FlatChem最新文献

Miniaturized and stabilized polarization-sensitive mid-Infrared photodetectors at room temperature are indispensable in fields ranging from medical diagnostics to military surveillance in the next-generation on-chip polarimeters. Emerging two-dimensional materials offer a promising avenue to fulfill these requirements, facilitated by their ease of integration onto complex structures, inherent in-plane anisotropic crystal structures that enhance polarization sensitivity, and robust quantum confinement effects that enable superior photodetection performance at room temperature. Here, we report the systematic investigation of polarization-dependent infrared photoresponse based on Ta₂NiSe₅, revealing significant anisotropy photocurrent with excellent stability at room temperature. Significantly, a large anisotropic ratio of Ta₂NiSe₅ ensures the polarization sensitivity achieves a ratio of 1.23 at 1550 nm. Moreover, at 4.6 μm, the device exhibits a peak photocurrent response of 1.16 A/W along the armchair orientation, with an anisotropy ratio of approximately 3.3. These findings not only enhance our understanding of the photophysical mechanisms in two-dimensional materials but also guide the optimization of photodetector design for enhanced performance.

As key components of next-generation battery energy storage systems, solid-state batteries have attracted widespread attention. Li₁₀GeP₂S₁₂ (LGPS)-type solid-state electrolytes (SSEs) are favored by researchers owing to their excellent ionic conductivity and potential high-temperature stability. However, the poor interface between LGPS-type SSEs and electrodes has seriously hindered the commercialization of LGPS all-solid-state lithium batteries. This review introduces the structure and Li-ion conduction mechanisms of LGPS-type SSEs and discusses the challenges related to LGPS-type SSEs/electrode interfaces, along with strategies for overcoming these challenges. To improve the interface compatibility, researchers have developed feasible methods for improving and optimizing LGPS-type SSEs. The review concludes with potential research directions and prospects of future LGPS all-solid-state lithium batteries.

Penta-octa-graphene (POG) consists of pentagonal and octagonal carbon rings, hosting type-I and type-II Dirac line nodes due to its sp² and sp³ mixed bonds. Inorganic analogs of 2D carbon lattices have increased the potential applications and changed the main properties of carbon-based structures. Therefore, this work proposes penta-octa-graphene based on silicon carbide using DFT simulations. With a cohesive energy of −5.22 eV/atom, POG-Si₅C₄ is energetically viable in comparison with other silicon carbide-based monolayers. Phonon dispersion analysis confirms the POG-Si₅C₄ dynamical stability. MD simulations demonstrate that this new monolayer can withstand temperatures up to 1020 K. Electronic analysis indicates it is a semiconductor with an indirect band gap transition of 2.02 eV. The mechanical properties exhibit anisotropy, with Young’s modulus ranging from 38.65 to 99.47 N/m and an unusual negative Poisson’s ratio of −0.09. The band edge alignment suggests that POG-Si₅C₄ holds potential for hydrogen generation through photocatalytic water splitting. This research opens possibilities for designing inorganic penta-octa-based structures and provides insights for future experimental and theoretical studies focused on exploring and optimizing advanced silicon-carbide 2D materials.

MXene’s outstanding performance in driving the Hydrogen Evolution Reaction (HER) has attracted significant interest. The HER involves hydrogen generation by electrolyzing water. It is widely recognized that hydrogen represents a renewable and future-oriented alternative energy source that is currently receiving significant attention. On the other hand, MXenes also have a crucial function as catalysts, elevating the pace and effectiveness of chemical reactions. Moreover, their properties make them essential in diverse fields, contributing to advancements in energy storage, sensing technology, and catalysis for improved reactions. Herein, we highlighted MXene nanocomposite materials from synthesized to utilization in HER reaction both experimentally and theoretically. Various MXene-based nanocomposites, which consist of monomer, carbon, and oxide that can be used in hydrogen evolution reactions, are also elaborated in detail. Ultimately, we concluded this review with the future prospect of MXenes in electrochemical HER.

Metal chalcogenides like Tin sulfide (SnS₂) presents as viable alternative electrocatalysts for alkaline water splitting (AWS) due to their huge abundance, stability, and environment friendly nature. However, insufficient exposed active sites and poor conductivity severely impede its large-scale applications. In this work, an in-situ hybridization of hexagonal SnS₂ with intercalation of reduced graphene oxide nanosheets (TS-rGOx) overcomes the problem of SnS₂ stacking. It further enhances the interlayer spacing thereby boosting the number of active sites. The resulting TS-rGOx exhibited excellent oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) activities demanding low overpotential of 313 mV and 196.2 mV at 20 mA/cm² with long term durability upto 60 h, which can be attributed to enhanced interlayer spacing of SnS₂, abundant active sites and higher conductivity resulting from the in-situ hybridization and intercalation of rGO nanosheets. This work opens a prospect towards the design and application of efficient SnS₂ based heterostructured electrocatalyst for AWS.

Exfoliated 2H-MoS₂ holds a promising future for various electrochemical applications. Nevertheless, its electrical conductivity and electrocatalytic efficiency are limited, restricting its standalone use. To address this limitation, this study proposes the electrochemical deposition of gold nanoparticles on layer-by-layer films of poly(diallyl dimethylammonium) hydrochloride interspersed with exfoliated 2H-MoS₂, previously assembled on ITO substrate. This modified electrode, denoted as ITO/PDAC/2H-MoS₂/Au, was assessed for its effectiveness in the voltametric detection of bisphenol-A (BPA). The optimal electrode architecture demonstrated a linear BPA detection range (0.9 µM-19 µM; R² > 0.99), with a limit of detection of 23 nM. Notably, the electrochemical deposition was effective on both bare and film modified ITO substrates. However, it was on the ITO/PDAC/2H-MoS₂/Au electrode that BPA detection achieved a reasonable level of sensitivity. During electrodeposition, superficial Mo(IV) is oxidized to Mo(VI) while sulfur vacancies are generated. These defect sites enhance the electrochemical activity of 2H-MoS₂ and play a pivotal role in nucleating, growing, and immobilizing gold nanoparticles, which collectively enhance the sensor’s performance.

Molybdenum disulfide (MoS₂) has been immensely explored for its potential usage in energy storage applications owing to its high theoretical specific capacitance and layered structure. Here, we have investigated the effect of selenium addition in MoS₂ forming MoS_2(1-x)Se_2x alloys and studied their electrochemical performance. Selenization was performed through a simple hydrothermal method. The electrochemical performance of MoS₁Se₁ was evaluated in a two-electrode configuration. The selenization is found to improve the electrochemical performance of MoS₂ and the MoS₁Se₁ alloy with the optimal S (sulfur) to Se (selenium) ratio of 1:1 exhibits an excellent areal capacitance of 2629.45 mF/cm² at 1 mA/cm², with an appreciable specific capacitance of 266.51 F/g at a current density of 0.5 A/g and excellent cycle stability of 81.64 % after 6000 cycles. Along with the experimental findings, Density functional theory calculations were also performed, revealing that the electronic properties of MoSSe systems can be tuned by varying the ratio of S and Se.

Interface engineering plays a critical role in the development of high-efficient fuel cell catalysts, as the interfaces across different components can synergistically and substantially accelerate electrocatalysis kinetics, together with improvement in mass transfer and structural stability. In this study, we report a feasible strategy to create PdPtAg-on-Au heterogenous nanoplates (PdPtAg-on-Au HNPs) and validate their structural advantages in electrocatalysis. By limiting the doping of Au nanoplates with Pt/Ag atoms on the surface and subsequently depositing Pd nanodots in a highly scattered pattern, abundant multimetallic interfaces form and enhance the methanol oxidation reaction (MOR) electrocatalytic process. The optimized PdPtAg-on-Au HNPs/C electrocatalysts exhibited superior mass activity, improved reaction kinetics, and long-term durability compared to commercial Pt/C. DFT simulations suggest that the chemical surrounding of the Pd/Pt catalytic active center with AuAg atoms can lower the reaction barrier and CO binding affinity. This work provides a feasible synthetic strategy for preparing multimetallic fuel cell electrocatalysts with advanced control over heterogeneous structures, highlighting the potential of interface engineering in the rational design of electrocatalysts.

Laser-induced graphene (LIG) on paper is a popular choice for fabricating flexible micro-supercapacitors (MSCs) as it is a simple and sustainable process. However, carbon-based MSC electrodes have limited energy densities. To address this challenge, this study presents a highly reproducible and cost-effective method for decorating manganese oxide (MnO_x) on interdigital LIG MSC electrodes, fabricated via a single-step direct laser writing (DLW) process on paper substrates. The paper fibers embedded with MnO_x precursors are transformed into graphene through laser processing while reducing the salt, resulting in the formation of MnO_x-LIG. The resulting MnO_x-LIG-MSC exhibits a specific capacitance of 12.30 mF cm⁻² (0.05 mA cm⁻²) with a 60 % retention at 1000 bending cycles (30°), due to the pseudocapacitive contribution of MnO_x. Furthermore, the devices exhibit high electrochemical stability, retaining 190 % of the initial specific capacitance after 10,000 cycles, and a high energy density of 2.6 μWh cm⁻² (at a power of 0.109 mW cm⁻²). The study demonstrates that manganese oxide-based LIG-MSCs have the potential to be used as energy storage devices for portable, low-cost, and flexible paper electronics.

Functional groups based on halides, such as fluorine (F), chlorine (Cl), bromine (Br), and iodine (I), are crucial for understanding the chemical reactivity of graphitic nanomaterials. Except for I, halogens exhibit electronegativity greater than carbon (C); therefore, charge transfer from carbon to halogen is expected. First-principles density functional theory calculations were performed to determine the role of different Cl-functional groups (methyl-trichloride, ethyl-trichloride, chloride, acyl-chloride, vinyl-chloride, acetyl hypochlorite, chloramines, sulfonyl chloride, and more) on the electronic properties of graphene and graphene nanoribbons (GNRs). GNRs with zigzag edges (ZGNRs) and armchair edges (AGNRs) were studied. We analyzed the optimized structures, band structure, density of states, cohesive energy, and band gap. Our results revealed that the based-Cl functional groups can provide an alternative route to activate the borders and surfaces of sp² carbon materials. Methyl-trichloride and acyl-chloride can induce magnetism and metallicity. Chloride and acyl-chloride are the most energetically stable functional groups attached to the edges. Surprisingly, methyl-trichloride or acyl-chloride functionalizing the surface of the AGNRs showed a direct (indirect) band gap for states with spin-up (spin-down). The results of aromatic (chlorobenzene- and dichlorobenzene-like structures) functionalization considering F, Cl, Br, and I are also shown. Finally, –F₂ and –ClF functionalization cases are discussed.