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We present a highly efficient single‐atom catalyst (SACs) tailored for nitroarene reduction using NaBH4 under ambient conditions. Employing an unique approach, we harnessed NaCl under high temperature to create host materials enriched with negatively charged nitrogenous and oxygenated functional groups, capable of anchoring and stabilizing Ni ions within the aromatic structure. The nickel single sites were prepared by a straightforward cation exchange method. STEM‐HAADF imaging confirmed the presence of nickel single‐atoms, while XPS, FTIR, and Raman spectra validated nickel coordination within the catalyst. Remarkably, the CN−Ni catalyst exhibited exceptional catalytic performance under ambient conditions, achieving a high catalytic activity with NaBH4 (TOF 2246± ${\pm }$ 452 h−1 and 107± ${\pm }$ 47 mmol g−1 min−1). It also demonstrated remarkable conversion exceeding 90 % and outstanding selectivity. Equally impressive was its ability to maintain full catalytic activity over multiple reaction cycles, highlighting its robustness. This work is a significant leap in SACs design, offering a versatile and highly effective preparation method for SACs based on N‐doped carbon with far‐reaching implications in industrial reduction reactions. [ABSTRACT FROM AUTHOR]

A new screen-printed electrode (SPE) modified with carbon black and ternary oxide (SiO2/TiO2/Nb2O5), denominated SPE/CB/SiTiNb and was developed for the direct detection of triclosan in tap water and mouthwash samples. The morphological characterization and electrochemical behavior of the sensors were performed by scanning electron microscopy, energy dispersive spectroscopy, and cyclic voltammetry. Differential pulse voltammetry was used to evaluate the proposed sensor in Britton–Robinson buffer 0.1 mol L−1 and showed a limit detection of 1.23 nmol L−1 in a linear range from 0.025 to 57.01 µmol L−1. Studies with possible interferents were performed demonstrating a significant selectivity of the sensor to the triclosan oxidation reaction. The sensor was applied in tap water and mouthwash real sample analyses, whose recoveries ranged from 93.4 to 98.8%, demonstrating that the sensor shows promise in the detection of triclosan in different matrices allied to high sensitivity, selectivity, low-cost, portability, disposability, and low sample volume, without pre-treatment, per analysis. [ABSTRACT FROM AUTHOR]

Over the last decade, the CO2 reduction reaction (CO2RR) has been increasingly exploited for the synthesis of high‐value raw materials in gaseous or liquid form, although no examples of CO2 fixation in nanoparticle systems have been demonstrated. Herein, CO2 fixation into solid nanomaterials by laser synthesis and processing of gold colloids in water, traditionally considered a green approach leading to ligand‐free nanoparticles without the formation of by‐products, is reported. If carbon monoxide‐rich gold nanoparticles are observable even after synthesis in deionized water, the presence of CO2 derivatives in alkaline water environment leads to C2 and C3 coupling with the production of carboxylic acids as a typical CO2RR fingerprint. While laser processing of preformed gold colloids is selective for C2 coupling, both C2 and C3 coupling to lactic acid are observed during pulsed laser ablation of a gold target. In the latter case, it is demonstrated that it is possible to synthesize photoluminescent organometallic nanocomposites in the blue spectral region with a quantum yield of about 20% under adequate experimental conditions. In this research, new pathways are offered to be explored in energetics, photonics, catalysis, and synthesis at the nanoscale. [ABSTRACT FROM AUTHOR]

Although several studies assess the biological effects of micro and titanium dioxide nanoparticles (TiO2 NPs), the literature shows controversial results regarding their effect on bone cell behavior. Studies on the effects of nanoparticles on mammalian cells on two-dimensional (2D) cell cultures display several disadvantages, such as changes in cell morphology, function, and metabolism and fewer cell–cell contacts. This highlights the need to explore the effects of TiO2 NPs in more complex 3D environments, to better mimic the bone microenvironment. This study aims to compare the differentiation and mineralized matrix production of human osteoblasts SAOS-2 in a monolayer or 3D models after exposure to different concentrations of TiO2 NPs. Nanoparticles were characterized, and their internalization and effects on the SAOS-2 monolayer and 3D spheroid cells were evaluated with morphological analysis. The mineralization of human osteoblasts upon exposure to TiO2 NPs was evaluated by alizarin red staining, demonstrating a dose-dependent increase in mineralized matrix in human primary osteoblasts and SAOS-2 both in the monolayer and 3D models. Furthermore, our results reveal that, after high exposure to TiO2 NPs, the dose-dependent increase in the bone mineralized matrix in the 3D cells model is higher than in the 2D culture, showing a promising model to test the effect on bone osteointegration. [ABSTRACT FROM AUTHOR]

The study aimed to develop an electrochemical sensor based on glassy carbon, mixed oxide (SiO2/TiO2/Sb2O5), and carbon black. The material was synthesized, characterized, and used to determine thiamethoxam in raw honey and water. The morphologic structure and electrochemical performance of the sensor was characterized by scanning electron microscopy and cyclic voltammetry. Differential pulse voltammetry with a concentration of 0.1 mol L−1 of Britton-Robinson buffer at pH 7.0 allowed the generation of a method to determine thiamethoxam in a linear range of 0.25 to 100.5 μmol L−1 and with a limit of detection of 0.012 μmol L−1. The system efficiently quantified traces of thiamethoxam in raw honey and tap water samples. The modified sensor did not present interferences of K+, Na+, Ca2+, Mg2+, glyphosate, imidacloprid, and carbendazim. In addition, the device showed good recovery values for thiamethoxam when applied directly to honey and water samples without any treatment, presenting an electrochemical sensor to monitor real-time hazardous substances in environmental and food matrices. [ABSTRACT FROM AUTHOR]

In the last decade, transition metal dichalcogenides (TMDs) have been intensively synthesized/studied thus linking their morphological aspect to their physical properties, and consequently leading to the understanding of the possible benefits of defects in such materials. Nevertheless, for future applications, quantifying and identifying defects in TMDs is still a milestone to reach in order to better employ these materials in optoelectronic devices. Raman Spectroscopy has been successfully employed in graphene to quantify punctual or line defects. In this paper, we bombarded monolayer MoSe2 with He ions and found out the existence of three defect activated Raman bands around 250–300 cm−1. Density functional theory calculations were employed to obtain the electronic and phonon dispersion bands, making it possible to infer that these bands arise from inter-valley Raman double resonance processes. Interestingly, the same punctual defect model, that allows one to predict the defect concentration at which graphene starts to become amorphous, also works for TMDs. Hence, this work opens the door to the macroscopic quantification of defects in TMDs, which is essential for technological applications. [ABSTRACT FROM AUTHOR]

Monolayers of molybdenum disulfide are of vital importance in the fabrication of optical and nanoelectronic devices. The development of thin and low-cost devices has increased the demand for synthesis processes. Usually, the synthesis of molybdenum disulfide monolayers requires temperatures of approximately 800 °C, which is a drawback for the applications mentioned above. Here, we propose a route using the atmospheric pressure chemical vapor deposition technique to grow monolayers of MoS2 at 550 °C mediated by using sodium as a catalyst. We produced single crystals and polycrystalline films by controlling the NaNO3/MoO3 catalyst/precursor ratio and the growth time. Using first-principles calculations, we determined that sodium was the nucleation site of the growth process. The precursor's ratio is crucial to decrease the formation energy and the synthesis temperature. First-principles calculations and experiments showed that the ideal precursor ratio was 0.3 and that the synthesis temperature should be decreased by 250 °C. We investigated the monolayers with optical microscopy, high-resolution scanning transmission electron microscopy, X-ray photoelectron spectroscopy, atomic force microscopy, Raman spectroscopy, photoluminescence spectroscopy, and transport experiments. The optical and electrical performances were comparable to those of monolayers grown at higher temperatures. We believe that a low-temperature synthesis recipe is essential to drive the fabrication of nanoscale optoelectronic devices. [ABSTRACT FROM AUTHOR]

Proton‐conducting membranes based on sulphonated poly (ether ether ketone) (SPEEK) polymer matrix and tin dioxide have been synthesized. Their local structure has been studied by FTIR and XRD whereas their structural features at nanometer scale has been investigated by Small‐Angle X‐ray Scattering (SAXS) and transmission electron microscopy (TEM). SAXS and TEM results show that incorporation of the inorganic particles in SPEEK promotes dispersion of the hydrophilic sulfonic groups in the polymer matrix, inhibiting the formation of the water‐filled ionic clusters usually observed in hydrated SPEEK membranes. The changes in SPEEK nanostructure are induced by incorporation of particles modified by Tiron that promotes the connectivity between hydrated channels and reduces diffusion of alcohol, as evidenced by permeability measurements. The resulting increase of proton conductivity compared to pristine SPEEK, particularly at medium temperature (80°C), combined to an improved dimensional stability, make this family of membranes very promising for future applications in fuel cell. [ABSTRACT FROM AUTHOR]

Glycerol is a major byproduct obtained in the production of biodiesel, an important renewable fuel. The presence of free glycerol in fuel can have structural and performance consequences with respect to the engine, making fuel quality control important. The standard method to analyze glycerol in biodiesel is gas chromatography, a time-consuming and expensive technique. In this context, an electrode based on glassy carbon electrodes (GCEs) modified with reduced graphene oxide and core-shell gold@palladium nanoparticles was developed for the determination of glycerol in biodiesel. The free glycerol analysis was performed in the aqueous phase obtained by liquid–liquid extraction from a biodiesel sample. Cyclic voltammetry was chosen as the method for glycerol electrochemical analysis to regenerate active sites and promote greater sensor stability. The modified Au@Pd/rGO/GCE electrode showed an excellent performance, obtaining a linear range of 18.2 to 109 µmol L−1 with a correlation coefficient of 0.9895, limits of detection and quantification of 5.33 and 17.6 µmol L−1, respectively, high stability during 1000 cycles, and recovery values of 86% and 87% in the quantification of glycerol in biodiesel samples. The proposed method proved to be a great alternative for the analysis of glycerol in biodiesel, being a fast, sensitive, and low-cost technique due to its high stability and the use of small quantities of reagents. [ABSTRACT FROM AUTHOR]

In the last decade, transition metal dichalcogenides (TMDs) have been intensively synthesized/studied thus linking their morphological aspect to their physical properties, and consequently leading to the understanding of the possible benefits of defects in such materials. Nevertheless, for future applications, quantifying and identifying defects in TMDs is still a milestone to reach in order to better employ these materials in optoelectronic devices. Raman Spectroscopy has been successfully employed in graphene to quantify punctual or line defects. In this paper, we bombarded monolayer MoSe2 with He ions and found out the existence of three defect activated Raman bands around 250–300 cm−1. Density functional theory calculations were employed to obtain the electronic and phonon dispersion bands, making it possible to infer that these bands arise from inter-valley Raman double resonance processes. Interestingly, the same punctual defect model, that allows one to predict the defect concentration at which graphene starts to become amorphous, also works for TMDs. Hence, this work opens the door to the macroscopic quantification of defects in TMDs, which is essential for technological applications. [ABSTRACT FROM AUTHOR]

Spintronics devices rely on the generation and manipulation of spin currents. Two-dimensional transition-metal dichalcogenides (TMDs) are among the most promising materials for a spin current generation due to a lack of inversion symmetry at the interface with the magnetic material. Here, we report on the fabrication of Yttrium Iron Garnet(YIG)/TMD heterostructures by means of a crude and fast method. While the magnetic insulator single-crystalline YIG thin films were grown by magnetron sputtering, the TMDs, namely MoS 2 and MoSe 2 , were directly deposited onto YIG films using an automated mechanical abrasion method. Despite the brute force aspect of the method, it produces high-quality interfaces, which are suitable for spintronic device applications. The spin current density and the effective spin mixing conductance were measured by ferromagnetic resonance, whose values found are among the highest reported in the literature. Our method can be scaled to produce ferromagnetic materials/TMD heterostructures on a large scale, further advancing their potential for practical applications.

This study presents the development of an electrochemical sensor, denoted as GCE/CB/SiAlSn, based on the modification of a glassy carbon electrode surface with the ternary oxide SiO 2 /Al 2 O 3 /SnO 2 associated with carbon black, for direct determination of the neonicotinoid pesticide clothianidin in different matrices, such as environmental and food samples. Morphological characterization by the scanning electron microscopy technique, electroanalytical analyses using the cyclic voltammetry technique and differential pulse voltammetry are presented which demonstrated that the developed electrochemical platform presents high sensitivity in the electroanalytical clothianidin determination. The linear range studied was from 2.99 × 10 -7 to 6.04 × 10 -5 mol L -1 , with an LOD of 2.47 nmol L -1 . This high sensitivity was explained using the synergistic relationship between carbon black and ternary oxide that maximized the electroactive surface area of the GCE/CB/SiAlSn sensor. Interferent studies were performed that showed high selectivity of the sensor to the pesticide in the presence of Ca 2+ , K + , Na + , and Mg 2+ and carbendazim, glyphosate, imidacloprid and thiamethoxam pesticides. The sensor was applied to real samples of tap water and apple juice obtaining recoveries from 91.0% to 103.0%.

In the last decade, transition metal dichalcogenides (TMDs) have been intensively synthesized/studied thus linking their morphological aspect to their physical properties, and consequently leading to the understanding of the possible benefits of defects in such materials. Nevertheless, for future applications, quantifying and identifying defects in TMDs is still a milestone to reach in order to better employ these materials in optoelectronic devices. Raman Spectroscopy has been successfully employed in graphene to quantify punctual or line defects. In this paper, we bombarded monolayer MoSe 2 with He ions and found out the existence of three defect activated Raman bands around 250-300 cm -1 . Density functional theory calculations were employed to obtain the electronic and phonon dispersion bands, making it possible to infer that these bands arise from inter-valley Raman double resonance processes. Interestingly, the same punctual defect model, that allows one to predict the defect concentration at which graphene starts to become amorphous, also works for TMDs. Hence, this work opens the door to the macroscopic quantification of defects in TMDs, which is essential for technological applications., (© 2021 IOP Publishing Ltd.)