FlatChem最新文献

There is a strong correlation between the concentration of creatinine in human urine and the overall health of the kidneys. Therefore, there has been a persistent need for a rapid, and cost-effective quantitative method to assay creatinine levels in urine. Herein, green fluorescent La³⁺ doped titanium carbide nanosheets (La³⁺-doped Ti₃C₂ NSs) are fabricated via HF etching method by using Ti₃AlC₂ as MAX phase material and La(NO₃)₃ as a doping agent. As synthesized fluorescent La³⁺-doped Ti₃C₂ NSs are stable, showing green fluorescence under UV light. The as-synthesized La³⁺-doped Ti₃C₂ NSs act as a fluorescent sensor for the sensitive recognition of creatinine biomarker. The La³⁺-doped Ti₃C₂ NSs-based fluorescence method showed a fluorescence quenching at emission wavelength 518 nm towards creatinine with a linear range of 0.25–7.5 μM and detection limit of 63.44 nM. The paper strip based on La³⁺-doped Ti₃C₂ NSs was developed for the visual identification of creatinine. Furthermore, La³⁺-doped Ti₃C₂ NSs were used as probes for imaging of Saccharomyces cerevisiae cells. Also, the as-fabricated La³⁺-doped Ti₃C₂ NSs propose a quick response giving a cost-effective analytical strategy for the selective assay of creatinine in biofluids (plasma and urine).

Inhibiting the rapid recombination of photogenerated carriers has been a serious challenge to improve photocatalytic efficiency. Constructing and boosting the built-in electric field in photocatalysts of 2D and 3D systems can effectively promote the separation and transfer of photogenerated charge carriers. Herein, we systematically summarize the construction principle, characterization methods about the direction and intensity of the built-in electric field, and several strategies to boost the built-in electric field including structure optimization, phase modulation, vacancy defects engineering, doping strategies, construction of charge transfer mediators. It is worth noting that the uneven charge distribution in the material (or differences in the position of the Fermi level) is a key issue in the construction and enhancement of built-in electric field. Finally, the application of the built-in electric field in photocatalytic water splitting, carbon dioxide reduction, nitrogen fixation and pollutant degradation are described. This review highlights a comprehensive understanding of the mechanism of built-in electric field in photocatalysis and offers some insights into the design and modification of photocatalysts for different applications.

Solar-driven conversion of CO₂ to value-added chemical fuels has been regarded as a promising strategy for solving the climate problem and energy crisis. To realize this goal, it is vital to design photocatalysts with abundant catalytic active sites and excellent charge separation efficiency. Here, perovskite nanocrystals (CsPbBr₃) were anchored on two-dimensional molybdenum nitride (MoN) using an in-situ growth method, forming a new and effective 0D/2D CsPbBr₃@MoN (CPB@MoN) nanoheterosturcture with close contact interface for CO₂ photoreduction. The introduction of MoN, acting as a charge transfer channel, could quickly trap the photoinduced charge from CsPbBr₃ and provide abundant catalytic sites for CO₂ photocatalytic reactions. For optimized CsPbBr₃@MoN composites, the CO yield was 13.86μmol/gh⁻¹ without any sacrificial reagent, which was a 4.5-fold enhancement of the pure CsPbBr₃. Further, in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) revealed the catalytic mechanism for the CO₂ photoreduction process. This work provides a new platform for constructing superior perovskite/MoN-based photocatalysts for photocatalytic CO₂ reduction.

Nanomaterials adorned on graphene comprise an essential component of a wide range of devices wherein graphene-based copper oxide nanocomposites have garnered significant attention in recent years. Copper oxides (CuO and Cu₂O) are semiconductors with distinctive optical, electrical, and magnetic properties. Their earth abundance, low cost, narrow bandgap, high absorption coefficient, and low toxicity of copper oxides are just a few key advantages. CuO is superior to Cu₂O in optical switching applications because of its narrower bandgap. Therefore, integrating graphene with copper oxides renders the ensuing nanocomposites much more valuable for various applications. Not surprisingly, a wide range of promising synthesis and processing techniques have been considered, focusing on multiple appliances such as sensors, energy storage, harvesting, and electrocatalysis. Herein, the most recent synthesis techniques and applications of doped, undoped, and hierarchical structures of CuO/Cu₂O-graphene-based nanocomposites are deliberated, including the potential future usages.

Compared to their three-dimensional (3D) counterparts, low-dimensional layered perovskite (2D) structures using bulky organic ammonium cations (PEA⁺) have significantly improved stability but generally worse performance. 3D perovskites with significant ion migration, one of the major concerns for structural instability, show better charge storage capacity. In contrast, strong van der Waals contacts and bulky spacer ligands in 2D perovskites inhibit the migration of halide ions. Mixed properties of 2D and 3D or quasi-2D layered perovskite demonstrate more efficient, tuneable optoelectronic properties and long-term stability. The performance and stability of the electrochemical supercapacitor may be significantly influenced by ion migration, as we have shown by fabricating porous electrodes from 3D-Cs₂AgBiBr₆ bulk perovskite, 2D/3D or quasi-2D PEA-Cs₂AgBiBr₆, and layered perovskite 2D PEA₄AgBiBr₈. The quasi-2D electrodes were found to have an energy density ∼1.75 times higher than the 3D perovskite electrodes and ∼4.5 times higher than that of pure 2D halide electrodes. Compared to 2D and 3D electrodes, quasi-2D has a maximum capacitance retention of around 93 % after 2000 operation cycles. Ex-situ X-ray diffraction was conducted to examine further structural changes in the quasi-2D, 2D, and 3D perovskite electrode materials. It was determined that the ordering arrangement of Ag⁺/Bi³⁺ cation improves the crystallinity of the structure, which enhances the device performance and stability of the quasi-2D electrode. Also, Ag³⁺ is essential for improving the strength of quasi-2D and 2D electrodes, as evidenced by X-ray photoelectron spectroscopy (XPS). A symmetric solid-state supercapacitor was fabricated and analyzed using a two-electrode method, demonstrating that the quasi-2D configuration has the highest energy density compared to the pure 2D and 3D perovskite electrode materials.

The limited specific capacity of graphite anodes constrains the advancement of lithium-ion batteries (LIBs), sodium-ion batteries (NIBs), and potassium-ion batteries (KIBs). To address this, we have explored the potential of van der Waals heterostructures for high-performance anode materials. Specifically, we designed and analyzed the NbS₂/Ti₂CS₂ heterostructure through first-principles calculations. This heterostructure demonstrates superior thermal stability and metallic conductivity. Furthermore, it allows for the stable adsorption of Li/Na/K atoms, indicating strong interactions that are advantageous for battery applications. Notably, the Li/Na/K ion diffusion barriers on NbS₂/Ti₂CS₂ are lower compared to other anodes, enhancing ion mobility. The average open-circuit voltages (OCVs) for NbS₂/Ti₂CS₂ as an anode in NIBs/KIBs range from 0 to 1 V, with a remarkable specific capacity of 489 mAh/g for NIBs. These findings position NbS₂/Ti₂CS₂ as an exceptional candidate for next-generation battery anodes, potentially revolutionizing the LIB/NIB/KIB landscape. Our research contributes to the ongoing development of advanced anode materials, offering new pathways for enhancing battery performance.

Importance of process parameters on thermal, microstructural, and magnetic properties of synthesized core/shell nanoparticles was investigated during their production via chemical vapor deposition (CVD). Herein, iron(II) sulfate heptahydrate and fumed silica powders were mixed in ethanol, and the solution was used for precursor preparation by utilizing spray dryer. These prepared precursors were treated in the CVD process under methane/hydrogen (CH₄/H₂) gas flow to synthesize graphene-encapsulated core/shell nanoparticles. CVD studies were performed at various temperatures (900–1000 °C), holding times (60, 90 min), and gas flow rates (100, 200 mL/min). After CVD studies, purification was applied to remove uncoated nanoparticles, and remaining fumed silica phases originated from the precursor via selective acid leaching using hydrofloric acid (HF) and hydrochloric acid (HCl) solutions. X-ray diffractometry, Raman and Mössbauer spectroscopy, Zeta potential measurement, thermogravimetry combined with differential scanning calorimetry, scanning and transmission electron microscopy/energy-dispersive spectroscopy, and vibrating sample magnetometry (VSM) results yielded the optimized CVD parameters as 950 °C, 60 min, CH₄/H₂: 1/1 and 50 mbar. The characterization results proved that multilayer graphene (d-spacing: 0.34 nm) encapsulated Fe/Fe₃C nanoparticles (average core size: ∼46.9 nm, shell thickness: ∼16.6 nm) can be successfully synthesized by using CVD process followed by a leaching treatment. VSM results revealed that synthesized nanoparticles had soft ferromagnetic properties (M_s: 90.6–185 emu/g; H_c: 255.4–301.6 Oe). Characterization results deepen the understanding of process parameters of CVD system on characteristics of core/shell nanoparticles.

Graphene nanosheets show great potential as electrode materials for supercapacitors due to their high surface area and excellent electrical conductivity. However, the low hydrophilicity of graphene nanosheets limits their electrochemical performance in aqueous supercapacitor applications. To enhance their electrochemical performance, we investigate the use of iodoacetic acid as an electrolytic functionalization agent for graphene nanosheets. Here, we demonstrate the successful electrolytic functionalization of graphene nanosheets under cathodic conditions in aqueous medium. The resulting material exhibits a high structural quality and carboxyl groups on the surface, which increases the hydrophilicity and wettability of the material. The applied voltage and the concentration of iodoacetic acid have been found to be key factors to optimize the process in order to get the maximum functionalization degree. The electrochemical performance demonstrates that iodoacetic acid functionalized graphene nanosheets exhibit significantly improved specific capacitance (220F/g at 0.5 A/g) and cycling stability of the symmetric cell compared to pristine graphene nanosheets, highlighting the potential of electrochemical functionalization to improve the performance of graphene-based materials in energy storage applications.

Zinc indium sulfide (ZnIn₂S₄) is a Cd-free semiconductor with great potential in various photocatalytic applications. However, its rapid photogenerated charge combination poses some challenges. Constructing ZnIn₂S₄-based heterojunction photocatalysts to address this has proven an effective solution. In this study, we loaded uniform Ni₃C nanoparticles as cocatalysts on layered ZnIn₂S₄ nanostructures to promote photocatalytic H₂ production activity. The optimal 3 % Ni₃C/ZnIn₂S₄ exhibited the highest H₂ generation rate of 393 μmol·g⁻¹·h⁻¹, 4.5 times greater than pure ZnIn₂S₄. The enhanced photocatalytic performance was ascribed to the incorporation of metallic Ni₃C, which provides more catalytically active sites and establishes electron transfer channels at the interfaces, facilitating the photogenerated carrier separation and H₂ production. The photocatalytic mechanism of Ni₃C/ZnIn₂S₄ was proposed through experimental measurements and DFT calculations. This study offers a way to develop efficient ZnIn₂S₄-based visible-light-driven photocatalysts.

Although chemotherapy remains a prevalent option in cancer treatment, its adverse effects on normal cells and suboptimal pharmacokinetics often limits its effectiveness. To address these challenges, this study successfully developed a new multifunctional drug delivery system comprising a covalent composite of graphene quantum dots and barium titanate nanoparticles. Notably, despite numerous reports on the surface modification of graphene quantum dots, studies focusing on cancer cell inhibition via different covalent bonds are scarce. To bridge this gap, this system was synthesized using eco-friendly esterification and amidation pathways. The anticancer drug doxorubicin was employed as a model drug, and hyaluronic acid was used to encapsulate the delivery system, enhancing its sustained release capabilities. Comprehensive material characterization confirmed the successful synthesis of the system. Its high drug loading capacity and acid-sensitive release can be attributed to the unique structure of the graphene quantum dots. Subsequent in vitro and in vivo biological evaluations not only demonstrated the system’s remarkable cancer inhibition efficacy but also accentuated the distinct impacts of the two bonding types. The underlying mechanism is believed to involve bonding affinity and electron transfer, findings that are corroborated by the experimental data. Additionally, results from animal models provide clear evidence for the potential application of this system (HA-DOX-GQD@BTNPs) in cancer therapeutics and imaging. In conclusion, this research elucidates the variances in drug carrier efficacy based on different covalent bond modifications for cancer treatment and introduces a novel drug delivery system that synergistically combines imaging and targeting capabilities.