Molar Ratio Of Precursors Research Articles

Gallatabenzene Ligands Emerging from Open Lutetocene and Yttrocene Methyl Complexes.

Utilizing ternary mixtures [LnMe3]n/K(2,4-dtbp)/GaMe3 (Ln=Lu, Y; 2,4-dtbp=2,4-di-tert-butyl-pentadienyl), a series of metallacycles is accessible via tandem salt metathesis/deprotonation. Depending on the precursor molar ratio, both gallatabenzene and lutetacyclic moieties with fully planar metallacycles are obtained, which were further analyzed using DFT calculations. The precursor molar ratio affects the extent of pentadienyl C-H-bond activation and oligomerization to tetra- and pentametallic arrays. Reacting a 1 : 2 : 2 mixture at -40 °C gave the open sandwich methyl complex (2,4-dtbp)2Lu(CH3), displaying a vital intermediate for subsequent ring-closure reactions.

Advanced nano-composite coatings of ZrB₂/ZrC/SiC on carbon fibers via eco-friendly precursor synthesis

This study presents a comprehensive investigation into the synthesis and characterization of ZrB2/ZrC/SiC composite coatings on carbon fiber substrates via a solution-based process followed by high-temperature pyrolysis. The precursor solution was prepared using Gum Ghatti (GG), zirconyl chloride, tetraethyl orthosilicate, and boric acid. Optimization of precursor concentration and molar ratios was performed to achieve suitable viscosity and composition. The pyrolysis process was conducted in an argon atmosphere, resulting in the formation of well-defined ZrB2, ZrC, and SiC phases. XRD analysis confirmed the phase composition, while SEM imaging revealed spheroidal particle aggregates with a uniform distribution of composite phases. TG-DTA analysis reveals the thermal decomposition behavior, highlighting distinct stages of mass loss and phase transformations. Coated carbon fibers exhibited enhanced oxidation resistance, as evidenced by TGA analysis. SEM analysis confirmed the uniform distribution and adhesion of the composite matrix on the carbon fiber substrate. This study demonstrates the successful synthesis of ZrB2/ZrC/SiC composite coatings with promising thermal properties for advanced applications.

Development of an Impinging Jet Microreactor Synthesis Process for Surfactant‐Free Pt‐Nanoparticles as PEMFC Catalyst Component

AbstractColloidal, surfactant‐free platinum nanoparticles were prepared via a self‐built continuous impinging jet microreactor synthesis process in alkaline aqueous methanol solution (Co4CatTM process). In these syntheses, methanol functions as a reducing agent as well as an additional solvent. Especially the synthesis of surfactant‐free nanoparticles remained challenging, and additionally, the transfer of this synthesis into a continuous process required several optimization steps. In this contribution we present highly controllable final particle sizes by adjusting process temperature, platinum precursor concentration and molar ratio of the hydroxide and platinum precursor used. The size objective of the surfactant‐free Pt nanoparticles was a range of 1 – 10 nm, due to the intended application in various catalytic processes, especially as PEMFC electrocatalyst. Dynamic light scattering (DLS), ζ‐potential measurements, transmission electron microscopy (TEM) and UV/Vis spectroscopy were used to monitor the particle stability over a certain period of time and study the rate of the reduction reaction in more detail.

Unraveling the Formation of Ternary AgCuSe Crystalline Nanophases and Their Potential as Antibacterial Agents.

AgCuSe nanoparticles could contribute to the growth of strongly light-absorbing thin films and solids with fast ion mobility, among other potential properties. Nevertheless, few methods have been developed so far for the synthesis of AgCuSe nanoparticles, and those reported deliver nanostructures with relatively large sizes and broad size and shape distributions. In this work, a colloidal cation exchange method is established for the easy synthesis of AgCuSe NPs with ca. 8 nm diameters and narrow size dispersion. Notably, in this lower size range the conucleation and growth of two stoichiometric ternary compounds are generally observed, namely the well-known eucairite AgCuSe compound and the novel fischesserite-like Ag3CuSe2 phase, the latter being less thermodynamically stable as predicted computationally and assessed experimentally. An optimal range of Cu/Ag precursor molar ratio has been identified to ensure the growth of ternary nanoparticles and, more specifically, that of the metastable Ag3CuSe2 nanophase isolated for the first occasion. The attained size range for the material paves the way for utilizing AgCuSe nanoparticles in new ways within the field of biomedicine: the results obtained here confirm the antibacterial activity of the new Ag x Cu y Se z nanoparticles against Gram-positive bacteria, with significantly low values of the minimal inhibitory concentration.

Sustainable Biocatalytic System for the Enzymatic Epoxidation of Waste Cooking Oil.

The present study is integrated in a global effort to capitalize waste cooking oil (WCO) into versatile compounds by introducing an oxirane ring into the unsaturated carbon chain of fatty acid residues (the epoxidation of double bound). Therefore, an enzymatic method was set up for the epoxidation of artificially adulterated WCO (SFw) and WCO under real conditions (SFr) derived from sunflower biomass. Commercial lipase (Novozyme, NZ) was used as a biocatalyst for generating the peracid requested by the epoxidation pathway. Optimum experimental conditions (e.g., 1.5 wt% NZ, 1:1:0.5 = H2O2/double bonds/peracid precursor (molar ratio) and 12 h reaction time) allowed for the conversion of 90% of the SFw substrate into products with an oxirane ring. Octanoic acid was selected as the best peracid precursor. The versatility of the developed system was tested for olive, milk thistle, hemp and linseed oils as both fresh and WCO samples. The characterization of the oil samples before and after the enzymatic epoxidation allowed for the evaluation of the system performance. SFw/SFr exhibited a better susceptibility to enzymatic epoxidation. In addition, the reusability of the biocatalytic system was investigated. Furthermore, different strategies, such as biocatalyst coating and the addition of organic solvents/buffers were applied, limiting enzyme leaching, for the better recovery of the biocatalyst activity.

Influence of the Gold Nanoparticle Size on the Colorimetric Detection of Histamine.

Histamine is a well-known biogenic amine (BA) that is often associated with allergic reactions and is a significant cause of foodborne illnesses resulting from the consumption of spoiled food. Detecting histamine is essential for maintaining food safety standards and preserving the quality. In this work, we developed a simple, low-cost, and rapid colorimetric method for detecting histamine. Gold nanoparticles (AuNPs) of different sizes (16, 25, and 40 nm) were synthesized by using the citrate reduction method. The particle size was controlled by adjusting the precursor molar ratio (MR), with smaller ratios leading to larger particles and a red-shift in the surface plasmon resonance (SPR) peak (520, 524, and 528 nm). The nanoparticles were allowed to interact with increasing concentrations of histamine (ranging from 1 to 100 ppm), and the changes in the absorbance spectra and color of the solution were monitored. AuNP aggregation was induced by interaction with histamine through amino and imidazole groups that will coordinate with the AuNP's surface via electrostatic and hydrogen-bonding interactions, causing the solution to turn blue from red. The size variations of AuNPs significantly affected the colorimetric response to histamine. Among the varied sizes, 25 nm AuNPs exhibited the lowest detection limit of 0.72 μM and a linear detection range of 1-10 ppm. Notably, this sensor offered rapid detection (under 1 min) and a remarkable selectivity toward histamine analyte, highlighting its potential for practical applications.

Danger in the Dark: Stability of Perovskite Solar Cells with Varied Stoichiometries and Morphologies Stressed at Various Conditions.

The long-term stability of perovskite solar cells (PSCs) remains a bottleneck for commercialization. While studies on the stoichiometry and morphology of PSCs with regard to performance are prevalent, understanding the influence of these factors on their long-term stability is lacking. In this work, we evaluate the impact of stoichiometry and morphology on the long-term stability of cesium formamidinium-based PSCs. We demonstrate that the lead iodide (PbI2) to formamidinium iodide (FAI) ratio influences stability under various stress factors (elevated temperature and light). A high molar ratio (PbI2/FAI > 1.1) in the perovskite precursor displays drastic degradation under ISOS-L1 (100 mW/cm2, 25 °C, maximum power point tracking) conditions. However, postdegradation analysis contradicts these results. Devices with PbI2/FAI ≤ 1.1 are stable under light, but intermittent current density-voltage characterizations indicate that device performance decreases during storage in the dark. Migration of iodide (I-) ions to the electron-transport layer (ETL) and iodine vacancies (VI-+) to the hole-transport layer (HTL) forms localized shunts in the absorber layer. Pinhole formation, surrounded by FA+-rich regions, explains the extent of damage in comparably aged films. In summary, this work emphasizes the importance of reporting stability under different stress conditions, coupled with postdegradation and dark recovery analyses of PSCs to better understand the complexities of perovskite instability under real-life conditions such as expected during outdoor operation.

Study on the Synthesis of Nano Zinc Oxide Particles under Supercritical Hydrothermal Conditions.

The supercritical hydrothermal synthesis of nanomaterials has gained significant attention due to its straightforward operation and the excellent performance of the resulting products. In this study, the supercritical hydrothermal method was used with Zn(CH3COO)2·2H2O as the precursor and deionized water and ethanol as the solvent. Nano-ZnO was synthesized under different reaction temperatures (300~500 °C), reaction times (5~15 min), reaction pressures (22~30 MPa), precursor concentrations (0.1~0.5 mol/L), and ratios of precursor to organic solvent (C2H5OH) (2:1~1:4). The effects of synthesis conditions on the morphology and size of ZnO were studied. It was found that properly increasing hydrothermal temperature and pressure and extending the hydrothermal time are conducive to the more regular morphology and smaller size of ZnO particles, which is mainly achieved through the change of reaction conditions affecting the hydrothermal reaction rate. Moreover, the addition of ethanol makes the morphology of nano-zno more regular and significantly inhibits the agglomeration phenomenon. In addition to the change in physical properties of the solvent, this may also be related to the chemical bond established between ethanol and ZnO. The results show that the optimum synthesis conditions of ZnO are 450 °C, 26 MPa, 0.3 mol/L, 10 min, and the molar ratio of precursor to ethanol is 1:3.

Recycling of fly ash to synthesize zeolites for efficient removal of dioxins

The large amount of fly ash (FA) produced by coal-fired power plants places tremendous pressure on the environment. Meanwhile, toxic dioxins emitted from municipal solid waste incineration plants are of great concern. To address these challenges, a win-win approach was proposed to re-utilize FA for synthesis of zeolite materials for dioxins adsorption. The results indicate that the Si/Al molar ratio in the liquid-phase precursor significantly influences the distribution of Si-Al 4-membered rings (Si/Al=1) and Si-Al 4-membered rings (Si/Al=3) in the system. These units are key secondary structures of the zeolite skeleton, determining the proportions of A-type and X-type zeolites in the product. With the increasing Si/Al molar ratio of precursor, the specific surface area and Si/Al molar ratio of zeolites derived from fly ash (ZFA) both increased, while they played a positive and negative role in dioxins adsorption, respectively. The adsorption of dioxins by ZFA peaked at a Si/Al molar ratio of precursor of 1.5, reaching 4.13×105 pg I-TEF/g, surpassing activated carbon by 1.46 times. This study not only elucidates the mechanism of Si/Al molar ratio of precursor on crystalline transformation of ZFA, but also confirms the potential of ZFA in dioxins adsorption.

Investigation on the pore structure-performance relationship of porous carbon adsorbents for SF6/N2 separation via fine pore modulation

The capture and recovery of SF6 as electron specialty gas from SF6/N2 by adsorptive separation have obvious advantages such as the mitigation of greenhouse effect and resource utilization of waste gas. The comprehensive understanding of pore structure-performance relationship of porous materials is beneficial for guiding the design of highly-efficient adsorbents for separating SF6/N2, but is presently limited. In this work, a series of citric acid (CA) and KOH with different molar ratios are designed to synthesize carbon adsorbents denoted as CAK via a one-step carbonization-activation method and probed for the adsorptive separation of SF6/N2. Characterization results reveal that the micropores in carbon adsorbents are finely tuned from 0.73 to 0.88 nm at an angstrom level through increasing the KOH/CA molar ratios in precursors, and the significant mesopores are formed in CAK4. Static adsorption results indicate that the SF6 adsorptive capacity at low pressure of 10 kPa increases and then decreases with the increasing contents of KOH, and the highest value is obtained in CAK2, while the diffusion rates illustrated from the adsorption kinetics continuously increase. By correlating the pore structures with adsorption capacity of adsorbents, the critical role of micropores with size ≤ 0.9 nm in determining the SF6 capacity at 10 kPa and mesopores in enhancing the mass transfer is quantitatively confirmed. The dynamic breakthrough results of CAKx carbon adsorbents for SF6/N2 separation are well explained with these understandings, which are important for guiding the design of porous adsorbents with high-performance for SF6 capture and recovery.

Polymer Supported Nitrogen-Bridged Symmetrical Binuclear Dioxidomolybdenum(VI) Complexes and Their Homogeneous Analogues as Potential Catalysts for Efficient Synthesis of 2-Amino-3-Cyano-4H-Chromenes/Pyrans.

Reaction of 2-chloromethyl-1H-benzimidazole with known intermediates (i-iii), prepared from diaminoguanidine hydrochloride with salicylaldehyde, 5-bromosalicylaldehyde or 3,5-di-tert-butylsalicylaldehyde, in the presence of triethylamine (NEt3) led to the formation of benzimidazole appended new ligands, H4L1-H4L3 (I-III). The homogeneous nitrogen-bridged symmetrical binuclear complexes, [(MoVIO2)2(L1)(H2O)2] (1), [(MoVIO2)2(L2)(H2O)2] (2) and [(MoVIO2)2(L3)(MeOH)2] (3) have been isolated by reacting these ligands with [MoVIO2(acac)2] in a 1 : 2 molar ratio in refluxing methanol. Using 1 : 1 (ligand to Mo precursor) molar ratio under above reaction conditions resulted in the corresponding mononuclear complexes, [MoVIO2(H2L1)(MeOH)] (4), [MoVIO2(H2L2)(H2O)] (5) and [MoVIO2(H2L3)(MeOH)] (6). The binuclear heterogeneous compounds [(MoVIO2)2(L1)(DMF)2]@PS (PS-1), [(MoVIO2)2(L2)(DMF)2]@PS (PS-2) and [(MoVIO2)2(L3)(DMF)2]@PS (PS-3) have been obtained by immobilization of 1-3 onto chloromethylated polystyrene (PS) beads. All synthesized ligands, homogeneous as well as supported compounds have been characterized by elemental analyses and various spectroscopic methods. Single crystal X-ray diffraction study of complexes 1 and 3 confirms their nitrogen-bridged symmetrical binuclear structures while 4 is mononuclear. Heterogeneous compounds (PS-1-PS-3) have further been studied by microwave plasma atomic emission spectroscopy, X-ray photoelectron spectroscopy, and field emission scanning electron microscopy along with energy dispersive spectroscopy. These compounds (homogeneous and heterogeneous) were explored for catalytic applications to one-pot multicomponent reactions (MCRs) for efficient synthesis of biologically active 2-amino-3-cyano-4H-chromenes/pyrans (21 examples). Optimising various reaction parameters helped in achieving as high as 97 % yields of products. Though, only half equivalent of the binuclear complexes (1-3) was required compared to mononuclear analogues (4-6) to achieve comparable yields, heterogeneous catalysts have an added advantage due to their stability and recyclability. Suitable reaction mechanism has also been proposed based on isolated intermediates.

Wet chemical synthesis of self-standing single-crystalline copper telluride Cu7Te4 nanorods: Characterizations and mechanism

Single crystalline Cu7Te4 nanorods were obtained from a two-step synthesis route. The first step is the electrochemical deposition of self-standing tellurium nanorods on Pt-coated glass electrode in an ionic liquid electrolyte acting as a structuring solvent. Afterwards, soft chemical transformation in Cu7Te4 is performed by immersing the Te-covered electrode in a Cu(II) solution in presence of ascorbic acid acting as reducer at room temperature and atmospheric pressure. Tellurium seems to undergo a reaction of disproportionation induced by the simultaneous presence of Cu(II) and Cu(I) into Te(IV) and Cu7Te4, which is supported by thermodynamic considerations. The copper telluride nanorods were analyzed by XRD, SEM-EDX, HRTEM-FFT/SAED, EELS and XPS that allowed to set the required parameters in terms of molar ratio of precursors in the bath to induce the targeted chemical reaction. The analyses highlight the obtention of single crystalline Cu7Te4 with a homogeneous chemical composition along the nanorods. A detailed analysis of the microstructure shows the presence of stacking local defects, leading to curved nanostructures.

Ni/Mn electroactive nanohybrids physic-chemical properties for ulterior new generation of supercapacitors

In this paper, highly mesoporous hierarchical mono- and bi- Ni and/or Mn based hydroxide and/or carbonate nanohybrids were synthesized using a facile free template hydrothermal method and investigated as high-performance electroactive nanomaterials for ulterior new generation of supercapacitors. Controlling the Ni/Mn precursors molar ratio and the growth conditions can offer preponderances for performances enhancing via a comparative products physic-chemical properties which were carried out using different techniques like: XRD, FTIR, Raman, XPS, HRTEM/FESEM, EDS, UV–visible and BET. The structural results confirmed the formation of MnCO3, α-3Ni(OH)2·2H2O and Ni(HCO3)2 phases in the synthesized nanomaterials, with different morphologies (nanofibers, nanocubes, porous micro/nanoflowers) depending on the hydrothermal synthesis conditions. Meanwhile, the influence of Ni and Mn transition metal species co-existence on the resulting composition and their optical properties were also discussed. Moreover, their electrochemical measurements were also performed in a 6 M KOH aqueous electrolyte using three electrode system. The results show that 2Ni(HCO3)2/MnCO3 nanohybrid exhibited the highest specific capacitance (capacity) of 2777 F g−1 at 5 mV s−1 (320 mAh.g−1 at 1 A g−1) with high rate capability. This excellent electrochemical kinetics performance is ascribed to the optimized composition of Ni/Mn and its unique nanostructured configuration with intercalated ions, indicating a great potential of this new kind of nanohybrids to deliver both high energy density and high power density in future energy storage devices.

Pulse electrodeposition of CuSbS2 thin films: Role of Cu/Sb precursor ratio on the phase formation and its performance as photocathode for hydrogen evolution§

In this paper, we outline the development of stoichiometric chalcostibite, CuSbS2 thin films, from a single bath by pulse electrodeposition for its application as a photocathode in photoelectrochemical cells (PEC). The Cu/Sb precursor molar ratio of the deposition bath was varied to obtain stoichiometric CuSbS2 thin films. The optimized deposition and dissolution potentials were −0.72 V and −0.1 V vs saturated calomel electrode, respectively. The formation of CuSbS2 was analyzed using different characterization tools. X-ray diffraction and Raman results showed the formation of the pure chalcostibite phase from a precursor bath with molar ratio Cu/Sb = 0.41. The heterostructure CuSbS2/CdS/Pt was tested as a photocathode in the PEC. The energy positions of the conduction and valence bands were estimated from the Mott Schottky plots. The conduction band and valence band offset of CuSbS2/CdS heterojunction were 0.1 eV and 1.04 eV, respectively. The electric field created in the junction reduced the recombination of the electron/hole pairs and improved charge transfer in the interface. The heterostructure CuSbS2/CdS/Pt demonstrated an improved photocurrent density of 3.4 mA cm−2 at 0 V vs reversible hydrogen electrode. The PEC efficiency obtained from the CuSbS2/CdS heterojunction was 0.56 %. Therefore, we demonstrated the feasibility of an inexpensive technique like electrodeposition for the development of an efficient earth-abundant photocathode.

Molten salt-shielded solid-state synthesis (MS5) reaction-driven >99% pure Ti3AlC2 MAX phase: effect of MAX phase purity on the interlayer separation of MXenes and Na-ion storage.

Ti3C2-X MXenes have attracted tremendous research interest because their 2D laminar morphology provides numerous functional applications. The application options rely on the purity and interlayer spacing of MXenes, which eventually depend on the purity of the MAX phase. This motivated us to synthesize pure MAX phases to produce MXenes at large scale using simpler and less expensive techniques. However, producing prerequisite pure MAX phases at atmospheric pressure and relatively lower temperatures is still a challenging task. This study reports the synthesis of thermally stable pure MAX phases (and MXenes) by systematically varying the molar ratio of the precursors, reaction temperature, and reaction time using a novel MS5 process under atmospheric pressure conditions. The purity of MAX phases under different synthesis conditions shows a direct interrelationship with the 2D laminar morphology of MXenes. The highest purity of >99% for the MAX phase was achieved by reacting Ti : Al : C precursors in a 3 : 1.5 : 1.9 molar ratio at 1350 °C for 90 min and delivered highly distinctive 2D nanostructured laminar MXenes with larger interlayer spacing and specific surface area (i.e., 8.8 ± 0.1 m2 g-1), which are superior to those in previously reported works. These results reveal that the precursor molar ratios and reaction conditions tailor the MAX phase purity, thereupon, they are crucial for achieving good quality 2D laminar MXenes with large specific surface areas, further enhancing the performance of MXene-related devices. The developed MS5-MXenes, when probed as electrodes for Na ion applications, show excellent initial and reversible capacity values of 142 mA h g-1 and 103 mA h g-1 (at 50 mA g-1), respectively.

Controlled synthesis of metal-organic frameworks via AC electrokinetic mixing-assisted microfluidics: A case study of ZIF-8

Metal-organic frameworks (MOFs) have great potential for a wide range of applications given their flexible structures and pore networks. Morphology control directly affects the properties and applications of MOFs. Unfortunately, governing the desired dimension and shape of MOFs is often limited by macrosystems that require organic solvents and additives while including time-consuming treatments. Microfluidics as a practical alternative provides precise manipulation of microscale liquid, has the potential to be a superior platform for directed crystal generation. Here we reported an AC electrokinetic (EK) mixing-assisted micro-synthesis method, which allowed the actively controlled synthesis of MOFs in aqueous phase. The effects of flow rate, molar-ratio of precursors, electric field intensity, and frequency on the synthesis of zeolitic imidazolate framework-8 (ZIF-8) were investigated. Using this method, the particle size of ZIF-8 were varied, and the geometry were changed between flower-like polyhedra, cubes, spheres, and rhombic dodecahedra. Furthermore, the synthesized various ZIF-8 provide different levels of immobilization sites based on their morphological deviations. The flower-like cubic ZIF-8 had defect structures and exhibited a maximum horseradish peroxidase (HRP) loading of about 16%. The study provides a simple, green and reliable tuning strategy for breaking the single morphological form of MOFs to enhance their physicochemical properties.

Fast-kinetics adsorption of a binary solution containing cationic and ionic pollutants using high-surface area activated carbon derived from macadamia nutshell

AbstractWastewater is characterized by multipollutant, and the presence of competitive adsorption could affect removal efficiency. Hence, the decontamination of water by adsorption in a multicomponent system allows an understanding of the practically and adsorbent efficiency. In this study, we present an analysis of the adsorption phenomena in a binary solution comprising compounds from distinct families, a dye, and an antibiotic, utilizing activated carbon obtained through a sustainable procedure. Locally available agricultural biowaste, specifically macadamia nutshell (MNS), served as a sustainable precursor to produce hierarchical porous activated carbon. The activation conditions were fine-tuned using the Box–Behnken experimental design. The resultant activated carbon was employed to remove a binary solution (BS) comprising the cationic dye, methylene blue (MB) and an ionic molecule amoxicillin (AMX) under specified conditions, including a pH range of 2 to 12, an initial concentration of BS ranging from 50 to 800 mg/L, and an adsorbent dosage within the range of 0.1 g to 0.3 g in a single adsorption system. The results revealed that higher temperatures adversely impacted the carbon yield, with a pronounced interaction effect observed between temperature and time. The activation temperature and K2CO3:precursor molar ratio predominantly influenced the textural and morphological properties of the activated carbon. Under optimal conditions (900 °C, 1 h, and a K2CO3:precursor ratio of 2:1), remarkably high-surface area (1225 m2/g), pore volume (0.801 cm3/g), and a nanopore size of 0.406 nm were achieved. In binary adsorption studies, R2-MNS demonstrated a maximum adsorption capacity of 578.925 mg/g. A pH above 4.5 produced an antagonistic effect on the removal of AMX due to competitive adsorption. Evaluation of three isotherm models demonstrated that the Khan isotherm best describes the affinity of BS to R2-MNS. The pseudo-second-order kinetic model best describes the data, indicating a chemisorption mechanism. The interparticle diffusion test revealed that the adsorbent exhibited very fast adsorption behaviour at the initial stage. Graphical abstract

On the structural and optical characterization of zinc aluminate nanoparticles synthesized via green microwave route

Zinc aluminate, a widely employed wide bandgap semiconductor, boasts exceptional mechanical and thermal properties, coupled with a high quantum yield. Its versatile applications include photocatalytic pollutant degradation, utilization in displays, and contributions to the medicinal field. However, challenges arise during synthesis processes, where high-temperature annealing reduces nanoparticle surface area, and cation contamination from precursors impacts material purity. In response to these challenges, green synthesis methods incorporating plant extracts as reductants have emerged to yield higher-quality phosphors. In this study, the focus is on microwave synthesis of Zinc Aluminate using Zinc Nitrate and Aluminum Nitrate in varying ratios as precursors. Comprehensive structural and optical characterizations, including X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Diffuse Reflectance Spectroscopy (DRS), and Photoluminescence Spectroscopy (PL), have been conducted to assess the influence of precursor molar ratios on the spinel growth and optimization of the synthesis process.

Facile one−step synthesis of Ag anchoring on Cu2O for enhanced SERS activity: Efficient charge transfer and adsorption

There is a keen research interest to develop inexpensive and ultrasensitive substrate materials for practical sensing application of surface enhanced Raman spectroscopy (SERS). Aiming to utilize synergistic enhancement contributions originated from plasmon adsorption and charge transfer (CT), it is highly desirable to construct hybrid substrates of noble metals and semiconductors. In this work, Ag nanoparticles−decorated Cu2O hybrids (Ag−Cu2O) were synthesized through a simple one−step growth method, i.e., reducing AgNO3 and CuCl2 by ascorbic acid (AA) in the presence of PVP. A systematic study has been carried out to characterize the material properties and SERS performance of Ag−Cu2O hybrids prepared under different molar ratios of precursors, growth temperatures and addition speed of reducing agent. Ag−Cu2O hybrids, composed of well−distributed Ag nanoparticles on Cu2O nanoplates, showed enhanced SERS performance in comparison with pure Cu2O. When 4−nitrobenzenethiol (4−NBT) was used as probe molecule, the optimal sample showed a calculated enhancement factor of 1.4 × 105 and a low detection of limit (LOD) of 1 × 10−10 M, which is four orders of magnitude lower than that of pure Cu2O. Ag−Cu2O hybrid substrates can also be used to detect dye molecues and the LODs for rhodamine 6G and crystal violet were 1 × 10−8 M and 1 × 10−9 M, respectively. It is feasible that the observed enhancement of SERS activity were benefited from synergistic contributions of the abundant “hot spots”, rich photo−induced charge transfer pathways, improved adsorption ability, and suppressed recombination of e−h pairs in Ag−Cu2O hybrids. This work provides a simple and controllable approach to fabricate metal/semiconductor hybrids as SERS sensing platform.

Structural and optical properties of carbon nanodots based on citric acid doped with nitrogen atoms

A study of the luminescent properties of carbon nanodots obtained by microwave and hydrothermal methods of synthesis from citric acid and urea was performed. The resulting nanoparticles were characterized using transmission electron microscopy, dynamic light scattering, and Fourier transform infrared spectroscopy. The sizes of the obtained carbon nanodots after dialysis was varied from 2 to 8 nm. FTIR spectra confirm the presence of oxygen-containing –OH, –CN and –NH groups in the resulting solutions. For all studied carbon nanodots, the maximum fluorescence intensity is observed upon excitation at a wavelength of 350 nm. The fluorescence spectrum does not change its position on the wavelength scale for the samples under study due to changes in the molar ratio of precursors and the method of synthesis. The highest fluorescence quantum yield was obtained for carbon nanodots with a ratio of citric acid and urea 1:4 obtained by the microwave synthesis method. The fluorescence lifetime of carbon nanodots doped with nitrogen atoms is ~7.4 ns. It is shown that a change in the ratio of precursors does not significantly affect the size and morphology of carbon nanodots.