Towards new binary compounds: Synthesis of amorphous phosphorus carbide by pulsed laser deposition

Bifunctional Interphase Promotes Li+ De-Solvation and Transportation Enabling Fast-Charging Graphite Anode at Low Temperature

The most successful lithium-ion batteries (LIBs) based on ethylene carbonate electrolytes and graphite anodes still suffer from severe energy and power loss at temperatures below -20 °C, which is because of high viscosity or even solidification of electrolytes, sluggish de-solvation of Li+ at the electrode surface, and slow Li+ transportation in solid electrolyte interphase (SEI). Here, a coherent lithium phosphide (Li3 P) coating firmly bonding to the graphite surface to effectively address these challenges is engineered. The dense, continuous, and robust Li3 P interphase with high ionic conductivity enhances Li+ transportation across the SEI. Plus, it promotes Li+ de-solvation through an electron transfer mechanism, which simultaneously accelerates the charge transport kinetics and stands against the co-intercalation of low-melting-point solvent molecules, such as propylene carbonate (PC), 1,3-dioxolane, and 1,2-dimethoxyethane. Consequently, an unprecedented combination of high-capacity retention and fast-charging ability for LIBs at low temperatures is achieved. In full-cells encompassing the Li3 P-coated graphite anode and PC electrolytes, an impressive 70% of their room-temperature capacity is attained at -20 °C with a 4 C charging rate and a 65% capacity retention is achieved at -40 °C with a 0.05 C charging rate. This research pioneers a transformative trajectory in fortifying LIB performance in cryogenic environments.

An enduring in vitro wound healing phase recipient by bioactive glass-graphene oxide nanocomposites

Bioactive glass (BG) is an interesting topic in soft tissue engineering because of its biocompatibility and bonding potential to increase fibroblast cell proliferation, synthesize growth factors, and stimulate granulation tissue development. The proposed BG with and without sodium (Na), prepared by the sol–gel method, is employed in wound healing studies. The BG/graphene oxide (GO) and BG (Na-free)/GO nanocomposites were investigated against fibroblast L929 cells in vitro; the 45S5 BG nanocomposites exhibited desired cell viability (80%), cell proliferation (30%), cell migration (25%), metabolic activity, and wound contraction due to extracellular matrix (ECM) production and enhanced protein release by fibroblast cells. Additionally, the antioxidant assays for BG, BG (Na-free), GO, and BG/GO, BG (Na-free)/GO were evaluated for effective wound healing properties. The results showed decreased inflammation sites in the wound area, assessed by the (2,2-diphenyl-1-picryl-hydrazyl-hydrate) (DPPH) assay with ~ 80% radical scavenging activity, confirming their anti-inflammatory and improved wound healing properties.

Novel Two-Dimensional ABX3 Dirac Materials: Achieving a High-Speed Strain Sensor via a Self-Doping Effect

The pristine semimetal property of two-dimensional (2D) Dirac materials has limited their practical applications in today's electronic devices. Here we report a new type of 2D Dirac material, termed ABX₃ (A = F, Cl, Br, or I; B = P or As; X = C or Si) monolayers. We demonstrate that 14 ABX₃ monolayers possess good stability and high Fermi velocities. The FPC₃, ClPC₃, BrPC₃, and FAsC₃ monolayers exhibit a pristine n-type self-doping Dirac cone due to the interactions of electrons between the A-B units and C₆ rings, which is beneficial for realizing high-speed carriers. Interestingly, the ClPSi₃ monolayer exhibits remarkable responses to strain because a self-doping Dirac cone can be induced by relatively small in-plane biaxial strains (-5%), and the current-voltage (I-V) curves verified that the response strength is 11.57 times that of the graphene-based strain sensor at a bias of 1.10 V, indicating that the ClPSi₃ monolayer could be used as a potential excellent strain sensor.

Energy landscapes of perfect and defective solids: from structure prediction to ion conduction

The energy landscape concept is increasingly valuable in understanding and unifying the structural, thermodynamic and dynamic properties of inorganic solids. We present a range of examples which include (i) structure prediction of new bulk phases including carbon nitrides, phosphorus carbides, LiMgF3 and low-density, ultra-flexible polymorphs of B2O3, (ii) prediction of graphene and related forms of ZnO, ZnS and other compounds which crystallise in the bulk with the wurtzite structure, (iii) solid solutions, (iv) understanding grossly non-stoichiometric oxides including the superionic phases of δ-Bi2O3 and BIMEVOX and the consequences for the mechanisms of ion transport in these fast ion conductors. In general, examination of the energy landscapes of disordered materials highlights the importance of local structural environments, rather than sole consideration of the average structure.

Inner filter effect as a sensitive sensing platform for detection of nitrofurantoin using luminescent drug-based carbon nanodots

In the present paper, a sensitive and selective inner filter effect sensing platform was designed to detect nitrofurantoin (NIT) in pharmaceutical dosage form. Nitrogen and phosphorus co-doped carbon nanodots (CNDs) prepared via solvothermal treatment of folic acid and phosphoric acid. The prepared CNDs exhibit greenish fluorescence at 470 nm when excited at 340 nm with fluorescence quantum yield up to 40%. The CNDs exhibit high stability in various pH, temperature, and ionic strength which adds valuable merits to its pharmaceutical applications. The emission is quenched in the presence of absorber (here NIT) while the fluorophores were not quench by the presence of common pharmaceutical excipients. A fluorometric assay was fabricated to determine NIT in capsules by quenching of the CNDs. The linear response for the proposed method was from 5.0 μM to 90 μM with the detection limit being 1.4 μM. To validate the method, the recovery of NIT in spiked sample was measured which was 96.6% -103.3%. The method was applied to the determination of NIT in pharmaceutical capsule samples, with comparable results of a reference method stated by the British Pharmacopeia (BP). Furthermore, the sub-acute toxicity studies of CNDs were investigated using normal male Balb/c mice forcefully drunk with 3 different dosages of CNDs. Animals did not produce treatment related signs of toxicity or mortality in any of the animals tested during the 28 days observation period. Additionally, no significant (P > 0.05) changes in the body weight, haematological and biochemical parameters compared with the control group were not revealed. Similarly, histopathological examination of the internal vital organs did not show any morphological alterations.

Highly Luminescent and Biocompatible P and N Co-Doped Passivated Carbon Nanodots for the Sensitive and Selective Determination of Rifampicin Using the Inner Filter Effect

The determination of rifampicin in pharmaceutical dosage forms using a rapid, sensitive, selective, biocompatible, and low-cost method is of vital importance in the pharmaceutical analysis field to ensure its concentration is within the effective range when administered. In this study, nitrogen-and-phosphorous-doped carbon nanodots (CNDs) were prepared using a single-step hydrothermal method with ciprofloxacin as the starting material. The CNDs showed a highly intense blue fluorescence emission centered at 450 nm, with a photoluminescence quantum yield of about 51%. Since the absorption of rifampicin was the same as the excitation spectrum of CNDs, inner filter effect (IFE) quenching occurred and it was used as a successful detection platform for the analysis of rifampicin in capsules. The detection platform showed a dynamic linear range from 1 to 100 μM (R2 = 0.9940) and the limit of detection was 0.06 μM (when S/N = 3). The average spike recovery percentage for rifampicin in the capsule samples was 100.53% (n = 5). Moreover, the sub-chronic cytotoxicity of CNDs was evaluated on healthy male mice (Balb/c) drenched with different amounts of CNDs (10 and 50 mg/kg). During this study period, no mortalities or toxicity signs were recorded in any of the experimental subjects. Based on the cytotoxicity experiment, the proposed nano-probe is considered safe and biocompatible.

Laser ablation synthesis of carbon-phosphides from graphene/nanodiamond-phosphorus composite precursors: Laser desorption ionisation time-of-flight mass spectrometry

RATIONALE

Carbon-phosphides are new and promising strategic materials with applications e.g. in optoelectronics. However, their chemistry and methods of synthesis are not completely understood, and only a limited number of C-P clusters have been detected up to now. Laser ablation synthesis (LAS) or laser desorption ionisation (LDI) has great potential to generate C_m P_n clusters in the gas phase and to act as the basis for the development of new technology.

METHODS

The LAS of carbon phosphides using mixtures of nano-carbon sources (graphene, nanodiamonds) with phosphorus allotropes (red, black, and phosphorene) was examined. Since phosphorene is not commercially available, it was synthesised. A reflectron time-of-flight mass spectrometer was used to produce and identify the C-P clusters. A transmission electron microscope was used to characterise the prepared composites.

RESULTS

LDI of various carbon-phosphorus composites generated a range of carbon-phosphides. From graphene-red phosphorus, C_m P⁺ (m = 3-47), C_m P₂ ⁺ (m = 2-44), C_m P₃ ⁺ (m = 1-42), C_m P₄ ⁺ (m = 1-39), C_m P₅ ⁺ (m = 1-37), C_m P₆ ⁺ (m = 1-34), C_m P₇ ⁺ (m = 1-31), C_m P₈ ⁺ (m = 1-29), C_m P₉ ⁺ (m = 1-26), C_m P₁₀ ⁺ (m = 1-24), C_m P₁₁ ⁺ (m = 1-21), and C_m P₁₂ ⁺ (m = 1-19) clusters were detected, while nanodiamond composites with red/black phosphorus and with phosphorene yielded C₂₄ P_5 + 2n ⁺ (n = 0-28), C₂₄ P_5 + 2n ⁺ (n = 0-16), and C₂₄ P_5 + 2n ⁺ (n = 0-14) clusters, respectively. In total, over 300 new carbon-phosphide clusters were generated.

CONCLUSIONS

The novel series of carbon-phosphide clusters generated from graphene or nanodiamond composites with red/black phosphorus or with phosphorene demonstrated rich carbon-phosphide chemistry that might inspire the development of novel nano-materials with specific properties.

Mechanical properties of pristine and defective carbon-phosphide monolayers: a density functional tight-binding study

Using density functional tight-binding theory, we investigated the elastic properties and deformation and failure behaviors of pristine and defective carbon-phosphide (CP) monolayers subjected to uniform uniaxial tensile strain along arm-chair (AC) and zig-zag (ZZ) directions. Two variants of CP (α-CP and β-CP) were studied and two types of carbon and phosphorous vacancies (single and double) were considered. It was found that carbon monovacancies have the lowest formation energy, while phosphorous divacancies have the highest one in both CP allotropes. A strong mechanical anisotropy for CP was found with the Young's modulus and the failure stress along ZZ direction being an order of magnitude larger than those along AC direction. In both allotropes, the Young's modulus, failure stress and strain are considerably affected by vacancies, especially along AC direction. Fracture of pristine CP monolayer occurred via the rupture of phosphorous-phosphorous bonds when CP monolayer is stretched along AC direction, while via the rupture of carbon-phosphorous bonds when stretched along ZZ direction. Defective α-CP and β-CP monolayers both undergo a brittle-like failure initiated around the hosted vacancies at a lower critical strain. The failure strain and stress along the AC direction are affected only by phosphorous vacancies, while along the ZZ direction, they are almost equally affected by both phosphorous and carbon vacancies. These understandings may provide useful guidelines for potential applications of CP monolayers in nanoelectromechanical systems.

Solvothermal synthesis of phosphorus and nitrogen doped carbon quantum dots as a fluorescent probe for iron(III)

Carbon quantum dots (CQDs) doped with phosphorus and nitrogen were prepared via a hydrothermal method starting from citric acid, urea and phosphoric acid in dimethylformamide solution. The size, morphology, surface composition, energy levels, and optical properties of the CQDs were characterized. They show both green down-conversion and up-conversion fluorescence. Ferric ions (Fe³⁺) are found to quench the fluorescence. Cyclic voltammetry was used to identify the HOMO and LUMO levels of the doped CQDs. The quenching mechanism, as confirmed by energy level calculations and absorption spectra, can be attributed to the selective coordination of Fe³⁺ by the surface functional groups on the CQDs. This facilitates the photo-induced electron transfer from the CQDs to the d orbitals of Fe³⁺. The CQDs are shown to be viable fluorescent probes for determination of Fe³⁺ with high selectivity and sensitivity. The assay has a linear response in the 0.1 μM to 0.9 μM Fe³⁺ concentration range and a 50 nM as limit of detection (at a S/N ratio of 3). Graphical abstract Fluorescence probe for determination of ferric ions based on carbon quantum dot quenching via chelation facilitate photo-electron transfer.

Photoluminescent coral-like carbon-branched polymers as nanoprobe for fluorometric determination of captopril

The authors describe the synthesis of fluorescent coral-like carbon nano-branched polymers (PCNBPs) co-doped with nitrogen and phosphorus. Uric acid and phosphoric acid act as nitrogen and phosphorus sources, respectively. The PCNBPs have a coral-like branched structure, are cross-connected, and < 20 nm in skeleton diameter. Their blue fluorescence, best measured at excitation/emission wavelengths of 330/425 nm, is quenched by mercury (II) ions due to the specifically restricted rigid conformation caused by the interaction of phosphorus, nitrogen, and oxygen groups on the surface of the PCNBPs. Fluorescence is selectivity quenched by Hg(II) but restored in addition of the hypertension drug captopril (CAP) in the range 50 nM to 40 μM concentration range. Fluorescence recovery is attributed to the effectively specific interactions between the thiol group of CAP and Hg(II). The method was applied to the determination of the concentration of Cap in pharmaceutical samples, and recoveries were between 97.6 and 105.1%. Graphical abstract Fluorescent coral-like carbon nano-branched polymers (PCNBPs) co-doped with nitrogen and phosphorus are described. Their fluorescence is selectivity quenched by Hg(II) but restored in addition of the hypertension drug captopril (Cap) in the range 50 nM to 40 μM concentration range.

Real-time tracing the changes in the intracellular pH value during apoptosis by near-infrared ratiometric fluorescence imaging

We developed a near-infrared ratiometric fluorescent nanoprobe with single-excitation dual-emission. The proposed nanoprobe was applied for real-time monitoring the changes in the pH value during hydrogen peroxide-induced apoptosis by ratio imaging. The pH value of HeLa cells changed from 6.6 to 5.6 after H₂O₂ (100 μM) stimulation for 40 min.

Highly passivated phosphorous and nitrogen co-doped carbon quantum dots and fluorometric assay for detection of copper ions

Carbon quantum dots are becoming powerful fluorophore materials for metal ion analysis. Here, highly passivated green phosphorous and nitrogen co-doped carbon quantum dots (C-dots) were prepared using low-temperature carbonization route. Strong green fluorescence emission around 490 nm and excitation wavelength independent C-dots were obtained. Morphological, surface, and optical properties of the C-dots were characterized. Fluorescence emission of C-dots was quenched selectively by copper ions and restored by adding copper chelators, such as EDTA and sulfide ions. Thus, C-dots were successfully used for direct determination of copper ions. Detection limit as low as 1.5 nM (s/n = 3) was achieved for copper ions. Such a low detection limit is very significant for metal analysis using our proposed facile method and low-cost substrates. Experimental results showed that the prepared C-dots demonstrated high sensitivity and selectivity for Cu²⁺ ion detection and the method is robust and rugged. Graphical abstract ᅟ.

Onion derived carbon nanodots for live cell imaging and accelerated skin wound healing

Nitrogen, sulfur, and phosphorous co-doped water-soluble carbon nanodots are synthesized from culinary waste onion peel powder (OPP) by a short microwave treatment. Onion Derived Carbon Nano Dots (OCND) that comprised hydrophilic group-decorated amorphous nano-dots exhibited bright, stable fluorescence at an excitation of 450 nm and emission wavelength at 520 nm along with a free radical scavenging property. The OCND exhibited excellent stability at different pH and UV exposure. Although extracted polyphenols degraded in the extract, interestingly it was shown to be cytocompatible and blood compatible as observed during cytotoxicity, fluorescence imaging of the cell and a hemolysis study. The present work not only focuses on the synthesis of OCND from the OPP extract but also provides an interesting fact that, even after the degradation of polyphenols in the extract, they are non-toxic to human cells (HFF & MG63) and RBCs. Moreover, OCND had no adverse effect on the migration rate of Human Foreskin-derived Fibroblasts (HFFs) as observed from a scratch assay. In addition to accelerating the migration rate of fibroblasts, the OCND altered intra- and extracellular reactive oxygen species (ROS) by enhancing the antioxidant mechanism of a fibroblast under oxidative stress. Further, OCND was observed to accelerate wound healing in a full thickness (FT) wound in a rat model for topical application, which can be attributed to its radical scavenging potential. In summary, this study leads to a new type of OCND synthesis route, which is inherently co-doped with phosphorous, sulfur and nitrogen and holds a great promise for a myriad of biological applications, including bio-imaging, free radical scavenging and wound healing.

Is the Metallic Phosphorus Carbide (β0-PC) Monolayer Stable? An Answer from a Theoretical Perspective

Phosphorus carbide (PC) has been the subject of major research efforts in recent years. In this regard, very recently, a stoichiometric metallic phosphorus carbide (β₀-PC) monolayer has been proposed as locally stable with one lone nonbonding electron in each C atom. Therefore, the ambiguity of coexistence of a nonbonding electron with metallic properties for β₀-PC is reported and hence deserves further explanation. Herein, using first-principles calculations, we have explored the stability and electronic properties of β₀-PC to resolve this ambiguity. The metallic behavior of β₀-PC is explained on the basis of electron delocalization involving P and C atoms along a zigzag chain of β₀-PC. We have also explored the possibility of getting a β₀-PC monolayer via homogeneous doping of C (P) into phosphorene (graphene) and layer exfoliation of 3D bulk PC with β-InS-like structure, which has been experimentally synthesized.

Nitrogen and Phosphorus Co-Doped Carbon Nanodots as a Novel Fluorescent Probe for Highly Sensitive Detection of Fe(3+) in Human Serum and Living Cells

Chemical doping with heteroatoms can effectively modulate physicochemical and photochemical properties of carbon dots (CDs). However, the development of multi heteroatoms codoped carbon nanodots is still in its early stage. In this work, a facile hydrothermal synthesis strategy was applied to synthesize multi heteroatoms (nitrogen and phosphorus) codoped carbon nanodots (N,P-CDs) using glucose as carbon source, and ammonia, phosphoric acid as dopant, respectively. Compared with CDs, the multi heteroatoms doped CDs resulted in dramatic improvement in the electronic characteristics and surface chemical activities. Therefore, the N,P-CDs prepared as described above exhibited a strong blue emission and a sensitive response to Fe(3+). The N,P-CDs based fluorescent sensor was then applied to sensitively determine Fe(3+) with a detection limit of 1.8 nM. Notably, the prepared N,P-CDs possessed negligible cytotoxicity, excellent biocompatibility, and high photostability. It was also applied for label-free detection of Fe(3+) in complex biological samples and the fluorescence imaging of intracellular Fe(3+), which indicated its potential applications in clinical diagnosis and other biologically related study.

Carbon phosphide monolayers with superior carrier mobility

Two dimensional (2D) materials with a finite band gap and high carrier mobility are sought after materials from both fundamental and technological perspectives. In this paper, we present the results based on the particle swarm optimization method and density functional theory which predict three geometrically different phases of the carbon phosphide (CP) monolayer consisting of sp2 hybridized C atoms and sp3 hybridized P atoms in hexagonal networks. Two of the phases, referred to as α-CP and β-CP with puckered or buckled surfaces are semiconducting with highly anisotropic electronic and mechanical properties. More remarkably, they have the lightest electrons and holes among the known 2D semiconductors, yielding superior carrier mobility. The γ-CP has a distorted hexagonal network and exhibits a semi-metallic behavior with Dirac cones. These theoretical findings suggest that the binary CP monolayer is a yet unexplored 2D material holding great promise for applications in high-performance electronics and optoelectronics.

Nitrogen and phosphorus co-doped graphene quantum dots: synthesis from adenosine triphosphate, optical properties, and cellular imaging

Graphene quantum dots (GQDs) are emerging zero-dimensional materials promising a wide spectrum of applications, particularly, as superior fluorescent reporters for bio-imaging and optical sensing. Heteroatom doping can endow GQDs with new or improved photoluminescence properties. Here, we demonstrate a simple strategy for the synthesis of nitrogen and phosphorus co-doped GQDs from a single biomolecule precursor (adenosine triphosphate - ATP). Such ATP-GQDs exhibit high fluorescence quantum yield, strong two-photon upconversion, small molecular weight, high photostability, and good biocompatibility. Furthermore, transferrin conjugated ATP-GQDs have been used for imaging and real-time tracking of transferrin receptors in live cells.