Wet Chemical Route Research Articles

Cobalt-rich spinel oxide-based wide angular spectral selective absorber coatings for solar thermal conversion applications

Solar energy conversion technologies attain enormous attention to create more efficient energy production sources to meet the current world's demand. The solar thermal conversion system converts solar energy to heat, and the receiver tube is crucial for achieving high photo-thermal conversion efficiency. The absorber coatings with high solar absorptance at normal and wide incidence angles of solar radiation improve the performance of concentrated and non-concentrated solar thermal systems. To achieve high photo-thermal conversion efficiency in the solar thermal conversion system, a novel spinel structured cobalt-rich transition metal oxide-based absorber coating was developed by a cost-effective wet chemical route. The developed absorber coatings with sub-micron scaled surface protrusions with porous structure (size 0.75 μm) exhibit an excellent spectral selectivity (α/ε = 0.91/0.13). In addition, the coatings show an excellent wide angular solar absorptance of 0.97–0.96 at incidence angles of 10°–40°. Extensive characterization has been carried out to analyze the structural properties of the absorber coatings and correlated to the spectral selectivity and wide angular solar absorptance property. The stability of the absorber coating at 400 °C for 100 h in an open-air atmosphere assessed by the performance criteria (PC) function value of 0.015 indicates the ability of the optimized absorber coatings to employ in solar thermal systems.

Organic green route synthesis of multifunctional colloidal sulfur formulation for pesticidal application

Crop protection through multifunctional low dimensional sulfur particles has numerous benefits over conventional chemical pesticides and formulations based on colloidal sulfur are emerging recently. A simple wet chemical route with acetic acid-thiosulphate-SDS system was reported to produce an aqueous colloidal sulfur formulation (CSF) of size ∼190 ​nm. This formulation was also stabilized with plant protective additives (neem oil, chitosan, tannic acid) and Taguchi methodology was applied to optimize the process and improve the stability of the formulation. Microscopic studies revealed that sulfur particles in the formulation are free from agglomerates and the developed formulation was investigated for antimicrobial and insecticidal activities. CSF was found to be effective on the tested phytopathogens (Aspergillus terreus, Fusarium solani and Venturia inequalis) with the supportive zone of inhibition and radial growth assays. Furthermore, CSF spraying onto the Pseudococcus mealybugs resulted in >80% mortality in 24 ​h and electron microscopy analysis displayed ultrastructural variations in the bodies of the insects with distorted morphology. CSF (with 18 ​mM sulfur) being non-toxic to earthworms and with its multifunctional properties could protect a wide range of crops. Its application as a foliar spray has the potential to replace commercial toxic pesticides.

Coherent nanointerface between light-harvesting and catalytic transition metal sulfides for efficient photochemical conversion

Creating atomically coherent interfaces can sharpen the physiochemical properties and functionalities of nanomaterials for efficient energy conversion via manipulating the charge flow. While coherent interfaces can be built between transition metal dichalcogenides with structural similarities and weak interlayer van der Waals interactions, it remains challenging to realize interfacial coherency with more generic transition metal chalcogenides via cost-effective wet chemical routes. Here we establish a coherent CdS(010)|CoS(010) interface via in-situ heteroepitaxial growth of CoS nanoflakes onto CdS nanowires. The uniform and oriented distribution of CoS nanoflakes on the CdS nanowires features an interesting “leaves-on-a-branch” nano-architecture with coherent interface and well-aligned energy levels, allowing efficient separation of photoexcited charge carriers. Combined with the outstanding proton reduction kinetics of the CoS “nanoleaves”, striking photochemical solar-to-hydrogen conversion performance can be obtained. Our findings provide a viable design strategy of nanojunctions with atomic level coherency and great application prospect in catalysis, nanoelectronics and many others.

NO2-sensing proprieties of WS2/WO3 heterostructures obtained by hydrothermal treatment of tungsten oxide seed materials

This work reports on the preparation of WS2/WO3 heterostructures for the development of nitrogen dioxide (NO2) sensors via a novel wet-chemical hydrothermal route approach. Different tungsten oxides were used as seed materials, and the heterostructure were formed using thioacetamide as a source of sulfur during a second hydrothermal treatment step. Structural and morphological characterizations demonstrated that the heterostructures can be described as WS2 nanosheets deposited over the tungsten oxide phase. Compared against the respective tungsten oxide seed materials, the heterostructures exhibited significant enhancement of the sensor response to NO2. High sensor signal to a 5 ppm exposure level was observed for the WS2/WO3 microplates at a working temperature of 200 °C, with good selectivity against reducing gases and a sub 2 ppm lower detection limit. To explain the enhancement of the sensor signal, we proposed an electronic sensitization mechanism based on the electronic barriers introduced by the p-n semiconductor junctions. Overall, this work introduces a low-cost, low-temperature, versatile wet-chemical synthetic route for the fabrication of transition metal dichalcogenide-metal oxide heterostructures with potential applications for the development of sensors capable of detecting NO2 at ppm levels.

A novel S-scheme Ws2/BiYWO6 electrostatic heterostructure for enhanced photocatalytic degradation performance towards the degradation of Rhodamine B.

Constructing S-scheme heterojunction between two semiconductor materials is an effective route to increase the photocatalytic degradation efficiency. Here, a novel S-scheme WS2/BiYWO6 heterojunction photocatalyst was prepared by wet chemical route. At the same time, the photocatalytic degradation performance of the fabricated materials was analyzed by the degradation of Rhodamine B under visible light. Of all prepared WS2/BiYWO6 composites, the 20wt.% WS2 loaded WS2/BiYWO6 composite exhibited an enhanced photocatalytic degradation ability than other prepared photocatalysts. Here, O2·- and ·OH radicals are performing a pivotal role in the Rhodamine B degradation and the optimized composite shows greater photocurrent intensity than pure BiYWO6 and WS2, respectively. Also, the synthesized photocatalyst maintains its stability with negligible changes even after three cycles. Thereby, the constructed S-scheme WS2/BiYWO6 heterojunction is a potential material for the wastewater remediation.

Monoclinic-rich CsPbBr3/α-Fe2O3 S-scheme heterojunction for highly efficient thermal-assisted CO2 photoreduction

A new monoclinic-rich CsPbBr3/porous α-Fe2O3 with 3D/3D heterojunction has been prepared by a facile one-step ligand-assisted reprecipitation (LARP) under low temperature and air atmosphere. The morphologies (i.e., cubic and monoclinic phases) of CsPbBr3 are easily tuned by varying the ratios of precursor solution during the LARP process. We observed that monoclinic-rich CsPbBr3 is favorable to the photocatalytic reduction of CO2 with the superior electron consumption rate of 1.42 mmol g−1 h−1. Upon the heterojunction of monoclinic-rich CsPbBr3 with porous α-Fe2O3, the electron consumption rate is further enhanced to 3.38 mmol g−1 h−1, which is ca. 2.4-fold improvements of pristine monoclinic-rich CsPbBr3. More importantly, the activity can maintain ca. 90% after three consecutive cycles of photocatalytic CO2 reduction. The surpassing performance could be attributed to the higher CO2 uptakes, superior charge separation properties of the CsPbBr3/α-Fe2O3 heterojunction. The apparent activation energies of CO and H2 production calculated by the Arrhenius equation are 26.67 and 31.95 kJ mol−1, respectively. Time-resolved photoluminescence and ultraviolet photoelectron spectroscopy were used to evidence that the S-scheme pathway with an interfacial charge transfer constant of 2.53 × 108 s−1 occurs at the interface of monoclinic-rich CsPbBr3/porous α-Fe2O3. This study demonstrates a very simple wet-chemistry route to synthesize efficient morphology-dependent perovskite/α-Fe2O3 heterojunctions with 3D/3D construction which may provide the promising applications in the solar conversions of CO2.

A Review on Pulsed Laser Preparation of Nanocomposites in Liquids and Their Applications in Photocatalysis

The purpose of photocatalysis is to realize the conversion between solar energy and chemical energy, and it is essential to develop a high-performance photocatalyst under visible-light irradiation. The conventional methods for photocatalyst preparation are mainly wet chemical routes, and abundant yields can be obtained. However, the products are not neat and accompanied by chemical groups and impurities, which are not beneficial for the enhancement of photocatalytic performance. In recent years, as a powerful tool for nanomaterial fabrication, pulsed laser heating in a liquid medium has been utilized to prepare a variety of nanocomposites. Products with synergistic effects and high crystallinity can be rapidly prepared under pulsed laser selective heating, which is beneficial for obtaining more effective photocatalytic performance. In this review, the typical characteristics of pulsed laser heating in liquids and their prepared nanocomposites for photocatalytic applications are summarized. This review not only highlights the innovative works of pulsed-laser-prepared nanocomposites in liquids for photocatalysis but also briefly introduces the specific challenges and prospects of this field.

Dielectric capacitance and energy storage performances of organic molecule stabilized hexagonal lead iodide with a layered network

Nanostructured lead iodide particles were synthesized by applying a wet chemical synthesis route in presence of aminobenzene and fluoro-aminobenzene as ligands. The ligands were performed as the stabilizer of the particles. Two types of devices were designed using aminobenzene and fluoro-aminobenzene stabilized lead iodide. The dielectric capacitance, AC-conductivity, field-driven polarization and energy storage performances of the devices were investigated under varying temperature and frequency conditions. The electrical performance of fluoro-aminobenzene stabilized lead iodide-based device exhibited superior performance than that of aminobenzene-stabilized lead iodide-based devices. The fluoro-aminobenzene based device showed the maximum dielectric constant value 398 under the frequency of 100 Hz at 80 °C and maintained a low dielectric loss and high quality factor within the frequency range from 100 Hz to 2 kHz. Both the devices demonstrated the small polaron hopping conduction mechanism. The fluoro-aminobenzene based device maintained a fatigue-free unipolar hysteresis loop under 4 kV/mm with the maximum polarization value of 0.21 μC/cm2 and attended a stable charge and discharge energy density for the period of 103 cycles.

Organic molecule functionalized lead sulfide hybrid system for energy storage and field dependent polarization performances

A wet chemical route is reported for synthesising organic molecule stabilized lead sulfide nanoparticles. The dielectric capacitance, energy storage performances and field-driven polarization of the organic–inorganic hybrid system are investigated in the form of a device under varying temperature and frequency conditions. The structural analysis confirmed the formation of the monoclinic phase of lead sulfide within the organic network. The band structure of lead sulfide was obtained by density functional theory calculation that supported the semiconductor nature of the material with a direct band gap of 2.27 eV. The dielectric performance of the lead sulfide originated due to the dipolar and the space charge polarization. The energy storage ability of the material was investigated under DC-bias conditions, and the device exhibited the power density values 30 W/g and 340 W/g at 100 Hz and 10 kHz, respectively. The electric field-induced polarization study exhibited a fatigue-free behaviour of the device for 103 cycles with a stable dielectric strength. The study revealed that the lead sulfide-based system has potential in energy storage applications.

Hydrothermal synthesis of homogenous and size-controlled uranium-thorium oxide micro-particles for nuclear safeguards

Particle analysis is one of the key-techniques used in the field of nuclear safeguards. Beyond traditional uranium isotopy measurement, other methodologies are implemented to better characterize nuclear materials. Among them, age dating at the particle scale enables to determine the time elapsed since the last chemical step of separation/purification or enrichment. The 230Th-234U couple being one of the most common radiochronometer, there is a need for morphology and size controlled uranium-thorium mixed oxides particles that could be used as reference materials during isotopic measurements. With this aim, uranium-thorium mixed oxide microspheres were synthesized using a wet chemistry route. The hydrothermal conversion of aspartate precursors at T = 433 K led to mixed dioxide micro-particles with controlled spherical morphology and size, up to 5 mol% in thorium. In order to remove impurities, densify the micro-particles, and control the chemical form of the final compounds, heat treatments were performed under various atmospheres. Nearly stoichiometric (U,Th)O2 dioxides were obtained under reducing conditions (Ar-4%H2) while U3O8-based samples were formed under air, with thorium incorporated in the structure up to 2 mol%. Last, the homogeneity of the cation distribution in the samples was evaluated by various methods, including PERALS α-scintillation counting, as well as X-EDS and LG-SIMS analyzes of individual particles, leading to consistent results. Particularly, the relative external reproducibility (2σ) of the 232Th+/238U+ ion ratios measured at the particle scale remained below 10%, paving the way to use these mixed oxide particles in the field of nuclear safeguards.

Colloidal titanium nitride nanobars for broadband inexpensive plasmonics and photochemistry from visible to mid-IR wavelengths

Developing colloidal plasmonic nanomaterials with high carrier density that show optical resonances and photochemical activity extending from the visible to the mid-infrared (MIR) ranges remains a challenging pursuit. Here, we report the fabrication of titanium nitride (TiN) nanobars obtained using a two–step procedure based on a wet chemical route synthesis of TiO2 nanowires and their subsequent high temperature annealing in ammonia flow. Electromagnetic simulations of the resulting TiN nanobars reveal a rich set of optical resonances featuring transverse, longitudinal and mixed transverse–longitudinal plasmonic modes that cover energies from the visible to MIR region. TiN nanobars decorated with Pt co-catalyst nanocrystals show enhanced photocatalytic hydrogen evolution activity in comparison to both isotropic TiN nanospheres of similar size and TiN nanocubes under near infrared excitation at 940 nm due to the enhanced hot electron generation. We also demonstrate that plasmonic TiN nanobars can be used for the detection of furfural molecular vibrations by providing a strong surface enhanced infrared absorption (SEIRA) effect in the MIR region.

Spark Ablation for the Fabrication of PEM Water Electrolysis Catalyst-Coated Membranes

Proton-exchange-membrane (PEM) electrolyzers represent a promising technology for sustainable hydrogen production, owing to their efficiency and load flexibility. However, the acidic nature of PEM demands the use of platinum-group metal-electrocatalysts. Apart from the associated high capital costs, the scarcity of Ir hinders the large-scale implementation of the technology. Since low-cost replacements for Ir are not available at present, there is an urgent need to engineer catalyst-coated membranes (CCMs) with homogeneous catalyst layers at low Ir loadings. Efforts to realize this mainly rely on the development of advanced Ir nanostructures with maximized dispersion via wet chemistry routes. This study demonstrates the potential of an alternative vapor-based process, based on spark ablation and impaction, to fabricate efficient and durable Ir- and Pt-coated membranes. Our results indicate that spark-ablation CCMs can reduce the Ir demand by up to five times compared to commercial CCMs, without a compromise in activity. The durability of spark-ablation CCMs has been investigated by applying constant and dynamic load profiles for 150 h, indicating different degradation mechanisms for each case without major pitfalls. At constant load, an initial degradation in performance was observed during the first 30 h, but a stable degradation rate of 0.05 mV h−1 was sustained during the rest of the test. The present results, together with manufacturing aspects related to simplicity, costs and environmental footprint, suggest the high potential of spark ablation having practical applications in CCM manufacturing.

Silver nanoparticles decorated N-rGO, and NS-rGO nano-hybrids as SERS sensors for hazardous material detection

We design and synthesize nanohybrids composed of Silver nanoparticle (AgNPs) with Nitrogen doped (N-rGO) and Nitrogen-Sulphur co-doped (NS-rGO) with GO, SERS probes for the detection of hazardous materials. Graphene oxide (GO) was synthesized using Hummer’s method, subsequently N-rGO and NS-rGO were achieved by hydrothermal treatment. GO showed sheet structure with partly folds and N-rGO and NS-rGO maintain ultrathin-layered structure even after doping with N and S molecules. The I D /I G ratio of N-rGO and NS-rGO composites were higher than neat GO, indicating incorporation of defects by replacing sp 2 C atoms by N and S atoms. The N-rGO and NS-rGO were further decorated with AgNPs by wet chemical route. Thereafter, nano-hybrids, Ag-N-rGO and Ag-NS-rGO were used as SERS probes for the detection of DNT, PA and DPA molecules. The unique properties of hybrid SERS substrate enables it to achieve nM LOD with excellent reproducibility and five orders of enhancement in Raman intensity. • We design and synthesize N-rGO and NS-rGO nanohybrids. • Synthesized nanohybrids were decorated with AgNPs using wet chemical route. • Fabricated nonohybrids were used as a SERS probes to detect DNT, PA and DPA. • Nanohybrid SERS substrate achieve nM sensitivity with excellent reproducibility. • The five orders of enhancement in intensity were achieved for all the molecules.

Effects of Silica Shell Encapsulated Nanocrystals on Active χ-Fe5C2 Phase and Fischer-Tropsch Synthesis.

Among various iron carbide phases, χ-Fe5C2, a highly active phase in Fischer–Tropsch synthesis, was directly synthesized using a wet-chemical route, which makes a pre-activation step unnecessary. In addition, χ-Fe5C2 nanoparticles were encapsulated with mesoporous silica for protection from deactivation. Further structural analysis showed that the protective silica shell had a partially ordered mesoporous structure with a short range. According to the XRD result, the sintering of χ-Fe5C2 crystals did not seem to be significant, which was believed to be the beneficial effect of the protective shell providing restrictive geometrical space for nanoparticles. More interestingly, the protective silica shell was also found to be effective in maintaining the phase of χ-Fe5C2 against re-oxidation and transformation to other iron carbide phases. Fischer–Tropsch activity of χ-Fe5C2 in this study was comparable to or higher than those from previous reports. In addition, CO2 selectivity was found to be very low after stabilization.

A facile synthesis of PEGylated Cu2O@SiO2/MnO2 nanocomposite as efficient photo-Fenton-like catalysts for methylene blue treatment.

The removal of toxic organic dyes from wastewater has received much attention from the perspective of environmental protection. Metal oxides see wide use in pollutant degradation due to their chemical stability, low cost, and broader light absorption spectrum. In this work, a Cu2O-centered nanocomposite Cu2O@SiO2/MnO2-PEG with an average diameter of 52nm was prepared for the first time via a wet chemical route. In addition, highly dispersed MnO2 particles and PEG modification were realized simultaneously in one step, meanwhile, Cu2O was successfully protected under a dense SiO2 shell against oxidation. The obtained Cu2O@SiO2/MnO2-PEG showed excellent and stable photo-Fenton-like catalytic activity, attributed to integration of visible light-responsive Cu2O and H2O2-responsive MnO2. A degradation rate of 92.5% and a rate constant of 0.086 min-1 were obtained for methylene blue (MB) degradation in the presence of H2O2 under visible light for 30min. Additionally, large amounts of •OH and 1O2 species played active roles in MB degradation. Considering the enhanced degradation of MB, this stable composite provides an efficient catalytic system for the selective removal of organic contaminants in wastewater.

Synthesis of spinel ferrites and application in the photodegradation of Rhodamine in water via pH control assistance

Nanostructured powders of cobalt ferrite with stoichiometry CoxFe3-xO4, where 0.4 ≤ x ≤ 1.2, were synthesized by the wet chemical route from the Co-precipitation method. Single-phase and crystalline nanopowders of spinel type structure with cubic symmetry and space group Fd3‾m were characterized by X-ray diffraction. The structural refinement was carried out by the Rietveld Method showing a transition of normal spinel to an inverse spinel, as a function of Co2+concentration. Both spectra, Infrared Spectroscopy and Diffuse reflectance spectroscopy were used to characterize chemical bonds Co2+ in tetrahedral coordination, for higher cobalt concentration, and band gap analysis, respectively. The photoactivity of powders was evaluated from the photodegradation of the Rhodamine 6G dye under UV light. CoFe2O4 nanoparticles showed the best photocatalytic degradation with 90.9% in an alkaline medium, which obeys a pseudo-first order kinetic reaction, being the maximum apparent rate constant equal to 10.23 × 10−3. Effects of the occupation of tetrahedral and octahedral sites in the spinel structure in the photoactivity parameter are discussed.

Metal Sulfide Artificial Solid-Electrolyte Interface for Improved Lithium Anode Stability

In the last decade, lithium metal has burgeoned into a potential anode material from Li-ion battery to next generation battery systems because of the low redox potential (-3.040 V vs SHE.) and high gravimetric energy density [1-3]. Unlike conventional batteries, the major challenges to be addressed in lithium metal anodes are the dendritic growth, continuous lithium depletion, rapid capacity loss and low Columbic efficiency [4]. These challenges can be averted using electrolyte additives or creating artificial solid electrolyte (SEI) interphases [5]. In the present work, nanostructured transition metal sulfide (MS) and lithium transition metal sulfide (LMS) are used as artificial SEI on lithium metal anode by modifying the lithium metal/electrolyte interfaces and homogenous lithium deposition.The nanostructured transition metal sulfide and lithium transition metal sulfide were synthesized by a simple wet chemical route at relatively low temperatures (150-200 °C). The synthesized LMS were typically of high purity and were filtered, washed, ball-milled, and calcined prior to use in the battery. The microstructure, structure and chemical analysis of the synthesized metal sulfide was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Figure 1(a) shows the morphology of the ball-milled LMS as a layered structure with varying sizes of 10 µm to 100 nm. The EDS analysis of the ball-milled powder majorly showed an M/S ratio of 1:1 and 1:2.The LSM was deposited on Li metal substrate by sputtering technique from a LSM target in Ar atmosphere. This film deposition was carried out at different sputtering time (10 sec -100 sec) and processing pressures. Homogeneous deposition of this LSM of few tens of nanometers thickness was successfully achieved. The electrochemical performance of the LSM artificial SEI was investigated in symmetric cells of two coated Li electrodes and compared to bare Li (Figure 1(b)). At different current densities of 0.5 and 1 mA/cm2, repeated Li plating and stripping revealed an enhanced cycling performance of metal sulfide coated Li compared to bare Li electrode. To better understand the interfacial stability, electrochemical impedance spectroscopy (EIS) studies were performed at different stages of cycling. The cycling performance of coated and bare Li anode was performed in a full cell containing NMC811 as cathode. After cycling, the microstructural changes in lithium metal anode were explored using SEM. Figure 1: (a) SEM image of the ball-milled layered lithium metal sulfide and (b) Time-voltage profiles of the symmetric cells with Li anode and coated Li anode at the current density of 0.5 mA/cm2 References [1] D. Lin, Y. Liu, Y.Cui, “Reviving the Lithium Metal Anode for High-Energy Batteries”, Nature Nanotechnology, 12 (2017), 194-206.[2] D. Aurbach, B.D. McCloskey, L.F. Nazar, P.G. Bruce, “Advances in Understanding the Mechanisms Underpinning Lithium-air Batteries”, Nature Energy, 1 (2016) 16128.[3] W. Xu, J. Wang, F. Ding, X.Chen, E. Nasybulin, Y. Zhang, J.G. Zhang, “Lithium metal Anodes for Rechargeable Batteries”, Energy and Environmental Science, 7 (2014) 513-537.[4]J. Liu, Z. Bao, Y. Cui, E.J. Dufek, J.B. Goodenough, P. Khalifah, Q. Li, B.Y. Liaw, P. Liu, A. Manthiram, Y.S. Meng, V.R. Subramanian, M.F. Toney, V.V. Viswanathan, M.S. Whittingham, J. Xia, W. Xu, J. Yang, X.Q. Yang, J.G. Zhang, "Pathways for Practical High-Energy Long Cycling Lithium Metal Batteries", Nature Energy, 4 (2019) 180-186.[5] K Kim, M. Balaish, M. Wadaguchi, L. Kong, J. Rupp, “Solid State Batteries: Solid-State Li-metal Batteries: Challenges and Horizons of Oxide and Sulfide Solid Electrolytes and their Interfaces”, Advanced Energy Materials, 11 (2021) 2170002 Figure 1

Photoluminescence properties of Eu3+-doped Na2CaSiO4 phosphor prepared by wet-chemical synthesis route

The present investigation focuses on the development of Eu3+ activated phosphors for near ultraviolet (NUV) excited light emitting diode (LED) applications. In this investigation, we have synthesized a series of Na2CaSiO4:Eu3+phosphors via wet-chemical method and characteristic of synthesized phosphors have been analyzed by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Thermo gravimetric analysis– Differential thermal analysis (TGA–DTA) and photoluminescence (PL) techniques. The recorded excitation band indicates a broad excitation band centered at 262 nm due to charge transfer (CT) band and sharp peaks at 395 nm and 466 nm due to 7F0→5L6 and 7F0→5D2 transition of Eu3+ ions. The highest excitation intensity was observed at 396 nm wavelength. Therefore under 396 nm excitation, the emission spectrum showed characteristics peaks located at 595 nm and 615 nm, which are attributed due to the 5D0→7F1 and 5D0→7F2 transition of Eu3+ ions. Emission spectra shows dominant emission peak at orange region around 595 nm due to the magnetic dipole transition of5D0→7F1. In addition, the effects of the Eu3+ ions on the emission intensity were investigated, it was found that the emission intensity increases as the concentration of Eu3+ ions increases up to 0.5 mol%. Thereafter, PL emission intensity was decreased due to concentration quenching. The CIE Chromaticity coordinate of the prepared phosphor was located in the orange region around (0.584, 0.421) with high color purity. As per the investigation of prepared Na2CaSiO4:Eu3+phosphors, it was concluded that it is a promising candidate for lighting and display applications.

Ruthenium and Nickel Molybdate-Decorated 2D Porous Graphitic Carbon Nitrides for Highly Sensitive Cardiac Troponin Biosensor.

Two-dimensional (2D) layered materials functionalized with monometallic or bimetallic dopants are excellent materials to fabricate clinically useful biosensors. Herein, we report the synthesis of ruthenium nanoparticles (RuNPs) and nickel molybdate nanorods (NiMoO4 NRs) functionalized porous graphitic carbon nitrides (PCN) for the fabrication of sensitive and selective biosensors for cardiac troponin I (cTn-I). A wet chemical synthesis route was designed to synthesize PCN-RuNPs and PCN-NiMoO4 NRs. Morphological, elemental, spectroscopic, and electrochemical investigations confirmed the successful formation of these materials. PCN-RuNPs and PCN-NiMoO4 NRs interfaces showed significantly enhanced electrochemically active surface areas, abundant sites for immobilizing bioreceptors, porosity, and excellent aptamer capturing capacity. Both PCN-RuNPs and PCN-NiMoO4 NRs materials were used to develop cTn-I sensitive biosensors, which showed a working range of 0.1–10,000 ng/mL and LODs of 70.0 pg/mL and 50.0 pg/mL, respectively. In addition, the biosensors were highly selective and practically applicable. The functionalized 2D PCN materials are thus potential candidates to develop biosensors for detecting acute myocardial infractions.

Dielectric Behaviour and Electrical Conductivity of α-BiNbO4 and β-BiNbO4 Ceramics

In this work, orthorhombic (α-BiNbO4) and triclinic bismuth niobate (β-BiNbO4) ceramics were prepared by a wet chemical route. The structure of the obtained powders was characterised by X-ray diffraction and the morphology by scanning electron microscopy. The dielectric measurements were performed in the radiofrequency region, at different temperatures, using the impedance spectroscopy technique. The α-BiNbO4 sample presented a temperature-dependent relaxation process, with the corresponding activation energy being calculated through the Arrhenius equation. The AC conductivity dependence on the frequency was in agreement with Jonscher’s universal power. The conduction mechanism in the α-BiNbO4 compound is governed by two processes, which can be ascribed to a hopping transport mechanism. The correlated barrier hopping model until 280 K and the non-overlapping small polaron tunnelling model above 280 K are the most suitable models to describe the conductivity of this sample. In the β-BiNbO4 compound, the motion of mobile charge carriers involves localised hopping between neighbouring sites.