Powder X-ray Diffraction Studies Research Articles

Tutton salt (NH4)2Zn(SO4)2(H2O)6: thermostructural, spectroscopic, Hirshfeld surface, and DFT investigations

ContextAmmonium Tutton salts have been widely studied in recent years due to their thermostructural properties, which make them promising compounds for application in thermochemical energy storage devices. In this work, a detailed experimental study of the Tutton salt with the formula (NH4)2Zn(SO4)2(H2O)6 is carried out. Its structural, vibrational, and thermal properties are analyzed and discussed. Powder X-ray diffraction (PXRD) studies confirm that the compound crystallizes in a structure of a Tutton salt, with monoclinic symmetry and P21/a space group. The Hirshfeld surface analysis results indicate that the main contacts stabilizing the material crystal lattice are H···O/O···H, H···H, and O···O. In addition, a typical behavior of an insulating material is confirmed based on the electronic bandgap calculated from the band structure and experimental absorption coefficient. The Raman and infrared spectra calculated using DFT are in a good agreement with the respective experimental spectroscopic results. Thermal analysis in the range from 300 to 773 K reveals one exothermic and several endothermic events that are investigated using PXRD measurements as a function of temperature. With increasing temperature, two new structural phases are identified, one of which is resolved using the Le Bail method. Our findings suggest that the salt (NH4)2Zn(SO4)2(H2O)6 is a promising thermochemical material suitable for the development of heat storage systems, due to its low dehydration temperature (≈ 330 K), high enthalpy of dehydration (122.43 kJ/mol of H2O), and hydration after 24 h.MethodsComputational studies using Hirshfeld surfaces and void analysis are conducted to identify and quantify the intermolecular contacts occurring in the crystal structure. Furthermore, geometry optimization calculations are performed based on density functional theory (DFT) using the PBE functional and norm-conserving pseudopotentials implemented in the Cambridge Serial Total Energy Package (CASTEP). The primitive unit cell optimization was conducted using the Broyden–Fletcher–Goldfarb–Shanno (BFGS) algorithm. The electronic properties of band structure and density of states, and vibrational modes of the optimized crystal lattice are calculated and analyzed.Graphical abstract

Pyrazolone-Based Zn(II) Complexes Display Antitumor Effects in Mutant p53-Carrying Cancer Cells.

The synthesis and characterization of nine Schiff bases of pyrazolone ligands HLn (n = 1-9) and the corresponding zinc(II) complexes 1-9 of composition [Zn(Ln)2] (n = 1-9) are reported. The molecular structures of complexes 2, 3, 4, 8, and 9 were determined by single-crystal X-ray diffraction analysis, highlighting in all cases a distorted tetrahedral geometry around the Zn(II) ion. Density functional theory studies are performed on both the HLn ligands and the derived complexes. A mechanism of dissociation and hydrolyzation of the coordinated Schiff base ligands is suggested, confirmed experimentally by powder X-ray diffraction study and photophysical studies. Complexes 1-9 were investigated in vitro as anticancer agents, along with mutant p53 (mutp53) protein levels in human cancer cell lines carrying R175H and R273H mutp53 proteins. Only those complexes with the highest Zn(II) ion release via dissociation have shown a significant cytotoxic activity with reduction of mutp53 protein levels.

Hydrothermal synthesis, characterization of Co3Sb4O6F6 and carbon doped Co3Sb4O6F6 and their application towards photocatalytic dye degradation, adsorption, catalytic Knoevenagel condensation and bacterial disinfection

Single crystals of Co3Sb4O6F6 have been grown by employing hydrothermal techniques. Table sugar was utilized to prepare carbon-doped Co3Sb4O6F6. The objective was to employ Co(II)-based metal oxyfluoride comprising a stereochemically active lone pair element (Sb3+) and its carbon-doped analogues for the multifunctional applications. The impact of carbon doping on Co3Sb4O6F6 has been evaluated towards the changes in photocatalytic, catalytic, and adsorbent efficiency. The changes in carbon percentage affect the physical and chemical properties of the host material. A larger percentage of carbon doping turns the photocatalytic ability of the host material into an adsorbent for the removal of dye. The single crystal X-ray diffraction study reveals that Co3Sb4O6F6 crystallizes into cubic symmetry. However, powder X-ray diffraction study reveals the structural transformation in the carbon-doped Co3Sb4O6F6. It also reduces the band gap energy of the host material, and 4 wt% C@Co3Sb4O6F6 turns out to be an efficient photocatalyst. Large-scale carbon doping (15 wt%) appears to be an effective strategy to increase the surface charge and BET surface area, as consequences adsorption property develops in 15 wt% C@Co3Sb4O6F6/H2O2 for the elimination of methylene blue (MB). This favourable chemical adsorption process occurs with large maximum adsorption capacity (qmax = 58.41169 mg g-1), as evident from the Langmuir adsorption isotherm. Scavenger experiment confirms that the photocatalytic activities of the as-synthesised compounds were triggered by the active participation of the hydroxyl radical (.OH). The catalytic efficiencies of both parent and doped compounds are also established for the solvent-free Knoevenagel condensation reaction with 90 % yield at moderate temperature. Bacterial disinfection studies by the ‘Disc diffusion method’ confirm that Co3Sb4O6F6 shows better efficiency than the carbon doped compound against both Gram-positive and Gram-negative bacteria.

Investigations on the synthesis, growth and physicochemical properties of nonlinear optical material: l-lysine monohydrochloride nickel bromide (LLMNB)

A good-quality single crystal of l-lysine monohydrochloride nickel bromide (LLMNB) with an optimum size of 7 mm × 3 mm x 2 mm was obtained within 40–45 days. SXRD examinations revealed the unit cell measurements and cell characteristics of l-lysine monohydrochloride nickel bromide (LLMNB) crystals. By using powder X-Ray diffraction (PXRD) studies, the grown crystal's crystalline nature was determined. The functional groups of the crystal were determined using Fourier transform infrared (FT-IR). The optical transmission of a LLMNB crystal was investigated to characterize the crystal. This illustrates the LLMNB crystal's broad transmission window spanning the whole visible range and its extremely low UV cut-off wavelength of 230 nm. According to the findings, the LLMNB crystal's SHG efficiency was 1.62 times higher than that of the reference crystal KDP. The dielectric property of the grown crystal was studied at various temperatures. The grown LLMNB crystal Vickers hardness number increases when a load is applied. Photoconductivity research looked into the nature of photoconductivity. Hence, all these investigations suggest that the grown LLMNB crystal can be used for nonlinear optical devices and it is a potential candidate for optoelectronic utilization.

Exploring 1T/2H MoS2 Nano Coral Structured Active Electrodes for Enhanced Pseudocapacitive Supercapacitors: A Rigorous Evaluation and Characterization Study

This article optimizes the synthesis parameters of nano coral structured (NC-S) molybdenum disulfide (MoS2) using hydrothermal method and enhances its physiochemical properties for high-performance supercapacitors (SC). This nano coral architecture of transition metal dichalcogenides has garnered significant attention for efficient pseudocapacitive charge storage in SC. Herein, this work demonstrates the fabrication of dual phase MoS2 by tailoring the reaction time of the NC-S. Furthermore, this effect has been explained with the help of several analytical techniques. The synthesized 1T/2H MoS2 NC-S phase was affirmed by powder X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy studies. The field emission scanning electron microscope and transmission electron microscope images unveiled nano corals like morphology with numerous active sites. Impressively, the as prepared 24, 36 and 48 h MoS2 NC-S entrenched as working electrode endows the achievement with a greater specific capacitance of about 761.82, 1550.86 and 1036.28 F/g at 1 A/g of current density manifests an outstanding rate capability of 94.5, 96.5 and 95.3% capacitive retention even after 1000 cycles. Among them, the 36 h (A-36) synthesized NC-S MoS2 possess high specific energy (43.61 Wh/kg) and power (225.50 W/kg) for this application. Additionally, it demonstrates a commendable capacitive retention of 97% for the two-cell asymmetric setup, even after 5000 cycles at 10 A/g of current density. This inventive configuration of a two-cell device is employed using a Swagelok setup, where the 1T/2H phase MoS2 NC-S//AC exhibit outstanding storage stability and sustained up to 180 sec. The promising results validate that this material can significantly enhance performance in energy storage applications.

Bioinspired poly(vinyl alcohol) films with tunable adhesion and self-healing for biodegradable electronics and beyond

AbstractPolymers have attracted attention for their use in enabling biodegradable electronics. However, many polymers suitable as substrates either have no adhesion or suffer from weak and unstable adhesion. Addressing this challenge, we report a simple method to achieve tunable adhesion on various surfaces for wide applications. We achieve this by combining poly(vinyl alcohol) (P), dopamine (DA) and citric acid (CA) to produce modified poly(vinyl alcohol) adhesive films. These films are derived from bio-based constituents through an environmentally benign, easily reproducible and scalable fabrication process. They offer strong adhesion to various surfaces, such as stainless steel (138–191 kPa) and Polytetrafluoroethylene (PTFE) (67–93 kPa) and facilitate easy detachment with water. Notably, the modified films showed a better degradation compared to pristine P films under anaerobic conditions. The extent of degradation was characterized both quantitatively and qualitatively. The biokinetic parameters of anaerobic digestion process were estimated using three different kinetic models. It is anticipated that DA and CA molecules penetrate the interplanar distance of P chains as supported by powder X-ray diffraction (XRD) studies, thus, accelerating the degradation process. Additionally, the inclusion of CA enhanced the stability of DA molecules against oxidation, increased the extent of H-bonding and acted as a plasticizer. The addition of DA and CA bestowed the films with self-healing property due to the presence of multiple H-bonds. Tensile experiments revealed that the strength of self-healed samples approached that of pristine samples. The findings of this study hold promise for the development of innovative, biodegradable poly(vinyl alcohol)-based self-healing adhesive films with potential applications across various domains like smart packaging, soft robotics, on-skin electronic tattoos and self-healing electronics.

Sodium yttrium fluoride doped with Er3+ ions for thermally and non-thermally coupled nano-thermometry and IR detection applications

Microwave-assisted combustion synthesis approach was adopted to prepare sodium yttrium fluoride doped with erbium (NaYF4: Er3+) nanoparticles. Powder x-ray diffraction study confirmed the formation of mixed phase of NaY1-xF4: xEr3+ (x = 1, 3, 5, 7 and 9 mol%) sample with cubic and hexagonal phases (predominant). Three characteristic emission peaks appearing at 526, 546 and 670 nm were attributed to the transitions 2H11/2, 4S3/2 and 4F9/2 to 4I15/2 respectively which are characteristic emissions of Er3+ ions when excited with 980 nm radiation. The optimal dopant concentration was determined as 7 mol% of Er3+ ions in yellowish-green region, and the asymmetric ratio was also calculated. The synthesized up-converting sample follows two-photon process for excitation which was confirmed by power law by varying pump-power in the range of 49–143 mW. The thermally and non-thermally coupled levels attributed to the transitions (2H11/2 and 4S3/2), (2H11/2 and 4F9/2) of Er3+ ions were employed to study the temperature sensing which was recorded in 300–550 K and the relative sensitivities were evaluated to be 0.92 and 0.58 %K−1 correspondingly. The significant thermal sensitivity of the synthesized phosphor materials promises its possibility in optical thermometry applications. The synthesized sample when excited with 980 nm laser radiation produced emission in the visible region which facilitates the utilization of sample as infrared (IR) detector. In the purview of solid-state lighting, the luminous efficiency and luminous efficacy of radiation were evaluated as 23.57 % and 161 lm/Wop respectively. The optical thermometry, IR detection and light generation capabilities of the hexagonal-phased sodium yttrium fluoride doped with erbium (NYF:Er) ions are demonstrated with the obtained results.

Hexagonal rod-like Eu3+doped CaMoO4 phosphors: Structural, photoluminescence and photometric properties for display device applications

A multicolored LED illumination device is a compact, durable, easy to obtain color-adjustable output illumination source. It is frequently utilized in the domains of room illumination and exterior displays. However, the advancement of multicolor LEDs has been hampered by the rise in price and the fall in luminous efficacy while changing illumination colors. In the present investigation we have prepared intense red emitting Eu3+ doped CaMoO4 phosphor nanopowders via simple solid-state reaction technique. The powder X-ray diffraction (PXRD) studies reveal the crystalline nature of the samples with scheelite–type mono phase tetragonal structure with I41/a space group. The band gap (Eg) energy values were estimated and found to range between 4.63–5.32 eV. Scanning electron microscopy (SEM) studies reveled the hexagonal rod-like structures with different Aloe Vera gel concentrations. The particle size was found to be around 40 nm. The vibrational modes of the prepared powders were evaluated by using Fourier Transform Infrared Spectroscopy (FTIR) and Raman spectroscopy. It was observed from the results that, there were 26 vibrational modes of CaMoO4 (Γ=3Ag + 5Au + 5Bg + 3Bu + 5Eg + 5Eu) 8 of which (4Au and 4Eu) were infrared active and 13 (Ag, Bg, and Eg) are Raman active. Photoluminescence (PL) emission intensity increases up to 5 mol% of Eu3+ ions load and subsequently it declines due to the concentration quenching phenomenon and effective energy transfer from Mo-O charge transfer band (CTB) to 5D0 levels of Eu3+. It was noticed from PL emission spectra that, four intense peaks located at 5D0 → 7F1 (590 nm), 5D0 → 7F2 (613 nm), 5D0 → 7F3 (654 nm), 5D0 → 7F4 (702 nm) of Eu3+ respectively. The Commission International de I'Eclairage (CIE) diagram indicates the red color emission and average correlated color temperature (CCT) value was found to be 2050 K. Further, the external quantum efficiency (QE) and color purity (CP) were calculated to check the phosphor efficiency and found to be 92% and 72% respectively. The present investigation opens up a new avenue in the fabrication of low-cost display devices with high color purity and luminous efficacy.

Synergistic Influence of Doping and Co‐Doping of Trivalent Ions (La+3 and Al+3) on YFeO3 Nanomaterials

Herein, the structural, optical, and magnetic properties of Y0.85La0.15FexAlyO3: (x; y) where x = 1; y = 0, x = 0.975; y = 0.025, x = 0.95; y = 0.05, and x = 0.9; y = 0.1 nanomaterials obtained from sol–gel method are reported. The X‐ray powder diffraction (XRD) for the structural characterization, scanning electron microscopy for crystallite size estimation, ultraviolet–visible absorption for optical studies, and vibrating‐sample magnetometer for magnetic studies are used in this investigation. An increase of orthorhombic crystal structure with an increase of Al content in the sample is observed from XRD studies. The existence of all the elements present in the samples is observed from energy‐dispersive X‐ray spectroscopy. The optical bandgap increases from 2.04 to 2.10 eV with an increase of Al concentration from 0 to 0.05. The observed magnetization value is 3.14 emu g−1 for y = 0.05, which is higher than y = 0 (2.11 emu g−1) and y = 0.024 (2.58 emu g−1). In summary, the obtained result (x = 0.95; y = 0.05) can be useful for different magnetic‐based applications.

Transdermal Hydrogen Sulfide Delivery Enabled by Open-Metal-Site Metal-Organic Frameworks.

Hydrogen sulfide (H2S) is an endogenously produced gasotransmitter involved in many physiological processes that are integral to proper cellular functioning. Due to its profound anti-inflammatory and antioxidant properties, H2S plays important roles in preventing inflammatory skin disorders and improving wound healing. Transdermal H2S delivery is a therapeutically viable option for the management of such disorders. However, current small-molecule H2S donors are not optimally suited for transdermal delivery and typically generate electrophilic byproducts that may lead to undesired toxicity. Here, we demonstrate that H2S release from metal-organic frameworks (MOFs) bearing coordinatively unsaturated metal centers is a promising alternative for controlled transdermal delivery of H2S. Gas sorption measurements and powder X-ray diffraction (PXRD) studies of 11 MOFs support that the Mg-based framework Mg2(dobdc) (dobdc4- = 2,5-dioxidobenzene-1,4-dicarboxylate) is uniquely well-suited for transdermal H2S delivery due to its strong yet reversible binding of H2S, high capacity (14.7 mmol/g at 1 bar and 25 °C), and lack of toxicity. In addition, Rietveld refinement of synchrotron PXRD data from H2S-dosed Mg2(dobdc) supports that the high H2S capacity of this framework arises due to the presence of three distinct binding sites. Last, we demonstrate that transdermal delivery of H2S from Mg2(dobdc) is sustained over a 24 h period through porcine skin. Not only is this significantly longer than sodium sulfide but this represents the first example of controlled transdermal delivery of pure H2S gas. Overall, H2S-loaded Mg2(dobdc) is an easily accessible, solid-state source of H2S, enabling safe storage and transdermal delivery of this therapeutically relevant gas.

Deciphering the influence of support in the performance of NiFe2O4 catalyst for the production of hydrogen fuel and nanocarbon by methane decomposition

Wet chemical synthesis route was used to synthesis nickel ferrite (NiFe2O4) nanoparticle. Later on the synthesized NiFe2O4 were supported on the surface of three traditional supports such as Al2O3, MgO and TiO2 to get NiFe2O4/Al2O3, NiFe2O4/TiO2 and NiFe2O4/MgO catalysts. The activity profile of each catalyst was evaluated in a fixed-bed reactor for direct methane decomposition at 800 °C. For both fresh and spent catalysts, many characterization techniques have been employed mainly XRD, FESEM, HRTEM, Raman spectroscopy, TGA, and nitrogen adsorption-desorption isotherm. X-ray powder diffraction studies revealed that all synthesized catalysts have a cubic spinel crystal structure. The XRD confirm the presence of NiFe2O4 particles in the component of fresh NiFe2O4/MgO, NiFe2O4/TiO2 and NiFe2O4/Al2O3 catalysts. Temperature Program Reduction (TPR) unveiled the presence of Ni oxides and Fe oxides by displaying reduction peaks in their respective temperature regions. The N2 adsorption-desorption isotherms of the fresh all catalysts reveal that these catalysts have a mesoporous structure. Activity data concluded NiFe2O4/MgO to be the most active catalysts among the tested catalysts methane conversion magnitude of 41.13 % and H2 formation rate of 84.40 × 10−5 mol H2 g−1 min−1. On the other hand, the H2 formation rate drastically declined and very poor activity of both NiFe2O4/TiO2 and NiFe2O4/Al2O3 catalysts was observed in the current work. XRD patterns, FESEM images and TGA analysis of spent NiFe2O4/MgO catalyst shown the filamentous carbon formation which secondarily confirm its higher activity, while its absence in catalysts of NiFe2O4/TiO2 and NiFe2O4/Al2O3. TGA analysis of the carbon deposited on the NiFe2O4/MgO catalyst showed that the amount of carbon was approximately 64 wt%. It was suggested that the formation of nickel-iron carbide revealed by XRD studies of spent catalysts may be the factor related to their poor activity while discussing the structure-activity relationship. Likewise, the higher degree of dispersion related to NiFe2O4/MgO as displayed by XRD, FESEM and TPR investigations, played a vital role in accelerating the rate of hydrogen formation.

Structural, optical, second harmonic, and mechanical studies on zinc chloride added alpha-glycine crystals

The slow evaporation solution method was employed to synthesize and crystallize zinc chloride doped α-glycine (ZCAG) single crystals. The single crystal X-ray diffraction studies of pure α-glycine single crystals revealed that the structure belong to primitive monoclinic lattice. Powder X-ray diffraction studies of ZCAG showed the well-defined sharp peaks and formation of centrosymmetric structure with space group P21/n. The increase in lattice volume of ZCAG suggested that the access of zinc chloride into the α-glycine crystal and the entry of zinc chloride to the α-glycine crystal was also established from the energy-dispersive X-ray analysis. Fourier transform infrared spectrum of ZCAG revealed that the functional groups of α-glycine was not transformed due to the introduction of zinc chloride into the lattice. The optical transparency of ZCAG was observed in the UV–visible region, and it exhibited a superior transmittance in the visible region. Energy bandgap value was determined and found to changes while increasing the dopant concentration. An emission peak was observed in the violet region from the photoluminescence spectra. The centrosymmetric ZCAG exhibited second harmonic generation efficiency of 1.44 times higher than standard potassium dihydrogen phosphate, possibly due to local non-centrosymmetry in the lattice, which is further augmented by lattice distortion induced by the dopant. Low dielectric constant and loss of the grown ZCAG crystals showed the remarkable application of non-linear optical. The Meyer index indicates that the grown ZCAG are categorized as soft materials.

Tailoring thermoelectric performance of n-type Bi2Te3 through defect engineering and conduction band convergence

Bi2Te3, an archetypical tetradymite, is recognised as a thermoelectric (TE) material of potential application around room temperature. However, large energy gap (ΔEc ) between the light and heavy conduction bands results in inferior TE performance in pristine bulk n-type Bi2Te3. Herein, we propose enhancement in TE performance of pristine n-type Bi2Te3 through purposefully manipulating defect profile and conduction band convergence mechanism. Two n-type Bi2Te3 samples, S1 and S2, are prepared by melting method under different synthesis condition. The structural as well as microstructural evidence of the samples are obtained through powder x-ray diffraction and transmission electron microscopic study. Optothermal Raman spectroscopy is utilized for comprehensive study of temperature dependent phonon vibrational modes and total thermal conductivity ( κ ) of the samples which further validates the experimentally measured thermal conductivity. The Seebeck coefficient value is significantly increased from 235 μVK−1 (sample S1) to 310 μVK−1 (sample S2). This is further justified by conduction band convergence, where ΔEc is reduced from 0.10 eV to 0.05 eV, respectively. To verify the band convergence, the double band Pisarenko model is employed. Large power factor (PF) of 2190 μWm−1K−2 and lower κ value leading to ZT of 0.56 at 300 K is gained in S2. The obtained PF and ZT value are among the highest values reported for pristine n-type bulk Bi2Te3. In addition, appreciable value of TE quality factor and compatibility factor (2.7 V−1) at room temperature are also achieved, indicating the usefulness of the material in TE module.

Tuning of thermoelectric performance by modulating vibrational properties in Ni-doped Sb2Te3

Sb2Te3, a binary chalcogenide-based 3D topological insulator, attracts significant attention for its exceptional thermoelectric performance. We report the vibrational properties of magnetically doped Sb2Te3 thermoelectric material. Ni doping induces defect/disorder in the system and plays a positive role in engineering the thermoelectric properties through tuning the vibrational phonon modes. Synchrotron powder x-ray diffraction study confirms good crystalline quality and single-phase nature of the synthesized samples. The change in structural parameters, including B iso and strain, further corroborate with structural disorder. Detailed modification of phonon modes with doping and temperature variation is analysed from temperature-dependent Raman spectroscopic measurement. Compressive lattice strain is observed from the blue shift of Raman peaks owing to Ni incorporation in Sb site. An attempt is made to extract the lattice thermal conductivity from total thermal conductivity estimated through optothermal Raman studies. Hall concentration data support the change in temperature-dependent resistivity and thermopower. Remarkable increase in thermopower is observed after Ni doping. Simulation of the Pisarenko model, indicating the convergence of the valence band, explains the observed enhancement of thermopower in Sb2−x Ni x Te3. The energy gap between the light and heavy valence band at Γ point is found to be 30 meV (for Sb2Te3), which is reduced to 3 meV (in Sb1.98Ni0.02Te3). A significant increase in thermoelectric power factor is obtained from 715 μWm−1K−2 for pristine Sb2Te3 to 2415 μWm−1K−2 for Ni-doped Sb2Te3 sample. Finally, the thermoelectric figure of merit, ZT is found to increase by four times in Sb1.98Ni0.02Te3 than that of its pristine counterpart.

Ni Single Atom Decorated Porous Hollow Carbon Nanosphere-Based Electrodes for High Performance Symmetric Solid-State Supercapacitors.

Ni single atom containing hollow carbon nanospheres with nitrogen doping has been synthesized by carbonization of Ni(NO3)2/phloroglucinol-formaldehyde polymer/silica composite. The samples have been characterized by powder X-ray diffraction, nitrogen adsorption/desorption, electron microscopic, Raman and X-ray photoelectron spectroscopic studies. The microstructure and surface area vary with the amount of Ni(NO3)2 employed in the syntheses and the carbonization environment. An optimized amount of nickel and argon as the carbonization gas afford Ni-1.0@N@HCN-Ar which possesses overall superior features. The uniformly dispersed Ni single atoms within the hollow porous carbon framework fully utilize all the electroactive sites thereby improving the supercapacitive performance. The specific capacitance of Ni-1.0@N@HCN-Ar reaches 777 F g-1 at 1 A g-1 with a Coulombic efficiency of 98.4 % and excellent recyclability. The energy and power density of Ni-1.0@N@HCN-Ar are found to be high; at 1 A g-1 its energy density is 155.4 Wh kg-1 with a power density of 600.3 W kg-1. At a high current density of 10 A g-1 the material shows a high energy density of 118.4 Wh kg-1 with excellent power density of 6003.4 W kg-1. A symmetric solid-state supercapacitor assembled with this material, Ni-1.0@N@HCN-Ar//Ni-1.0@N@HCN-Ar using H2SO4/PVA gel electrolyte shows a superior energy density value of 30 Wh kg-1 at a power density of 1200 W kg-1.

Ni-Doped cerium oxide on rGO: A hydrothermal approach for high-performance supercapacitors

This work describes the hydrothermal method for synthesizing a novel nanocomposite: Nickel -doped Cerium oxide on reduced graphene oxide (Ni-CeO2/rGO). The resulting material exhibits exceptional electrocatalytic behavior, showing promise for supercapacitor applications. The Phase morphology, elemental analysis, surface area and oxidation state were confirmed by powder X-ray diffraction studies (PXRD), Raman spectrum, High Resolution Transmission Electron Microscopy (HRTEM), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray (EDX), Brunauer-Emmett Teller (BET) and XPS respectively. Electrochemical analysis involving cyclic voltammetry (CV), Galvanostatic charge/ discharge, and Electrochemical impedance spectroscopy (EIS). The specific capacitance is 262.1Fg-1, 504Fg-1, and 728Fg-1 for CeO2, CeO2/rGO, Ni-CeO2/rGO it depicts its suitability for energy storage. This study establishes the Ni-CeO2/rGO nanocomposite as a highly effective material for advanced energy storage applications.

Influence of pH on growth, structural, thermal, linear and nonlinear optical properties of L-asparagine monohydrate single crystal

This report presents investigation on influence of pH on growth, structural, thermal, linear and nonlinear optical properties of L-asparagine monohydrate (LAM) single crystal for the first time. Single crystals of LAM were grown at different pH by solution growth method by allowing slow evaporation of solvent. Crystal grown at pH 6.4 grows slowly as compare to other crystals grown at other pH values. The slight variation in lattice parameters of grown crystals has been confirmed by powder X-ray diffraction study. FT-IR study confirms the presence of functional groups of LAM in all grown crystals. Influence of pH on optical quality of crystals has been discussed. The crystal grown at pH 5.4 has maximum optical transparency and shows 2 and 20 % more transmission than crystals grown at pH 4.4 and 6.4, respectively. Other optical parameters like cutoff wavelength (λmax), band gap (Eg), linear refractive index (n), reflectance, extinction coefficient (k), electrical susceptibility (χ), optical conductivity(σop), electrical conductivity (σel) and Urbach energy (Eu) of all crystals have been evaluated from transmission data. The LAM crystal grown at pH 6.4 show high values of third order nonlinear optical parameters, as compare to other grown crystals, that attest its suitability for applications like higher harmonic generation, optical switching, optical limiting and other photonic applications over other grown crystals. Thermal stability of the grown crystals has been attested by TG-DTA study.

Intramolecular Charge Transfer and Stimuli-Responsive Emission in Cholesterol-Appended Phenothiazine-Cyanostyryl-Based Donor-Acceptor Systems.

Organic fluorescent molecules have received considerable attention owing to their various optoelectronic applications. Herein, we report the design and synthesis of two cholesterol-functionalized cyanostyrene-phenothiazine-based D-π-A systems that are emissive in both the solution and solid states. The newly synthesized cholesterol-appended phenothiazine-cyanostyrene diads PTCS-1 and PTCS-2 vary in the N-alkylation of phenothiazine, respectively, with─octyl and─hexyl chains. Both molecules are highly fluorescent and show reasonably good quantum yields in nonpolar solvents because of twisted intramolecular charge transfer (TICT). The molecules exhibit aggregation-induced emission in the solid state. Due to the presence of flexible alkyl chains in the phenothiazine and cholesterol moieties, PTCS-1 and PTCS-2 show mechanochromic luminescence switching in response to external shear stress and emission recovery under methanol vapor. Powder X-ray diffraction studies prove that the emission switching on the applied stimuli in both PTCS-1 and PTCS-2 is attributed to the reversible transformation between the crystalline and amorphous states. Time-dependent density functional theory (TD-DFT) studies are carried out to gain insight into the ICT interactions. TD-DFT analysis at the TD-M06-2X/def2-TZVP level further revealed that in both molecules, the lowest unoccupied molecular orbital (LUMO) + 2, LUMO, highest occupied molecular orbital (HOMO), and HOMO - 1 orbitals are responsible for the charge transfer interactions. These ICT interactions are identified as π-π* type interactions.

Effect of Polymorphism on the Sorption Properties of a Flexible Square-Lattice Topology Coordination Network.

The stimulus-responsive behavior of coordination networks (CNs), which switch between closed (nonporous) and open (porous) phases, is of interest because of its potential utility in gas storage and separation. Herein, we report two polymorphs of a new square-lattice (sql) topology CN, X-sql-1-Cu, of formula [Cu(Imibz)2]n (HImibz = {[4-(1H-imidazol-1-yl)phenylimino]methyl}benzoic acid), isolated from the as-synthesized CN X-sql-1-Cu-(MeOH)2·2MeOH, which subsequently transformed to a narrow pore solvate, X-sql-1-Cu-A·MeOH, upon mild activation (drying in air or heating at 333 K under nitrogen). X-sql-1-Cu-A·MeOH contains MeOH in cavities, which was removed through exposure to vacuum for 2 h, yielding the nonporous (closed) phase X-sql-1-Cu-A. In contrast, a more dense polymorph, X-sql-1-Cu-B, was obtained by exposing X-sql-1-Cu-(MeOH)2·2MeOH directly to vacuum for 2 h. Gas sorption studies conducted on X-sql-1-Cu-A and X-sql-1-Cu-B revealed different switching behaviors to two open phases (X-sql-1-Cu·CO2 and X-sql-1-Cu·C2H2), with different gate-opening threshold pressures for CO2 at 195 K and C2H2 at 278 K. Coincident CO2 sorption and in situ powder X-ray diffraction studies at 195 K revealed that X-sql-1-Cu-A transformed to X-sql-1-Cu-B after the first sorption cycle and that the CO2-induced switching transformation was thereafter reversible. The results presented herein provide insights into the relationship between two polymorphs of a CN and the effect of polymorphism upon gas sorption properties. To the best of our knowledge, whereas sql networks such as X-sql-1-Cu are widely studied in terms of their structural and sorption properties, this study represents only the second example of an in-depth study of the sorption properties of polymorphic sql networks.

Fabrication, characterization and application of W/N co-doped zinc oxide nanoparticles as a promising photoanode for dye-sensitized solar cells

In the present investigation, undoped, W doped, and W/N co-doped ZnO nanoparticles were prepared by sol–gel route. Here, the ZnO layers were fabricated via the doctor blade method. Hexagonal wurtzite structure is determined by XRD studies. The formation of a hexagonal wurtzite structure was observed from X-ray powder diffraction (XRD) resulting in a slight increase in crystallite size with an increase in doping content. The UV observation shows that W/N co-doping shifted the absorption spectra towards a higher wavelength and reduces the band gap energy. The EDS spectra confirms the high purity and triumphant doping of the W(tungsten) and N(nitrogen) into the ZnO lattice. The morphology of undoped and W/N co-doped ZnO nanoparticles was demonstrated by using FESEM and HRTEM. The 2 % W and 1.5 % N co-doped ZnO photoanode based DSSC (dye-sensitized solar cells) gained the highest short circuit current density of 8.44 mAcm−2 having an open-circuit voltage of 0.65 V, and PCE (power conversion efficiency) of 3.60 %.