Two-dimensional Nanosheets Research Articles

Atomic vacancies of molybdenum disulfide nanoparticles stimulate mitochondrial biogenesis

Diminished mitochondrial function underlies many rare inborn errors of energy metabolism and contributes to more common age-associated metabolic and neurodegenerative disorders. Thus, boosting mitochondrial biogenesis has been proposed as a potential therapeutic approach for these diseases; however, currently we have a limited arsenal of compounds that can stimulate mitochondrial function. In this study, we designed molybdenum disulfide (MoS2) nanoflowers with predefined atomic vacancies that are fabricated by self-assembly of individual two-dimensional MoS2 nanosheets. Treatment of mammalian cells with MoS2 nanoflowers increased mitochondrial biogenesis by induction of PGC-1α and TFAM, which resulted in increased mitochondrial DNA copy number, enhanced expression of nuclear and mitochondrial-DNA encoded genes, and increased levels of mitochondrial respiratory chain proteins. Consistent with increased mitochondrial biogenesis, treatment with MoS2 nanoflowers enhanced mitochondrial respiratory capacity and adenosine triphosphate production in multiple mammalian cell types. Taken together, this study reveals that predefined atomic vacancies in MoS2 nanoflowers stimulate mitochondrial function by upregulating the expression of genes required for mitochondrial biogenesis.

Analysis of electronic properties and sensing applications in Graphene/BC3 heterostructures

Many research studies have been conducted into the applications of the heterostructures of graphene (Gr) and boron carbide (BC3) in real-world devices after they were synthesized successfully by researchers. Thanks to their unique electronic attributes and high surface-to-volume ratio, the above-mentioned two-dimensional nanosheets (NSs) such as have enjoyed the interest of many research groups and scientists. Within this piece of research, the electronic and structural attributes of pure Gr (PGr), pure BC3 (PBC3) and their in-plane heterostructures were investigated by employing the DFT along with the density functionals B3LYP and WB97XD. The results demonstrated that by increasing the concentration of the B-C, there was a gradual increase in the bandgap. Also, the structural stability of the NSs was good and the cohesive energy was favourable. In addition, the adhesion attributes of these NSs were investigated towards two toxic gasses, namely CO and SO2. Amongst the heterostructures, after exposure to CO and SO2, the adhesion energy of GBC3I was greater, which was approximately −0.487 eV and −0.229 eV, respectively. Following the adhesion of SO2 onto the surface of the NSs, apart from the PGr, there was a significant change in their electronic attributes such as conductance, workfunction, Fermi level, the LUMO, the HOMO and the bandgap. However, following the adhesion of CO, the above-mentioned attributed remained almost the same. Based on the NBO and Mulliken charge analysis, there was a charge transport from the gasses to the NSs. Despite the fact that the adhesion energies for CO were relative higher than the adhesion energies for SO2for the NSs, the analysis of the MEP maps, the charge transport and the electronic attributes demonstrated that the NSs can be used as promising nanosensors for the detection of SO2 rather than CO.

Lignocellulosic materials extraction from waste baby diaper to prepare light-responsive metal oxide/carbon composite for efficient organic dye pollutant removal

The bimetal oxide comprising nickel incorporated β-Bi2O3 on graphitic carbon in the form of bismuth nickel oxide (BNO@C) was prepared by waste lignocellulosic materials collected from cheap and readily available baby diapers. The prepared BNO@C was used to photocatalytically degrade methylene blue under UV-light irradiation. Prior to the photocatalytic performance analysis, the formation of BNO@C was confirmed by various morphological and structural analysis including SEM, TEM, XRD, and XPS analyses. As a result, the two-dimensional nanosheet morphology and tetragonal primitive lattice-structure with 2+ and 3+ oxidation stated Ni and Bi in BNO@C structural formulation were confirmed. In photocatalysis experimentation examined with BNO@C, the maximum methylene blue removal percentage of 96.7 % was achieved within 16 min. The influence of Ni2+ in BNO@C was identified by performing the photocatalytic performance of bare NiO@C and Bi2O3@C, yielding maximum dye removal of 32.8 % and 64.5 %, respectively. The efficacy of Ni in BNO@C toward increasing catalytic efficiency was identified using DFT analysis, revealing the acting of Ni as active sites for improved light absorption tendency. These findings show a novel strategy to prepare a low-cost BNO@C catalyst with efficient photocatalytic activity, opening a new path for a cost-efficient wastewater treatment approach.

Nitrogen-rich carbon nanosheets supported copper catalysts for oxidative carbonylation of ethanol

Two-dimensional (2D) nitrogen-rich carbon nanosheets NC-x with a nitrogen content of 5.2 %-6.8 wt% were characterized by a one-step co-pyrolysis method and employed as Cu catalyst supports for oxidative carbonylation of ethanol. Carbon nanosheets with abundant nitrogen defects were achieved by tuning the dosage of ammonium oxalate, in which the Cu/NC-12 catalyst performed excellent activity. Furthermore, Cu/NC-x catalysts presented significantly superior catalytic activity than that of copper/carbon nanosheets (Cu/C) catalyst, it can be ascribed to the most suitable nitrogen doping to promote the exposure and dispersion of Cu species and pyridine nitrogen served as the main anchor sites to increase the ratio of Cu+/(Cu++Cu0). Density functional theory calculations further proved that introducing nitrogen atoms into carbon nanosheets effectively reinforced binding to Cu4 and adsorption of intermediates with NC, and a remarkable activity on Cu/NC-12 was achieved by a more favorable insertion of CO in the rate-determining step.

Ultrasensitive xylene sensor based on RuO2-modified BiVO4 nanosheets

Two-dimensional (2D) BiVO4 nanosheets (NSs), featuring distinctive chemical properties and dangling-bond-rich surfaces, are promising for developing high-performance gas sensors. However, the previously reported 2D BiVO4 NSs-based devices suffer from a low responsivity and poor selectivity. In this work, we introduce RuO2 nanoparticles to boost the gas sensing properties of 2D BiVO4 NSs-based sensor. Intriguingly, the RuO2-decoration changes the selectivity of the corresponding gas sensor from acetone to xylene. Compared to the pristine BiVO4 sensor, the RuO2-BiVO4 sensor displays a reduced optimal operating temperature of 260℃ and exhibits a response of 19.0–5 ppm xylene, reaching a five-fold enhancement. Simultaneously, the RuO2-BiVO4 sensor also exhibits a rapid response and recovery time of 10 and 25 s respectively, as well as robust long-term stability with less than 5 % variation in response after a storage of 60 days. The improvement in sensing performance can be attributed to the RuO2-decoration from three aspects: heterojunction construction, surface state modulation and gas oxidation catalysis on the surface. This work not only provides a high-performance xylene sensing material but also provides insightful comprehension regarding the modification effects of RuO2.

Constructing Cu-Mn bimetallic synergistic sites in 2D metal-organic framework nanosheets to induce polarized charge distribution: Electronic structure transformation and evaluation of Fenton-like performance

Heterogeneous Fenton-like process based on H2O2 was an efficient method for the abatement of micropollutants in water. However, the mass transport resistance caused by the limited access between catalytic sites and target chemicals still restrict the decontamination efficiencies. Metal-organic frameworks (MOFs) with uniformed pores and anbundant metal sites shows great potentail in environmental remediation, Here, a novel two-dimensional nanosheet consisting of Cu and Mn bimetallic-oxygen clusters (CuMn-BDC, BDC refers to terephthalic acid organic ligand) was rationally designed and characterized. The introduction of second metal Mn changed the surface electronic distribution and accelerated the electron transfer of pristine Cu-based nanosheet, leading to improved catalytical acticities and removal effeciencies (kSA) for Sulfamethoxazole (SMX). The catalytic activity of CuMn-BDC obtained (5.76 × 10–4) was 3.95 times higher than that of Cu-BDC (1.46 × 10–4), demonstrating that the CuMn-BDC showed higher reaction rates than that of Cu-BDC when same amount of H2O2 was added. The interfacial micro-electric fields in bimetallic MOFs increased the interaction of organic pollutants and transfer the electron to activate H2O2. Several quenching experiments, electron paramagnetic resonance spectra and theoretical calculations were performed to study the reaction mechanism systematically. Further the powder was fabricated into membrane with higher water stablities. This study shed light on develop efficient 2D-MOFs catalyst for the abatement of micropollutants in water.

Integration of vanadium diphosphide with 2D cobalt phosphide architected as an extensible redox active positrode for alkaline supercapacitor

Metal phosphides in the form of rationally constructed two-dimensional (2D) nanosheets hold significant promise as versatile materials for energy storage applications. This study introduces a novel hybrid supercapacitor electrode, composed of a binder-free vanadium phosphide integrated cobalt phosphide (VP@CP) on a nickel foam substrate. The fabrication process involves the hydrothermal growth of Co2(OH)2BDC (BDC- 1,4-benzenedicarboxylate) nanosheets on a Ni-foam substrate (CMF-Ni), followed by the deposition of VO2 on CMF nanosheets (VO@CMF-Ni) using chronoamperometry and phosphorization of the VO@CMF-Ni to yield VP@CP-Ni nanosheets. Particularly, the density functional theory (DFT) results show that the VP2 integrated Co2P sample provides metallic behavior and low adsorption energy of OH− ions, resulting in improved electrochemical redox process. These bimetallic phosphides exhibit outstanding properties, including enhanced pathways for rapid ion transport and storage, increased electronic conductivity, and expanded electroactive regions facilitating the faradaic charge storage process. Due to the presence of vanadium and cobalt coupled sites, the fabricated VP@CP-Ni electrode was able to attain a maximum areal capacity (CAR) of 971 mA h cm−2 at 6 mA cm−2. Additionally, the fabricated hybrid device (HDC) exhibits an impressive specific energy (SE) of 30.9 Wh kg−1 at a specific power (SP) of 1344 W kg−1, and excellent cyclic durability. These remarkable results stimulate the exploration of such possible 2D VP@CP-Ni nanosheets with promising charge storage electrode capabilities to develop a future era of energy storage devices.

High-Performance Ultraviolet to Near-Infrared Antiambipolar Photodetectors Based on 1D CdSxSe1-x/2D Te Heterojunction.

Antiambipolar heterojunctions are regarded as a revolutionary technology in the fields of electronics and optoelectronics, enabling the switch between positive and negative transconductance within a single device, which is crucial for diverse logic circuit applications. This study pioneers a mixed-dimensional photodetector featuring antiambipolar properties, facilitated by the van der Waals integration of one-dimensional CdSxSe1-x nanowires and two-dimensional Te nanosheets. This antiambipolar device enables flexible control over carrier transport via gate voltage, thus paving new paths for future optoelectronic devices. Furthermore, by precisely managing the stoichiometry of the ternary alloy CdSxSe1-x nanowires, fine-tuning of the nanowire band structure is achieved. This allows for customizable heterojunction band alignment (Type I and Type II), enabling adjustable band alignment. Through sophisticated band engineering, optimal Type II band alignment is achieved at the CdSxSe1-x/Te interface, significantly enhancing the device's photoelectric conversion efficiency through the synergistic effect of different dimensional materials. Exhibiting outstanding photoresponse across a broad spectral range from ultraviolet to near-infrared, especially under 450 nm illumination, the CdSxSe1-x/Te heterojunction photodetector demonstrates superior performance, including an impressive responsivity of 284 A W-1, a high detectivity of 1.07 × 1017 Jones, an elevated external quantum efficiency of 7.83 × 104 %, and a swift response time of 11 μs. Ultimately, this customizable antiambipolar photodetector lays a solid foundation for the advancement of next-generation optoelectronic technologies.

Highly porous Pt3Ni nanosheets for enhanced hydrogen evolution reaction

Two-dimensional (2D) nanosheets with high surface-to-volume ratios have garnered significant attention for their electrocatalytic properties. This study explores the characterization and electrocatalytic performance of highly porous monometallic platinum (Pt) nanosheets and bimetallic platinum-nickel (Pt3Ni) nanosheets for the hydrogen evolution reaction (HER) in both alkaline and acidic media. Advanced characterization techniques were employed to elucidate the morphological and compositional properties of the Pt and Pt3Ni nanosheets. Electrochemical characterization demonstrated that Pt3Ni nanosheets/C outperformed Pt nanosheets/C and commercial Pt/C in terms of HER activity and stability. The enhanced HER performance of Pt3Ni nanosheets/C is believed to be due to the dominance of the Volmer-Tafel mechanism. These findings highlight the potential of 2D bimetallic nanosheets and suggest a promising avenue for advancing hydrogen energy technologies.

Fe-MOFs nanosheets for photo-Fenton degradation of carbamazepine

Iron(II)-based metal organic framework (Fe(II)-MOF) nanosheets have emerged as promising candidates for photo-Fenton catalysis. However, efficiently synthesizing Fe(II)-MOF nanosheets remains a significant challenge. Here, a bottom-up synthesis strategy is proposed to prepare two-dimensional Fe-MOF nanosheets (TFMN) with micrometer lateral dimensions and nanometer thickness, featuring Fe(II) as the metal nodes. The application of TFMN in the photo-Fenton degradation of carbamazepine (CBZ) demonstrates remarkable CBZ degradation performance and excellent efficiency across a wide range of pH values. The electron density and density of states are further calculated by density functional theory. Mechanism analysis identifies h+, •OH and •O2− as the predominant active species contributing to the catalytic oxidation process in the Vis/TFMN/H2O2 system.

Novel two-dimensional FeB nanosheets for photoacoustic imaging-guided NIR-photothermal therapy

The development of biosafe near infrared (NIR)-photothermal nanomaterials is meaningful for tumor-targeted photothermal therapy and photoacoustic imaging for high-performance theranostics, but still challenging. Herein, we propose a new ultrasound-assisted chemical etching method based on the Fenton reaction to synthesize a novel kind of two-dimensional iron boride nanosheets (FBN) as NIR-photothermal nanomaterials. The developed FBN theranostic agent exhibits high NIR adsorption and NIR-photothermal conversion efficiencies, realizing biosafe and high efficacy of photoacoustic imaging-guided tumor-targeted NIR-photothermal therapy of tumor mice.

Co-regulation of microstructure and intrinsic groups in carbon nitride to achieve high-efficient pollutant degradation under visible light: Roles of N species

Owing to the drawback of the lower separation and shorter lifetime of carriers in carbon nitride (CN), this study reported that the CN composites with different morphologies and the N species were successfully synthesized through the regulation of intrinsic functional groups. Results showed that the formed tubular structure in 1D CN nanotubes (1D CNNTs) could intensify the utilization of visible light (Vis) because of the multiple diffraction or scattering of light, bridge the mass transfer distance and provide more active sites. Meanwhile, 1D CNNTs showed excellent TC degradation rates (0.3777 min-1) under Vis, which were 13, 630 and 6-36 times higher than these of two-dimensional CN nanosheets, three-dimensional CN microspheres and reported CN based catalysts, respectively. The analysis of active species showed O2·- and h+ were the main active species for TC degradation. The degradation pathways and comprehensive toxicities of TC were also comprehensively analyzed. Theoretical calculation exhibited that the introduction of N vacancy and -NHx groups effectively accelerating separation of carriers, prolonging carrier lifetime and enhancing the adsorption ability and relative electron transfer of O2 to the production of O2·-. In addition, the prepared catalysts presented better stability and anti-interference ability. Therefore, this study would provide a new view for regulation of intrinsic functional groups in CN to achieve efficient pollutant degradation under Vis.

Ferrocene-based 2D metal–organic framework nanosheet for highly efficient photocatalytic seawater uranium recovery

Sustainable uranium supply is critical for the long-term development of nuclear energy. The photocatalytic reduction of soluble hexavalent uranium to insoluble tetravalent uranium using photocatalysts has been recognized as a highly promising method for uranium recovery. However, existing photocatalysts face limitations such as restricted visible-light absorption and poor charge transfer capability, which hinder their photocatalytic uranium recovery performance. In this work, 1,1′-ferrocene dicarboxylic acid (FcDA) was introduced to synthesize the photocatalyst Zr-Fc-MOF3. The incorporation of FcDA broadened the visible light absorption range and reduced the band gap of Zr-Fc-MOF3, thereby enhancing electron-hole pair separation and carrier transport efficiencies. Moreover, the two-dimensional (2D) nanosheet structure of Zr-Fc-MOF3 provided a large surface area, allowing full exposure of active sites. Additionally, Fe(II) in FcDA generated photoelectrons upon light excitation to facilitate uranium reduction, and the recyclable redox behavior of Fe(II) conferred high reusability of the photocatalyst. Consequently, Zr-Fc-MOF3 demonstrated a high photocatalytic uranium recovery capacity of 8.29 mg g−1 over 10 days in natural seawater (NSW), with a uranium recovery rate of 0.829 mg g−1 d−1, surpassing most other photocatalysts applied in NSW. These findings suggest that designing 2D nanosheet materials with ligands capable of efficient photoelectron generation is a promising approach for developing high-performance uranium recovery photocatalysts.

Highly Sensitive Ammonia Gas Sensors at Room Temperature Based on the Catalytic Mechanism of N, C Coordinated Ni Single-Atom Active Center

HighlightsExploiting single-atom catalytic activation and targeted adsorption properties, Ni single-atom active sites based on N, C coordination are constructed on the surface of two-dimensional MXene nanosheets (Ni–N–C/Ti3C2Tx), enabling highly sensitive and selective NH3 gas detection.The catalytic activation effect of Ni–N–C/Ti3C2Tx effectively reduces the Gibbs free energy of the sensing elemental reaction, while its electronic structure promotes the spill-over effect of reactive oxygen species at the gas–solid interface.An end-sealing passivation strategy utilizing a conjugated hydrogen bond network of the conductive polymer was employed on MXene-based flexible electrodes, effectively mitigating the oxidative degradation of MXene-based gas sensors.

Anti-corrosion design of layered zirconium-based metal–organic frameworks (Zr-MOF) enhanced epoxy nanocomposite coatings

In this work, two-dimensional UiO-67 nanosheets are successfully modified on graphene oxide (GO). The synthesized GO@2D-UiO-67 composite not only exhibits the electrical insulation characteristics of Zr-MOF, but also leverages the passive barrier effect of its 2D layered structure to prepare a highly anticorrosive epoxy coating. Electrochemical measurements reveal that the impedance modulus of the GO@UiO-67/EP composite coating remain two orders of magnitude higher than that of the pure EP coating even after 28 days of immersion in 3.5 wt% NaCl solution. This good long-term anti-corrosion performance could derive from the enhanced crosslinking density of composite coating due to the incorporation of GO@UiO-67 nanosheets. Furthermore, the shielding effect of layered structure and the corrosion inhibition behavior of organic ligands are proved to improve the corrosion resistance properties of composite coating. This research fills the application void of two-dimensional Zr-MOF composites in resin coatings, as well as serves as a forward-looking initiative to enhance the long-term corrosion protection of epoxy resin coatings.

Solid Lithiation and Exfoliation for Scalable Synthesis of Two-Dimensional Nanosheets toward Industrialization.

Two-dimensional (2D) materials show intriguing and diverse properties in different fields, stimulating chemists to develop synthetic and functional methodologies for producing solution-processable nanosheets on a large scale. However, it is still challenging to prepare 2D materials for industrial applications without sacrificing their lab-scale properties. Solid lithiation and exfoliation can achieve the hundred-gram-scale production of transition metal telluride nanosheets, making it one of the most effective strategies for mass production of 2D nanomaterials. In this Perspective, we highlight the advantages, propose the challenges, and discuss the opportunities of solid lithiation and exfoliation as a promising and commercially viable production method for 2D nanomaterials.

Boosting oxygen evolution reaction by FeNi hydroxide-organic framework electrocatalyst toward alkaline water electrolyzer

The oxygen evolution reaction plays a vital role in modern energy conversion and storage, and developing cost-efficient oxygen evolution reaction catalysts with industrially relevant activity and durability is highly desired but still challenging. Here, we report an efficient and durable FeNi hydroxide organic framework nanosheet array catalyst that competently affords long-term oxygen evolution reaction at industrial-grade current densities in alkaline electrolyte. The desirable high-intensity performance is attributed to three aspects as follows. First, two-dimensional nanosheet porous arrays with maximum specific surface facilitate mass/charge transfer to accommodate high-current-density catalysis. Second, in situ derived FeNi hydroxide motifs offer bimetallic synergistic catalysis centers with high intrinsic activity. Third, carboxyl ligands alleviate metal oxidation favorable for charge tolerability against peroxidation dissolution under strong polarization. As a result, this catalyst requires an overpotential of only 280 mV to deliver high current density up to 1 A/cm2 with long durability over 1000 h. Moreover, an alkaline water electrolyzer with this catalyst alternative demonstrates an increased economic effectiveness compared to commercial levels at present.

Facile Synthesis of Ni(OH)2 through Low-Temperature N-Doping for Efficient Hydrogen Evolution

Nickel hydroxide is a potentially cheap non-precious metal catalytic material for alkaline hydrogen evolution reactions (HERs). Herein, a nickel form (NF)-based nitrogen-modified nickel hydroxide (N-Ni(OH)2/NF) with interlaced two-dimensional (2D) nanosheet structures was synthesized by a simple one-step ammonia vapor-phase hydrothermal method for efficient electrocatalytic HERs. The effect of the reaction temperature of the catalyst preparation on the HERs’ performance was studied in detail. The HER activity of N-Ni(OH)2/NF is enhanced by the large specific surface area, mass transfer and electron conductivity provided by a unique and suitable 2D nanostructure and nitrogen doping. The obtained N-Ni(OH)2/NF not only shows a superior HERs performance, but also exhibits good stability during long-term electrolysis.

Magneto-Luminescent Two-Dimensional Nanosheets of Gadolinium and Gold Nanocluster Assemblies with Surface Molecular Functionalization for White Light Emission.

We report the formation of photoluminescent two-dimensional (2D) crystalline nanosheet assemblies of gadolinium ions and ligand-stabilized gold nanoclusters (Gd-Au NCs). Transmission electron microscopy, selected area electron diffraction in conjunction with atomic force microscopy, and field-emission scanning electron microscopy analyses substantiated the 2D nature of Gd-Au NC nanosheets. The optical and magnetic properties of the nanosheets were investigated by photoluminescence measurements and vibrating-sample magnetometry analyses. The so-formed crystalline product was further utilized to generate a synchronous tricolor (orange, green, and blue) emission from a single excitation wavelength through an inorganic surface complexation reaction. The independent emissions were tunable after ligand functionalization by acetylsalicylic acid and fluorescein on the Gd-Au NC assembly. Interestingly, the assembled superstructure with augmented quantum yield led to white light emission at λexc ≈ 325 nm with CIE of (0.34, 0.33) and CRI value of >85 in the liquid phase. Furthermore, the ability to modulate the luminescence properties through the surface complexation of the 2D nanosheets of Au NCs may bring about new avenues toward applications in light-emitting devices, sensing, and biomedical imaging.

In Situ PL Probes the Effect of 2D SnSe Nanosheets on the Crystallization Process of CsPbI2Br Perovskite Solar Cells.

Reducing defects in the active layer is important for improving the crystalline quality of all-inorganic perovskite solar cells (PSCs). Exploring novel additives is one of the most promising approaches to minimize active layer defects. In this work, two-dimensional (2D) SnSe nanosheets with excellent optoelectronic properties are prepared using an ultrasonic exfoliation method. The prepared 2D SnSe nanosheets are introduced into a CsPbI2Br precursor, which reduces the defect formation at grain boundaries and enhances the crystallinity of CsPbI2Br perovskites. We use the in situ photoluminescence (PL) technique to investigate the role of 2D materials in the crystallization process. The results show that SnSe nanosheets primarily shorten the grain boundary merging time and reduce the defect generation during the grain boundary merging stage, thereby regulating the crystallization of perovskite. In addition, SnSe nanosheets passivate uncoordinated Pb atoms at grain boundaries by Se atoms, further reducing the defect density in perovskite. As a result, PSCs exhibit a higher power conversion efficiency (PCE) of 14.24% and a Voc of 1.22 V. This study highlights the role of 2D materials in enhancing the crystalline quality and PCE of PSCs.