Synthesis Of Nitride Research Articles

Synthesis, Characterization and Dissolution behavior of Nitrides of U-Zr and U-Pu-Zr metallic alloy fuels for Aqueous reprocessing

The aqueous based PUREX process is an alternate choice to pyro-reprocessing of metallic alloy fuels (U-Zr/U-Pu-Zr). Direct dissolution of metallic alloy fuels in a nitric acid medium is not feasible due to vigorous reaction exhibited by the alloys when exposed to this medium. Conversion of metallic alloys into their oxides is a challenging method due to poor dissolution of oxides in nitric acid. Excellent dissolution of nitrides compared to oxides of metallic alloy fuels lead to exploit the nitride route for aqueous reprocessing. Hence, a novel method was adopted to prepare the nitrides of unirradiated U-Zr and U-Pu-Zr alloys via hydridation using UH3, as source-cum-getter instead of hydrogen cylinder. In this context, nitrides of unirradiated U-Zr/U-Pu-Zr metallic alloys were prepared by nitridation via hydridation. Initially, nitrides of U and Zr metals were synthesized and the formation of ZrN and U2N3 and UN phases were confirmed by powder X-ray diffraction measurements. Subsequently, nitrides of unirradiated U-Zr and U-Pu-Zr alloys were synthesized and characterized by X-ray diffraction, scanning electron microscopy and particle analyzer. The dissolution behavior of nitrides of Zr, U, U-Zr and U-Pu-Zr alloys were examined in nitric acid (12 M) medium under reflux conditions at 383 K for 8 h. The present study highlights the potential of the nitride route for efficient dissolution of actinides (U and Pu) and it is very important to develop flow sheets for the aqueous reprocessing of metallic alloys fuels.

Template-free synthesis of hierarchical graphitic carbon nitride (H-gC3N4) embedded with NiO for water splitting and CO2 reduction with the role of hole scavenger: A comparative investigation

Hierarchical graphitic carbon nitride (H-gC3N4) embedded with nickel oxide (NiO) were synthesized using a template-free hydrothermal approach. The performance of NiO/H-gC3N4 composite was investigated for photocatalytic water splitting in a slurry system to produce H2. Similarly, photocatalytic CO2 reduction to generate CO under visible light was conducted in a gas-phase photoreactor system. Optimized 2% NiO/H-gC3N4 composite enables H2 production of 1010 μmol g−1 h−1, which was 13.93 folds higher than using pure H-gC3N4. Similarly, the highest CO evolution rate of 96.7 μmol g−1 h−1 was obtained, 3.85 folds higher than using H-gC3N4. The enhanced photoactivity resulted mainly from the distinctive interlayer structure, improved light penetration, reduced charge carrier recombination and increased surface-reactive active sites. The methanol sacrificial reagent, owing to its capacity to generate extra protons, proved pathways in augmenting the yields of both H2 and CO. While the efficiency of water splitting for H2 production surpassed that of CO2 reduction, it exhibited lower stability. The recently developed composite demonstrated consistent and sustained photocatalytic efficiency for CO production throughout five consecutive cycles.

Facile one-pot synthesis of niobium-containing carbon nitride and the catalytic application for synthesis of dimethyl carbonate

Dimethyl carbonate (DMC) is a building block in wide chemical-related fields and the transesterification of ethylene carbonate (EC) and methanol/ethanol is a sustainable route for the synthesis of DMC. Herein, in order to explore efficient heterogeneous catalysts, niobium-containing carbon nitride materials were synthesized by a convenient one-pot calcination method. By reserving the main chemical functionalities of carbon nitride, the Nb-CN composites contained both acidic and basic properties, and Nb can be dispersed by carbon nitride. In the transesterification of EC with methanol, under the reaction temperature of 140 °C and reaction time of 4 h, the conversion of EC and the selectivity of DMC reached 53.8% and 100%, respectively, and the activity of the catalyst did not decrease significantly after several recycling runs. Furthermore, the Nb-CN could promote transesterification reactions of other cyclic carbonate and alcohols.

In-situ synthesis of dual-phase nitrides and multiple strengthening mechanisms in FeCoCrNiAl0.5 high entropy matrix composite coatings by laser cladding and plasma nitriding

To enhance the wear resistance of high entropy alloy (HEA) coatings and broaden their applications under extreme conditions, this study proposed an in-situ synthesis process of a dual-phase strengthened nitrides layer on laser cladded HEA coating. The microstructural evolution and mechanical properties of FeCoCrNiAl0.5 HEA coating by plasma nitriding were systematically investigated, revealing formation and strengthening mechanisms of nitrides. In comparison to the traditional nitrided substrate 38CrMoAl, the results showed that the nitrided HEA coating exhibited high hardness and wear resistance, characterized by dual-phase nitrides AlN+CrN due to the negative Gibbs free energy, negative nitride formation enthalpy and higher atomic specific surface areas. While only a single-phase iron nitride with lower hardness was obtained on the nitrided 38CrMoAl. The microhardness and wear mass loss of the nitrided HEA coating were 1167 HV and 0.435×10−6 mg/mm, respectively, which were 33.4% higher and 63.3% lower than those of the nitrided 38CrMoAl. The strengthening effects attributed to the refinement of dual-phase nitrides, interstitial solid solution by N atoms, dispersion strengthening by higher proportion of nitrides.

Controllable fabrication of N-doped carbon nanotubes coated Co4N nanoparticles to boost hydrogen evolution reaction

Transition metal nitrides (TMNs) have attracted great attention as ideal active materials in the field of electrocatalysts in recent years due to their excellent electrical conductivity, wide band gap and adjustable morphology. Pure phase Co4N nanoparticles encapsulated nitrogen-doped carbon (NC) nanotubes (Co4N@NC) were in-situ synthesized by one-pot method. In this paper, the morphology of carbon nanotubes is controlled by adjusting the pyrolysis time, so that more active sites are exposed on carbon nanotubes. Thus, the cobalt nitride catalyst with excellent catalytic performance for hydrogen evolution reaction (HER) in acidic electrolyte was obtained. In summary, due to the protection of mesoporous nitrogen-doped carbon to Co4N nanoparticles, large electrochemically active surface area, good conductivity and more exposed active sites, Co4N@NC possesses excellent HER performance in acidic electrolytes. The overpotential of Co4N@NC at the current density of 10 mA cm−2 is 117 mV (η10), and it shows long-term stability in 0.5 M H2SO4 solution for 50 h. This study provides a strategy for the development of catalysts for the controllable synthesis of high-performance transition metal nitrides.

Tailored Synthesis of CN-PPy Composite for Enhanced Electrochemical Functionality

This study details the synthesis of pure carbon nitride (CN) and composite polypyrrole through an in-situ polymerization method. The prepared samples were comprehensively characterized using Fourier Transform Infrared Spectroscopy (FT-IR), Field Emission Scanning Electron Microscopy (FESEM), and X-ray Diffraction (XRD). These analyses confirmed the chemical bonding, structural, and morphological characteristics of the products. Electrochemical measurements, conducted through cyclic voltammetry (CV) and Linear Sweep Voltammetry (LSV), revealed significant current rates in both anodic and cathodic peaks, indicating superior electrochemical properties. This work not only details the synthesis process but also provides a thorough understanding of the structural, morphological, and electrochemical aspects, exhibiting the materials’ potential for various applications in electrochemical devices.

Density functional theory study of the reaction mechanism of aluminum nitride synthesis by sol–gel method

In recent years, aluminum nitride has undergone significant advancements and has found extensive application in optoelectronic and microelectronic devices due to its remarkable physicochemical properties. The quality of aluminum nitride powder plays a critical role in determining device performance, thus making the synthesis of high-quality powder a prominent area of research. The sol–gel method is a widely used approach for producing superior powders. In this study, we investigated the ammonolysis-polymerization mechanism of tris(dimethylamino)aluminum monomer and dimer using Gaussian16 software at the B3LYP-D3BJ/6-311G(d,p) level. Our objective was to provide theoretical guidance for the experimental synthesis of aluminum nitride powders using the sol–gel method. Our findings demonstrate that the ammonolysis reaction of tris(dimethylamino)aluminum dimer proceeds through six spontaneous steps. The two calculated polymerization steps also exhibit spontaneous behavior. All reactions demonstrate rapid occurrence, suggesting the theoretical feasibility of the ammonolysis-polymerization reaction of tris(dimethylamino)-aluminum dimer for synthesizing aluminum nitride.

A facile synthesis of 2D bimetallic solid solution nitrides for robust stability in lithium-ion battery

Nanostructured transition metal nitrides (TMNs) demonstrate immense promise for lithium-ion battery applications owing to their outstanding conductivity and high theoretical capacity. However, challenges such as the expansion of volume, aggregation concerns, and rapid capacity decay still need to be effectively addressed. Herein, a facile synthesis of 2D nitrides, including TiVN, NbVN and TiNbN, is achieved through nitriding their corresponding MXenes. The distinct 2D layered structure enables them fast lithium-ion transport and inhibits volume variation, thereby improving rate performance and stability. Moreover, the incorporation of bimetallic elements in solid solution induces lattice distortion, creating lattice vacancies and increasing lithium storage capacity. Atomic-level interactions within solid solutions, confirming by the shifts of binding energy, contribute to improved structural stability and accelerated charge transfer. The theoretical calculation further proves that the bimetallic solid solution structure elevates the d-band center and increases the Li+ adsorption energy. Consequently, the synthesized TiVN, NbVN and TiNbN demonstrate remarkable lithium storage performance. Especially, NbVN with a porous morphology stands out by achieving a specific capacity of 216.6 mAh/g after 1,400 cycles at 1 A/g, significantly outperforming Nb4N5 and VN. This work may provide valuable insights for the efficient synthesis and electrochemical applications of two-dimensional solid-solution nitrides.

Use of graphitic carbon nitrides as solar-light-driven photocatalysts for the reduction of p-nitrobenzoic acid

The use of graphitic carbon nitrides (g-C3N4) as photocatalysts for the reduction of p-nitrobenzoic acid (PNBA) under simulated sunlight has been investigated. The photocatalysts were synthesized through the thermal polymerization of melamine and urea. The effects of the g-C3N4 precursor employed in the synthesis, the thermal exfoliation treatment, the addition of sacrificial agents, and the pH conditions were evaluated. It was found that the presence of carboxylic acids as sacrificial electron donors was required to attain the photocatalytic reduction of PNBA, while amines or alcohols did not lead to any activity for this purpose. Furthermore, it was observed that the precursor used in the synthesis of graphitic carbon nitride had a slight influence on the photocatalytic activity, whereas the thermal treatment of the bulk g-C3N4 materials exhibited a favourable effect. The best results were obtained upon addition of oxalic acid at pH = 3 using the carbon nitride exfoliated materials, achieving in these conditions the complete removal of PNBA after ca. 60 min of irradiation. Time resolved profiles of p-aminobenzoic acid (PABA) agree with an initial reduction of PNBA to form this compound, followed by oxidation of PABA by reactive oxygen species formed in the reaction medium.

Coupling NiFe-MOF with antiperovskite nickel-based nitrides as efficient electrocatalysts for overall water splitting

The exploration of high-performance, durable and cost-effective catalysts for overall water splitting, including the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), has always been a vibrant topic in electrochemical water splitting techniques. Here we report a facile strategy for the synthesis of antiperovskite bimetallic nitrides (FeNNi3 and CuNNi3) and their NiFe-MOF morphology on nickel foams (NF) for HER and OER respectively in alkaline media. The NiFe-MOF and FeNNi3 nanoparticle exhibit strong coupling and synergistic effects, resulting in a solid integrated structure and fast electron transfer. The FeNNi3 towards HER shows an overpotential of 57 mV at 10 mA cm−2 in alkaline media, and its MOF morphology shows a low overpotential of 219 mV at 10 mA cm−2 towards OER. The alkaline electrolyzer of FeNNi3/NF || NiFe-MOF@FeNNi3/NF for overall water splitting demonstrates a low cell voltage of 1.49 V at 10 mA cm−2 with high cycling durability. This work investigates antiperovskite nitrides' capabilities for overall water splitting and provides guidance on designing high-performance catalytic materials.

In-situ synthesis of nitrides and oxides through controlling reactive gas atmosphere during laser-powder bed fusion of Fe-12Cr-6Al

This study endeavors to investigate the feasibility of in situ synthesis of nitrides and oxides within Fe-12Cr-6Al alloys through precise modulation of reactive gas atmosphere during the Laser-Powder Bed Fusion process. A focused study on elucidating the effects of critical process parameters, such as laser power, scanning speed, and hatch distance, was undertaken to discern their impact on the material's microstructure, oxygen/nitrogen content, and hardness. Synthesis of nano-sized AlN and Al2O3 precipitates within the Fe-12Cr-6Al matrix was achieved when nitrogen was used for a process gas. A rise in laser power from 120 W to 200 W, coupled with a reduction in scanning speed from 1200 mm/s to 400 mm/s, resulted in decreased porosity and an increase in grain size. Additionally, all printed samples showed lower oxygen content compared to the initial powder, while nitrogen ratios were notably higher. A marginal increase of the Vickers hardness value, from 240 ± 4.5 to 266 ± 3 HV, was observed as the laser power increased and the scanning speed decreased. The hardness values were higher than those obtained from different production methods with identical compositions. These compelling results suggest a positive impact of nitride precipitates and oxide precipitates to improve hardness values.

Cyanuric Acid-Assisted Synthesis of Hierarchical Amorphous Carbon Nitride Assembled by Ultrathin Oxygen-Doped Nanosheets for Excellent Photocatalytic Hydrogen Generation.

Amorphous carbon nitride with typical short-range order arrangement as an effective photocatalyst is worth exploring but remains a great challenge because its disordered structure induces severe recombination of photogenerated charge carriers. Herein, for the first time, we demonstrate that a hierarchical amorphous carbon nitride (HACN) with structural oxygen incorporation can be synthesized via a cyanuric acid-assisted melem hydrothermal process, accompanied by freeze-drying and pyrolysis. The complex composed of melem and cyanuric acid exhibiting a unique 3D self-supporting skeleton and significant phase transformation is responsible for the formation of an interconnected hierarchical framework and amorphous structure for HACN. These features are beneficial to enhance its visible light harvesting by the multiple-reflection effect within the architecture consisting of more exposed porous nanosheets and introducing a long band tail absorption. The well-designed morphology, band tail state, and oxygen doping effectively inhibit rapid band-to-band recombination of the photogenerated electrons and holes and facilitate subsequent separation. Accordingly, the HACN catalyst exhibits exceptional visible light (λ > 420 nm)-driven photoreduction for hydrogen production with a rate of 82.4 μmol h-1, which is 21.7 and 9.5 times higher than those of melem-derived carbon nitride and crystalline nanotube carbon nitride counterparts, respectively, and significantly surpasses those of most reported amorphous carbon nitrides. Our controlling of rearrangement of the in situ supramolecular self-assembly of melem oligomer using cyanuric acid directly instructs the development of highly efficient amorphous photocatalysts for converting solar energy into hydrogen fuel.

Improved quantum-mechanical model for evaluating the difficult synthesis of nitride and oxygen perovskites

Most nitride perovskites have been reported using computational prediction; very few have been synthesized experimentally. Using an improved quantum-mechanical model, we predicted that four hexavalent cations, Mo6+, Os6+, Po6+ and Ru6+, can dope the nitride perovskites LaWN3 and LaReN3, and we explain why most of the numerically predicted nitride perovskites are more difficult to synthesize than oxygen perovskites. Based on first principles, the calculated results for the structural and stable properties of the doped perovskites LaW1-xBxN3 (BMo6+, Os6+, Po6+ and Ru6+) also confirm the accuracy of the improved model. The proposed model suggests that there are two potential barriers in nitride perovskites, whereas oxygen perovskites have one potential barrier and a potential well between the cations and anions. The numerical results show that the width of the potential well or second potential barrier plays a crucial role in the successful synthesis of perovskites. This model is of great value for the future synthesis of perovskites.

Nitrogen-Rich Molybdenum Nitride Synthesized in a Crucible under Air.

The triple bond in N2 is significantly stronger than the double bond in O2, meaning that synthesizing nitrogen-rich nitrides typically requires activated nitrogen precursors, such as ammonia, plasma-cracked atomic nitrogen, or high-pressure N2. Here, we report a synthesis of nitrogen-rich nitrides under ambient pressure and atmosphere. Using Na2MoO4 and dicyandiamide precursors, we synthesized nitrogen-rich γ-Mo2N3 in an alumina crucible under an ambient atmosphere, heated in a box furnace between 500 and 600 °C. Byproducts of this metathesis reaction include volatile gases and solid Na(OCN), which can be washed away with water. X-ray diffraction and neutron diffraction showed Mo2N3 with a rock salt structure having cation vacancies, with no oxygen incorporation, in contrast to the more common nitrogen-poor rock salt Mo2N with anion vacancies. Moreover, an increase in temperature to 700 °C resulted in molybdenum oxynitride, Mo0.84N0.72O0.27. This work illustrates the potential for dicyandiamide as an ambient-temperature metathesis precursor for an increased effective nitrogen chemical potential under ambient conditions. The classical experimental setting often used for solid-state oxide synthesis, therefore, has the potential to expand the nitride chemistry.

Evaluating the influencing mechanism of solvents on the self-assembly synthesis of carbon nitride towards a high photocatalytic performance

The micro-structure of photocatalyst is an underlying factor affecting its activity. This work aims to clarify and get an applicable knowledge concerning the influences of different solvents on the formation of carbon nitride (CN) with different microstructures. In this bottom-up preparation of CN, solvent with smaller molecule size and lower viscosity benefits the insertion, avoiding a bulk structure. Furthermore, solvent with stronger polarity tends to cause rough and irregular surface. The CN sample prepared using ethanol as solvent (CN-E) shows the lowest PL emission and the highest photocatalytic activity compared to its counterparts, owing to its ideal hollow structure with moderate aspect ratio. The results synergistically address that: 1) Solvent with smaller molecule size，lower viscosity and moderate polarity results in an ideal hollow microstructure; 2) this microstructure is beneficial to the mass transfer and further photocatalytic process; 3) light-harvesting and conversion efficiencies are greatly improved thanking to the multi-reflection of light brought by the hollow structure. It can be concluded that the photocatalytic activity of carbon nitride is closely related with its microstructure which can be effectively tuned through the use of solvents, and we expect that by establishing this correlation, applicable knowledge could be acquired and so as to apply.

In-situ synthesis of TiN and its effects on Fe-12Cr-6Al in laser powder bed fusion

This study examines the feasibility of in-situ synthesis of various nitride and oxide precipitates and their impact on Fe-12Cr-6Al alloy characteristics using an N2 reactive gas atmosphere and Ti addition during the L-PBF process. This study focused on elucidating the effects of adding Ti on the Fe-12Cr-6Al's melt pool dynamics, microstructure, precipitate characteristics, oxygen/nitrogen content variation, and mechanical properties. Without Ti, the resulting melt pools exhibited a shallow and wide morphology, contrasting with the formation of compact and deeper melt pools in the presence with Ti. Furthermore, Ti-based nitrides yielded a discernible enhancement in grain refinement compared to Al-based nitrides. In-situ Al2O3, AlN, and AlN-O nano precipitates were synthesized within the Fe-12Cr-6Al matrix with the nitrogen process gas. However, adding Ti transformed the nanoparticles, resulting in TiN, TiAl-N, and Al2O3@TiN. The addition of Ti increased the oxygen content from 0.0051 to 0.0315 wt.% and the nitrogen content from 0.02 to 0.08 wt.%. In-situ synthesis of Ti-rich precipitates and the solid solution effect of Ti led to significant mechanical property enhancement, including a yield strength (YS) of ∼109 MPa, ultimate tensile strength (UTS) of ∼200 MPa, a total elongation (TE) of ∼7.4%, and a Vickers hardness (HV) of ∼47. This study offers compelling and thorough evidence regarding the in-situ synthesis of diverse nitride and oxide nano-precipitates. It explores how the addition of Ti to the FeCrAl alloy alters the types and shapes of nitride and oxide nano-precipitates and assesses the impact of these precipitates on the properties of the Fe-12Cr-6Al alloy.

High-temperature synthesis of cast vanadium nitrides and aluminum oxynitrides

This paper presents experimental results concerning the one-step preparation of cast divanadium nitride and aluminum oxynitride (AlON) by high-temperature synthesis under 5 MPa of N2 from green mixtures containing vanadium oxide, aluminum, and aluminum nitride. It was shown that the mixtures with a wide range of component ratios are capable to burn with the temperature exceeding the melting point of the final products, divanadium nitride and aluminum oxynitride, that makes it possible to obtain them in the form of a melt with subsequent separation of vanadium nitride (lower ingot) and aluminum oxynitride (upper ingot). The resulting products had no cohesion and were easily separated from each other. Variation in the content of aluminum nitride in the charge markedly affected the synthesis process, phase composition, and microstructure of the target products. The content of excess aluminum nitride in the starting mixture α = 10% was found to be optimum on a yield/composition of the target products.

One-Step Synthesis of Alkali Metal-Hydroxyl Double Modified Graphite Phase Carbon Nitride and Photocatalytic Degradation of Phenolic Compounds

In this work, potassium ion-hydroxyl double modified graphite phase carbon nitride (KCN–OH) was synthesized in one step by alkali hydrothermal (AH) method. The as-prepared catalysts were characterized by XRD, FT-IR, UV–Vis, N2 adsorption, SEM, XPS, PL, ESR, TPD and EIS. The introduction of potassium ion causes the reduced crystal size, increased specific surface area and promoted electron–hole separation efficiency of as-prepared catalyst. The hydroxyl group not only further improves the electron–hole separation efficiency but, as the electron donor group, can also make stronger interaction between catalyst and acidic phenolic compounds. The photocatalytic degradation of phenol was investigated under visible light. The results show that the phenol degradation rate constant of KCN–OH is 0.22 h[Formula: see text] under visible light, which is over 3.7 and 2.0 times higher than that of neat g-C3N4 and single hydroxyl-modified g-C3N4. KCN–OH also displays outstanding catalytic and structural stability. The possible reaction mechanism is discussed in this paper.

High temperature synthesis, surface characterization, and photoluminescence property of boron carbon nitride

The present study demonstrates the synthesis of boron carbon nitride (BCN) by molten salt method which utilizes melamine (source of carbon and nitrogen), boric acid (source of boron) and potassium chloride as the salt. The synthesis is performed at 915 °C for 4 h under N2-atmosphere. The synthesized material is further acid-treated. The physicochemical characterization data for as-synthesized and acid-treated materials confirm successful synthesis of BCN. SEM and AFM data display that synthesized BCN pre and post acid-treatment exhibit sheet-type morphology. Thermogravimetric analysis data confirm that the acid-treated material is thermally stable up to 800 °C, with only 2 % mass-loss is observed till 800 °C. Water contact angle measurement study demonstrates that acid-treatment significantly improves the surface hydrophilicity. Additionally, the low photoluminescence peak intensity of the acid-treated material indicates low electron-hole pair recombination rate. The synthesized material may be useful for the photocatalytic degradation of potentially toxic chemicals from water.

Mechanochemically synthesized MnO2-gCN nanocomposite for photocatalytic dye and phenol degradation: A combined experiment and DFT study

We present the large-scale synthesis of Manganese dioxide-graphitic carbon nitride (MnO2-gCN) nanocomposite using a mechanochemical process. Hydrothermally synthesized rod-shaped MnO2, combined with pyrolyzed gCN powder in appropriate proportions was mechanically ball-milled to form the MnO2-gCN composite structure. The resulting nanocomposite characterized through X-ray diffraction, Fourier transformed infrared spectroscopy, scanning electron microscopy, UV–Vis spectroscopy, and photoluminesce study revealed the successful anchoring of gCN with MnO2 nanostructure. Subsequently, the photocatalytic activity of MnO2-gCN nanocomposite was assessed by studying the degradation of Rhodamine B, Eosin B, Congo red, Methylene Blue dyes and toxic phenol pollutants under UV light exposure. The MnO2-gCN hybrid catalyst demonstrated impressive degradation efficiency, ca. 90% for Rhodamine B dye and 70% for phenol in 3 h and remarkable stability upto three cyclic runs. The superior performance of the composite, in comparison to its individual counterparts (MnO2 or gCN), can be attributed to the effective separation of photogenerated electron-hole (e−−h+) pairs and the suppression of charge recombination at the interface. First principle based density functional theory calculations also support the experimental findings and the conclusion of this study.