FlatChem最新文献

Highly determined materials have been applied to energy storage devices such as supercapacitors, batteries, etc., to investigate their electrochemical features and match them with ongoing technological developments. In this regard, electrodes based on graphene and layered double hydroxide with two divergent charge-storage mechanisms have been perused to expand the energy storage functionalities. Graphene materials as efficient electrodes have occupied a significant place in supercapacitors and batteries due to their outstanding electrical conductivity, flexibility, and large surface area. Additionally, according to the substantial electrochemical charge transport capabilities, layered double hydroxides are extensively employed in energy storage devices. This review comprehensively investigates the cooperation effect of the electrode composites of the graphene materials and layered double hydroxides and their optimization progress. The electrochemical characteristics of the electrodes have been considered, including specific capacitance, energy density, power density, and capacity retention, affected by pH, synthesis method, reaction temperature, and time. Eventually, the future trend of the electrode materials and their enhancing performance perspective is represented.

Graphene research has captivated researchers worldwide, propelling innovation across diverse industries. Through the liquid-phase exfoliation methodology of graphite powder, we have demonstrated a rapid route for obtaining few-layer and multi-layer graphene using a natural surfactant, cardanol. Aqueous phase exfoliation of graphite in the presence of cardanol as a surfactant was conducted to obtain pre-exfoliated graphite suspensions. The influence of different ultrasonication times, 10, 20, and 30 min, and contact times with the surfactant, 1 and 60 min, on the stability and concentration of dispersed exfoliated graphite was evaluated. Results indicate that ultrasonication for 20 min resulted in improved stability and reduced graphene flake sizes, making it suitable for scalable graphene production. Subsequently, the most stable dispersions of exfoliated graphite were subjected to CO₂-pressurized treatment. Promising results were obtained when employing cardanol at its critical micelle concentration. The graphene exhibited good structural quality, low defect density, and small stacking, with an average size of 15 nm, where 40 % of the stacked graphene was smaller than 5 nm. The findings provide valuable recommendations for the scalable production of graphene with multilayers and a few layers (FLG/MLG), using cardanol, a friendly surfactant, and a novel method of exfoliation utilizing supercritical CO₂. This technology represents an innovative approach, with potential applications in supercapacitors, solar cells, biosensors, polymer composites, and advanced materials.

The doping of lighter non-metals like boron and nitrogen into fullerene $\left(C_{60}\right)$ represents a promising advancement in the field of nanoelectronic devices. These doped two-dimensional (2D) materials offer improved stability and enhanced adsorption characteristics compared to pure form. Notably, It displays semiconducting behaviour, resulting in higher conductivity and carrier mobility. This study investigates the structural, electronic, optical, and conductivity/carrier transport properties of 2D polymer sheets made of fullerene, both with and without boron and nitrogen doping. We employ density functional theory (DFT) with PBE and HSE functionals, considering the inclusion of van der Waals (vdW) interactions. The research findings indicate that the $2D$ sheets of $C_{60},C_{58}{B}_1{N}_1$, and $C_{54}{B}_3{N}_3$ exhibit band gaps of approximately $0.97eV\left(1.51eV\right),1.08eV\left(1.65eV\right)$, and $1.05eV\left(1.56eV\right)$, respectively, as obtained from PBE (HSE) calculations. Moreover, according to the deformation potential theory, $C_{58}{B}_1{N}_1$ exhibit ultra-high conductivity (${10}^{14}{\Omega }^{-1}{cm}^{-1}{s}^{-1}$ at room temperature). These sheets display cohesive energies of −8.76, −8.72, and $-8.67eV$, respectively, indicating their stability. These results are promising and underscore the significance of a single pair of $BN$ dopants in fullerene monolayers for advancing next-generation 2D nano-electronic applications.

The preservation of Silicon nanoparticles (Si NPs)’ structural integrity and surface protection during cycling is vital for optimal Si-graphene electrodes, controlling volumetric changes during lithiation/delithiation. Weak physical adherence of Si NPs to the carbon matrix compromises electrode performance, highlighting the need for effective bonding mechanisms. This research focuses on Si/reduced graphene oxide (Si/RGO) composites, employing a scalable, low-temperature synthesis method to examine effect of bonding between Si NPs and RGO in mitigating the volumetric fluctuations during cycling. Characterization techniques, including FTIR, XRD, Raman spectroscopy, SEM, EDX and TGA confirm successful synthesis, offering structural and chemical insights. Electrochemical assessments, including EIS, CV, and GCD, reveal that covalently coupled Si/RGO composites outperform counterparts, demonstrating superior rate and cyclic performance. The first delithiation capacity of 1275 mAh g⁻¹ surpasses directly assembled Si/RGO and pristine RGO-based anodes, with corresponding values of 736 and 511 mAh g⁻¹, respectively and is retained to 670 mAh g⁻¹ (1.8 times the capacity compared to a graphite anode) at 0.1 A g⁻¹ after 100 cycles. Furthermore, the research challenges the notion that a high reduction temperature is obligatory for achieving high conductivity in RGO, as observed through improved charge/electron transfer kinetics, detailed in subsequent sections.

2D materials, such as transition metal dichalcogenides (TMDCs), have garnered considerable attention in recent years due to their unique properties and wide-ranging potential applications. Among them, molybdenum disulfide ($\mathrm{Mo}{S}_2$) stands out for its remarkable electronic, optical, and mechanical characteristics. This study aims to optimize the synthesis of liquid-phase exfoliated $\mathrm{Mo}{S}_2$ using ultrasound, focusing on absorbance in the UV–Vis spectrum and the increase in the direct bandgap. The variables studied in this research include ultrasound power and time, as well as the mass of $\mathrm{Mo}{S}_2$, while the response variables involve the area under the curve (absorbance) of excitonic transitions A–D from UV–Vis spectra and the direct bandgap values of $\mathrm{Mo}{S}_2$ A–D excitons obtained through Tauc-Mott models. To predict the optical properties of exfoliated $\mathrm{Mo}{S}_2$, we developed Artificial Neural Network (ANN) algorithms, which were subsequently optimized using a Genetic Algorithm (GA). The performance of the ANN models was assessed using Root Mean Square Error (RMSE) and Standard Error of Prediction (SEP). The results demonstrate that the combined GA-ANN model serves as a valuable tool for predicting the optical properties of exfoliated $\mathrm{Mo}{S}_2$ nanosheets under various experimental conditions. The selected treatments from the optimization process were further characterized using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), and Raman spectroscopy, providing additional insights into and correlating with the optical properties. Characterizations through TEM and SEM confirmed the effectiveness of ultrasonic exfoliation in reducing the size of $\mathrm{Mo}{S}_2$ particles and generating smaller particles with varied shapes, including thin flakes. The XRD and Raman spectroscopy analyses revealed changes in the crystalline structure, particle size distribution, and molecular composition of exfoliated $\mathrm{Mo}{S}_2$ selected samples.

Zearalenone, a major mycotoxin encountered in numerous agricultural products, is associated with an array of adverse health implications, notably endocrine disturbances and carcinogenic tendencies. Given the global challenge posed by this toxin, an innovative electrochemical biosensor was crafted using hydrothermally synthesized Bi₂S₃ nanorods. Integrating these nanorods with Carbon Nanofibers (CNF) through a meticulous ultrasonication technique resulted in a high-performance sensing interface optimized for zearalenone detection in intricate agricultural settings. Advanced characterization techniques, encompassing X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and energy-dispersive X-ray spectroscopy (EDX), corroborated the fine-tuned integration of Bi₂S₃ within the porous CNF matrix. This Bi₂S₃@CNF nanocomposite not only showcased superior electrochemical attributes, but its broad linear detection range and low detection threshold underscore its aptitude for real-world applications. In light of these findings, the Bi₂S₃@CNF nanocomposite stands poised as a pivotal tool in revolutionizing zearalenone detection methodologies, emphasizing the critical role of nanotechnology in addressing contemporary analytical challenges.

Selective sensing properties of transition metal dichalcogenides (MoX₂, X  = S, Se) towards specific volatile organic compounds (VOCs) associated with lung-cancer are investigated using state-of-the-art density-functional theory (DFT) methods. In the present investigation, a combination of DFT and the non-equilibrium Green’s functions (NEGF) formalism are employed to probe the sensing of four VOCs; namely: (i) Isoprene “C₅H₈”, (ii) Toluene “C₇H₈”, (iii) Cyclopropanone “C₃H₄O”, and (iv) Isopropanol “C₃H₈O”; and four interfering air molecules CO₂, H₂O_, N₂ and O₂. We find that the doping of single atom of selected transition metals (TMs = Mn, Fe, Ni, Cu) can enhance both the sensitivity and the selectivity of MoX₂. Our results show that the selectivity is rather distinct towards the detection of VOCs when TMs doping is targeting the chalcogenide site. Adsorption energies, charge transfers, electronic properties through density of states and band structures, and the sensor responses are obtained in all the cases, particularly for C₅H₈ and C₃H₈O, which show superior selectivities. Enhanced selectivity is attributed to the enhancement in the polarity of the substrate after the TMs doping targeting the chalcogenide sites. Our work demonstrates the potential of MoX₂ based single atom catalysts as efficient biosensor towards the specific VOCs for the early diagnosis of lung cancer.

PACS Numbers: 31.15.E-, 68.43.-h, 68.43.Fg, 82.33.Pt, 87.15.Aa, 87.15.Kg, 87.19.Xx, 87.19.xj.

In this study, we report negative photoconductivity in SnO₂/SnSe₂ nanosheets. We synthesized 2D n-type SnSe₂ nanosheets by the hydrothermal route and observed highly stable and repeatable negative photoconductivity (NPC) in the presence of both visible (532 nm) and near-infrared (NIR, 905 nm) irradiation. The existence of native SnO₂ skin on SnSe₂ nanosheets was confirmed with X-ray photoelectron spectroscopy (XPS). Negative photoresponse was improved significantly after Au nanoparticles (∼3.4 nm) functionalization of SnO₂/SnSe₂ nanosheet. Au-SnO₂/SnSe₂ exhibited responsivity/detectivity of 47.55 mA/W & 1.49 × 10¹⁰ Jones and 47.8 mA/W &1.5 × 10¹⁰ Jones at 10 V bias in visible and NIR light intensity of 50 µW/cm², respectively, and quite a faster fall time of 841 µs and 791 µs in NIR exposure. The origin of NPC in SnSe₂ is attributed to the trapping of photogenerated hot carriers by surface adsorption of oxygen in ambient air. The NPC was further increased due to a significant increment of dark current (as well as I_dark/I_light) after Au nanoparticles functionalization on SnO₂/SnSe₂.

The oxygen evolution reaction (OER) is vital in electrocatalytic water-splitting. However, efficient non-precious metal electrocatalysts are required to improve the reaction efficiency. Therefore, this study aims to increase the OER activity of FeNi₃ nanosheets using high-energy H⁺-ion irradiation to create multiple defects. The optimized sample (FeNi₃-16) achieves a lower overpotential of 260 mV at a current density of 10 mA cm⁻² than its pristine counterpart (FeNi₃, 320 mV). Density functional theory (DFT) calculations show that the multiple defects in Fe and Ni can synergistically reduce the d-band centres of the Fe and Ni sites, which improves the electron transfer efficiency during the OER. This ion-irradiation technique may be applied to other electrocatalysts for various energy device.

Compact lithium-ion batteries for miniaturized devices require high-volumetric-performance anodes. Either the graphite with high density or the porous nanocarbons with high gravimetric performance is limited in volumetric performance. Herein, we construct a series of anode materials, i.e. the collapsed carbon nanocages with different dopants, by capillarity compression, which achieves a high density of ∼0.97 g cm⁻³ but remains abundant micropores with increased active sites and enlarged interlayer distance. The N&S dual-doping redistributes the charges of sp² carbon to an optimal status, leading to the high Li-ion capacity, meanwhile facilitates the wettability at the electrode/electrolyte interface, leading to the enhanced Li-ion diffusion coefficient. Accordingly, the collapsed N&S dual-doped carbon nanocages (cNSCNC) anode exhibits a record-high volumetric capacity of 1578 mAh cm⁻³ at 0.1 A g⁻¹, excellent rate capability and cycling stability, thus achieving an ultrahigh volumetric energy density of 1087 Wh L⁻¹ at 120 W L⁻¹ for the cNSCNC//LiFePO₄ full cell.