of the chemical ordering showed a short-range chemical ordering for the pure composition and an increased A-site disorder for dysprosium doped NBT system. The increased disorder may speak for increased relaxor properties in the RE doped compositions.

The effect of an alumina-based binder on the structure of a commercial Fe-ZSM-5 catalyst has been investigated. Several ex-situ characterization techniques were used to show that the binder in the catalyst formulation allows obtaining a material that possesses improved features in terms of Fe species dispersion, framework Al content and acidity. UV–Vis and X-ray absorption spectroscopy showed that the extent of Fe agglomeration in the extruded catalyst was significantly lower compared to that in the catalyst without binder. 27Al and 29Si-MAS NMR spectroscopy demonstrated a remarkable difference in terms of framework Al migration. NH3-TPD experiments corroborated the NMR results suggesting a retention of Bronsted acidity in the extruded catalyst. We tentatively propose that by providing extra-framework Al species prior to the treatment at elevated temperature, the binder hinders the framework Al dislodgment and Fe agglomeration during calcination.

Selenium X-ray absorption spectroscopy (XAS) has found widespread use in investigations of Se-containing materials, geochemical processes, and biologically active sites. In contrast to sulfur K beta X-ray emission spectroscopy (XES), which has been found to contain electronic and structural information complementary to S XAS, Se K beta XES remains comparatively underexplored. Herein, we present the first Se Valence-to-Core (VtC) XES studies of reduced Se-containing compounds and FeSe dimers. Se VtC XES is found to be sensitive to changes in covalent Se bonding interactions (Se-Se/Se-C/Se-H bonding) while being relatively insensitive to changes in Fe oxidation states as selenide bridges in FeSe dimers ([Fe2Se2](2+) vs [Fe2Se2](+)). In contrast, Se K beta HERFD XAS is demonstrated to be quite sensitive to changes in the Fe oxidation state with Se K beta HERFD XAS demonstrating experimental resolution equivalent to K alpha HERFD XAS. Additionally, computational studies reveal both Se VtC XES and XAS to be sensitive to selenium protonation in FeSe complexes.

Scanned-direct absorption spectroscopy was implemented to improve sensing capabilities in the mixing volume (MV) of the 60 MW Interaction Heating Facility (IHF) at NASA Ames Research Center. The IH...

By virtue of the crucial effect of the crystal structure and transition metal (TM) redox evolution on the performance of LiNixCoyMnzO2 (NCM) cathode, systematical investigation is carried out to better understand the charge mechanism upon deep charging. Based on the results of X-ray diffraction and high-resolution transmission electron microscope, phase transformations existing on particle surface are promoted by high potential because of the deeper lithium vacancies, accompanied by more substantial structure instability. Soft X-ray absorption spectroscopy indicates that Ni acts as the major contributor to charge compensation while Co displays a remarkable redox activity over the deep charge range. The elevated integrated intensity of pre-edge in O K-edge spectra reveals the extensive amount of holes formed in O 2p orbitals and the enhanced hybridization of TM 3d - O 2p orbitals. Considering the close relationship between thermal behavior and structural evolution, the tendency of phase transitions and O2 release upon heating is accelerated by voltage rise, demonstrating the aggravated instability due to deeper Li utilization. Remaining Li contents in NCM are employed to estimate the amount of oxygen released in structural transformation and its detrimental effect on stability declares Li content-dependent characteristics. Furthermore, the extended Li vacancies, higher proportion of Ni4+ and stronger orbital hybridization are considered as three factors impeding the thermal stability of the highly-delithiated NCM.

Perovskite LaCoO3 is being increasingly explored as an effective low-cost electrocatalyst for the oxygen evolution reaction (OER). Sr doping in LaCoO3 (La1−xSrxCoO3) has been found to substantially increase its catalytic activity. In this work, we report a detailed study on the evolution of the electronic structure of La1−xSrxCoO3 with 0 ≤ x ≤ 1 and its correlation with electrocatalytic activity for the OER. A combination of X-ray photoemission spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) was used to unravel the electronic density of states (DOS) near the Fermi level (EF), which provide insights into the key electronic structure features for the enhanced OER catalytic activity. Detailed analysis on the Co L-edge XAS suggest that LaCoO3 has a low spin state with t2g6eg0 configuration at room temperature. This implies that the high OER catalytic activity of LaCoO3 should not be rationalized by the occupancy of eg = 1 descriptor. Substituting Sr2+ for La3+ in LaCoO3 induces Co4+ oxidation states and effectively dopes hole states into the top of valence band. A semiconductor-to-metal transition is observed for × ≥ 0.2, due to the hole-induced electronic DOS at the EF and increased hybridization between Co 3d and O 2p. Such an electronic modulation enhances the surface adsorption of the *OH intermediate and reduces the energy barrier for interfacial charge transfer, thus improving the OER catalytic activity in La1−xSrxCoO3. In addition, we found that the La1−xSrxCoO3 surface undergoes amorphization after certain period of OER measurement, leading to a partial deactivation of the electrocatalyst. High Sr doping levels accelerated the amorphization process.

Doping alkali metal atoms, especially lithium (Li), in nanocarbon materials has always been considered to be one of the most effective methods to improve the optical properties of the system. In this theoretical work, we doped a Li atom to the recently observed all-carboatomic molecule, cyclo[18]carbon (C18), and finally obtained two stable configurations with Li inside and outside the ring. The calculation results show that the energy barrier of transition between the two Li@C18 configurations is low, so the conversion is easy to occur at ambient temperature. Further study reveals that the state of Li@C18 complex, namely its dominant configuration, can be switched by applying a proper external electric field (EEF). The electronic structure, absorption spectrum, and optical nonlinearity of the two configurations are found to be significantly different, which indicates that the optical properties of the Li@C18 complex can be effectively regulated by switching the location of doped Li atom between inside and outside the carbon ring. With the help of various wavefunction analysis methods, the nature of the discrepancies in the properties of Li@C18 complex with different configurations was deeply revealed. The relevant results are expected to provide theoretical guidance for development of cyclocarbon-based optical molecular switches.

Due to the characteristic emission of phosphors, phosphor-converted LEDs have been employed to provide the requisite light sources for indoor plant growth in the optical agricultural industry. Herein, we prepared a series of Mn2+ co-doped NaSrB5O9:Dy3+ phosphors via a solid-state reaction method. These phosphors have significant three-band emissions at 467 nm (blue region), 606 nm (orange region), and 765 nm (far-red region), ascribed to the 4F9/2-6H15/2 and 4F9/2-6H13/2 transitions of the Dy3+ ions and the 4T1g(G)-6A1g(S) spin-forbidden transition of the Mn2+ ions, respectively, when excited by light of 376 nm (near-UV region). The co-dopant in the host material facilitates tunable photoluminescence (PL) due to energy transfer from the Dy3+ ions to the Mn2+ ions. The three emission peaks from the prepared phosphors well match with the absorption spectra of the photosynthesis pigments of plants, chlorophyll and phytochrome, which can absorb blue (400–500 nm), orange-red (550–700 nm), and infrared (IR) radiation, indicating that these phosphors have potential applications in the fabrication of plant-growth LEDs. Prior to the PL studies, the structure of the phosphors was determined by X-ray diffraction, refined by Rietveld method and chemically quantified by X-ray photoelectron spectroscopy.

Herein, we investigate silicate-phosphate glasses from the SiO2–P2O5–K2O–MgO–SO3 system enriched with various amounts of sulfur, as a nutrient indispensable for the proper development of plants, in order to gain a profound understanding of the structure of such materials. An inherent capability of glasses from the studied system to incorporate sulfate groups into the vitreous matrix was discussed on the basics of the results from XRF, XRD and internal Al2O3 standard techniques. It has been found, that as much as 3 mol.% of SO3 can be loaded into the glass batches to obtain fully amorphous material, while beyond this limit K2SO4 crystallizes within the matrix. Comprehensive spectroscopic investigation, comprising Raman, Middle Infrared (MIR), 29Si and 31P MAS-NMR, X-ray absorption spectroscopy (XANES and XAS) techniques, has been implemented in order to determine an impact of sulfur on silicate-phosphate glass framework. On this basics, it has been concluded, that sulfur exists in the vitreous matrix in the form of specific domains, in which [SO4]2- anions are surrounded by the shell of charge-compensating K+ cations. Such sulfate groupings maintain their individuality without direct bonding to silico-oxygen or phospho-oxygen subnetwork. Spectroscopic results revealed also, that the presence of sulfur affects silico-oxygen subnetwork to a significantly greater extent than the phospho-oxygen one. It has been demonstrated, that along with SO3 addition, the more polymerized Q S i 3 units increase in abundance at the expense of less polymerized Q S i 2 groups. Results of the present study are believed to contribute to a greater understanding of the nature of sulfur-bearing oxide glasses.

In this study, we report room temperature positive magneto capacitance due to Ti+4 and Mn+3 valence states interactions in La0.7Pb0.3Mn0.4Ti0.6O3+δ (δ = 0.15) i.e. La0.66Pb0.3Mn0.4Ti0.56O3 and negative magneto capacitance due to Fe+3 and Mn+4 valance states interactions in Fe doped composition La0.7Pb0.3Mn0.4Fe0.6O3. Rietveld analysis shows similar structural properties of Fe and Ti doped compositions. Synchrotron X-ray absorption spectroscopy (XAS) studies show (i) the presence of Ti+4, Mn+3 and Mn+4 in La0.66Pb0.3Mn0.4Ti0.56O3 and (ii) Fe+3, Mn+3 and Mn+4 in La0.7Pb0.3Mn0.4Fe0.6O3. At room temperature, Fe doped composition shows nearly three times more magnetic moment in comparison to the magnetic moment of Ti doped composition. La0.7Pb0.3Mn0.4Fe0.6O3 composition shows maximum ∼64% negative magneto capacitance while La0.66Pb0.3Mn0.4Ti0.56O3 shows maximum ∼ 12% positive magneto capacitance. Size, quantity, number of d electrons and type of interactions among the valence states Fe+3 (0.645 A), Ti+4 (0.605 A), Mn+3 (0.645 A), Mn+4 (0.53 A) affect the electronic, magnetic and magnetoelectric properties of La0.66Pb0.3Mn0.4Ti0.56O3 and La0.7Pb0.3Mn0.4Fe0.6O3 manganites.

In this work, hierarchical NiS@ZnIn2S4 heterostructure was developed by constructing ultra-thin ZnIn2S4 (ZIS) nanosheets on hollow NiS nanospheres for hydrogen production from photocatalytic water splitting. The NiS@ZIS displayed a strong optical absorption ability in the visible region and a high specific surface area of 33.14 m2/g. The Type-I band alignment in NiS@ZIS heterostructure was determined by the combination of UV–vis absorption spectroscopy and Mott-Schottky curves. The photocatalytic hydrogen production of NiS@ZIS (1.24 mmol g−1 h−1) was nearly 5.6 times higher than that of ZIS under visible light, in the absence of any co-catalyst and sacrificial agent. The separation and migration of charge in NiS@ZIS were characterized by a series of spectroscopy and photo/electrochemical tests, which verified the efficient charge transfer from ZIS to NiS.

Hypothesis Due to the intrinsic nature of the surface-enhanced Raman scattering (SERS), the detection of molecules with weak binding affinities toward metal substrates is critical for development of a universal SERS sensing platform. We hypothesized the physical trapping of small pesticide molecules for active hot spot generation using tyramine-mediated crosslinking chemistry and silver nanoparticles (Ag NPs) enhances SERS detection sensitivity. Experiments Tyramine-mediated crosslinking chemistry for sensor application was validated by ultraviolet–visible absorption spectroscopy, scanning electron microscopy, dynamic light scattering, and Raman spectroscopy. SERS sensing platform using tyramine-mediated crosslinking reaction was systematically studied for detection of 1,4-dyethylnylbenzene as a model analyte. This sensor system was applied to detect two other pesticides, thiabendazole and 1,2,3,5-tetrachlorobenzene, which have different binding affinities toward metal surfaces. Findings The SERS signal of 1,4-dyethylnylbenzene obtained using this sensor system was 3.6 times stronger than that obtained using the Ag colloidal due to the nanogap of approximately 1.3 nm within the generated hot spots. This sensor system based on tyramine-mediated crosslinked Ag NPs was evaluated as a promising tool to achieve a solution based sensitive detection of various pesticide molecules that cannot be adsorbed on the surfaces of typical SERS substrates such as metal nanoparticles.

CaWO4:xEu3+,yTm3+ crystals were obtained by facile synthesis at low temperature by the microwave-assisted hydrothermal method (MAH). The phase formation, morphology, luminescent properties and energy transfer were investigated. The X-ray diffraction (XRD) results show the formation of a scheelite-like tetragonal structure without the presence of secondary phases. The growth mechanism of hierarchical microstructures based on self-assembly and Ostwald-ripening processes was evaluated, obtaining different types of morphologies. The luminescence spectra of CaWO4:Eu3+,Tm3+ at 325 nm excitation show the predominance of red emission at the 5D0 → 7F2 (Eu3+) transition at 624 nm. This feature signals dominant behavior of the electric dipole type. The presence of Tm3+ is notably evident in the absorption spectra by the related excitation transitions: 3H6 → 1G4, 3H6 → 3F3 and 3H6 → 3H4. Color parameters are discussed to characterize CaWO4:Eu3+,Tm3+ emission. The study of the emission spectrum as a function of the concentration of Eu3+ (x mol%) and Tm3+ (y mol%) indicates that the CaWO4:Eu3+,Tm3+ phosphors show stronger red emission intensity and exhibit the CIE value of x = 0.63 and y = 0.35. The photoluminescence results show 97% high color purity for CaWO4:4 mol%Eu3+, a high CRI (92%) and a low CCT of 1085 K. These results demonstrate that the CaWO4:Eu3+,Tm3+ red phosphors are promising as color converters for application in white light-emitting diodes and display devices.

Green synthesis using soluble starch as stabilizing agent in aqueous medium is an approach towards to develop an eco friendly method for synthesis of nanoparticles. It has advantages over conventional method involving toxic reagents. Cadmium sulfide is a suitable material among the II-VI compounds for optoelectronic and solar applications. We report a study on the optical properties of CdS nanocrystals prepared by green synthesis method. Cadmium sulfide nanoparticles were prepared using starch as stabilizing agent. The sample was characterized by X-ray diffraction, Scanning electron microscope, UV–Visible absorption spectroscopy, and photoluminescence spectroscopy. From the study, the blue shift in absorption wavelength with respect to bulk CdS indicate the increased in effective energy band gap and formation of nano sized CdS particles. The estimated size confirms the weak confinement regime as the size comparable to exciton Bohr radius. Photoluminescence spectrum shows band edge emission and deep trap states emission. The CdS nanoparticles exhibit photo catalytic activity against methyl orange under visible light irradiation. The 75% photo degradation was observed for 90 min irradiation time.

Dye-sensitized solar cells (DSSCs) which also called Gratzel cells are a novel type of solar cells. Their advantages are mainly due to low cost production, low energy payback time, flexibility, performance also at diffuse light and multicolor options. DSSCs become more and more interesting since huge variety of dyes including natural dyes can be used as light harvesting elements. Natural dyes are environmentally and economically superior to synthetic-based dyes because these are nontoxic and cheap. Different natural dyes and their mixture extracts have been prepared and used as sensitizers in the fabrication of dye-sensitized solar cells (DSSCs). The dyes have been extracted from plant leaves including lemon, parsley, spinach, hibiscus-rosa sinensis, pomegranate fruit and vegetable beetroot. This article showed the effect of single and mixture natural dyes on the DSSC performance. The single dyes extracted from parsley, lemon and spinach leaves chlorophyll and hibiscus-rosa sinensis, pomegranate juice anthocyanin and beetroot betalain. The dyes mixture was prepared by mixing from both chlorophyll & anthocyanin and chlorophyll & betalain. The absorption spectra of these dyes have been investigated by UV–VIS spectrophotometry. The dyes have shown absorption in broad range of the visible region (400–700 nm) of the solar spectrum and appreciable adsorption onto the semiconductor (TiO2) surface. The adsorption of the dyes mixture onto the TiO2 electrode has higher absorbance than single dye and improved the conversion efficiency of solar cell.

Doping of isovalent (S, Se, and Te) elements in ZnO is a new doping method. However, the factors affecting the photocatalytic performance of a doped system by triaxial strain are often ignored. In this study, we have applied strain on model and performed first-principle calculation to investigate the effect of triaxial strain on the stability of the doped system, red shift of the absorption spectrum, electric dipole moment, and carrier lifetime. Calculation results showed that all doped systems exhibited high binding energy and stability under unstrained conditions. However, when the applied strain was increased, the energy of all the systems increased, and the stability decreased. The stability, red shift of absorption spectrum, electric dipole moment, and carrier lifetime of all doped systems were studied. When the tensile strain was 5%, the red shift of the absorption spectrum and the electric dipole moment of the doped system (Zn36SO35) were the largest. Moreover, the carrier lifetime of the doped system (Zn36SO35) was the longest. Considering the red shift of the absorption spectrum, electric dipole moment, and carrier lifetime, the photocatalytic performance of the doped system (Zn36SO35) was the best, when the tensile strain was 5%.

Good-quality single crystals of 2- Amino-5-methylpyridinium phosphate (2A5MPP) have been grown by slow evaporation technique. The cell parameters of the grown crystals were studied and the crystal belongs to monoclinic structure with the space group P21/n. FTIR spectral analyses were carried out in order to determine the functional groups. The UV–visible absorption spectra were recorded for the grown crystal. The nonlinear refractive index and third order susceptibility values of 2A5MPP crystal are estimated using a Z-scan technique.

Controlling the transmission of thin films with external stimuli is an important goal in functional optical materials and devices. Tuning is especially challenging where both broad band (neutral density filtering) and spectrally varied (colour) transmission are required. The external control provided by photochemically driven switching, between transmission levels and colours, is functionally simple from a device perspective. The limits due to the spectral ranges of individual photochromic compounds can be overcome by combining several photochromes within one material or device. Here we show that a combination of photochromic molecular switches immobilised in a PMMA polymer matrix enables tuning of colour and transparency. We show that only a single excitation wavelength is required through the use of the primary inner filter effect and the layered construction of the films in which the photochromes nitrospiropyran (NSP), and nitrothiospiropyran (TSP) or 1,2-bis-terthienyl-hexafluorocyclopentene (DTE) are separated spatially. The approach taken circumvents the need to match photochemical quantum yields and thermal reactivity of the component photochromes. The photochemical switching of the films was characterised by UV/vis absorption spectroscopy and shows that switching rates and photostationary states are limited by inner filter effects rather than the intrinsic properties of photochromes, such as photochemical quantum yields and thermal stability. The photochemical behaviour and stability of the photochromes in solution and in the PMMA films were compared and the concentration range over which self-inhibition of photochemical switching occurs was established. The rate of photochemical switching and the difference in transmission between the spiropyran and merocyanine forms in solution enable prediction of the performance in the films and enable rational design of colour tuning ranges and responsivity in thin film filters., A multilayer coating, with a different photochrome in each layer, enables predictable control over transmission and colour with a single wavelength of light, which is an important goal in functional optical materials and devices.

A porous 3D multifunctional Zn-MOF (1), namely {[Zn2.5(DDPP)(OH)(H2O)]•H2O•1.5DMF}n (H4DDPP = 3,5-di(2',5'-dicarboxylphenyl)pyridine, DMF = N,N-dimethylformamide) was solvothermally synthesized by the reaction of H4DDPP ligand and Zinc salts. 1 exhibits a high adsorption performance for N2 (246.2 cm3 g-1 at 77 K) and CO2 (116.1 cm3 g-1 at 273 K) as well as excellent selective separation for CO2/CH4 (V:V = 0.5:05) and CO2/CH4 (V:V = 0.05:0.95) with the selectivity coefficiens are 79.3 and 25.4 at 298 K and 1 bar, respectively. Meanwhile, 1 shows a great performance for H2O vapor sorption and the uptake amount of H2O vapor is 281.9 cm3 g-1 (at 298 K and P/P0 = 0.99), which is comparable to that reported in the literatures. Furthermore, 1 has excellent separation ability for H2O vapor in H2O/CH3OH mixed vapor and the selectivity of 1 for H2O/CH3OH (V:V = 0.1:0.9) and H2O/CH3OH (V:V = 0.05:0.95) is 254.6 and 94.9 at 298 K and 1 bar, repectively. More importantly, Grand Canonical Monte Carlo (GCMC) simulation shows that the reason for the good adsorption capacity of 1 for CO2 and H2O vapor is attributed to the pore structure of 1 and the interaction between the coordinated H2O molecules and μ3-OH- in 1 and CO2 or H2O molecule. In addition, 1 shows sensitive sensing ability for nitrofurantoin (NFT) and the detection limit (DL) was 5.3×10-8 M. Moreover, the fluorescence sensing mechanism of 1 for NFT can mainly be attributed to the competitive absorption between the absorption spectrum of NFT and the emission spectrum of 1, the weak interactions between μ3-OH- in 1 and NFT and photoinduced electron transfer from 1 to NFT.

Coriandrum sativum and Allium sativumare belong to family alliaceae which is famous for its culinary and medicinal properties. These two sativum species’ seeds and cloves extracts are chosen to synthesize the cobalt oxide nanoparticles because it is eco- benign, secure as well as cost – effective method. The reducing sugar such as glucose which is present naturally in the extract used as reducing agent instead a harmful chemicals as reducing agent. The synthesized cobalt oxide nanoparticles using sativum species were characterization using UV–Visible spectroscopy, FT-IR spectroscopy, EDAX and SEM. The optical absorption spectrum for Co3O4 nanoparticles are studied using UV–Visible spectroscopy. The FT-IR spectrum confirms the presence of functional group in cobalt oxide nanoparticles. Scanning Electron Microscopy was employed to analyze the morphology, it shows that synthesized cobalt oxide nanoparticles show different morphology, which depends on the nature of the extract and of the compound present the extract. The EDAX studies show that the presence of cobalt and oxygen elements in the synthesized nanoparticles. Photo - catalytic activity of the synthesized nanoparticles was evaluated by degradation of Rhodamine B dye.

Amorphous and crystalline SiC nanoparticles were synthesized via laser ablation of SiC micro-sized powder in water and ethanol. X-ray and HRTM analysis showed the amorphous nature of SiC nanoparticles with an average particle size of 44 nm in water and crystalline 6H-SiC polytype nanoparticles with an average size of 18 nm in ethanol. The direct and indirect bandgap of SiC nanoparticles were determined from UV–visible absorption spectra. PL emission characteristics were studied and crystalline SiC nanoparticles exhibit tunable PL emission covering UV to the visible region.

Based on the host-guest molecular recognition capability of cucurbit[6]uril (CB[6]) modified on the gold surface, sensitive spectrophotometric and electrochemical methods for the detection of metformin (MET) have been developed. The molecular recognition between cucurbit[7]uril (CB[7]) or CB[6] and MET is initially demonstrated and the related recognition mechanism is further deliberated. First, CB[6]-modified gold nanoparticles (AuNPs/CB[6]) were synthesized and then characterized by ultraviolet visible light spectrum (UV–vis) and transmission electron microscopy (TEM). The aggregation of AuNPs/CB[6] prompted by MET triggered changes of color and the absorption spectrum, that explored for the visual identification and spectrophotometric determination of MET. Under the optimized detection conditions, the UV–vis spectrometry had a good linear relationship in the range of 6–700 μmol/L, and the detection limit was 2 μmol/L. In addition, a single-layer CB[6]-modified gold electrode (GE-CB[6]) detection system for MET was constructed. As the concentration of MET in the solution continues to increase, the charge transfer resistance (Rct) in the Nyquist diagram of the electrochemical impedance method (EIS) continues to increase. In the concentration range from 10 pmol/L to 20 nmol/L, the logarithm of the MET concentration has a good linear relationship with Rct, and the detection limit of this method is 1.35 pmol/L. Both methods have good concentration sensitivity to MET in different concentration ranges, providing a powerful tool for the detection of MET.

In this work pristine and Cr-doped NiO were synthesized by microwave-assisted method. The products were characterized by X-ray diffraction (XRD), UV–vis absorption spectroscopy and photoluminescence (PL) spectroscopy. The significant feature of this manuscript is that the effects of pristine and Cr-doped NiO on the structural and optical properties of Cr-doped NiO were investigated for the first time. The average particle size of different samples was below 24 to13 nm. Pristine and Cr-doped NiO antibacterial activity is shown by all the prepared samples.

In this study, we aim to contribute an understanding of the pathway of formation of Fe species during top-down synthesis of dispersed Fe on N-functionalized few layer graphene. We use X-ray absorption spectroscopy to determine the electronic structure and coordination geometry of the Fe species and in situ high angle annular dark field scanning transmission electron microscopy combined with atomic resolved electron energy loss spectroscopy to localize these, identify their chemical configuration and monitor their dynamics during thermal annealing. We show the high mobility of peripheral Fe atoms, first diffusing rapidly at the trims of the graphene layers and at temperatures as high as 573 K, diffusing from the edge planes towards in-plane locations of the graphene layers forming three-, four-coordinated metal sites and more complexes polynuclear Fe species. This process occurs via bond breaking which partially reduces the extension of the graphene domains. However, the vast majority of Fe is segregated as a metal phase. This dynamic interconversion depends on the structural details of the surrounding graphitic environment in which these are formed as well as the Fe loading. N species appear stabilizing isolated and polynuclear Fe species even at temperatures as high as 873 K. The significance of our results lies on the fact that single Fe atoms in graphene are highly mobile and therefore a structural description of the active sites as such is insufficient and more complex species might be more relevant, especially in the case of multielectron transfer reaction. Here we provide the experimental evidence on the formation of these polynuclear Fe-N sites and their structural characteristics.

Wide-ranging application in various fields from biomedicine, catalysis and optoelectronic materials to sensors, and environmental pollution prevention by synthesising Metal oxide nanoparticles. In this present work Eco-friendly synthesis of Nickel Oxide Nanoparticles (NiO-NPs) using Avicennia Marina leaf extract in an aqueous medium. The prepared NiO-NPs were characterized by UV–Visible, FT-IR, X-ray diffraction, AFM, FE-SEM, TEM, and electrochemical techniques to find the band gap energy, functional group, grain size, morphology, and the structure, particle size respectively. UV–Vis absorption spectrum of nickel oxide nanoparticles (NiO-NPs) shows a peak in the region of 297 nm. The FTIR spectrum of NiO-NPs shows bands at 872 cm−1 and 466 cm−1. From the FESEM results, the average size of NiO-NPs is seen to be in the range of 30–100 nm. Electrochemical studies were carried out to assess the redox behavior of NiO-NPs. The obtained results confirmed the formation of nickel oxide nanoparticles from the biomaterial leaf component. The methanol oxidation of NiO-NPs has been studied by voltammetry.

Solution-processable molecular dopants are popular wet-lab mediators to engineer the electronic properties of organic semiconductors and to optimize the level performance of their corresponding devices. Nonetheless, the exact doping mechanism that is operative during the interaction of organic semiconductors with Lewis acid species is not fully elaborated. The products of the doping reactions between Lewis acids and organic semiconductors have not been studied in detail. Here we focus on the macromolecular poly[bis(4-phenyl)(2,4-dimethylphenyl)]amine (PTAA) and molecular fluorinated anthradithiophene (diF-TES-ADT) organic semiconductors for addressing their chemical integrity after p-doping by the tris(pentafluorophenyl) borane [B(C6F5)3] Lewis acid agent. The PTAA and diF-TES-ADT organic substrates are studied in mixtures with B(C6F5)3 at three discrete concentration regimes. In the dilute solution regime, UV-Vis absorption spectroscopy verifies the effectiveness of p-doping by the changes observed in the absorption spectra of the solutions at increased B(C6F5)3 content. In the concentrated solution regime, the reactivity of B(C6F5)3 with PTAA and diF-TES-ADT is monitored by proton nuclear magnetic resonance (1H-NMR) and electrospray ionization mass spectroscopy (ES-MS), as well as thin-layer chromatography (TLC). Finally, in the solid-state the photophysical properties of spin-coated PTAA:B(C6F5)3 and diF-TES-ADT:B(C6F5)3 films are examined as a function of their B(C6F5)3 content. Density functional theory (DFT) calculations corroborate the experimental findings. Both theoretical and experimental results exclude the formation of Lewis adduct species in the PTAA:B(C6F5)3 and diF-TES-ADT:B(C6F5)3 systems. In agreement with recent literature, the B(C6F5)3 reactivity is attributed to the Brønsted-type acidity of the hydrated B(C6F5)3-OH2 complex that induces p-doping via the protonation of the organic substrates. The formation of the B(C6F5)3-OH2 acidic agent is identified experimentally by its characteristic 1H-NMR signal at 4.7 ppm. All results for the three concentration regimes provide evidence for the occurrence of PTAA and diF-TES-ADT decomposition in the presence of B(C6F5)3. At high B(C6F5)3 loadings, ES-MS spectroscopy and TLC analysis suggest that B(C6F5)3 remains unreacted, revealing the catalytic role in the decomposition process of PTAA and diF-TES-ADT. The results suggest that after interacting with Lewis acids, organic semiconductors may undergo detrimental decomposition reactions. This potentially undesired chemical reactivity should be considered for evaluating the operation stability of the p-doped electronic devices.

Electrochemical energy conversion technologies involving processes such as water splitting and O2/CO2 reduction, provide promising solutions for addressing global energy scarcity and minimizing adverse environmental impact. However, due to a lack of an in-depth understanding of the reaction mechanisms and the nature of the active sites, further advancement of these techniques has been limited by the development of efficient and robust catalysts. Therefore, in situ characterization of these electrocatalytic processes under working conditions is essential. In this review, recent applications of in situ Raman spectroscopy and X-ray absorption spectroscopy for various nano- and single-atom catalysts in energy-related reactions are summarized. Notable cases are highlighted, including the capture of oxygen-containing intermediate species formed during the reduction of oxygen and oxidation of hydrogen, and the detection of catalyst structural transformations occurring with the change in potential during the evolution of oxygen and reduction of CO2. Finally, the challenges and outlook for advancing in situ spectroscopic technologies to gain a deeper fundamental understanding of these energy-related electrocatalytic processes are discussed.

Single-atoms (SAs) with atomically coordinated reaction centers are considered the next generation of catalysts that can exhibit exceptional catalytic efficiency. However, the general concern about thermodynamic vulnerabilities of SAs questions their practical value. Moreover, whether the inherent catalytic nature of SAs is superior compared with that of larger nanoparticles is still under debate. Here, we address two controversies by a comparative study using two catalysts: Pt/TiO2 and Pt/CeOx–TiO2. Based on a hierarchical study of density functional theory, time-resolved catalysis performance test, in situ infrared spectroscopy, and operando X-ray absorption spectroscopy, we could unveil the catalytic nature of Pt-SAs and their stability. By utilizing the heterogeneous interface formed between TiO2 supporting particles and CeOx clusters formed on the surface of TiO2, we preferentially synthesized Pt-SAs pinned at the CeOx–TiO2 interfaces on CeOx–TiO2 hybrid-oxide supports. The strong electronic coupling between the Pt-SAs and the Ce ions at the CeOx–TiO2 interfaces enhanced the catalytic activity toward CO oxidation of Pt-SAs and improved the long-term stability under CO oxidation conditions. The CO oxidation activity of Pt-SAs stabilized at CeOx–TiO2 was improved by 13.5 times at 200 °C compared with the Pt-SAs on TiO2. The results present how to easily improve the activity and stability of Pt-SAs using a simple interface control method. Moreover, we demonstrate that the catalytic activity and the stability of Pt-SAs can be monitored through the chemical state of the interfaces. Our study provides comprehensive understanding about the catalytic nature as well as a novel strategy toward applications of Pt-SAs, enabling sustainable use of Pt in heterogeneous catalysts.

Heavy glass system (HGS) with batch compositionsTeO2-Bi2O3-Na2O co-doped with rare earth ions Er2O3&Yb2O3 are synthesized by melt- quench and press method. The batch composition is taken (80-x-y)%TeO2-10%Bi2O3-10%Na2O-x%Er2O3-y%Yb2O3 where (x, y) are (0.1, 0) and (0.5, 0.5). Thermal study of the synthesized sample is done by Differential Scanning Calorimetry (DSC). Amorphous nature of samples is characterized by X-Ray diffractogram. Heaviness of the samples justifies by the calculated densities of the glass samples. For the study of optical properties, Refractive index (R.I.), Optical energy gap (Eg), Urbach’s energy (Eu) absorption spectroscopy in ultra violet –visible-Infrared (UV–VIS-IR) region is carried. For upconversion (UC) characteristics photoluminescence spectroscopy studied.

Transition metal sulphides exhibit excellent optical, photo electrical and thermoelectric properties. These materials have attracted much attention because of its applications in the field of electroluminescence devices, light emitting displays, cathode material for rechargeable lithium battery, magnetic devices, dye degradation and optical sensors. In the present work, iron doped Nickel sulphide nanoparticles are synthesized using chemical precipitation method. Nickel chloride and Ferric chloride are used as precursors and sodium sulphide as a stabilizing agent. The performance of the synthesized nanoparticles are analysed by varying the molarity of the iron chloride from 0.01 M to 0.05 M. The synthesized nanoparticles are characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Ultraviolet Visible spectroscopy (UV–Vis) and Photoluminescence (PL) studies. FT-IR spectral analysis shows the band at 630 cm−1 corresponds to the bending vibration of metal sulphur bond (Ni-S) and the bands observed around 585 cm−1 and 456 cm−1 are ascribed to Fe–O stretching vibrations of tetrahedral and octahedral lattice sites respectively. The XRD analysis shows the crystalline nature of nanoparticles and the average nano-crystallite size is found to be 18 nm − 26 nm. The crystallite size increases with increase in the concentration of iron. The morphology of the samples is analyzed using scanning electron microscope and is found to be spherical in shape. The optical properties are characterized using UV–Vis spectral analysis and PL study. UV–Visible absorption spectra show absorption peaks of iron doped nickel sulphide nanoparticles and the band exhibits a blue shift, indicates quantum size effect. Electrochemical studies revealed two oxidation peaks at a potential about −0.3 V and 0.7 V for pure nickel sulphide nanoparticles and in addition to it, a redox peak is observed at a potential about −0.5 V due to the doping of iron into the nickel sulphide nanoparticles. The synthesized nanoparticles may be used as high-performance electrode materials for supercapacitor applications.

Layered double perovskite are currently investigated as emerging halide-based materials for optoelectronic applications. Herein, we present the synthesis of Cs4MnxCd1-xSb2Cl12 (0 ≤ x ≤ 1) nanocrystals (NCs). X-ray powder diffraction evidences the retention of the same crystal structure for all the inspected compositions; transmission electron microscopy revealed monodisperse particles with a mean size between 10.7 nm and 12.7 nm. The absorption spectra are mostly determined by transitions related to Sb3+, whereas Mn2+ induced a red emission in the 625 – 650 nm range. The photoluminescence emission intensity and position varies with the Mn2+ content and reaches the maximum for the composition with x = 0.12. Finally, we demonstrate that the photoluminescence quantum yield of the latter NCs was increased from 0.3% to 3.9% through a post-synthesis treatment with ammonium thiocyanate. The present work expands the knowledge of colloidal layered double perovskite nanocrystals, stimulating future investigations of this emerging class of material.

The quantitative understanding of how atomic-level catalyst structural changes affect the reactivity of the electrochemical CO2 reduction reaction is challenging. Due to the complexity of catalytic systems, conventional in situ X-ray spectroscopy plays a limited role in tracing the underlying dynamic structural changes in catalysts active sites. Herein, operando high-energy resolution fluorescence-detected X-ray absorption spectroscopy was used to precisely identify the dynamic structural transformation of well-defined active sites of a representative model copper(II) phthalocyanine catalyst which is of guiding significance in studying single-atom catalysis system. Comprehensive X-ray spectroscopy analyses, including surface sensitive Δμ spectra which isolates the surface changes by subtracting the disturb of bulk base and X-ray absorption near-edge structure spectroscopy simulation, were used to discover that Cu species aggregated with increasing applied potential, which is responsible for the observed evolution of C2H4. The approach developed in this work, characterizing the active-site geometry and dynamic structural change, is a novel and powerful technique to elucidate complex catalytic mechanisms and is expected to contribute to the rational design of highly effective catalysts.

Lithium titanium oxide Li 4 Ti 5 O 12 (Li[Li 1 / 3 Ti 5 / 3 ]O 4 ) has been receiving significant attention as an ideal electrode material for lithium-ion batteries, because its cubic lattice parameter ( a c ) changes negligibly during the electrochemical reaction. However, this same characteristic hinders in-depth understanding of the reaction mechanism, restricting widespread applications, such as use in electric vehicles. We thus employed the recently developed operando X-ray absorption spectroscopy (XAS) and X-ray diffraction (XRD) technique, combined with multivariate curve resolution by alternating least squares (MCR-ALS) method. The MCR-ALS analyses of both the XAS and XRD data confirmed a two-phase reaction scheme consisting of Li[Li 1 / 3 Ti 5 / 3 ]O 4 and Li 2 [Li 1 / 3 Ti 5 / 3 ]O 4 , but differences in the structural transformations clearly appeared at the two different scales. Linear, reversible changes in the bond distance between Ti and O atoms were observed at the atomic scale ( ∼ 1 nm), whereas hysteresis in a c between the discharge and charge reactions was observed at the microscale ( ∼ 100 nm). This difference was found to originate from the difference in spatial resolutions between the XAS and XRD techniques.

Oxynitrides have been shown to be promising visible light water splitting photocatalysts, but rapidly degrade under operating conditions. With a custom designed photoelectrochemical cell, we perform operando grazing incidence X-ray absorption spectroscopy measurements on the oxynitride semiconductor SrTaOxNy during photocatalytic solar water splitting. We show that the nature of the A-site (Sr) and its evolution during operation have large impacts on the overall stability and catalytic activity of the material, leading to an enriched BO2 (Ta(OH)/TaO(OH)) like surface. However, this usually beneficial effect with respect to increased surface hydrophilicity has complications for the efficiency of the photocatalytic process, as the OH and O(OH) intermediates formed are in competition between O2 generation and NOx species formation in the initial stages of operation. Operando characterisation of the evolution of the electronic structure of the photocatalyst proves to be an invaluable tool for the rational design and discovery of new and better performing materials.

Pure and doped ZnS thin films were synthesised using Successive Ionic Layer Adsorption and Reaction (SILAR) over glass substrate with 15 deposition cycles at ambient temperature. In this study, pure ZnS nanoparticles were doped with the Cu, Co and Ag elements. The structural and optical properties of pure and doped ZnS thin films were explored. The structural and morphological properties of pure and doped ZnS thin films were characterized by powder X-ray diffraction and Scanning Electron Microscope (SEM). The SEM images confirmed that average diameter of nano-particles of ZnS was between 53 and 90 nm. Optical properties determined from UV–VIS spectrophotometry were used to analyse the measured absorbance. The Zinc sulphide thin film shows high absorption in the visible region. Further, ZnS doped with Co, Cu and Ag with doping concentration of 3% was investigated for the feasibility and quality of the solar cells. The optical absorption peak was approximately located at 350 nm. The increase of bandwidth with decrease of the absorption values were observed with doped ZnS thin films and the Ag doped ZnS thin film has broad absorption spectra over the visible light region.

Silver nanoparticle (AgNP) synthesis using microalgae is a promising low-cost sustainable alternative. High CO2 tolerant microalgae have not yet been explored for this application. This study pretends to determine the potential of an environmental green algae Desmodesmus abundans acclimated to low and high CO2 (LCA and HCA strains, respectively) as a platform for AgNPs synthesis and evaluate the effect of pH (5, 7.5, 11) and biological component (cells, supernatant and both components) in comparison to a collection strain Spirulina platensis. Exponential grown cultures were centrifuged, the pellet resuspended in 10 mM AgNO3 prepared in water or supernatant at different pH and incubated for 40 h (24 °C, continuous light). After, the filtrated solution was characterized using UV–visible absorption spectra, Zetasizer and scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy. Results showed drastic differences between strains. No nanoparticles were observed with strain LCA, except at pH 11 using the pellet, which generated large particles (127.8 ± 14.8 nm diameter, −26.7 ± 2.4 mV zeta potential). In contrast, the HCA strain in these conditions showed the smallest AgNPs with the lowest zeta potential (14.9 ± 6.4 nm, −32.7 ± 5.3 mV). When the supernatant was conserved, HCA exhibited AgNPs in all pH solutions, with smallest sizes at pH 11 (27.7 ± 14.0 nm, −20.0 ± 1.8 mV). In addition, the HCA supernatant alone showed reducing potential for AgNP synthesis (51.8 ± 20.7 nm, −17.4 ± 1.3 mV). S. platensis also generated AgNPs in all conditions, but nanoscale particles were observed only at pH 11 (18.3 ± 7.5 nm, −33.9 ± 2.4 mV). In conclusion, high CO2 atmospheres seem to potentiate AgNPs synthesis by microalgae with interesting properties accordingly to biological component employed, representing a potential byproduct in CO2 mitigation systems.

Single-atom catalysts (SACs) that can achieve maximum atom utilization and provide well-defined active sites in energy conversion reactions have attracted much attention in the past decade. In general, the local structures of active sites in SACs largely determine their catalytic activity and selectivity. Therefore, identifying the local environments of active sites in specific SACs is essential to understand their catalytic functions in various reactions. Recent research works have demonstrated that synchrotron-radiation spectroscopic characterization methods possess unparalleled capacity in the identification of local environments of SACs due to their wide energy regulation window and high resolution. In this review, we aim to discuss the practical applications of some ex/in situ synchrotron-radiation spectroscopic techniques in recently reported advanced SACs. The experimental analyses from various techniques, such as X-ray absorption spectroscopy (XAS), photoemission spectroscopy (PES) and Fourier-transform infrared spectroscopy (FTIR), are highlighted. The built structure-activity relationships towards identified active sites are also discussed. Finally, a summary of spectral imputs and related significance is made and the research perspectives are suggested.