This work studies the optoelectronic, and structural characteristics of CsPbIBr2 perovskite solar cells (PSCs) improved by 4 % Zirconium (Zr) doping and a bilayer electron transport layers (ETLs) ...composed of TiO2 and Zr-doped WO3. X-ray diffraction (XRD) examination of pure and Zr-doped CsPbIBr2 films revealed increased crystal size (39.2–41.2 nm) and lowered lattice constant following Zr doping, suggesting better crystallinity. The calculated energy band gap of pristine and Zr-doped CsPbIBr2 film decreases (1.986–1.926 eV), which improves the light absorption efficiency, while the increase in the refractive index implies that light is slowed down more as it passes through the material, which increases light trapping and absorption within the material. The XRD of Zr-WO3 ETL indicated a monoclinic crystal structure and increased lattice constant, allowing charge carrier transmission. Raman spectroscopy confirms the structural integrity of Zr-WO3. UV–Vis absorption spectra suggest enhanced absorption in the visible region and higher bandgap compared to Zr-doped CsPbIBr2. J-V tests reveal an efficiency rise from 8.54 % to 10.20 % with the proposed of double ETLs, exhibiting substantial breakthroughs in PSCs performance.
Enhanced Efficiency through Zr doping and bilayer ETL of Zr–CsPbIBr2: Increased Grain Size, Reduced Energy Band Gap, Elevating Efficiency from 8.54 % to 10.20 %. Display omitted
•The inclusion of 4 % Zr doping into CsPbIBr2 perovskite films, significantly improves the structural and optoelectronic properties of solar cells.•The dual-layer ETLs comprising TiO2) and 4 % Zr-WO3, enhancing the optoelectronic and photovoltaic performance.•The efficiency increases in PSCs from 8.54 % to 10.20 %, evidenced through J-V testing with the introduction of the double ETLs.
Metal oxide nanocomposites are in high demand due to their versatile properties and wide range of applications in modern technology, including energy storage devices, electrode material design, and ...dye-sensitized solar cells (DSSCs). Nanocomposites of LaxCe2-xO3/SnO2 were prepared via sol-gel method. This research work has reported a detailed study of the dielectric properties of LaxCe2-xO3/SnO2 nanocomposites at high frequencies (1 MHz–3 GHz). After forming a mixed phase, the surface morphology was confirmed by HR-TEM, resulting in a significant change in particle size and distribution. Different polarization stages, the effect of grain boundaries and the relaxation phenomenon were discussed with the impact of La3+ contents. Relaxation behaviour at high frequency was examined due to strong polarization. In addition, a high dielectric constant value at high frequency shows that these nanocomposites are eligible to store more energy. At x = 0.6, the maximum value of the dielectric constant was observed. Results demonstrate that LaxCe2-xO3/SnO2 nanocomposites are competent for microwave, high-frequency devices and energy storage applications.
•Nanocomposites of metal oxides are high demanding for energy storage devices, and DSSCs.•XRD analysis confirmed the polycrystalline nature of nanocomposites and crystallite size up to 11–13 nm.•Surface morphology and particle size distribution were studied using transmission electron microscopy (TEM).•Relative permittivity, electric modulus, and the relaxation phenomenon at high frequencies.•The excellent storage capacity makes them applicable for advanced microwave devices.
Tin anodes show a rich structure and reaction chemistry which we have investigated in detail. Upon discharge five plateaus are observed corresponding to β-Sn, an unidentified phase (Na/Sn = 0.6), an ...amorphous phase (Na/Sn = 1.2), a hexagonal R-3m Na5Sn2, and fully sodiated I-43d Na15Sn4. With charging there are six plateaus related to the formation of Na5Sn2 followed by the formation of amorphous phases and β-Sn. Upon cycling the formation of metastable Na5Sn2 seems to be suppressed.
Theoretical voltages calculated from existing crystal structures using DFT provide a good match with constant current and quasi-equilibrium measurements (GITT). Search for additional (meta)stable phases using cluster-expansion method predicts many phases lower in energy than the convex hull obtained from known structures, including the R-3m Na5Sn2 phase. The presence of multiple phases in varying lattices with similar formation energy suggests why the reaction mechanism is non-reversible. 119Sn Mössbauer spectroscopy results indicate a decrease of the isomer shift with increasing Na/Sn content, which is less pronounced than for Li–Sn compounds likely due to the lower electropositivity of Na.
The electrode surface is terminated with an SEI layer rich in carbonates (Na2CO3 and Na CO3R) as evidenced by XPS. After charge at 2 V, strong evidence for the formation of oxidized Sn4+ is obtained. Subjecting the electrode to a rest after charge at 2 V reveals that aging in the electrolyte reduces the oxidized Sn4+ into Sn2+ and Sn0, and concomitantly suppresses the electrolyte decomposition represented by an anomalous discharge plateau at 1.2 V. Thereby, the catalytic decomposition of the electrolyte during discharge is caused by nanosized Sn particles covered by oxidized Sn4+ and not by pure metallic Sn.
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► Bulk structure of Na–Sn studied by XRD, DFT and Mössbauer spectroscopy. ► Identification of new R-3m phase of composition Na5Sn2. ► Surface chemistry probed by XPS as a function of Na content. ► Catalytic decomposition of electrolyte caused by Sn4+ and not metallic Sn.
•Graphene oxide (FL-GOc) and reduced graphene oxide (FL-RGOc): XRD, TEM, XPS, REELS.•FL-GOc: stacking nanostructure—22×6nm (DxH), 0.9nm layers separation (XRD).•FL-RGOc: stacking nanostructure—8×1nm ...(DxH), 0.4nm layers separation (XRD).•Reduction: oxygen group degradation, decreasing distance between graphene layers.•Number of graphene layers in stacking nanostructure: 6–7 (FL-GOc), 2–3 (FL-RGOc).
The commercial and synthesised few-layer graphene oxide, prepared using oxidation reactions, and few-layer reduced graphene oxide samples were structurally and chemically investigated by the X-ray diffraction (XRD), transmission electron microscopy (TEM) and electron spectroscopy methods, i.e. X-ray photoelectron spectroscopy (XPS) and reflection electron energy loss spectroscopy (REELS).
The commercial graphene oxide (FL-GOc) shows a stacking nanostructure of about 22×6nm average diameter by height with the distance of 0.9nm between 6-7 graphene layers, whereas the respective reduced graphene oxide (FL-RGOc)—about 8×1nm average diameter by height stacking nanostructure with the distance of 0.4nm between 2-3 graphene layers (XRD). The REELS results are consistent with those by the XRD indicating 8 (FL-GOc) and 4 layers (FL-RGOc). In graphene oxide and reduced graphene oxide prepared from the graphite the REELS indicates 8–11 and 7–10 layers. All graphene oxide samples show the C/O ratio of 2.1–2.3, 26.5–32.1 at% of C sp3 bonds and high content of functional oxygen groups (hydroxyl—COH, epoxy—COC, carbonyl—CO, carboxyl—COOH, water) (XPS). Reduction increases the C/O ratio to 2.8–10.3, decreases C sp3 content to 11.4–20.3 at% and also the content of COC and CO groups, accompanied by increasing content of COH and COOH groups. Formation of additional amount of water due to functional oxygen group reduction leads to layer delamination. Removing of functional oxygen groups and water molecules results in decreasing the distance between the graphene layers.
Abstract
Niobium pentoxides (Nb
2
O
5
) have attracted extensive interest for ultrafast lithium‐ion batteries due to their impressive rate/capacity performance and high safety as intercalation ...anodes. However, the intrinsic insulating properties and unrevealed mechanisms of complex phases limit their further applications. Here, a facile and efficient method is developed to construct three typical carbon‐confined Nb
2
O
5
(TT‐Nb
2
O
5
@C, T‐Nb
2
O
5
@C, and H‐Nb
2
O
5
@C) nanoparticles via a mismatched coordination reaction during the solvothermal process and subsequent controlled heat treatment, and different phase effects are investigated on their lithium storage properties on the basis of both experimental and computational approaches. The thin carbon coating and nanoscale size can endow Nb
2
O
5
with a high surface area, high conductivity, and short diffusion length. As a proof‐of‐concept application, when employed as LIB anode materials, the resulting T‐Nb
2
O
5
@C nanoparticles display higher rate capability and better cycling stability as compared with TT‐Nb
2
O
5
@C and H‐Nb
2
O
5
@C nanoparticles. Furthermore, a synergistic effect is investigated and demonstrated between fast diffusion pathways and stable hosts in T‐Nb
2
O
5
for ultrafast and stable lithium storage, based on crystal structure analysis, in situ X‐ray diffraction analysis, and density functional theoretical calculations. Therefore, the proposed synthetic strategy and obtained deep insights will stimulate the development of Nb
2
O
5
for ultrafast and long‐life LIBs.
•Polybromination by NBS and IR activation of potential antileishmanial guanidine.•Conformational study is performed by Nuclear Magnetic Resonance and SCXRD.•Hirshfeld surface and fingerprint plots of ...compounds showed a high Br—C contact.•XRPD and SCXRD X-ray patterns agree.•Conformational changes from Z to E promoted by polybromination.
Leishmaniasis is a neglected disease that affects regions such as South Asia, South Africa, and Latin America, less developed regions. The research proposed the conformational study of brominated guanidine compounds with potential antileishmanial activity using Nuclear Magnetic Resonance (NMR) and X-ray diffraction (XRD) techniques. The present study involves the brominated molecules LQOF-G2, LQOF-G30, LQOF-G35 and LQOF-G35-Br. The latter was synthesized by the reaction of LQOF-G35 with NBS under IR irradiation at 120 Watts of potency and dichloromethane as solvent by 12 h of exposition. The obtained results demonstrated the efficiency of the bromination method, since two bromine atoms entered the molecule. Furthermore, NMR analysis showed a conformational change from Z to E when compound LQOF-G35 was brominated to LQOF-G35-Br. This behavior was confirmed by a comparative XRD study of the LQOF-G35 and LQOF-G35-Br compounds. The antileishmanial activity of LQOF-G2 e LQOF-G35 motivated the synthesis of new brominated compounds LQOF-G30 e LQOF-G35-Br.
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•XRD, FT-IR, UV–Vis and Raman spectroscopy.•Photoluminescence.•DFT calculations.
A new intercalation crystalline polymer compound of bis m-nitroanilinium tetrachlorocadmate (II) {(m-C6H7N2O2)2CdCl4}n ...was synthesized and analyzed using single crystal SXRD, differential scanning calorimetry (DSC), DFT analysis, thermal gravimetric analysis (TGA) and FT-IR, Raman, UV–Vis, fluorescence spectroscopy techniques. X-ray diffraction analyses (SXRD, PXRD) show a layered structure consisting of alternating organic bilayers and two-dimensional inorganic sheets in which each CdCl6 octahedron shares four corners with adjacent octahedra. The crystal packing is consolidated by means of classic and non-classic hydrogen bonds and π-π interactions. At room temperature photoluminescence spectra of {(m-C6H7N2O2)2CdCl4}n yield broad peaks in the 469–770 nm range with full width at half maximum (FWHM) values up to 153 nm. Besides, this compound exhibits a semiconducting behavior with bright red-light under 360 nm ultraviolet photoexcitation and possesses a large Stokes shift and direct band gap of 2.69 eV which overlaps well with solar spectrum. The CIE chromaticity coordinates of {(m-C6H7N2O2)2CdCl4}n are (x = 0.4704 and y = 0.4523). The color rendering index CRI and the low correlated color temperature CCT are 84 and 2861 K, respectively. Electronic structure (BS, DOS and PDOS), and optical properties (dielectric constant ε(ω), refractive index n(ω), reflectivity R(ω), absorption coefficient α(ω), optical conductivity σ(ω) and energy loss function L(ω) with the incident photon energy) were determined using (DFT) calculations by CASTEP code.
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In-situ X-ray diffraction (XRD) is a powerful tool to assess the hydration of cementitious materials, providing time-resolved quantitative analysis with reasonable accuracy without disturbing sample. ...However, the lack of guidelines and well-established procedures for data collection and analysis is the limiting factor for spreading this technique. This paper discussed using in-situ laboratory XRD to assess cement hydration. The first part was dedicated to a literature review on the topic. Then, experimental strategies were discussed, and recommendations related to the data analysis routine were drawn; the advantages and limitations of this technique were also discussed. We can conclude that the critical factors for a successful analysis are the choice of an adequate experimental setup with good statistics and low measurement time, the proper consideration of different amorphous contributions in the XRD pattern, and a good data analysis routine. Independent techniques are highly recommended to support the in-situ XRD data.
