Mixture Of Urea Research Articles

Multicomponent Synthesis of C(8)-Substituted Purine Building Blocks of Peptide Nucleic Acids from Prebiotic Compounds.

We have explored the reaction of a three-components mixture of aminomalononitrile, urea and α-amino acid methyl esters for the multicomponent synthesis substituted purines resembling PNA's building blocks. 2,6-diamino-purines, 6-amino-3,9-dihydro-2H-purin-2-one (iso-guanines), and 3,9-dihydro-6H-purin-6-one derivatives, selectively decorated at C(8)-position of the purine ring with different amino acid residues, were obtained from acceptable to good yields. The regio-selectivity of the transformation was controlled by the use of urea in the ternary mixture and by the annulation agent involved in the ring-closure of amino-imidazole carbonitrile intermediates. Solvent free conditions, microwave irradiation and simple one-carbon containing reagents further satisfied the major requirement of atom economy and sustainable chemistry. Due to the prebiotic nature of the three-components mixture and of annulation agents, it also embodies the possibility for the synthesis of novel PNAs bearing purine nucleobases decorated at C(8)-position of the imidazole ring as alternative RNA analogues in molecular evolution.

Analysis of potential genotoxicity of deicing material in the test for induction of dominant lethal mutations in germ cells of male Drosophila

Introduction. Long-term use of deicing materials (DM) is one of the significant factors causing the active distribution of various chemical compounds that are part of multicomponent deicing mixtures in the environment. In this regard, the expansion of methodological approaches to assessing their biological hazard remains important. Materials and methods. The DM used for research based on a mixture of urea with magnesium and ammonium nitrates. The DM was tested in the form of an aqueous solution and added to the soil to obtain an aqueous extract. The analysis includes test for induced dominant lethal mutations in Drosophila male germ cells. Results. All samples tested significantly reduced the fertility of Drosophila males. The frequencies of early dominant lethal mutations (EDLM) significantly exceeded the levels of the controls, and the effects of the soil extract appeared at the lowest concentration – 5 g/L and of the DM solution – 10 g/L. The trend in the rate of late dominant lethal mutations (LDLM) indicates to the death of sperm or a decrease in mating potency. Limitations. The method of inducing dominant lethal mutations in Drosophila melanogaster and the genotoxic effects assessment of DM in the germ cells of male flies within the study has no restrictions. Conclusion. The conducted test is so far the only one in the field of research into the genetic safety of multicomponent DMs using a method for induced dominant lethal mutations in Drosophila male germ cells. The results prove the high informative rate of the methodological approach which involves analyzing soil extracts to identify and assess a genotoxicity of DM component composition when it enters the soil which can become as a transit layer for migration of DM components and their products transformation into groundwater.

Recycling potential of Cupriavidus necator for life support in space: Production of SCPs from volatile fatty acid and urea mixture

The International Space Station currently requires four annual replenishments for food supply, a practice that won't be feasible for deep space missions due to the greater distances. Based on the design of closed ecological life support systems, two waste streams were identified: urea from the crew urine, volatile fatty acids (VFAs) from a first stage of anaerobic digestion of waste. The objective of this study was to assess the ability of bacterium Cupriavidus necator to produce single cell protein on urea and VFAs. Thus, the effect of carbon sources (glucose vs VFAs) and the dilution rate on the biomass composition was determined in continuous cultures. Complete transformation of the carbon source into protein-rich biomass was achieved up to 78 % cell dry weight (CDW). For both carbon sources, the protein content increased from 55.0 %CDW to 78 %CDW with a decrease in the dilution rate. Conversely, the nucleic acid and polyhydroxyalkanoate contents decreased with the dilution rate from 8.8 %CDW to 4.8 %CDW and 9.8 %CDW to 0.6 %CDW respectively. Working at a low dilution rate seems to be a good way to maximize protein content while minimizing unwanted nucleic acids and polyhydroxyalkanoates.

Structure and transport properties of LiTFSI-based deep eutectic electrolytes from machine-learned interatomic potential simulations.

Deep eutectic solvents have recently gained significant attention as versatile and inexpensive materials with many desirable properties and a wide range of applications. In particular, their characteristics, similar to those of ionic liquids, make them a promising class of liquid electrolytes for electrochemical applications. In this study, we utilized a local equivariant neural network interatomic potential model to study a series of deep eutectic electrolytes based on lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) using molecular dynamics (MD) simulations. The use of equivariant features combined with strict locality results in highly accurate, data-efficient, and scalable interatomic potentials, enabling large-scale MD simulations of these liquids with first-principles accuracy. Comparing the structure of the liquids to the reported results from classical force field (FF) simulations indicates that ion-ion interactions are not accurately characterized by FFs. Furthermore, close contacts between lithium ions, bridged by oxygen atoms of two amide molecules, are observed. The computed cationic transport numbers (t+) and the estimated ratios of Li+-amide lifetime (τLi-amide) to the amide's rotational relaxation time (τR), combined with the ionic conductivity trend, suggest a more structural Li+ transport mechanism in the LiTFSI:urea mixture through the exchange of amide molecules. However, a vehicular mechanism could have a larger contribution to Li+ ion transport in the LiTFSI:N-methylacetamide electrolyte. Moreover, comparable diffusivities of Li+ cation and TFSI- anion and a τLi-amide/τR close to unity indicate that vehicular and solvent-exchange mechanisms have rather equal contributions to Li+ ion transport in the LiTFSI:acetamide system.

ЕЛЕКТРОХІМІЧНЕ ОСАДЖЕННЯ НАНОКРИСТАЛІЧНОГО КОМПОЗИТУ НІКЕЛЬ–ЦЕРІЮ(IV) ОКСИД З НИЗЬКОТЕМПЕРАТУРНОГО ЕВТЕКТИЧНОГО РОЗЧИННИКА ДЛЯ ВИГОТОВЛЕННЯ ЕЛЕКТРОКАТАЛІЗАТОРІВ ДЛЯ ВОДНЕВОЇ ЕНЕРГЕТИКИ

This study reports the patterns of electroplating a composite coating containing phases of nanocrystalline metallic nickel and cerium dioxide from an electrolyte based on a new generation of ionic liquids, deep eutectic solvents (DESs). Currently, the use of DESs is an extremely promising direction for the electrochemical deposition of electrocatalytic coatings for electrochemical energy, particularly for "green" hydrogen energy. The electrolyte for deposition contained a liquid eutectic mixture of choline chloride and urea (the so-called "reline", a typical representative of DESs), in which nickel (II) chloride (0.1 mol/dm³) and cerium (III) chloride (0.2–0.4 mol/dm3) were dissolved. According to the results of energy-dispersive X-ray analysis and XRD investigations, the composite coating contains approximately 12–16 at.% cerium, presumably in the form of cerium dioxide. A reaction scheme for the formation of the composite nanocoating, which includes a combination of chemical and electrochemical stages, is proposed. It was found that the incorporation of cerium oxide leads to a significant increase in electrocatalytic activity (compared to nickel coating) in the cathodic hydrogen evolution reaction and anodic oxygen evolution and urea oxidation reactions. It is hypothesized that the observed enhancement in electrocatalytic effect is due to the formation of additional active catalytic sites on the surface containing cerium in different oxidation states (e.g., Ce(+4)/Ce(+3)), which can act as electron carriers in both cathodic and anodic reactions. A significant advantage of this composite is its bifunctionality as an electrocatalyst, meaning it can be used for both cathodic and anodic processes. The obtained results can be used in the development of new high-efficiency processes for the electrochemical synthesis of "green" hydrogen.

Solvent-free synthesis of highly dispersed zinc-doped porous carbons as efficient dibenzothiophene adsorbents

Designing efficient adsorbents for the deep removal of refractory dibenzothiophene (DBT) from fuel oil is vital for addressing environmental issues such as acid rain. Herein, zinc gluconate and urea-derived porous carbons SF-ZnNC-T (T represents the carbonization temperature) were synthesized without solvents. Through a temperature-controlled process of “melting the zinc gluconate and urea mixture, forming H-bonded polymers, and carbonizing the polymers,” the optimal carbon, SF-ZnNC-900, was obtained with a large surface area (2280 m2 g), highly dispersed Zn sites, and hierarchical pore structures. Consequently, SF-ZnNC-900 demonstrated significantly higher DBT adsorption capacity of 43.2 mg S g−1, compared to just 4.3 mg S g−1 for the precursor. It also demonstrated good reusability, a fast adsorption rate, and the ability for ultra-deep desulfurization. The superior DBT adsorption performance resulted from the evaporation of residual zinc species, which generated abundant mesopores that facilitated DBT transformation, as well as the formation of Zn-Nx sites that strengthened the host-guest interaction (ΔE = −1.466 eV). The solvent-free synthesized highly dispersed Zn-doped carbon shows great potential for producing sulfur-free fuel oil and for designing metal-loaded carbon adsorbents.

Characterisation Analysis of Sulphur and Phosphorous Doped and Co-doped Graphitic Carbon Nitride (g-C3N4) Materials

Graphitic carbon nitride (g-C3N4) is tailored with doping of different non-metals (Sulphur and Phosphorus). For synthesis through thermal condensation method, the mixtures of urea and dopant with diverse concentrations have been added for preparation of materials. The basic effect of doping and its concentration on the structural morphology and absorption spectra of the samples is investigated in detail. Pure g-C3N4 suffers from high recombination rate of photogenerated electron-hole pairs resulting in low photocatalytic activity. Different techniques like X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transforms infrared (FTIR) spectroscopy, and Photoluminescence spectroscopy (PL) have been used for the characterization. X-ray diffraction studies confirm the formation of the g-C3N4 structure and SEM images reveal crumpled sheets and irregular plate like shapes of the doped graphitic nitride samples. FTIR analysis identify the presence of surface amino (N-H) and water (O-H) groups, cyano terminal group (C≡N), (C≡C), C–N) and (C=N) bonds and breathing mode of the tri-s-triazine units in the samples. PL spectra shows that the sulphur and phosphorus co-doped PSGCN (8 wt.%) sample is better for photocatalytic activity.

PSXI-18 Effects of different fiber levels on rumination and inflammatory markers in feedlot cattle

Abstract Adding fiber to feedlot diets is essential to maximize performance, optimize feed conversion and maintain animal health. Monitoring blood inflammatory markers and rumination behavior can help to identify fiber levels that maximize performance and animal well-being. We aimed to evaluate the effect of fiber levels on inflammatory markers, lactate dehydrogenase and haptoglobin and rumination of Nellore cattle in confinement fed with diets containing 12% and 7% forage NDF, over a period of 50 d. Diets included corn silage as the source of forage fiber with 23.3% and 13.6% corn silage in the dry matter 64% and 73.5% ground corn, and 0.2 and 0.5% potassium chloride, respectively for the 12% and 7% fNDF. Soybean meal (1.5%); cottonseed (7%), urea (1.2%), and mineral mixture (2.7%) containing 25 ppm of monensin were present in both treatments. Average initial body weight (BW) was 460 ± 38 kg and average age was 20 mo. Bulls (n = 20) were randomly distributed for each treatment with animal being the experimental unit. The feeding behavior was monitored on d 21 and 42, with observations at each 10-min interval, over 24 h and data obtained were averaged for analysis and blood samples were collected immediately after behavior analysis. Blood samples were obtained by puncturing the jugular vein, centrifuged to separate the serum, stored at -20°C and subsequently analyzed. Lactate dehydrogenase was analyzed in an automatic biochemistry system using cattle specific cattle kits (LABTEST Diagnóstica SA). Haptoglobin analyses were carried out by ELISA (Vidavet-Veterinary Lab). Data were evaluated by PROC GLIMMIX from SAS. A significant interaction was observed between minutes of rumination and fNDF levels in relation to the concentration of lactate dehydrogenase (P < 0.0001), expressed by the solution: Lactate = 1,272.12 + 908.86 * (tract = 7) + 1,1427 -3.3170 * (treat = 7) * rumination. For animals receiving the 7% fNDF diet, the concentration of lactate dehydrogenase decreased as the minutes of rumination increased, with a significant linear effect (P < 0.001). On the other hand, for animals treated with 12% fNDF, no significant correlation was observed (P = 0.34) with increasing rumination time. There was also an interaction between minutes of rumination and fNDF levels for haptoglobin concentration (P < 0.01), expressed by the solution: Haptoglobin = 0.1901 + 0.4865 * (treat = 7) + 0.000828 - 0.00163 * (treat = 7) * rumination. In animals treated with 7% fNDF, haptoglobin concentration decreased with increasing minutes of rumination, with a significant linear effect (P = 0.02). Our data demonstrates that, for the low forage diet, as bulls increased rumination time there was an improvement (a decrease) in inflammatory markers concentrations.

Piezoelectric assisted boosting photocatalytic hydrogen evolution over a finely prepared Pt/TiO2/g-C3N4 composite system using lactic acid as sacrificial agent

A one-step calcination method was employed to fabricate a new TiO2/g-C3N4(TCN) composite catalyst. The therein TiO2 nanoparticles with good dispersion were synthesized through a sol-gel method and followed by additional heat treatment. The ultra-thin and flat g-C3N4(CN) nanosheets were synthesized by calcining a mixture of urea and melamine. The obtained TCN exhibited significantly excellent performance, especially when 3 wt% Pt was added and lactic acid (HL) was used as a sacrificial agent, achieving a rate of 32.5 mmol/h/g. This improvement can be attributed to the uniform dispersion of nano TiO2 particles on g-C3N4, the flat ultra-thin layer structure of CN, and the constructed heterojunctions between two, which promote the separation of photogenerated electron-hole pairs. Measurements of PL and photocurrent response confirmed enhanced efficiency in interface charge separation and transfer. Additionally, it demonstrated lower internal resistance in EIS tests. Notably, owing to the piezoelectric properties of CN, when the reaction liquid was subjected to additional ultrasonic treatment, the hydrogen production rate further increased to 43.57 mmol/h/g and 2.9 mmol/h/g, respectively, in simulated sunlight and visible light response. The piezoelectric effect of CN induced by ultrasound regulated the bandgap width of the catalysts, broadening their response to visible light.

H2S induced in-situ formation of recyclable metal sulfide-based sorbent for elemental mercury sequestration in natural gas

Enlightened by the phenomenon that hydrogen sulfide (H2S) can readily decompose on metal oxides to generate sulfide species and the obtained metal sulfides are generally adopted as Hg-affine ligands for Hg0 capture, a urea modified copper oxide (U-CuO) was prepared via high-temperature calcination of the mixture of urea and copper nitrate for Hg0 removal in natural gas containing H2S. Benefitted from the decomposition of urea and the release of gaseous decomposition products, the as-synthesized U-CuO was enriched with abundant base sites and lattice oxygen, and characterized with developed textural features, which facilitates the diffusion and adsorption of H2S and subsequent sequestration of Hg0. The Hg0 adsorption capacity and uptake rate of U-CuO under simulated natural gas (N2 + 500 ppm H2S+8% H2O) reached as high as 134.06 mg g−1 and 58.32 μg g−1 min−1, respectively, which largely surpassed those of most CuS-based sorbents for Hg0 immobilization. Besides, U-CuO sorbent also exhibited satisfactory recyclability only through simple thermal treatment, the Hg0 removal efficiency of U-CuO maintained above 97 % even after ten adsorption-regeneration rounds. This preparation strategy not only provides valuable hints to guide the design and synthesis of Hg0 sorbents used for natural gas containing H2S but also inspires further investigation for the cost-effective performance enhancement of Hg0 sorbents.

Structure and Properties of Thermally Stabilized and Ecologically Friendly Organic Cotton Fibers as a New Activated Carbon Fiber Precursor

Organic cotton precursor yarn was impregnated in an aqueous solution consisting of diammonium hydrogen phosphate (DAP), boric acid (BA), and urea (U) mixtures before the thermal stabilization stage and then subjected to heat treatments in an air environment at 245 °C. The effect of chemical pretreatment on organic cotton yarn was examined using methods such as X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and infrared (IR) spectroscopy. The XRD analysis revealed a gradual decrease in the crystalline structure, attributed to the disruption of intermolecular hydrogen bonds. DSC and TGA measurements showed an improved thermal stability due to the formation of pre-graphitic structures with aromatic entities at higher temperatures. For samples chemically impregnated and then stabilized, the char yield values increased from 25% to 68% at 500 °C and 23% to 53% at 1000 °C. Analysis of IR spectra indicated a gradual reduction in both intermolecular and intramolecular hydrogen bonds associated with dehydration and dehydrogenation reactions. The IR spectra also confirmed a decrease in crystallinity with increasing oxidation time, which is consistent with the findings from X-ray diffraction. In addition, the IR spectra showed the presence of C = C bonds, indicating the formation of a crosslinked ladder-like structure. The results showed that DAP-BA-U integration increased the thermal stability of organic cotton fibers and the obtained samples were ready for the next stage, carbonization.Graphical

Structure and interactions of CO2 with reline (a 1:2 choline chloride – Urea mixture) according to quantum chemical calculations and molecular dynamics simulation

Quantum chemical DFT calculations [B3LYP+GD3/6-311++g(2d,2p)] of the structure and interactions in various complexes of CO2 molecule with a choline cation, a chloride anion, urea molecules, a choline chloride ion pair and a 1:2 choline chloride – urea complex were carried out. The contributions of Coulomb and van der Waals interactions were calculated. The QTAIM method was used to evaluate the strength of various bonds. A molecular dynamics simulation of CO2 molecules in reline in the NPT ensemble (1 atm, 298 K) was also carried out. The radial distribution functions of the particle centers of mass, local mole fraction functions, spatial distribution functions, and density profiles were calculated. Stronger interactions, compared to the other DES components, were observed in case of the chloride anion and the CO2 molecule according to the DFT calculations. However, in the system, stronger interactions were observed between the chloride anion and the system components, namely NHCl and OHCl hydrogen bonds. This made the chloride anion inaccessible and unable to interact with the CO2 molecule, according to the MD simulation results. Additionally, the presence of a fairly extensive surface layer containing DES and CO2 molecules was shown.

Influence of anodic treatment of a copper-nickel alloy in a eutectic mixture of choline chloride and urea on the surface morphology and electrocatalytic behavior in the hydrogen evolution reaction

For the first time, we investigated the process of potentiostatic anodic treatment of the surface of a copper (≈55%)-nickel alloy in a eutectic mixture of urea and choline chloride (reline), which is a typical representative of a new generation of ionic liquids, deep eutectic solvents. The anodic behavior of the alloy in the used solvent was characterized by cyclic voltammetry, and the nature of the electrochemical dissolution reactions of individual components of the alloy corresponding to several anodic current waves registered in voltammograms was determined. It was established that the anodic dissolution of the alloy occurs under conditions of salt surface passivation due to the formation of a layer of poorly soluble products of the electrode reaction. It was shown that under conditions of prolonged (150 min) potentiostatic polarization of the alloy in reline for various values of the electrode potential (in the range from 0.1 to 1.7 V relative to the Ag reference electrode), the chemical composition of the surface remained unchanged (i.e., there was no selective etching of individual components of the alloy), but an evolution of surface morphology patterns was observed, the specific type of which depended on the value of the applied potential. Anodic treatment of the Cu-Ni alloy in the reline solvent at any of the investigated anodic potentials led to an increase in the surface roughness coefficient, and electrochemical polishing did not occur. Analysis of kinetic data related to the hydrogen evolution reaction on the surfaces of reline-treated copper-nickel alloys in a 1 M NaOH aqueous solution showed a significant increase in exchange current density. This indicates enhancement of electrocatalytic activity compared to the untreated surface. The observed effect is likely associated with an increase in the true surface area of the alloy available for electrochemical reaction and an increase in the surface concentration of electrocatalytic sites resulting from the anodic dissolution of the alloy. The obtained results can be used in the development of highly efficient and relatively inexpensive electrocatalysts for hydrogen energy.

Nghiên cứu tổng hợp vật liệu composite SiO2/g-C3N4 cho quá trình quang xúc tác phân hủy rhodamine B

In this study, a visible-light-driven SiO2/g–C3N4 composite was prepared by heating a mixture of SiO2 and urea. The products were characterized by X-ray diffraction (XRD), infrared spectra (IR), scanning electron microscopy (SEM), and ultraviolet–visible diffuse reflectance spectroscopy (UV-Vis DRS). Results indicate that the composite only contained SiO2 and g-C3N4, and the SiO2/g–C3N4 composite had higher photocatalytic activities in the degradation of rhodamine B (82.2%) compared to the pristine g-C3N4 (43.9%) under visible light. The SiO2/g–C3N4 composite is a promising new material for the photodegradation of organic pollutants in wastewater due to its high photocatalytic performance, low cost, and convenient collection for reuse.

Ternary Ionic Liquid Analogues as Electrolytes for Ambient and Low-Temperature Rechargeable Aluminum Batteries.

Rechargeable aluminum (Al) metal batteries are enticing for the coming generation of electrochemical energy storage systems due to the earth abundance, high energy density, inherent safety, and recyclability of Al metal. However, few electrolytes can reversibly electrodeposit Al metal, especially at low temperatures. In this study, Al electroplating and stripping were investigated from 25 °C to -40 °C in mixtures of aluminum chloride (AlCl3), 1-ethyl-3-methyl-imidazolium chloride ([EMIm]Cl), and urea. The ternary ionic liquid analogue (ILA) consisting of AlCl3-urea-[EMIm]Cl in a molar ratio of 1.3:0.25:0.75 enabled reversible Al electrodeposition at temperatures as low as -40 °C while exhibiting the highest current density and the lowest overpotential among all of the electrolyte mixtures at 25 °C, including the AlCl3-[EMIm]Cl binary mixture. The ILA electrolyte was further tested in a rechargeable Al-graphite battery system down to -40 °C. The addition of urea to AlCl3-[EMIm]Cl binary mixtures can improve the Al electrodeposition, extend the liquid temperature window, and reduce the cost.

In Situ Self-Assembly of Nitrogen-Doped 3D Flower-like Hierarchical Porous Carbon and Its Application for Supercapacitors.

The hierarchical porous carbon-based materials derived from biomass are beneficial for the enhancement of electrochemical performances in supercapacitors. Herein, we report the fabrication of nitrogen-doped 3D flower-like hierarchical porous carbon (NPC) assembled by nanosheets using a mixture of urea, ZnCl2, and starch via a low-temperature hydrothermal reaction and high-temperature carbonization process. As a consequence, the optimized mass ratio for the mixture is 2:2:2 and the temperature is 700 °C. The NPC structures are capable of electron transport and ion diffusion owing to their high specific surface area (1498.4 m2 g-1) and rich heteroatoms. Thereby, the resultant NPC electrodes display excellent capacitive performance, with a high specific capacitance of 249.7 F g-1 at 1.0 A g-1 and good cycling stability. Remarkably, this implies a superior energy density of 42.98 Wh kg-1 with a power density of 7500 W kg-1 in organic electrolyte for the symmetrical supercapacitor. This result verifies the good performance of as-synthesized carbon materials in capacitive energy storage applications, which is inseparable from the hierarchical porous features of the materials.

Synergistic effect of N doping and oxygen vacancies over TiO2 nanosheets with enhanced photocatalytic removal of tetracycline

The increasing pollution from non-biodegradable antibiotics poses a significant threat to ecosystems and human health. TiO2 is widely acknowledged as the premier photocatalyst for removing antibiotics from wastewater. To address the limitations of TiO2 in wide forbidden band width and low efficiency separation/migration of carriers, N-doping and oxygen vacancies (OVs) are co-modified within TiO2 nanosheets through the one-step calcination of a mixture of H2TiO3 and urea. The results indicate that the co-modified sample (TiO2-U5) exhibited the highest TC removal efficiency of 90% after 60 minutes of reaction, with a kinetic constant 3.6 times higher than that of pristine TiO2. The effective mineralization of TC is confirmed by three-dimensional excitation-emission matrix fluorescence spectroscopy (3D EEMs). Systematic characterization of the photocatalyst structure and monitoring of intermediates/products reveal that the synergistic effect of N-doping and oxygen vacancies (OVs) enhances band alignment, light response, and carrier separation/migration, thus improving the photocatalytic degradation performance of TC. This study highlights the significant potential of adjusting charge transport and enriching active sites through the co-introduction of doping and surface defects on TiO2 for the photocatalytic degradation of antibiotics.

Ferroelectric-assisted enhancement of the photocatalytic activity of g-C3N4/TiO2 nanotubes heterojunctions through the addition of strontium

The effect of adding strontium to nanocomposites formed of g-C3N4/TiO2 nanotubes (TiNT) (g-C3N4: 4.0 wt%) on the photocatalytic activity was herein investigated using formic acid as a model target pollutant. g-C3N4 material was prepared by a solvothermal method using a mixture of urea and cyanuric chloride as precursors and acetonitrile as a solvent at 220 °C for 15 h, while TiNT material was obtained by the alkaline hydrothermal method of P25 at 130 °C for 20 h. A series of xSr-gC3N4/TiNT nanocomposites were then synthesized through progressive incorporation of strontium (from 0.2 to 1.0 wt%) at the surface of the composites. Samples were then characterized mainly using N2 adsorption–desorption measurements, X-ray diffraction, UV–vis diffuse reflectance, Raman and photoluminescence (PL) spectroscopies, and scanning and transmission electron microscopy (with energy-dispersive X-ray spectroscopy and Z-mapping). The Sr-containing g-C3N4/TiNT composites were then also fully characterized by electrochemical impedance spectroscopy (EIS) for their dielectric properties, while a deep kinetics analysis was also performed. Such an approach allowed us to establish a correlation between photocatalytic performance and the material's propensity to be polarized. Results emphasize the beneficial role of ferroelectricity induced by adding strontium. Indeed, enhancement of the photocatalytic activity by 2.3 times compared to a Sr-free counterpart was related to the material's ability to be polarized for Sr loadings ≤ 0.6 wt%. At higher Sr loadings, supplementary factors (decrease of the anatase crystallinity, formation of TiO2(B), disruption of the g-C3N4/TiO2 interaction, or lower mobility of photogenerated charges) negatively impact the activity, counterbalancing partly the beneficial ferroelectric effect. In this way, this study emphasizes the role played by ferroelectric effects in enhancing the photocatalytic ability of a given semiconductor.

A novel strategy for preparing high-performance, low-cost biomass charcoal for dye adsorption using aquatic agricultural waste lotus stem fibers

In this study, lotus stem (LS), a natural, abundant, and underutilized aquatic agricultural waste, was used to prepare biochar (BC) as a potential adsorbent for sewage treatment. A two-step process for the production of LS based nitrogen-doped BC (NLBC) has been developed, involving low-temperature pyrolysis of LS and urea mixture, followed by high-temperature pyrolysis of the pre-carbonized BC via NaOH immersion technique. The two-step activation treatment not only can effectively maintain the structural integrity of LS, but contribute to exposing more active sites for effective adsorption of methylene blue (MB). The obtained NLBC possesses a large pore volume (0.997 cm3 g−1) and great specific surface area of 1478.93 m2 g−1, contributing to its maximum adsorption capacity of 2320.81 mg g−1 for MB. The behavior of MB adsorbed onto NLBC conforms to pseudo-second-order kinetics and Langmuir–Freundlich models. The adsorption capacity remains stable across a range of pH, varying salt concentrations, and cyclic repetitions. The adsorption mechanism was ascribed to the synergetic effects of pore filling, H-bonding, and electrostatic interaction through comparative analysis before and after adsorption. The results indicate that NLBC is an environmentally friendly, cost-effective, and efficient for dye-containing wastewater treatment.

Electron‐Deficient Boron‐Doped g‐C3N4 as an Efficient and Robust Photocatalyst for Visible‐Light Driven Hydrogen Evolution from Water Splitting

AbstractElemental doping is considered to be a promising approach for altering the electronic structure, optical absorbance, and charge separation characteristics of graphitic carbon nitride (g‐C3N4, termed as CN), thus boosting its photocatalytic performance for practical applications. Herein, a series of boron (B) doped g‐C3N4 (named as BCN) photocatalysts are developed via one‐step pyrolysis of a mixture of urea and 3‐methoxycarbonyl‐5‐nitriophenylboronic acid (MCNPBA). The results show that B‐atoms have been successfully incorporated into the g‐C3N4 network. The as‐synthesized BCN‐x (x shows the weight content of MCNPBA) photocatalysts are evaluated in photocatalytic hydrogen (H2) evolution from water splitting under visible‐light (λ ≥ 420 nm). The optimized BCN‐10 sample shows a maximum H2 evolution rate of 1789.93 µmol h─1 g─1, which is 6.2 times higher than that of g‐C3N4 (289.73 µmol h─1 g─1). This is attributed to the fact that the electron‐deficient B‐atoms are lewis acids that trap electrons, which in turn expands visible‐light absorption, narrows the bandgap, and prevents the recombination of photogenerated charge carriers. Moreover, B‐doping can readily modify the valence and conduction band positions of g‐C3N4, therefore augmenting the photocatalytic H2 evolution activity. This paper presents a unique rational framework for developing other functionalized electron‐deficient elemental‐doping g‐C3N4‐based photocatalysts for practical applications in solar‐to‐fuel conversion.