Phosphorene Nanosheets Research Articles

O-doping effects on the adsorption and detection of acetaldehyde and ethylene oxide on phosphorene monolayer: A DFT investigation

In this study, density functional theory (DFT) was employed to assess the electronic and structural properties of pristine and O-doped phosphorene nanosheets. The adsorption of acetaldehyde and ethylene oxide was assessed on pristine and O-doped phosphorene monolayers. Acetaldehyde and ethylene oxide exhibit stronger interaction with O-doped rather than pristine phosphorene. The adsorption of acetaldehyde and ethylene oxide on O-doped phosphorene is sufficiently strong to allow a fast recovery time. Moreover, the work function calculations show effective adjustment by selective adsorption of these compounds. Therefore, O-doped phosphorene-based nanomaterials can be used for the detection and sensing.

Theoretical studies of phosphorene as a drug delivery nanocarrier for fluorouracil.

The interactions between phosphorene nanosheets (PNSs) and 5-fluorouracil (FLU) were explored using the density functional theory (DFT) method and molecular dynamics (MD) simulations. DFT calculations were performed utilizing M06-2X functional and the 6-31G(d,p) basis set in both gas and solvent phases. Results showed that the FLU molecule is adsorbed horizontally on the PNS surface with an adsorption energy (Eads) of -18.64 kcal mol-1. The energy gap (Eg) between the highest occupied and lowest unoccupied molecular orbitals (HOMO and LUMO, respectively) of PNS remains constant after the adsorption process. The adsorption behavior of PNS is not affected by carbon and nitrogen doping. The dynamical behavior of PNS-FLU was studied at T = 298, 310, and 326 K reminiscent of room temperature, body temperature, and temperature of the tumor after exposure to 808 nm laser radiation, respectively. The D value decreases significantly after the equilibration of all systems so that the equilibrated value of D is about 1.1 × 10-6, 4.0 × 10-8, and 5.0 × 10-9 cm2 s-1 at T = 298, 310, and 326 K, respectively. About 60 FLU molecules can be adsorbed on both sides of each PNS, indicating its high loading capacity. PMF calculations demonstrated that the release of FLU from PNS is not spontaneous, which is favorable from a sustained drug delivery point of view.

Revealing the biotoxicity of phosphorene oxide nanosheets based on the villin headpiece.

Phosphorene, a novel member of the two-dimensional nanomaterial family, has demonstrated great potential in biomedical applications, such as photothermal therapy, drug delivery and antibacterial. However, phosphorene is unstable and easily oxidized in an aerobic environment. In this paper, using larger-scale molecular dynamics simulations, we investigated the disruption of phosphorene oxide (PO) to the structure of a model protein, villin headpiece subdomain (HP35). It shows that the disruption of PO nanosheets to the protein structure is enhanced with increasing oxidation concentration of PO, while PO's oxidation mode has very little effect on the PO-HP35 interaction. PO with a low oxidation concentration has certain biocompatibility to HP35. Oxygen atoms filling into the groove region in the puckered surface of phosphorene enhance the dispersion interaction between phosphorene and HP35, which enhances the disruption of phosphorene to the structure of HP35. Compared with the dispersion interaction, the electrostatic interaction between PO and the protein has a negligible effect on the structural damage of HP35. These findings might shed light on the biological toxicity of PO nanosheets and would be helpful for future potential biomedical applications of PO nanosheets, such as nanodrugs and antibacterial agents.

Theoretical study for exploring the adsorption behavior of aniline and phenol on pristine and Cu-doped phosphorene surface

This research investigates the adsorption behavior of aniline and phenol on pristine and Cu-doped phosphorene surfaces using density functional theory calculations. The calculation of adsorption energy, energy gap, total electron density plot, the density of states spectrum, and charge transfer analysis is performed. The results show that the adsorption energy of aniline and phenol on pristine phosphorene surfaces are −0.630 and −0.602 eV, respectively which are not typical for the chemisorption process. While the adsorption energy of aniline and phenol on the Cu-doped phosphorene surface are −1.27 and −1.14 eV, respectively which could be in the chemisorption process range. The other calculated parameters such as a change in the energy gap and charge transfer also support the shift in adsorption energy via replacing a P atom with a Cu atom. The Löwdin charge analysis shows that pristine and Cu-doped phosphorene nanosheets acted as an electron acceptor toward aniline and phenol. Based on the results of this work, it can be suggested that using a Cu-doped phosphorene nanosheet could be an effective strategy to increase the adsorption energy and remove volatile organic compounds such as aniline and phenol.

Band Edges Engineering of 2D/2D Heterostructures: The C3 N4 /Phosphorene Interface.

We investigate the interface between carbon nitride (C3 N4 ) and phosphorene nanosheets (P-ene) by means of Density Functional Theory (DFT) calculations. C3 N4 /P-ene composites have been recently obtained experimentally showing excellent photoactivity. Our results indicate that the formation of the interface is a favorable process driven by Van der Waals forces. The thickness of P-ene nanosheets determines the band edges offsets and the charge carriers' separation. The system is predicted to pass from a nearly type-II to a type-I junction when the thickness of P-ene increases, and the conduction band offset is particularly sensitive. Last, we apply the Transfer Matrix Method to estimate the efficiency for charge carriers' migration as a function of the P-ene thickness.

Phase-change nanofluids based on n-octadecane emulsion and phosphorene nanosheets for enhancing solar photothermal energy conversion and heat transportation

To offer a solution for low heat transfer and solar energy-storage performance of conventional phase-change fluids, we designed a direct absorption solar energy collecting system based on n -octadecane/phosphorene (PR) nanosheet phase-change nanofluids for capturing solar energy with high energy conversion efficiency and rapid heat response and transfer. The phase-change nanofluids were fabricated through homogenously dispersing PR nanosheets in the n -octadecane aqueous emulsion. The resultant nanofluids exhibit good dispersion stability and suitable viscosity under an optimal emulsifier content of 9.0 wt % and a homogenization rate of 16,000 rpm. Although the nanofluids show a relatively lower latent-heat capacity compared to pristine n -octadecane emulsion, their thermal response and heat transfer were enhanced significantly due to the introduction of PR nanosheets, leading to an increase in thermal conductivity by 98.59% for the nanofluids containing 1.0 wt % PR nanosheets. More importantly, the n -octadecane/PR nanosheet nanofluids exhibit an excellent optical absorption capacity for solar photothermal conversion and thermal energy storage. The nanofluid containing 1.0 wt % phosphorene nanosheets presents a relative thermal storage capacity of 152% by taking pristine n -octadecane emulsion as a control. The nanofluids also show good working stability for the long-term use in solar photothermal conversion and thermal energy storage. The phase-change nanofluids developed in this study exhibit great application potential in solar energy capture and photothermal energy utilization thanks to their enhanced thermal conductivity, high energy-storage density, suitable viscosity, thermal reliability, and excellent photothermal conversion and energy-storage capability. • A novel type of phase-change nanofluids was developed for high-efficient solar energy utilization. • The nanofluids were fabricated by a combination of n -octadecane emulsion and phosphorene. • The nanofluids present good dispersion stability, high thermal conductance, and suitable viscosity. • The nanofluids exhibit an excellent solar photothermal conversion and energy-storage capability. • The nanofluids find great potential for solar energy capture and harvest applications.

A Sensitive Electrochemical Aptasensor Based on Black Phosphorus Nanosheet for Carbaryl Detection

Carbaryl is a broad-spectrum carbamate insecticide widely used to control pests on crops, trees and ornamental plants. Carbaryl residues in fruits and vegetables and other foods can accumulate in the human body and damage human health. Therefore, it is very essential to establish a sensitive and reliable method for determination of carbaryl. Black phosphorene nanosheets (BPNPs) modified glassy carbon electrode was herein prepared using poly(3,4-dioxyethylenethiophene)-poly(styrene sulfonate) (PEDOT: PSS) as both membrane and stabilizer. The nanocomposites (BP-PEDOT: PSS) were synthesized by combining BP at the ratio of PEDOT: PSS, which improved conductivity and stability of BP. In order to enhance the electrochemical signal and build the carbaryl aptamer sensor, the surface of BP-PEDOT: PSS was modified by Au nanoparticles (Au NPs). The carbaryl aptamer modified with sulfhydryl groups was immobilized in the outer layer of Au NPs, and the target carbaryl was specifically recognized and captured by carbaryl aptamer and adsorbed on the electrode surface, thus causing changes in the interfacial electrochemical signal. The conditions were optimized and characterized by cyclic voltammetry (CV), and linear equation was obtained as ΔI(μA) = −11.35logC−29.70, R2 = 0.997. The detection range was 0.01 ng/mL–10 μg/mL, with a limit of detection of 7.0 pg/mL.

Preparation and Application of Electrochemical Horseradish Peroxidase Sensor Based on a Black Phosphorene and Single-Walled Carbon Nanotubes Nanocomposite.

To design a new electrochemical horseradish peroxidase (HRP) biosensor with excellent analytical performance, black phosphorene (BP) nanosheets and single-walled carbon nanotubes (SWCNTs) nanocomposites were used as the modifier, with a carbon ionic liquid electrode (CILE) as the substrate electrode. The SWCNTs-BP nanocomposite was synthesized by a simple in situ mixing procedure and modified on the CILE surface by the direct casting method. Then HRP was immobilized on the modified electrode with Nafion film. The electrocatalysis of this electrochemical HRP biosensor to various targets was further explored. Experimental results indicated that the direct electrochemistry of HRP was realized with a pair of symmetric and quasi-reversible redox peaks appeared, which was due to the presence of SWCNTs-BP on the surface of CILE, exhibiting synergistic effects with high electrical conductivity and good biocompatibility. Excellent electrocatalytic activity to trichloroacetic acid (TCA), sodium nitrite (NaNO2), and hydrogen peroxide (H2O2) were realized, with a wide linear range and a low detection limit. Different real samples, such as a medical facial peel solution, the soak water of pickled vegetables, and a 3% H2O2 disinfectant, were further analyzed, with satisfactory results, further proving the potential practical applications for the electrochemical biosensor.

Electrochemically exfoliated phosphorene nanosheet thin films for wafer-scale near-infrared phototransistor array

Two-dimensional (2D) black phosphorus (BP), or phosphorene, has recently emerged as a promising 2D semiconductor because of its p-type charge transport behavior and near-infrared photoresponsivity. However, the application of BP in practical electronic and optoelectronic devices is hindered by challenges in producing high-quality BP films over large areas. In this manuscript, we present a facile solution-based process to create wafer-scale BP films for fabrication of p-channel field-effect transistors that are responsive to near infrared light. Few-layer BP nanosheets are first exfoliated from the bulk crystal via electrochemical intercalation of cationic molecules and then vacuum-filtered through an anodic aluminum oxide membrane. The resulting BP film can be transferred onto an SiO2-coated silicon substrate, thereby allowing for realization of field-effect transistors after electrode deposition and thermal annealing. The transistor array exhibits spatial uniformity in electrical performance with an average hole mobility of ~0.002 cm2 V−1 s−1 and on/off ratio of 130. Furthermore, gate-induced modulation of the BP channel allows for enhancement in the photoresponsivity for 1550-nm light illumination up to 24 mA W−1, which benefits the application of the phototransistor array for near infrared imaging.

Phosphorene nanosheet decorated graphitic carbon nitride nanofiber for photoelectrochemically enhanced hydrogen evolution from water splitting

BackgroundPhosphorene nanosheet is a p-type semiconductor with excellent optoelectronic property and large surface area, while graphitic carbon nitride (g-C3N4) nanofiber is a n-type visible-light-driven photocatalyst. The fabrication of p-n heterostructured nanocomposites for hydrogen evolution from water splitting via photoelectrochemistry is an exceptionally promising technique. MethodPhosphorene and g-C3N4 were prepared by electrospinning and ultrasonic exfoliation procedures, respectively, and then mixed physically by Van deer Waal force to form the p-n heterojunction. The photoelectrochemical hydrogen evolution from water splitting was performed under solar light irradiation. Significant findingsThe morphological analysis show that 100–200 nm phosphorene nanosheets are successfully decorated on 450-nm g-C3N4 nanofibers. After adding 4–18 wt% phosphorene onto g-C3N4 nanofiber (P/CN), the specific surface area of P/CN nanocomposites is in the range of 52.1–68.3 m2 g−1. The addition of 13 wt% phosphorene is optimal for P/CN nanocomposite to maximize the hydrogen evolution rate of 2,208 μmol h−1 g−1 by accelerating the electron transfer to enhance the PEC performance in P/CN heterostructure under illumination. Results have signified that the metal-free P/CN photocatalyst can provide an effective solar-light-responsive capability toward water splitting, which can create a promising strategy to fabricate low-dimensional electrode materials for a wide variety of water-energy nexus and green energy applications.

Electrochemical Exfoliation of Two-Dimensional Phosphorene Sheets and its Energy Application.

Recently, single or few-layer phosphorene has attracted intense attention due to its exceptional physicochemical properties. To this end, mass production of high-quality phosphorene nanosheets with specific functionalities represents a pivotal factor for the basic academic studies and practical applications. Among the current synthetic methods, electrochemical exfoliation of black phosphorous is one of the most hopeful ways for mass-production of phosphorene sheets owing to the uncomplicated apparatus, low cost as well as significant efficiency. Especially, regulating the electrochemical parameters not only induces adjustable phosphorene characteristics but also enables them a promising candidate in energy applications. In this Review, a concise and crucial studies of the recent and most representative developments in this domain was introduced, including the relationship between exfoliation philosophy, internal mechanisms, processing techniques, and multiple applications of phosphorene. At the end, a summary discussion and future perspectives is also provided.

Tension-induced phase transformation and anomalous Poisson effect in violet phosphorene

Two-dimensional violet phosphorene (VP) nanosheets are promising semiconductor materials with unique cross structures distinct from those of their allotropes such as black phosphorene and blue phosphorene, but their mechanical behaviors remain almost unexplored. By using the first-principles calculations, in this paper we investigate the mechanical behaviors of monolayer, bilayer, and bulk VP under uniaxial tension. A phase transformation from the open-pore phase to closed-pore phase is observed in VP structures when under a specific tensile strain. It is revealed that the phase transformation is attributed to the competition between the rotation and elongation of sub-nano rods in VP structures during the loading process. Due to the phase transformation, the in-plane Poisson's ratio of monolayer VP can become greater than 1.2, while the bulk VP possesses a negative out-of-plane Poisson's ratio with a magnitude up to -0.3 at a certain strain. These results indicate that Poisson effects in VP are superior to those in any other existing two-dimensional materials. In addition, based on the tensor analysis of elastic constants, a strong mechanical anisotropy is observed in VP structures both before and after the phase transformation. Besides the mechanical properties, the band gap of all VP structures decreases as the applied tensile strain increases, which can eventually transform into the metallic state prior to their fracture. The combination of unique phase transformation, anomalous Poisson effect, strong mechanical anisotropy and tunable electronic properties render VP be a novel nanoscale metamaterial with multifunctional applications.

Exploration of phosphorene as doxorubicin nanocarrier: An atomistic view from DFT calculations and MD simulations

Potential capability of phosphorene nanosheet (PNS) as doxorubicin (DOX) nanocarrier was investigated using density functional theory (DFT) method and molecular dynamics (MD) simulations. Both DFT calculations and MD simulations revealed that the DOX molecule is adsorbed horizontally onto the PNS surface with the nearest interaction distance of 2.5 Å. The binding energy of DOX is predicted to be about − 49.5 kcal.mol−1, based on the DFT calculations. After DOX adsorption, the Eg value of PNS remains almost constant in both gas and solvent phases. The dynamical behavior of PNS-DOX was studied at T = 298, 310, and 326 K that reminiscent of room temperature, body temperature, and temperature of tumor after exposure to 808 nm laser radiation, respectively. The diffusion coefficient values of DOX molecule are proportional to temperature. We found that PNS can hold a high amount of DOX on both sides of its surface (66% in weight). MD simulations showed that the dynamical behavior of simulated systems are not affected by pH variances.

CS2 And H2S adsorption studies on novel hex-star phosphorene nanosheet – a DFT perspective

The adsorption properties of carbon disulfide (CS2) and hydrogen sulfide (H2S) gas molecules on hex-star phosphorene nanosheet (hex-star PNS) are studied. Initially, the structural stability of hex-star PNS is ensured based on phonon band structure and formation energy. The hex-star PNS possesses an energy band gap of 1.393 eV. Besides, upon adsorption of CS2 and H2S on hex-star PNS, the changes in the electronic properties are noticed through electron density difference, band structure, and density of states spectrum. The CS2 and H2S are physisorbed on hex-star PNS, confirming the reversibility of base material. Hence, the results suggest the deployment of hex-star PNS as a sensing substrate toward CS2 and H2S molecules.

Tetrahydrofuran and 2-methyltetrahydrofuran adsorption studies on violet phosphorene nanosheets based on first-principles studies

The allotrope of phosphorous, namely violet phosphorene (violet PNS) is investigated for the possible application as a chemical nanosensor. Initially, the stability of violet PNS is studied from the formation energy, which is observed to be −5.311 eV/atom confirming the stable geometry of violet PNS. The violet PNS is used as a base material to adsorb 2-Methyltetrahydrofuran (Me-THF) and tetrahydrofuran (THF). The adsorption energy of THF and Me-THF on violet PNS exhibits physisorption. The electronic particulars of violet PNS owing to THF and Me-THF are analysed based on the band structure, projected density of states (PDOS), and electron density difference results. Besides, the decrease in the energy band gap of violet PNS is noticed due to THF and Me-THF molecular adsorption. The chemi-resistive character of violet PNS is ensured based on average energy gap variations. Thus, the results support the deployment of violet PNS as a proper base substrate for THF and Me-THF detection.

Prediction of spin-dependent electronic structures of 3d transition metals doped Hittorf's violet phosphorene towards spintronics

Modulation of spin-dependent properties in semiconductor is of importance in exploring the potential application in spintronics. Here, we theoretically investigated the structural deformation, electronic characters, and magnetic properties of the single-layered Hittorf's violet phosphorene nanosheet with 3 d transition metal atoms (ranging from Sc to Ni) doping and under external electric field. The electronic band structures and magnetic properties was found to be obviously modulated by the dopants: the existence of a large spin splitting of the dopant 3 d states tailors the semiconducting phosphorene into simple magnetic semiconductor or bipolar magnetic semiconductor, except for the case of Sc. The application of an appropriate electric field to V-doped system could induce a transition from bipolar magnetic semiconductor to half metal with the carriers fully spin-polarized in alternative spin channel. Moreover, Hittorf's violet phosphorene-based field-effect transistor was proposed with the aim of realizing gate-voltage control on the carriers' spin orientation. Our findings pointed out the possibilities for realizing spin-dependent field-effect transistor in doped Hittorf's violet phosphorene nanosheet and opened a window for the burgeoning field of multifunctional 2D nanoelectronics and spintronics devices. • Ranging from Ti to Ni dopants can behave (bipolar) magnetic semiconductors. • Sc-doped Hittorfene is a nonmagnetic semiconductor. • The application of the electric field to V-doped Hittorfene can induce half metal transition. • The reversed carriers' spin orientation would be potential for spintronic devices.

Recent advances in g-C3N4 based gas sensors for the detection of toxic and flammable gases: a review

In recent years, many 2D nanomaterials like graphene, MoS2, phosphorene, and metal oxide nanosheets have been investigated for gas sensing applications due to their excellent properties. Amongst other 2D nanomaterials, graphitic carbon nitride (g-C3N4) has attracted significant attention owing to its simple synthesis process, tunable electronic properties, and exceptional physicochemical properties. Such remarkable properties assert g-C3N4 as a potential candidate for the next-generation high-performance gas sensors employed in the detection of toxic and flammable gases. Although several articles and reviews are available on g-C3N4 for their synthesis, functionalities, and applications for the detection of humidity. Few of them have focused their attention on gas sensing using g-C3N4. Thus, in this review, we have methodically summed up the recent advances in g-C3N4 and its composites-based gas sensor for the detection of toxic and flammable gases. Moreover, we have also incorporated the synthesis strategies and the comprehensive physics of g-C3N4 based gas sensors. Additionally, different approaches are presented for the enhancement of gas sensing/detecting properties of g-C3N4 based gas sensors. Finally, the challenges and future scope of g-C3N4 based gas sensors for real-time monitoring of gases have been discussed.

Construction of iron-mineralized black phosphorene nanosheet to combinate chemodynamic therapy and photothermal therapy

Chemodynamic therapy (CDT) by triggering Fenton reaction or Fenton-like reaction to generate hazardous hydroxyl radical (•OH), is a promising strategy to selectively inhibit tumors with higher H2O2 levels and relatively acidic microenvironment. Current Fe-based Fenton nanocatalysts mostly depend on slowly releasing iron ions from Fe or Fe oxide-based nanoparticles, which leads to a limited rate of Fenton reaction. Herein, we employed black phosphorene nanosheets (BPNS), a biocompatible and biodegradable photothermal material, to develop iron-mineralized black phosphorene nanosheet (BPFe) by in situ deposition method for chemodynamic and photothermal combination cancer therapy. This study demonstrated that the BPFe could selectively increase cytotoxic ·OH in tumor cells whereas having no influence on normal cells. The IC50 of BPFe for tested tumor cells was about 3–6 μg/mL, which was at least one order of magnitude lower than previous Fe-based Fenton nanocatalysts. The low H2O2 level in normal mammalian cells guaranteed the rare cytotoxicity of BPFe. Moreover, the combination of photothermal therapy (PTT) with CDT based on BPFe was proved to kill tumors more potently with spatiotemporal accuracy, which exhibited excellent anti-tumor effects in xenografted MCF-7 tumor mice models.

Defects investigation of bipolar exfoliated phosphorene nanosheets

Two-dimensional (2D) phosphorene has gained attention due to its exceptional chemical, physical, and optoelectronic properties. However, defects analysis in exfoliated phosphorene through experimental techniques is still largely missing. In this paper, a combination of high-resolution transmission electron microscopy (HRTEM) imaging and density functional theory calculations were provided to study the point defects, grain boundaries (GBs), and amorphization phenomenon in exfoliated phosphorene nanosheets via bipolar electrochemistry method. The HRTEM results demonstrate that the single vacancies (SV) and di-vacancies (DV), ad-atoms, and GBs defects are formed in phosphorene nanosheets. However, the exfoliated black phosphorus nanosheets maintained its orthorhombic crystal structure. In addition, amorphization on the edges and surface of nanosheets is unavoidable in the presence of oxygen. Our first-principles simulation confirms the breakage of P-P bonds of phosphorene upon surface oxidation, which results in amorphization. The defect analysis of phosphorene nanosheets obtained from this study could benefit both fundamental research and technological applications.

Enhanced thermal transportation across an electrostatic self-assembly of black phosphorene and boron nitride nanosheets in flexible composite films.

For effective heat dissipation in portable electronics, there is a great demand for lightweight and flexible films with superior thermal transport properties. Despite extensive efforts, enhancing the intrinsic low thermal conductivity of polymers while simultaneously maintaining their flexibility is difficult to achieve due to the dilemma of quarrying appropriate filler loading. Herein, a cellulose nanofiber-based film with high in-plane thermal conductivity up to 72.53 W m-1 K-1 was obtained by harnessing the advantage of functionalized boron nitride nanosheets (f-BNNS) and black phosphorene (BP) via the vacuum filtration process. Besides, our unique design based on the electrostatic coupling of black phosphorene and functionalized boron nitride nanosheets significantly reduced the interfacial thermal resistance of the composite films. This work offers new insights into establishing a facile, yet efficient approach to preparing high thermal conductive heat spreaders.