FlatChem最新文献

We have computationally studied eight carbon monolayer materials, including the recently synthesized biphenylene, graphyne, and DHQ-graphene, as precursors of the bilayer C₂H-diamanes. The interlayer C-C bonds of about 1.6 Å confirmed the strong covalent bonding between the monolayers. Density functional theory calculations revealed that the considered diamanes have a wide range of band gaps ranging from 1.5 to 4.2 eV. Diamanes, which are based on graphene allotropes, significantly expand the range of electronic and optical properties of conventional graphene derivatives and other traditional carbon materials. Tight-binding molecular dynamics simulations showed that diamanes are less stable than monolayers due to tendency of interlayer bonds tend to break. Out of the eight considered structures, only three diamonds were identified as certain stable systems suitable for processing at elevated temperatures of about 500 K. The nudged elastic band approach provided an understanding of the rate-defined thermal decomposition steps and corresponding energy barriers, which are equal to 2.79, 4.86, and 5.41 eV for the three stable diamanes. The elastic constants of the considered diamanes are comparable to those of graphene. The absorbance spectra of diamanes are calculated using linear response time-dependent density functional theory.

Extremely efficient nanomaterials are urgently needed in the field of photocatalysis for solar energy conversion and fuel production applications. MXenes are gaining significant attention as a promising layered material for usage in energy conversion processes. Large surface area, controllable surface functionalities (–OH, –O, and –F), high electrical conductivity, and metallic active sites are the unique properties of MXenes. MXenes used as co-catalysts with other photocatalytic materials and reduce the recombination in photo generated charge carriers which further improve the efficiency of the material. This review summarizes the synthesis of MXenes, their surface modifications, heterojunction schemes and applications in photocatalytic CO₂ reduction and H₂ production application. Furthermore, several methods for the preparation of MXene-based nanostructures with enhanced photocatalytic activity are also discussed. Photocatalysis involves the generation of photo-generated electrons in semiconductor materials and their effective migration to MXenes for the initiation of photochemical processes at various heterojunctions. This review also explores the underlying processes and basic concepts of photocatalysis at different heterojunction configurations. Lastly, the review presents the challenges and future advancements in MXene based heterojunction for viable renewable fuels.

2D layered materials have been the center of attraction for material science researchers after the discovery of graphene. Among the various layered 2D materials, transition metal oxychalcogenide (TMOCh) materials possess a unique position due to their exciting properties and applications. Numerous reported articles are available on these materials, but we realized that a systematic classification of them, along with their general properties and applications, was missing. So, in this review, we attempted to present a systematic approach to study more about these materials conveniently. We have classified these TMOChs based on precursor materials used (i.e., quaternary or more than that) along with the transition metal, oxygen, and chalcogen (S, Se, and Te) into three categories such as TMOChs with 1. Alkaline earth metals, 2. Post transition metals, 3. Rare earth metals. Here, we consider the compounds with fixed compositions of at least one transition metal, oxygen, and chalcogen combined with any other metals from the above three categories. The detailed discussion of various synthesis routes adopted for preparing these materials is discussed thoroughly, along with their crystal structure, electronic structure, and X-ray diffraction (XRD) patterns. The next section of the review covers a broad discussion of different properties exhibited by these materials, like optoelectronic, thermoelectric, magnetic, thermal transport, nonlinear optical, semiconducting, and resistivity. Based on these fascinating properties, TMOCh materials have a wide range of applications in various fields, which are well discussed in the application segment of this review. We have tried to provide the reader with a complete understanding of these layered materials through this review, from their synthesis to applications, with the necessary description, figures, and tables to support it.

Zeolitic imidazolate framework/graphene oxide (ZIF/GO) hybrid materials are taken into consideration in the field of nanotechnology due to their intelligent integration of structure and function. This comprehensive review explores the synergistic combination of ZIFs and GO as a hybrid material, offering enhanced properties for multifaceted applications. The self-assembly of ZIFs, composed of metal ions coordinated with imidazolate linkers, provides a highly ordered porous framework, while GO, derived from oxidized graphene sheets, exhibits high surface area and mechanical strength. The integration of ZIFs and GO results in tunable porosity, improved electrical conductivity, and increased stability. This review discusses the synthesis strategies employed for fabricating ZIF/GO hybrids, such as in situ growth, solvothermal and hydrothermal methods, ultrasound, and nanopore lithography approaches. It elucidates the physical properties and chemical properties of ZIF/GO hybrids, encompassing structural characteristics, morphological features, thermal stability, electrical conductivity, electrochemical performance, and mechanical behavior. Furthermore, it explores the diverse applications of ZIF/GO hybrid materials in catalysis, energy storage, and transfer, as well as biomedical applications. The challenges and limitations associated with ZIF/GO hybrids are addressed, encompassing fabrication issues, stability concerns, selectivity optimization, and performance enhancement. This comprehensive review highlights the immense potential of ZIF/GO hybrid materials for multifaceted applications in nanotechnology, providing valuable insights for researchers and paving the way for future advancements in the field.

During the time of the industrial revolution, there was a growing need for energy storage composites that were dependable, high-performing and possessed qualities like flexibility, affordability, and durability. The advancements in electronics and other related technologies drove this demand. The mechanical, physical, and optical characteristics of MXene (a class of two-dimensional inorganic compounds) materials have attracted significant attention in the present century due to their suitability for manufacturing high-performance energy storage devices. MXenes significantly improve the energy storage capabilities of supercapacitors by offering shorter ion diffusion paths, excellent conductivity, and a vast surface area. The hydrophilicity of MXenes, along with their surface redox processes and metallic conductivity, plays a crucial role in enabling high-rate and high-performance pseudocapacitive energy storage materials. Throughout this overview, we have explored the process of synthesizing MXene, its unique properties, and the mechanisms of charge storage. We have thoroughly explored the latest progress and discoveries in nanocomposites based on MXene. After evaluating the potential of MXene composites for creating environmentally friendly energy storage materials with impressive performance, we discussed the future challenges and possibilities of this field.

With recent advancements in nanomedicine, there has been growing interest in developing drug delivery systems with multifunctional capabilities. In this study, we developed a novel dual drug delivery system by combining two drug carriers via positive and negative electrostatic interactions. First, we modified polyethyleneimine (PEI) with graphene quantum dots (GQDs) to create a positively charged particle (GPI) with high drug loading efficiency and good dispersibility. Second, we embedded the pyrenebutyric acid structure in hyaluronic acid (HA) through EDC/NHS cross-linking and used TAK-632 as the hydrophobic drug to create negatively charged particles (HANPs) with hydrogel-like properties and the CD44 receptor. After the two components were constructed, the increase in the particle charge and simultaneous delivery of both drugs synergistically enhanced the therapeutic effect of this strategy. Qualitative tests confirmed the successful synthesis of the drug carrier, while the potential of this system as a cancer treatment strategy was evaluated in HCT116 cancer cells (through MTT cell viability assays) and in vivo mice xenograft experiments. Our results demonstrated that the dual drug delivery system, HANPs(TAK)/GPI(DOX), had a significant inhibitory effect on the growth of cancer cells both in vitro and in vivo, suggesting that this system is a promising candidate for a new type of treatment.

The brush coating method allows the advantage of being able to produce thin films simply and quickly. This study introduces a method for thin-film production by brushing a solution containing graphene doped in Al₂O₃ using the sol–gel method. Graphene oxide (GO) is suitable for semiconductors with bandgap values of about 1.7 eV at room temperature, and the characteristics of the thin films were analyzed according to the doping ratio. First, X-ray photoelectron spectroscopy measurements were obtained to analyze the chemical composition of the thin-film surface. Since graphene is a carbon isomer, the characteristic of oxygen vacancies was confirmed by the increasing C–C bond intensity with increasing GO doping concentration. In addition, Raman analysis was performed to analyze the concentration of molecular groups of compounds for defects in graphene. Thereafter, through atomic force microscopy measurements, as the graphene doping ratio increased, the average roughness increased from 1.785 to 33.67, the residual DC voltage also increased by about 48.42 %, and the polar anchoring energy also increased by about 16.33 %. In addition, response-time–transmittance measurements were performed to measure the electro-optical properties of the thin film, and excellent Vth and stable response speed were obtained. Additionally, the validity of the results was supported through bandgap analysis. Finally, the degree of alignment of liquid–crystal molecules on the film surface was confirmed by polarized optical microscopy and pretilt angle measurements, and the suitability of the thin film for display devices was shown via transmittance measurements. As a result, GO:Al₂O₃ hybrid thin film is an excellent candidate for use as an alignment film for solar energy, secondary batteries, and next-generation liquid crystal displays.

This study introduces a simple one-step approach for synthesizing phenol-functionalized reduced graphene oxide for electroanalytical purposes, just using gallic acid (GA) and graphene oxide (GO). GA serves as both a reductant for GO and a stabilizing, functionalizing agent, introducing phenolic groups to the nanomaterial. This functionalization imparts remarkable attributes to the nanomaterial, allowing complete dispersion in aqueous solutions and tuning of its electrochemical performance, making it very convenient for electrode modification. The resulting nanomaterials (GA-rGO) underwent characterization through UV–visible, Fourier-transform infrared (FTIR), and Raman spectroscopies, as well as scanning electron microscopy (SEM). Glassy carbon electrodes modified with aqueous dispersions of these nanomaterials (GA-rGO/GCE) were employed in voltammetric experiments to evaluate the optimal dispersion composition for electroanalytical application.

These GA-rGO/GCE displayed high electrocatalytic activity for the electrochemical oxidation of relevant clinical and environmental analytes. The unique functionalization of GA-rGO facilitated the selective accumulation of dopamine (DA) and uric acid (UA) on the electrode surface, even in the presence of significant amounts of ascorbic acid (AA) in mixtures. Under the specified conditions, voltammetric currents display linear increments over the concentration ranges of 3.0 x 10^-7 M to 2.0 x 10^-5 M for DA and 7.0 x 10^-6 M to 1.0 x 10^-4 M for UA. The sensor demonstrated a low detection limit of 0.090 and 2.1 μM for DA and UA, respectively. The reliability of the electroanalytical performance of the proposed sensor in real samples was demonstrated by the quantification of DA in medications, as well as DA and UA in human urine samples, yielding recovery values between 82 % and 105 %, with relative standard deviation below 11 %.

Replacing the formidable oxygen evolution reaction (OER) with other oxidizable species is an appealing approach to attain highly efficient hydrogen (H₂) generation with a lower potential. Accordingly, the kinetically favorable electrooxidation reaction of urea or hydrazine molecule can increase the return on energy profiteering and prevent pollutant emission. Thus, opening up an innovative direction to replace the sluggish OER and generate high-purity H₂ gas via an energy-saving approach. Thus, constructing highly efficient and stable bifunctional electrodes/electrocatalysts is a key to realize economical and sustainable H₂ production. In this work, we developed defect-enriched two-dimensional (2D) heterogeneous nickel copper selenide (D/Ni-Cu-Se) on a conductive Ni foam (NF) scaffold as an integrated bifunctional electrocatalytic electrode for energy-saving for H₂ production. The self-supported D/Ni-Cu-Se/NF electrode with a regulated interfacial property and abundant metal defects is fabricated through a hydrothermal approach and a metal-defect engineering route. The thus-prepared electrode exhibits a high electrocatalytic performance for both hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) in a 1.0 M KOH electrolyte, achieving the catalytic current density of 10 mA cm⁻² at a potential of 87.7 mV and 1.335 V vs. RHE, respectively. In relation, the two-electrode urea-water electrolyzer and hydrazine-water electrolyzer utilizing the bifunctional D/Ni-Cu-Se/NF as both the cathode and anode electrodes reveal a cell voltage of ∼ 1.395 V and 0.268 V at 10 mA cm⁻² in 1.0 M KOH/0.33 M urea and 1.0 M KOH/0.25 M hydrazine, respectively, which is much less than that of conventional water electrolysis (1.572 V). The implemented electrolyzer systems consequently endow high long-term durability over 48 h of continuous electrolysis, indicating that the defect-rich D/Ni-Cu-Se/NF can serve as a potential bifunctional electrocatalyst with an outstanding electrolysis performance and excellent stability for H₂ generation. Indeed, such a novel bifunctional electrode configuration and corresponding electrolysis performances are much desired for energy-saving electrolytic H₂ production and pave the way for exploring highly efficient and robust electrodes.