Regulating the reactivity of black phosphorous through protective chemistry (original) (raw)
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Ambient Protection of Few-Layer Black Phosphorus via Sequestration of Reactive Oxygen Species
Advanced materials (Deerfield Beach, Fla.), 2017
Few-layer black phosphorous (BP) has emerged as a promising candidate for next-generation nanophotonic and nanoelectronic devices. However, rapid ambient degradation of mechanically exfoliated BP poses challenges in its practical deployment in scalable devices. To date, the strategies employed to protect BP have relied upon preventing its exposure to atmospheric conditions. Here, an approach that allows this sensitive material to remain stable without requiring its isolation from the ambient environment is reported. The method draws inspiration from the unique ability of biological systems to avoid photo-oxidative damage caused by reactive oxygen species. Since BP undergoes similar photo-oxidative degradation, imidazolium-based ionic liquids are employed as quenchers of these damaging species on the BP surface. This chemical sequestration strategy allows BP to remain stable for over 13 weeks, while retaining its key electronic characteristics. This study opens opportunities to pract...
Noncovalent Functionalization of Black Phosphorus
Angewandte Chemie, 2016
The first non-covalent functionalization of black phosphorus (BP) is presented. The treatment of BP with electron-withdrawing 7,7,8,8-tetracyano-p-quinodimethane (TCNQ) leads to electron transfer from BP to the organic dopant. On the other hand, the non-covalent interaction of BP with perylene diimide is mainly due to van-der-Waals interactions but also leads to a considerable stabilization of the BP flakes against oxygen degradation. BP has recently emerged as a very interesting new two-dimensional material.[1] The individual layers of BP exhibit a honeycomb structure differing to that of graphene because of a marked puckering of the sp 3 P-atoms[2,3] Owing to its intrinsic direct bandgap being a good trade-off between charge carrier mobility and current on/off ratios and because of its unusual in-plane anisotropy, BP exhibits a tremendous potential in both electronics and optoelectronics.[4-9] Few-layer nanosheets (flakes) of BP can be obtained by mechanical exfoliation of the bulk crystals as well as through solvent exfoliation. However, so far practical applications are restricted because of the instability of BP with respect to ambient oxygen and moisture.[10-14] Concepts for chemical stabilization are urgently desired. Encapsulation methods have been proposed to preserve its intrinsic properties, but the chemical control over the reactivity still remains an open challenge.[3] Recently, in collaboration with the group of Coleman, we reported the liquid exfoliation of solvent-stabilized few-layer BP flakes. During this procedure the stability at ambient conditions increased from ca. 1h for mechanically cleaved BP to ca. 200 h for 1-cyclohexyl-2-pyrrolidone (CHP)-exfoliated few-layer BP. First appealing applications beyond electronics as gas sensors, saturable absorbers and reinforcing fillers for nanocomposites could be demonstrated.[15] The chemistry of BP, however, remains almost unexplored.[16] So far only single flake chemistry with diazonium salts and TiL 4 complexes have been reported.[23,24] We describe now for the first time non-covalent functionalization of bulk BP with TCNQ and perylene bisimides (PDI) demonstrating pronounced charge-transfer and van-der-Waals
Recent Progress on Stability and Passivation of Black Phosphorus
Advanced materials (Deerfield Beach, Fla.), 2018
From a fundamental science perspective, black phosphorus (BP) is a canonical example of a material that possesses fascinating surface and electronic properties. It has extraordinary in-plane anisotropic electrical, optical, and vibrational states, as well as a tunable band gap. However, instability of the surface due to chemical degradation in ambient conditions remains a major impediment to its prospective applications. Early studies were limited by the degradation of black phosphorous surfaces in air. Recently, several robust strategies have been developed to mitigate these issues, and these novel developments can potentially allow researchers to exploit the extraordinary properties of this material and devices made out of it. Here, the fundamental chemistry of BP degradation and the tremendous progress made to address this issue are extensively reviewed. Device performances of encapsulated BP are also compared with nonencapsulated BP. In addition, BP possesses sensitive anisotrop...
TEM Studies on Antibacterial Mechanisms of Black Phosphorous Nanosheets
International Journal of Nanomedicine
Purpose: Recently, two-dimensional (2D) nanomaterials are gaining tremendous attention as novel antibacterial platforms to combat against continuously evolving antimicrobial resistance levels. Among the family of 2D nanomaterials, black phosphorus (BP) nanosheets have demonstrated promising potential for biomedical applications. However, there is a need to gain nanoscale insights of the antibacterial activity of BP nanosheets which lies at the center of technical challenges. Methods: Ultra-large BP nanosheets were synthesized by liquid-exfoliation method in the eco-friendly deoxygenated water. Synthesized BP nanosheets were characterized by TEM, AFM, and Raman spectroscopy techniques and their chemical stability was evaluated by EDS and EELS elemental analysis. The antibacterial activity of BP nanosheets was evaluated at nanoscale by the ultramicrotome TEM technique. Further, HAADF-STEM image and EDS elemental line map of the damaged bacterium were utilized to analyze the presence of diagnostic ions. Supportive SEM and ATR-FTIR studies were carried out to confirm the bacterial cell wall damage. In vitro colony counting method was utilized to evaluate the antibacterial performance of ultra-large BP nanosheets. Results: Elemental EELS and EDS analysis of BP nanosheets stored in deoxygenated water confirmed the absence of oxygen peak. TEM studies indicate the various events of bacterial cell damage with the lost cellular metabolism and structural integrity. Colony counting test results show that as-synthesized BP nanosheets (100 μg/mL) can kill~95% bacteria within 12 hours. Conclusion: TEM studies demonstrate the various events of E. coli membrane damage and the loss of structural integrity. These events include the BP nanosheets interaction with the bacterial cell wall, cytoplasmic leakage, detachment of cytoplasm from the cell membrane, reduced density of lipid bilayer and agglomerated DNA structure. The EDS elemental line mapping of the damaged bacterium confirms the disrupted cell membrane permeability and the lost cellular metabolism. SEM micrographs and ATR-FTIR supportive results confirm the bacterial cell wall damage.
Coordination Chemistry Reviews, 2025
Black phosphorene (BP), an exciting allotrope of phosphorus, has sparked widespread attention owing to its unique physicochemical characteristics and numerous potentials in the environmental, energy, and biological sectors. The current review delves further into BP, concentrating on its layered structure, unusual features, and broad applications. Methods of synthesis of BP, such as liquid exfoliation, chemical vapor deposition, and mechanical exfoliation, are reviewed, and characterization procedures critical to ensuring the quality of BP are described. Its anisotropic mechanical, electrical, and optical properties are investigated using insights gained from its hexagonal lattice atomic structure and puckered layers. In environmental contexts, BP shows potential for water purification due to its strong adsorption and degradation capabilities against various contaminants, including dyes, medicines, pesticides, heavy metals, and organic compounds. Its potential in environmental sensing is also emphasized, notably for detecting gasses, heavy metals, and pollutants. Moving on to energy applications, BP is used in batteries, supercapacitors, and hydrogen generation, where its unique electrical and structural properties improve energy storage and conversion efficiency. BP improves medication delivery systems in biomedical applications by providing biocompatibility and customizable delivery capabilities. Furthermore, its biological imaging and diagnostics applications are reviewed, focusing on optical properties and contrast enhancement capabilities. Nonetheless, despite BP's significant potential, serious hurdles persist. Issues including stability under ambient settings, large-scale synthesis limits, and biocompatibility difficulties require resolution for more considerable practical use. The paper concludes by exploring future challenges and solutions to motivate readers. In summary, BP stands as a flexible material prepared to drive innovation in environmental, energy, and biological applications, although attaining its revolutionary influence will depend on overcoming present technological, scientific, and scaling limitations.
The atomic level mechanism of white phosphorous demolition by di-iodine
Dalton Transactions, 2018
A detailed mechanism of the I 2-induced transformation of white phosphorus into PI 3 emerges from a DFT analysis. This multi-step process implies that at any stage one P-P and two I-I bonds cleavages, associated with the formation of two P-I bonds plus an in situ generated brand new I 2 molecule. Significant electron transfer between the atoms is observed at any step, but the reactions are better defined as concerted rather than redox. Along the steepest descent to the product, no significant barrier is encountered except for the very first P 4 activation, which costs +14.6 kcal mol −1. At the atomic level, one first I 2 molecule, a typical mild oxidant, is first involved in a linear halogen bonding interaction (XB) with one P donor, while its terminal I atom is engaged in an additional XB adduct with a second I 2. Significant electron transfer through the combined diatomics allows the external I atom of the dangling I 3 grouping to convey electrons into the σ* level of one P-P bond with its consequent cleavage. This implies at some point the appearance of a six-membered ring, which alternatively switches its bonding and no-bonding interactions. The final transformation of the P 2 I 4 diphosphine into two PI 3 phosphines is enlightening also for the specific role of the I substituents. In fact, it is proved that an organo-diphosphine analogue hardly undergoes the separation of two phosphines, as reported in the literature. This is attributable to the particularly high donor power of the carbo-substituted P atoms, which prevents the concertedness of the reaction but favors charge separation in an unreactive ion pair. † Electronic supplementary information (ESI) available. See
Energy Storage Materials, 2021
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Degradation Studies of Air-Exposed Black Phosphorous and Black Arsenic Phosphorous
ChemEngineering
This work investigates the effects of oxygen and humidity on black phosphorous (BP) and black arsenic phosphorous (AsxP1−x ) flakes using Raman spectroscopy and in situ electric transport measurements (four-probe resistance and thermoelectric power, TEP). The results show that the incorporation of arsenic into the lattice of BP renders it more stable, with the degradation times for BP, As0.2P0.8, and As0.4P0.6 being 4, 5, and 11 days, respectively. The P-P Raman peak intensities were determined to decrease with exposure to oxygen and moisture. The TEP measurements confirmed that both BP and AsxP1−x are p-type semiconductors with the TEP of As0.4P0.6 stabilizing more slowly than that of BP. In addition, the four-probe resistance of BP and AsxP1−x stabilized significantly faster when exposed to air after being degassed in a vacuum. This was attributed to the charge transfer between the oxygen redox potential of air and the Fermi energy (EF) of the semiconductors.
The Journal of Physical Chemistry C, 2018
Simulations based on electronic density functional theory have been employed to study the environmental stability of phosphorene under mechanical stress as well as oxidative conditions. To understand the mechanical response, bi-axial strain was applied along zigzag and armchair directions and the potential energy surface was generated. Poisson's ratio and Young's modulus were calculated along each direction indicating anisotropic response of the material. Under large strain conditions, several stable or metastable phases were identified including transformation from black phosphorus to white phosphorus and polymeric phases. To evaluate the chemical stability, surface mixing energies of phosphorene oxide were calculated as a function of oxygen coverage. Results indicate the formation of PO 3 and PO 4 chains at oxygen coverage above 0.5 monolayers, suggesting a multistep oxidation process that would ultimately lead to the formation of P 2 O 5. Ab initio molecular dynamics simulations with an additional water molecule revealed the hydrophobic nature of pristine black phosphorus in comparison to the hydrophilic nature of oxidized black phopshorus.
Lattice Opening Upon Bulk Reductive Covalent Functionalization of Black Phosphorus
Angewandte Chemie International Edition
The chemical bulk reductive covalent functionalization of thin layer black phosphorus (BP) using BP intercalation compounds has been developed. Through effective reductive activation, covalent functionalization of the charged BP is achieved by organic alkyl halides. Functionalization was extensively demonstrated by means of several spectroscopic techniques and DFT calculations, showing higher functionalization degrees than the neutral routes.