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Laser-induced graphene (LIG) has been extensively explored for various applications due to its low cost, simple preparation, and excellent physical and chemical properties. Compared to non-degradable polymers such as polyamide (PI), bio-based precursors offer immense advantages for more sustainable development. In this study, folate was innovatively proposed as the precursor for high-quality LIG synthesis, which was further used for the development of strain sensors and electrochemical catalysis. The folate-based LIG strain sensor demonstrated a broad operating range (0–12%), high sensitivity (with a gauge factor up to 361), exceptional stability, and reliability (exhibiting a consistent response over 10,000 repeated stretching cycles). Moreover, it exhibited precise detection capabilities for subtle deformations induced by human respiration, speech, swallowing, pulse beating, and joint movements. In terms of electrochemical catalysis, folate-based LIG demonstrated a remarkable enhancement in increasing the degradation rate of pollutants like Rhodamine B through the electro-Fenton process. The findings of this study suggest that LIG derived from folate processes shows huge promise for applications such as medical monitoring, micromotion recognition, and water pollutant remediation. [ABSTRACT FROM AUTHOR]

Hybrid water electrolyzers that use facile organic oxidation reactions (OOR) as an alternative to the sluggish oxygen evolution reaction (OER) are projected as high-value electrolyzers due to the simultaneous production of H2 and value-added chemicals. In the present study, electro-oxidative dehydrogenation of benzylamine (BAm) to benzonitrile (BN) is carried out as an alternate oxidation reaction to OER, coupled with the hydrogen evolution reaction (HER), in a hybrid water electrolysis system. For this, heterostructures of Ni2Co layered double hydroxide (LDH) and reduced graphene oxide (rGO) are synthesized by using flocculation of oppositely surface-charged nanosheets and used for the benzylamine oxidation reaction (BAmOR). The Ni2Co-LDH/rGO heterostructures require 1.35 V vs RHE to achieve a current density of 10 mA cm–2 in the presence of BAm, compared to 1.61 V vs RHE without BAm, indicating that BAmOR can be a potential alternate to OER. Upon utilizing Ni2Co-LDH/rGO heterostructures as the anode and commercial Pt as the cathode in a hybrid water splitting cell, faradaic efficiencies of ∼94% and ∼85% are achieved for H2 and BN production, respectively. Additionally, the hybrid electrolysis cell is capable of producing 38.6 μmol cm–2 h–1 H2 even at a cell voltage of 1.39 V, whereas the traditional water electrolysis cell requires a cell voltage of 1.68 V to yield a similar (34.7 μmol cm–2 h–1) amount of H2. This clearly suggests that substituting the OER with BAmOR is beneficial for not only achieving high efficiency in H2 production but also producing value-added BN. [ABSTRACT FROM AUTHOR]

BiOI is a promising photoelectrocatalyst for oxidation reactions. However, the limited photoelectrocatalytic (PEC) activity necessitates the development of new strategies to modify its surface chemistry and thus enhance functional properties. Herein, we present a simple method to increase photocurrent in a BiOI‐based photoanode by exfoliating microspheres of the oxyhalide produced through hydrothermal synthesis. Following exfoliation in isopropanol, the resulting layered BiOI‐based colloid contains a greater variety of species, including Bi2O2CO3, I3−, IO3−, Bi5+, and hydroxides, compared to the original BiOI. These additional species do not directly enhance the PEC oxygen evolution reaction (OER) performance. Instead, they are consumed or converted during PEC OER, resulting in more active sites on the photoelectrode and reduced resistance, which ultimately improves the water oxidation performance of the exfoliated BiOI. Over long‐term chronoamperometry, the exfoliated BiOI demonstrates a photocurrent twice as high as that of the BiOI microspheres. Analysis of the species after PEC OER reveals that the combination of IO3−, Bi5+, and I3− species on the BiOI is beneficial for charge transfer, thus enhancing the intrinsic PEC properties of the BiOI. This study offers new insights into the role of surface chemistry in determining PEC performance, aiding the optimization of 2D materials‐based photoelectrocatalysts. [ABSTRACT FROM AUTHOR]

In recent years, the use of biomolecules as dispersants for the preparation of 2D nanomaterials by direct liquid-phase exfoliation (LPE) using ultrasonication has attracted increasing attention as a convenient and cost-effective approach to ensure simultaneously the biocompatibility of these nanostructures. In this work, we prepare MoS2 quantum dots (QDs) by the LPE method using deoxyadenosine monophosphate (dAMP) as an exfoliation agent that provides a good biocompatibility of the QDs too. As a result, a visible-range photoluminescence from MoS2 QDs surrounded by nucleotides is observed for the first time. Different structures of MoS2 QDs with dAMP are analyzed employing the DFT calculations. It is shown that dAMP can form coordination bonds with the Mo atoms located at the QD edges or at the defect sites where direct contacts with these atoms can occur. The covalent bonds facilitate strong adsorption of dAMP on a MoS2 QD. The structural flexibility of the nucleotide adsorbed on the MoS2 QD enables a combination of noncovalent stacking interaction of the nucleobase and a coordination bond of the phosphate group with the Mo atoms located at the edges to occur. This leads to the formation of a very energetically stable complex. [ABSTRACT FROM AUTHOR]

Fluorographene (FG) with narrow lateral size and thickness distributions was prepared by a liquid-phase exfoliation method, based on liquid cascade centrifugation. The Rtec MFT-5000 tribo-meter was used to investigate the lubricating performance of bentonite grease enhanced by the as-prepared FG. The results showed that the coefficient of friction and the wear volume of bentonite grease with 0.3 wt% FG were decreased by 20.4% and 44.9%, respectively, as compared to those of the base grease. The main reason is that FG can promote the formation of the tribo-chemical reaction film consisting of complex carbon oxide, Fe2O3 and FeF3 on the friction surface, which can remarkably improve the performance of friction reduction and prevent the appearance of severe wear. [ABSTRACT FROM AUTHOR]

Liquid‐phase exfoliation, a technique for enhancing the properties of biochar, has been recognized as effective, circumventing the limitations of other methods such as high expenses, scalability, and complexity. This study explored the synergistic effect achieved by combining chicken feathers with elephant grass to create a composite feedstock for biochar production. The biochar was subjected to liquid‐phase exfoliation using acid and acetone. Elemental analysis indicated that the co‐carbonization of the combined biomass produced an enriched hybrid biochar. The oxygen content in both exfoliation routes (acid and acetone) increased, with an increase and decrease in carbon content in acetone and acid exfoliation, respectively. Textural analysis revealed significant enhancement, with surface areas of the acid‐exfoliated biochar more than twice the size of the hybrid biochar. The pore volume of both exfoliated samples was double that of the hybrid biochar. Microscopic surface examination revealed rougher, porous structures in the exfoliated biochars in comparison with the smooth, cohesive surface in hybrid biochar. Functional group analysis showed the presence of aromatic rings, a carbocyclic group, and an alkene, suggesting potential applications in adsorption. This study provides an efficient method for using liquid‐phase exfoliation to enhance biochar properties, benefiting industries reliant on biochar production and biomass utilization by improving product quality, sustainability, and environmental impact. [ABSTRACT FROM AUTHOR]

An X-ray analysis of exfoliated MoS2, produced by means of microwave-assisted liquid-phase exfoliation (LPE) from bulk powder in 1-methyl-2-pyrrolidone (NMP) or acetonitrile (ACN) + 1-methyl-2-pyrrolidone (NMP) solvents, has revealed distinct structural differences between the bulk powder and the microwave-exfoliated samples. Specifically, we performed X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) measurements to identify the elements of our exfoliated sample deposited on a Si substrate by drop-casting, as well as their chemical state and its structural crystalline phase. In the exfoliated sample, the peaks pattern only partially resemble the theoretical Miller indices for MoS2. In contrast, the bulk powder's spectrum shows the characteristic peaks of the 2H polytype of MoS2, but with some broadening. Notable is the retention of partial crystallinity in the post-exfoliation phases, specifically in the normal-to-plane orientation, thus demonstrating the effectiveness of microwave-assisted techniques in producing 2D MoS2 and attaining desirable properties for the material. XPS measurements confirm the success of the exfoliation procedure and that the exfoliated sample retains its original structure. The exfoliation process has been optimized to maintain the structural integrity of MoS2 while enhancing its surface area and electrochemical performance, thereby making it a promising material for advanced electronic and optoelectronic applications ranging from energy storage to sensing devices under ambient conditions. [ABSTRACT FROM AUTHOR]

Achieving dispersions of antimony sulfide (Sb2S3) in environmentally friendly solvents is of paramount importance for safer and sustainable processing due to its wide range of applications. The efficacy of liquid-phase exfoliation (LPE) depends on the choice of solvents, and the determination of the Hansen solubility parameters (HSP) is crucial. In this work, employing the Hansen solubility sphere method, the HSP values of Sb2S3 are determined to be 20.8, 10.8, and 13.4 MPa1/2, which correspond to dispersive, polar, and hydrogen-bonding interactions, respectively. Environmentally friendly solvents, such as 2-butanol and isopropyl alcohol (IPA), have been identified as good solvents for exfoliation. Subsequently, the stability of the dispersions is investigated using an analytical centrifuge. Through the in situ visualization of transmission profiles and various stability parameters like the instability index, sedimentation velocity, and decay time constants, 2-butanol is found to have excellent dispersion stability. To further explain the observed stability, density functional theory (DFT) calculations are carried out. The adsorption energy of 2-butanol on the surface of Sb2S3 is higher than that of IPA, leading to better solute–solvent interactions and, hence, better dispersion stability. Subsequently, the dispersions are utilized to fabricate thin films using the spray-coating method. The solution-processed Sb2S3 photodetector exhibits an impressive responsivity of 68 mA/W, noise-equivalent power (NEP) of 0.3 pW/Hz–1/2, and detectivity of 2.4 × 1011 Jones. [ABSTRACT FROM AUTHOR]

We investigate the molecular mechanism underlying the liquid‐phase exfoliation of graphene in aqueous/N‐methyl‐2‐pyrrolidone (NMP) solvent mixtures and calculate the associated free energies, considering different NMP concentrations and exfoliation temperatures. We employ steered molecular dynamics to establish a path for the exfoliation of a graphene sheet from graphite within each solvent environment. Then, we conduct umbrella sampling simulations throughout the created paths to compute the potential of mean force (PMF) of the graphene sheet. As the exfoliated nanosheet disperses into the liquid, it becomes fully covered by an adsorbed solvent monolayer. We analyze the composition of the monolayer by measuring the direct contacts of either NMP or water molecules with the carbon surface. The carbon surface exhibits a preference for adsorbing NMP over water. The NMP molecules form a hydrophobic compact monolayer structure, effectively protecting the carbon interface from unfavorable interactions with water. The creation of the hydrophobic monolayer is a key factor in the exfoliation process, as it effectively inhibits the restacking of exfoliated nanosheets. An adequate level of graphene solubility is achieved through the addition of 20 % to 30 % water by weight to the NMP solvent. This finding holds significant importance for improving production efficiency and reducing dependence on organic solvents in the industrial manufacturing of graphene. [ABSTRACT FROM AUTHOR]

The utilization of two-dimensional (2D) materials in optoelectronic devices has witnessed a surge. Production of 2D ultrathin molybdenum disulfide (MoS2) nanosheets without the use of toxic precursors and without altering the phase of the material is still a task. We developed a cost-effective liquid-phase exfoliation method that is free of additives, utilizing ultrasound to produce a significant amount of nearly single-layered MoS2 nanosheets by employing isopropyl alcohol and deionized water as a cosolvent. This work addresses the deficiencies in the current state-of-the-art studies by exploring the mechanism governing ultrasonic cavitation, resulting in MoS2 nanosheets. Various sonication durations were altered to investigate the relationship between the duration of sonication and the dimensionality of the resulting nanosheets. The findings revealed that prolonged sonication durations yielded bilayered and trilayered nanosheets. The reduction in layer thickness was confirmed by Raman modes as the sonication time increased. Size-dependent optical studies indicated that the optical properties have enhanced as the sonication time increased. An open-aperture Z-scan investigation was conducted to explore the size-dependent nonlinear optical features of MoS2 nanosheets, employing a 532 nm neodymium-doped yttrium aluminum garnet pulsed laser in a nanosecond pulsed regime. The optical limiting performance of the nanosheets sonicated at various time intervals was accessed and it was observed that as the nanosheets' thickness decreases, the optical limiting behavior improves. Due to two-photon absorption, MoS2 nanosheets display optical limiting behaviors through reverse saturable absorption. Optical limiting thresholds as low as 2.98 × 1012 W/m2 are attained. This significant enhancement suggests that these ultrathin MoS2 nanosheets are suitable for applications in laser shielding. [ABSTRACT FROM AUTHOR]

Graphene-based chemical sensors hold promise across diverse applications owing to their exceptional sensitivity and selectivity. However, achieving their long-term durability and reusability while preserving high sensitivity remains a significant challenge, particularly in harsh environments where exposure to strong chemicals is inevitable. This paper presents a novel approach to address this challenge by synergistically integrating liquid-phase exfoliated graphene (LPEG) with polytetrafluoroethylene (PTFE) within a single sensing strip. Through a comprehensive experimental investigation, we demonstrate the fabrication of highly durable and reusable chemical leak detection sensors by combining LPEG and PTFE. Furthermore, we explore the sensing mechanism, highlighting the roles of LPEG and PTFE in enhancing sensitivity and selectivity, along with durability and reusability. Performance evaluation reveals the sensors' robustness against mechanical and chemical degradation, coupled with excellent recyclability. This innovative approach holds promise for applications in environmental monitoring, industrial safety, and healthcare, thus advancing the field of graphene-based chemical leak detection sensors. [ABSTRACT FROM AUTHOR]

TiO2/C nanocomposite films were applied on water treatment. Expanded graphite nanosheets (EG) were obtained by UVC-assisted liquid-phase exfoliation technique, without the addition of acids, surfactants, or aggressive oxidizing agents, which characterizes the process as an eco-friendly method. The carbon nanosheets were synthesized directly from graphite bulk at different times and deposited on TiO2 films surface by airbrush spray coating method, forming a TiO2/C heterojunction. The increase in the exfoliation time promoted a more efficient photocatalytic dye removal under visible light. Morphological modifications, changes in the electronic structure, and wide range of light absorption were observed from the TiO2/C heterojunction formation. The results showed that hybrid TiO2/C supported photocatalyst is a promise alternative for practical photocatalytic applications under sunlight. [ABSTRACT FROM AUTHOR]

Liquid-phase exfoliation was employed to synthesize Sr2Nb3O10 perovskite nanosheets with thicknesses down to 1.76 nm. Transmission electron microscopy (TEM), atomic force microscope (AFM), X-ray photoelectron spectrometer (XPS), and other characterization techniques were used to evaluate the atomic structure and chemical composition of the exfoliated nanosheets. A UV photodetector based on individual Sr2Nb3O10 nanosheets was prepared to demonstrate the application of an ultraviolet (UV) photodetector. The UV photodetector exhibited outstanding photocurrent and responsivity with a responsivity of 3 × 105 A·W−1 at 5 V bias under 280 nm illumination, a photocurrent of 60 nA, and an on/off ratio of 3 × 102. [ABSTRACT FROM AUTHOR]

The fabrication of few-layer borophene (BP) from bulk boron (b-B) is of great importance and still a scientific challenge due to the complex structure and crystallinity of b-B. Herein, we propose a novel technique to prepare a few-layer BP on a large scale with a large lateral size in a well-controlled manner. For this, we employed the Hummers' method-assisted liquid-phase exfoliation. In the first step, the chemical exfoliation of the b-B as a precursor was performed by the modified Hummers' method. After chemical exfoliation, mechanical delamination was employed by using an immersion sonicator. Finally, BP sheets were collected with dimensions ranging from several hundred nanometers to a few micrometers and an average thickness of 4.2 nm. We envision that the proposed low-cost, flexible, and large-scale production method will provide unique advantages for the application of few-layer BP in the realization of highperformance electronics, optoelectronics, flexible devices, sensing systems, energy conversion, and storage devices. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDs) are promising 2D materials which are attracting significant interest because of their distinctive physicochemical properties. The possibility of being exfoliated and dispersed in liquid solutions offers a viable pathway to scalable production. This personal account focuses on recent advancements in 2D TMD inks produced by liquid‐phase exfoliation (LPE) methods and intercalation‐based electrochemical exfoliation. In particular, different LPE production strategies, like ultrasonication LPE, high‐shear mixing exfoliation, and microfluidization, are introduced alongside a broad range of liquid media employed to provide functionalized TMD inks. The main advantage of TMD inks is its scalability, for practical applications in printed optoelectronics, energy storage, and conversion. Furthermore, the chemical functionalization of TMD inks can solve the poor electrical conductivity attributed to edge defects inherent in TMD inks. Finally, the ultimate orientations for future applications of chemically functionalized TMD devices are forecasted, with a specific focus on wearable and flexible printed electronics. [ABSTRACT FROM AUTHOR]

Photosynthetic reaction center (pRC) purified from Rhodobacter sphaeroides 2.4.1 purple bacteria was deposited on a graphene carrier exfoliated from the liquid phase and layered on the surface of SiO2/Si substrate for optoelectronic application. Light-induced changes in the drain-source current vs. gate voltage are demonstrated. Dried photosynthetic reaction centers/graphene composite on SiO2/Si shows a photochemical/-physical activity, as a result of interaction with the current flow in the graphene carrier matrix. The current changes are sensitive to light, due to the contribution from the charge separation in the pRC, and to the applied gate and drain-source voltages.

Disulfide zirconium (ZrS2) is a two-dimensional (2D) transition metal disulfide and has given rise to extensive attention because of its distinctive electronic structure and properties. However, mass production of high quality of ZrS2 nanosheets to realize their practical application remains a challenge. Here, we have successfully exfoliated the bulk ZrS2 powder with the thickness of micron into single and few-layer nanosheets through liquid-phase exfoliation in N-methylpyrrolidone (NMP) assisted via aliphatic amines as intercalators. It is found that the exfoliation yield is as high as 27.3%, which is the record value for the exfoliation of ZrS2 nanosheets from bulk ZrS2 powder, and 77.1% of ZrS2 nanosheets are 2–3 layers. The molecular geometric size and aliphatic amine basicity have important impact on the exfoliation. Furthermore, the ZrS2 nanosheets have been used as catalyst in the electrocatalytic dinitrogen reduction with the NH3 yield of 57.75 μg h−1 mgcat.−1, which is twice that by ZrS2 nanofibers reported in literature and three times that by the bulk ZrS2 powder. Therefore, the liquid phase exfoliation strategy reported here has great potential in mass production of ZrS2 nanosheets for high activity electrocatalysis.

Photocatalytic degradation technique is an effective route for degrading the polluting sources by using photocatalysts. In recent years, van der Waals material based photocatalysts has been drawing more and more attention due to their excellent photodegradation performance. In this research, we have developed a type of highly efficient layered photocatalyst, CdPS 3 nano flakes prepared by the liquid-phase exfoliation method. We compared different photodegradation rates of rhodamine B (RhB) by using photocatalysts of CdPS 3 ground bulk powder and CdPS 3 nanosheets exfoliated by three different dispersants, i.e., N-methyl pyrrolidone (NMP), deionized (DI) water and sodium cholate (SC). For a complete degradation of RhB (80 mL, 100 mg/L), the SC-exfoliated CdPS 3 nanosheets exhibited the highest degradation efficiency within 15 min. These SC-exfoliated nanosheets also demonstrated good potential for degrading methylene blue (MB), potassium dichromate (PD), tetracycline (TC) and methyl orange (MO). The strong dark adsorption and dye-sensitized photocatalytic properties of CdPS 3 nanosheets could both contribute to high degradation efficiencies of RhB and MB, synergistically. Capture experiments revealed that superoxide radicals dominated the degradations of these pollutants. Additionally, for PD and MO, hydroxyl radicals and holes were also important active species in the photodegradation redox reactions. [ABSTRACT FROM AUTHOR]

The green exfoliation of graphite using the serum from skim natural rubber latex, with some left-over ammonia, was investigated. The methods proposed to increase the exfoliation yield included varying the graphite concentration from 10 to 25 mg/ml of serum, using smaller graphite powders obtained from the sedimentation of a graphite precursor, and increasing rotor speed of a homogenizer. The two former cases were performed in an ultrasonic bath. In the first case, using 10 mg of graphite/ml of serum gave the maximum yield of 0.70%. In the second case of using graphite suspended in the supernatant after 15-min settling as starting material in exfoliation, the yield was increased to 0.74% at the graphite concentration of 25 mg/ml. In the last case, using the homogenizer probe at 5,400 rpm for 20 min gave the yield up to 10.5%. Based on Raman spectroscopy, all these exfoliated products were multilayer graphene-based materials and could be comparable to the commercial graphene-based product. [ABSTRACT FROM AUTHOR]

Antimony emerges as one of the interesting monoelemental graphene analogs, having unique properties and a wide range of applications. Among the solution-processing routes, liquid-phase exfoliation (LPE) offers various advantages. However, the choice of solvent greatly influences the exfoliation efficiency. Here, detailed work has been carried out on the LPE of antimony and its dispersion stability. By employing the Hansen solubility sphere method, the Hansen solubility parameters of antimony are determined to be 22.53, 14.03, and 18.31 MPa1/2, corresponding to the dispersion interactions, polar interactions, and hydrogen bonding interactions, respectively. To further understand the solute–solvent interactions, the stability of the dispersions is investigated both qualitatively and quantitatively using an accelerated centrifuge-based technique employing space-time-resolved extinction profiles (STEP). The sedimentation kinetics of the dispersions are studied using various metrics like instability index, integral extinction, and cumulative sedimentation velocity distribution. Among the solvents studied, isopropyl alcohol, ε-caprolactone, N-methyl pyrrolidone, dimethyl sulfoxide, and ethanol are found to have better dispersion stability. Interestingly, some of the solvents with high dispersion concentrations appear to be relatively less stable. Combining Hansen solubility parameters with stability analysis helped in identifying the efficient solvents for obtaining the stable antimonene dispersions. Furthermore, antimonene nanosheets embedded in the carbon nanotubes matrix are used as anode materials for lithium-ion battery applications. The excellent cyclic stability exhibited by antimonene indicates it to be a promising candidate for next-generation energy storage systems. [ABSTRACT FROM AUTHOR]

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Graphene-based chemical sensors hold promise across diverse applications owing to their exceptional sensitivity and selectivity. However, achieving their long-term durability and reusability while preserving high sensitivity remains a significant challenge, particularly in harsh environments where exposure to strong chemicals is inevitable. This paper presents a novel approach to address this challenge by synergistically integrating liquid-phase exfoliated graphene (LPEG) with polytetrafluoroethylene (PTFE) within a single sensing strip. Through a comprehensive experimental investigation, we demonstrate the fabrication of highly durable and reusable chemical leak detection sensors by combining LPEG and PTFE. Furthermore, we explore the sensing mechanism, highlighting the roles of LPEG and PTFE in enhancing sensitivity and selectivity, along with durability and reusability. Performance evaluation reveals the sensors’ robustness against mechanical and chemical degradation, coupled with excellent recyclability. This innovative approach holds promise for applications in environmental monitoring, industrial safety, and healthcare, thus advancing the field of graphene-based chemical leak detection sensors.

Nonaqueous dispersions of graphene nanoplatelets (GrNPs) can be used to prepare thin films and coatings free of surfactants, but typically involve polar organic solvents with high boiling points and low exposure limits. Here, we describe the mechanochemical exfoliation and dispersion of GrNPs in volatile aprotic solvents such as ethyl acetate (EtOAc) and acetone, which rank favorably in green solvent selection guides. GrNPs in powder form were exfoliated with a solvent on a horizontal ball mill for 48 h and then sonicated at moderate power to produce suspensions in excess of 300 μg/mL with minimum loss of dispersion stability over 7 weeks at room temperature. Atomic force microscopy of individual particles indicates a median thickness and lateral width of 8–10 layers and 180 nm, respectively. GrNP films can be deposited by conventional airbrush equipment with a dry time of seconds and applied as layers and coatings that enhance the reproducibility and performance of electronic devices. We demonstrate the utility of spray-coated GrNPs as contact layers for low-cost electrochemical sensing with improvements in intrabatch reproducibility and as conformal coatings on metal heat sinks with enhanced rates of heat dissipation. [ABSTRACT FROM AUTHOR]

Violet phosphorus (VP) is a stable layered van der Waals phosphorus allotrope with unique electronic and optoelectronic properties. In this study, 2D VP nanosheets (NSs) are prepared by liquid phase exfoliation (LPE) method under ambient conditions. The prepared VP NSs are characterized and utilized for photoelectrochemical (PEC)‐type photodetector (PD). The systematic PEC measurements reveal that the as‐prepared VP‐based PD shows tunable photo‐response activities from ultraviolet to visible region. A current density of 0.52 µA cm−2, a photo‐responsivity of 31.70 µA W−1, and a detectivity of 7.92 × 1010 Jones can be obtained in 1.0 m KOH under 350 nm irradiation at 0 V, revealing the good self‐powered capability of VP‐based PD. Furthermore, the cycle and time stability tests exhibit the good chemical and environmental stability of the as‐prepared PD via processing 10 000 s on/off switching and placing after one month. It is expected that this work can offer an understanding of a PEC‐type VP NSs‐based PD, and highlight the further promising applications of 2D VP NSs for other optoelectronic devices. [ABSTRACT FROM AUTHOR]

Photosynthetic reaction center (pRC) purified from Rhodobacter sphaeroides 2.4.1 purple bacteria was deposited on a graphene carrier exfoliated from the liquid phase and layered on the surface of SiO2/Si substrate for optoelectronic application. Light-induced changes in the drain-source current vs. gate voltage are demonstrated. Dried photosynthetic reaction centers/graphene composite on SiO2/Si shows a photochemical/-physical activity, as a result of interaction with the current flow in the graphene carrier matrix. The current changes are sensitive to light, due to the contribution from the charge separation in the pRC, and to the applied gate and drain-source voltages. [ABSTRACT FROM AUTHOR]

Liquid-phase exfoliation of graphene using a suitable solvent is safe, although the sonication period needs further exploration, which may affect the exfoliation process. This study investigated graphene exfoliation in chloroform through UV-Vis spectroscopy. Graphite powder at different ratios was soaked in chloroform and sonicated at different sonication times from 30 min to 180 min and then subjected to centrifugation at 4,000 rpm for 30 min. The supernatant was collected and analysed using UV-Vis spectroscopy at wavelengths between 220 nm and 800 nm. The UV absorbance intensity showed that the presence of exfoliated graphene peaks is free of interference at 120 min. A comparative study was conducted by using graphene in chloroform as controls and adding bioactive glass (BG) within graphite powder-chloroform emulsions in different concentrations at 120 min. Graphene appearance at the anticipated absorption peak at ~270 nm was observed, and BG addition led to agglomeration, which could provide an idea for a better material formulation strategy in developing films that combined graphene/BG because of their exceptional properties suitable for diverse potential biomedical application. [ABSTRACT FROM AUTHOR]

During water electrolysis, adding an electrocatalyst for the hydrogen evolution reaction (HER) is necessary to reduce the activation barrier and thus enhance the reaction rate. Metal chalcogenide-based 2D nanomaterials have been studied as an alternative to noble metal electrocatalysts because of their interesting electrocatalytic properties and low costs of production. However, the difficulty in improving the catalytic efficiency and industrializing the synthetic methods have become a problem in the potential application of these species in electrocatalysis. Liquid-phase exfoliation (LPE) is a low-cost and scalable technique for lab- and industrial-scale synthesis of 2D-material colloidal inks. In this work, we present, to the best of our knowledge, for the first time a systematic study on the surfactant-assisted LPE of bulk Bi2S3 crystalline powder to produce nanosheets (NSs). Different dispersing agents and LPE conditions have been tested in order to obtain colloidal low-dimensional Bi2S3 NSs in H2O at optimized concentrations. Eventually, colloidally stable layered nano-sized Bi2S3 suspensions can be produced with yields of up to ~12.5%. The thus obtained low-dimensional Bi2S3 is proven to be more active for HER than the bulk starting material, showing an overpotential of only 235 mV and an optimized Tafel slope of 125 mV/dec. Our results provide a facile top-down method to produce nano-sized Bi2S3 through a green approach and demonstrate that this material can have a good potential as electrocatalyst for HER. [ABSTRACT FROM AUTHOR]

Large-scale production of graphene nanosheets (GNSs) has led to the availability of solution-processable GNSs on the commercial scale. The controlled vacuum filtration method is a scalable process for the preparation of wafer-scale films of GNSs, which can be used for gas sensing applications. Here, we demonstrate the use of this deposition method to produce functional gas sensors, using a chemiresistor structure from GNS solution-based techniques. The GNS suspension was prepared by liquid-phase exfoliation (LPE) and transferred to a polyvinylidene fluoride (PVDF) membrane. The effect of non-covalent functionalization with Co-porphyrin and Fe-phthalocyanines on the sensor properties was studied. The pristine and functionalized GNS films were characterized using different techniques such as Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and electrical characterizations. The morphological and spectroscopic analyses both confirm that the molecules (Co-porphyrin and Fe-phthalocyanine) were successfully adsorbed onto the GNSs surface through π-π interactions. The chemiresistive sensor response of functionalized GNSs toward the low concentrations of nitrogen dioxide (NO2) (0.5–2 ppm) was studied and compared with those of the film of pristine GNSs. The tests on the sensing performance clearly showed sensitivity to a low concentration of NO2 (5 ppm). Furthermore, the chemical modification of GNSs significantly improves NO2 sensing performance compared to the pristine GNSs. The sensor response can be modulated by the type of adsorbed molecules. Indeed, Co-Por exhibited negative responsiveness (the response of Co-Por-GNS sensors and pristine GNS devices was 13.1% and 15.6%, respectively, after exposure to 0.5 ppm of NO2). Meanwhile, Fe-Phc-GNSs induced the opposite behavior resulting in an increase in the sensor response (the sensitivity was 8.3% and 7.8% of Fe-Phc-GNSs and pristine GNSs, respectively, at 0.5 ppm NO2 gas). [ABSTRACT FROM AUTHOR]

The development of sodium ion batteries will require high‐performance electrodes with very large areal capacity and reasonable rate performance. Although red phosphorus is a very promising electrode material, it has not yet fulfilled these requirements. Here, liquid phase exfoliation is used to convert solid red phosphorus into amorphous, quasi‐2D nanoplatelets. These nanoplatelets have lateral sizes of hundreds of nanometers, thickness of 10s of nanometers and are quite stable in ambient conditions, displaying only low levels of oxidation on the nanosheet surface. By solution mixing with carbon nanotubes, these nanoplatelets can be fabricated into nanocomposite battery anodes. After employing an extended activation process, good cycling stability over 1000 cycles and low‐rate capacitances >2000 mAh gP−1 is achieved. Because of the high conductivity and mechanical robustness provided by the nanotube network, it is possible to fabricate very thick electrodes. These electrodes display extremely high areal capacities approaching 10 mAh cm−2 at currents of ≈1 mA cm−2. Detailed analysis shows these electrodes to be limited by solid‐state diffusion such that the thickest electrodes have state‐of‐the‐art rate performance and a near‐optimized combination of capacity and rate performance. [ABSTRACT FROM AUTHOR]

The recent advent of two-dimensional (2D) materials has had a ground-breaking impact on science and technology. To exploit in technology their unique thickness-dependent physicochemical properties, the large-scale production of 2D materials is mandatory, but it represents an open challenge still due to various pitfalls and severe limitations including the toxicity of state-of-the-art solvents. Thus, liquid-phase exfoliation based on green and bioderived solvents represents an ideal methodology for massive production. This is particularly crucial for introducing 2D materials in technological applications such as the production of drinking water and agri-food industrial processes. Here, we assessed the production of 2D nanosheets (specifically, graphene, WS2, MoS2) with liquid-phase exfoliation assisted by eco-friendly solvents, with a comparative evaluation of green solvents in terms of the yield and, moreover, the aspect ratio, defectivity, and crystalline quality of the produced nanosheets. In particular, we focus on the most promising green solvents in terms of the yield and the crystalline quality of the produced nanosheets: Polarclean, Iris, and Cyrene, which were compared with acetone/water mixtures, isopropyl alcohol (IPA), triethanolamine (TEA), aqueous solutions of urea, and an ethanol/water mixture as well as two toxic solvents largely used for the production of 2D nanosheets: N-methyl-2-pyrrolidone (NMP) and N, N-dimethylformamide (DMF). Remarkably, the density of defects was particularly low in the liquid-phase exfoliation with Polarclean, as indicated by the Raman spectrum of graphene, with the I(D)/I(G) ratio below 0.1. Furthermore, Polarclean and Iris also enable ink-jet printing with functional inks of 2D materials based on green solvents due to their low dynamic viscosity at room temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] The superiority of graphitic carbon nitride (g-C 3 N 4) nanosheet results from its large specific surface area, which can be achieved by exfoliation of the bulk layered structure. Liquid-phase exfoliation (LPE) is the best-known method for the synthesis of two-dimensional (2D) g-C 3 N 4 nanosheets. However, experimental investigations do not allow for a molecular-level understanding of the process. Molecular dynamics (MD) simulations are expected to provide microscopic insights and quantitative evaluation of the energy consumption during LPE, thus facilitating the search of effective solvents for the LPE of 2D materials. MD simulations are carried out to simulate the LPE process by performing potential of mean force calculations for the separation of two stacked g-C 3 N 4 nanosheets. Free energy of exfoliation is evaluated and compared among nine common solvents with distinct molecular structures. The most probable path for the exfoliation process is identified. The free energy of exfoliation is found to correlate directly with the solvent free energy of a single g-C 3 N 4 nanosheet. The solvation is enthalpy-driven and affected by the mobility of the solvent molecules around the nanosheet. Based on the MD results, several strategies are proposed to guide the selection of solvents for effective LPE. [ABSTRACT FROM AUTHOR]

Grinding-assisted liquid-phase exfoliation is a widely used method for the preparation of two-dimensional nanomaterials. In this study, N-methylpyrrolidone and acetonitrile, two common grinding solvents, were used during the liquid-phase exfoliation for the preparation of MoS2 nanosheets. The morphology and structure of MoS2 nanosheets were analyzed via scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. The effects of grinding solvents on the gas-sensing performance of the MoS2 nanosheets were investigated for the first time. The results show that the sensitivities of MoS2 nanosheet exfoliation with N-methylpyrrolidone were 2.4-, 1.4-, 1.9-, and 2.7-fold higher than exfoliation with acetonitrile in the presence of formaldehyde, acetone, and ethanol and 98% relative humidity, respectively. MoS2 nanosheet exfoliation with N-methylpyrrolidone also has fast response and recovery characteristics to 50–1000 ppm of CH2O. Accordingly, although N-methylpyrrolidone cannot be removed completely from the surface of MoS2, it has good gas sensitivity compared with other samples. Therefore, N-methylpyrrolidone is preferred for the preparation of gas-sensitive MoS2 nanosheets in grinding-assisted liquid-phase exfoliation. The results provide an experimental basis for the preparation of two-dimensional materials and their application in gas sensors. [ABSTRACT FROM AUTHOR]

[Display omitted] Transition metal dichalcogenides (TMDs), like other two-dimensional layered materials beyond graphene, have gained enormous interest in recent years owing to their distinct electronic and optical properties, and potential applicability in areas such as sensing, nanoelectronics and catalysis. Surfactant-assisted exfoliation is commonly used to prepare aqueous dispersions of TMD nanosheets, but a clear picture of the TMD and surfactant features that influence the dispersion process is still lacking. In this work, we present a systematic study of the dispersibility of MoS 2 , WS 2 and MoSe 2 in aqueous medium using a cationic (cetyltrimethylammonium bromide, CTAB) and an anionic (sodium cholate, SC) dispersant, in a wide concentration range (seven orders of magnitude) and resorting to a carefully controlled sonication-centrifugation procedure. We present detailed, high precision dispersibility curves (concentration of dispersed TMD versus concentration of surfactant used), together with zeta potential and pH measurements, allowing insight into the influence of the type of metal and chalcogen, surfactant charge and surfactant concentration, on the effectiveness of the exfoliation and stabilization. The metal (Mo vs. W) influences the dispersibility at low surfactant concentrations, while the chalcogen (S vs. Se) plays a more significant role as the surfactant concentration is increased, alongside the surfactant charge. Structural characterization by scanning electron microscopy (SEM), Raman spectroscopy and atomic force microscopy (AFM) shows that the methodology applied yields well-exfoliated nanosheets with controlled mean lateral dimension (≈ 100 nm) and thickness (≤5 layers). Finally, the type of ionic surfactant (cationic vs. anionic) and its concentration play a pivotal role in the profile of the dispersibility curves, leading us to propose two types of master curves with distinct regions of phase behavior. [ABSTRACT FROM AUTHOR]

Measuring relative humidity is important for a myriad of industries, including production, agriculture, environmental monitoring, and medicine. Thin-film, fast-response sensors are particularly interesting for wearable applications, such as monitoring breathing. We report on humidity sensors made from graphene deposited as a thin film by the Langmuir-Blodgett (LB) method from three types of graphene in solution. We demonstrate humidity sensing and respiration monitoring from graphene made by bath sonication, probe sonication, and electrochemical exfoliation. We characterize the morphology and chemical composition of the three film types and compare their performance as sensors. We conclude that although all three types can be used for sensing, they each have their particular advantages and drawbacks. [ABSTRACT FROM AUTHOR]

The paper presents the investigation results of the morphology of carbon nanoparticles formed during liquid-phase exfoliation of thermally expanded graphite in tert-butanol. The thermally expanded graphite used in this work was obtained by thermal expansion of graphite nitrate with acetic and formic acids in the thermal shock mode at 500°C and 900°C. Initial cointercalate was shown by powder X-ray diffraction analysis to be the mixture of the II^nd and the IV^th stage intercalation compounds. It has been established by transmission electron microscopy that dispersions of carbon nanoparticles formed during the exfoliation of thermally expanded graphite in tert-butanol via sonication contain mainly few-layer graphenes, the planar dimensions of which reach 8 μm. The influence of the conditions for thermally expanded graphite obtaining on the morphology of resulting carbon nanoparticles is discussed. Dispersions based on thermally expanded graphite obtained at a lower temperature, in addition to few-layer graphenes, also contain a significant amount of amorphous carbon particles with planar sizes up to 100 nm.

The flourishing of the Internet of Things (IoT) in recent years creates a huge demand for various humidity sensors, since the humidity is closely related to our daily life. Transparent humidity sensors have great application prospects in the fields such as smart furniture and human-machine interface. However, it is difficult for devices made from traditional moisture sensitive materials to have both high optical transparency and sensitive humidity response. Herein, we developed a novel humidity sensor based on 2D MoO3-x nanosheets, in which the nanosheets were liquid-phase exfoliated from α-MoO3 powder. With the assistance of ethyl cellulose, a high concentration dispersion of oxygen-deficient MoO3-x nanosheets can be easily prepared by probe sonicating. The as-prepared humidity sensor shows a transmittance as high as 86% in visible range. Under a constant bias, the current of the sensor increases monotonically over a broad RH range from 11% to 95%. Moreover, the fast response and recovery speed in the subsecond timescale (0.12 s and 0.53 s) enables the transparent humidity sensor to work as a real-time device in the expiration monitoring system. This work demonstrates a promising application of 2D MoO3-x nanosheets and opens up a new avenue for designing transparent humidity sensors.

To date, multiple graphene@MXene hybrids have been reported via various synthesis approaches, but almost all the graphene@MXene hybrids inevitably used the reduced graphene oxide that prepared by chemical oxidation/reduction method, which generally involved the complex and dangerous operation procedure, and the highly toxic chemical reagent. How to prepare graphene@MXene hybrid through a simple, safe and eco-friendly synthetic route is highly desired. Compared with traditional synthesis technology, ultrasound synthesis strategy displays the merits of simplicity, low cost and environment protection. Herein, MXene (Ti3C2Tx) nanoflakes coupled with graphene nanosheets (graphene@MXene) were prepared in N-methylpyrrolidone (NMP) by simple ultrasound-assisted liquid-phase exfoliation method for the first time. Besides, the effect of types of solvent with different viscocity, sonication temperature and sonication duration time on the property of graphene@MXene hybrids were systematacially investigated. It is found the liquid-phase exfoliated graphene owned excellent electron transfer ability and the MXene (Ti3C2Tx) nanoflakes possessed outstanding adsorption property, the as-synthesized graphene@MXene hybrid exhibited significant signal synergistic enhancement effect toward the oxidation of hazardous veterinary drug residue compound (chlorpromazine) and food additives (rhodamine B). Based on this, a novel and sensitive electrochemical sensor was fabricated, the linear detection ranges were 5 nM to 0.5 μM for chlorpromazine with sensitivity of 1090 µA μM−1 cm−2, and 10 nM to 2.5 μM for rhodamine B with sensitivity of 440 and 102.14 µA μM−1 cm−2. Besides, the detection limits were evaluated to be as low as 1.25 nM and 2.45 nM for chlorpromazine and rhodamine B, respectively.

In recent years, interest in the liquid-phase exfoliation (LPE) of layered crystals has been growing due to the efficiency and scalability of the method, as well as the wide range of practical applications of the obtained dispersions based on two-dimensional flakes. In this paper, we present a comparative study of as-grown and liquid-phase exfoliated GaSe1−xSx flakes. Bulk GaSe1−xSx crystals with x ~ 0, 0.25, 0.5, 0.75, 1 were synthesized by melting stoichiometric amounts of gallium, selenium, and sulfur particles in evacuated ampoules. X-ray diffraction analysis showed that the crystal structure does not change considerably after LPE, while the analysis of the Raman spectra revealed that, after liquid-phase processing in IPA, an additional peak associated with amorphous selenium is observed in selenium-rich GaSeS compounds. Nevertheless, the direct and indirect transition energies determined from the Kubelka-Munk function for LPE crystals correlate with the band gap of the as-grown bulk GaSeS crystals. This finding is also confirmed by comparison with the data on the positions of the photoluminescence peak. [ABSTRACT FROM AUTHOR]

In this work, we apply liquid cascade centrifugation to highly concentrated graphene dispersions produced by liquid-phase exfoliation in water with an insoluble bis-pyrene stabilizer to obtain fractions containing nanosheets with different lateral size distributions. The concentration, stability, size, thickness, and the cytotoxicity profile are studied as a function of the initial stabilizer concentration for each fraction. Our results show that there is a critical initial amount of stabilizer (0.4 mg/mL) above which the dispersions show reduced concentration, stability, and biocompatibility, no matter the lateral size of the flakes. [ABSTRACT FROM AUTHOR]

High‐end technological applications of thin boron nanosheets (BNS), including single layer borophene, have inspired the scientific community to develop fabrication routes to achieve scalable preparation. Among the different strategies, liquid‐phase exfoliation is one of the facile methods. However, this method has certain drawbacks, such as the use of high‐cost boron precursors (boron powder having particle size in micrometer) and possesses lower quality and size nonuniformity in the as‐prepared BNS. To address these issues, the production of high‐quality and uniform BNS is reported from low‐cost boron chunks (bulk boron having > 1 cm particle size) by using an ultrasonication‐assisted liquid‐phase exfoliation method. The as‐prepared BNS shows strong optical fluorescence characteristics and exhibits good electrical and photoconductivity values indicating its suitability for various applications. As an application study, the catalytic potential of the as‐prepared BNS is explored for the degradation of diverse organic pollutants using peroxymonosulfate as an oxidizing agent. The density functional theory is used to calculate the energy minima of different boron crystallographic phases along with the interactions of peroxymonosulfate with BNS. The facile strategy reported here is expected to pave the way for scalable production of ultrathin BNS from a low‐cost precursor. [ABSTRACT FROM AUTHOR]

• Raman attenuation method used for the first time to measure absorption coefficients of nanosheets prepared by liquid-phase exfoliation method. • The first use of cryo-pretreatment for the preparation of GaSe nanosheets combined with a salt-assisted exfoliation method. • GaSe nanosheets prepared using cryo-mediated have one of the remarkable features of low surface roughness, while the duration of cryo-pretreatment can change the distribution of nanosheets. In this study, a novel preparation method combining cryo-mediated method and salt-assisted liquid-phase exfoliation is presented for the preparation of Gallium Selenide (GaSe) nanosheets and the absorption coefficient are estimated by the Raman signal attenuation method on silicon substrates.It was found that Potassium citrate (C 6 H 5 K 3 O 7 ·H 2 O) as an accelerator increased the lateral size of GaSe nanosheets, while employing liquid nitrogen as a cryo-mediation significantly reduced the surface roughness of the nanosheets. Furthermore, a correlation exists between the duration of cryo-pretreatment and the thickness distribution of GaSe nanosheets.Using the absorption overlayer model, the study experimentally determined more accurate absorption coefficient of 2D GaSe nanosheets by analyzing the changes in Raman signal intensity on a silicon substrate induced by GaSe nanosheets with varying thicknesses, resulting in an average absorption coefficient of 5.68×104 cm−1.This study introduces a novel approach to prepare GaSe and other two-dimensional (2D) material nanosheets with large size and low roughness, based on which the absorption coefficient of GaSe nanosheets are also determined in a more precise way. [ABSTRACT FROM AUTHOR]