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At the atomic-cluster scale, pure boron is markedly similar to carbon, forming simple planar molecules and cage-like fullerenes. Theoretical studies predict that two-dimensional (2D) boron sheets will adopt an atomic configuration similar to that of boron atomic clusters. We synthesized atomically thin, crystalline 2D boron sheets (i.e., borophene) on silver surfaces under ultrahigh-vacuum conditions. Atomic-scale characterization, supported by theoretical calculations, revealed structures reminiscent of fused boron clusters with multiple scales of anisotropic, out-of-plane buckling. Unlike bulk boron allotropes, borophene shows metallic characteristics that are consistent with predictions of a highly anisotropic, 2D metal.

As the promising and highly‐focused materials after silicon, carbon, and phosphorus promote the development of nanotechnology due to its allotropes with unique structures and properties. The carbon allotropes of 0D fullerene, 1D carbon nanotube, and 2D graphene stimulate the investigation of structures, synthesis, properties, and further applications of carbon nanomaterials. Analogous to carbon, phosphorus is demonstrated to have a rich phase diagram. 0D phosphorus fullerenes, 1D phosphorus nanotubes and fibrous red phosphorus, and recently 2D black phosphorene and violet phosphorene have unique structures analogous to carbon fullerene, carbon nanotube, and graphene, is developed. The photoelectronic properties and further applications of the phosphorus allotropes as semiconductors, energy storage materials, biomaterials, and sensors are also investigated. Great efforts are dedicated to studies of the synthesis, structure, and properties of carbons and phosphorus. However, there is no systematic review of the structure of phosphorus allotropes compared to carbon allotropes. Herein, the structures along with possible future perspective of carbon and phosphorus allotropes review and compare in this work based on the classification of different dimensions. Great efforts are dedicated to studies the synthesis, structure, and properties of carbons and phosphorus. However, as the promising and highly‐focused materials after silicon, the development of carbon and phosphorus allotropes is still undiscussed. Herein, a systematic review, comparison and the possible future perspective of carbon and phosphorus allotropes, is provided based on the classification of different dimensions.

Strong chemical activity and extreme instability in ambient conditions characterize carbyne, an infinite sp 1 hybridized carbon chain. As a result, much less has been explored about carbyne as compared to other carbon allotropes such as fullerenes, nanotubes and graphene. Although end-capping groups can be used to stabilize carbon chains, length limitations are still a barrier for production, and even more so for application. We report a method for the bulk production of long acetylenic linear carbon chains protected by thin double-walled carbon nanotubes. The synthesis of very long arrangements is confirmed by a combination of transmission electron microscopy, X-ray diffraction and (near-field) resonance Raman spectroscopy. Our results establish a route for the bulk production of exceptionally long and stable chains composed of more than 6,000 carbon atoms, representing an elegant forerunner towards the final goal of carbyne’s bulk production. One-dimensional linear carbon chains reaching a length close to 800 nm have been synthesized at high temperature and high vacuum using double-walled carbon nanotubes as nanoreactors.

Carbon is the fourth-most prevalent element in the Universe and essential for all known life. In the elemental form it is found in multiple allotropes, including graphite, diamond and fullerenes, and it has long been predicted that even more structures can exist at pressures greater than those at Earth’s core 1 – 3 . Several phases have been predicted to exist in the multi-terapascal regime, which is important for accurate modelling of the interiors of carbon-rich exoplanets 4 , 5 . By compressing solid carbon to 2 terapascals (20 million atmospheres; more than five times the pressure at Earth’s core) using ramp-shaped laser pulses and simultaneously measuring nanosecond-duration time-resolved X-ray diffraction, we found that solid carbon retains the diamond structure far beyond its regime of predicted stability. The results confirm predictions that the strength of the tetrahedral molecular orbital bonds in diamond persists under enormous pressure, resulting in large energy barriers that hinder conversion to more-stable high-pressure allotropes 1 , 2 , just as graphite formation from metastable diamond is kinetically hindered at atmospheric pressure. This work nearly doubles the highest pressure at which X-ray diffraction has been recorded on any material. X-ray diffraction measurements of solid carbon compressed to pressures of about two terapascals (approximately twenty million atmospheres) find that carbon retains a diamond structure even under these extreme conditions.

In recent years, a plethora of theoretical carbon allotropes have been proposed, none of which has been experimentally isolated. We discuss here criteria that should be met for a new phase to be potentially experimentally viable. We take as examples Haeckelites, 2D networks of sp2-carbon–containing pentagons and heptagons, and “penta-graphene,” consisting of a layer of pentagons constructed from a mixture ofsp²- andsp³-coordinated carbon atoms. In 2D projection appearing as the “Cairo pattern,” penta-graphene is elegant and aesthetically pleasing. However, we dispute the author’s claims of its potential stability and experimental relevance.

A 2D metastable carbon allotrope, penta-graphene, composed entirely of carbon pentagons and resembling the Cairo pentagonal tiling, is proposed. State-of-the-art theoretical calculations confirm that the new carbon polymorph is not only dynamically and mechanically stable, but also can withstand temperatures as high as 1000 K. Due to its unique atomic configuration, penta-graphene has an unusual negative Poisson’s ratio and ultrahigh ideal strength that can even outperform graphene. Furthermore, unlike graphene that needs to be functionalized for opening a band gap, penta-graphene possesses an intrinsic quasi-direct band gap as large as 3.25 eV, close to that of ZnO and GaN. Equally important, penta-graphene can be exfoliated from T12-carbon. When rolled up, it can form pentagon-based nanotubes which are semiconducting, regardless of their chirality. When stacked in different patterns, stable 3D twin structures of T12-carbon are generated with band gaps even larger than that of T12-carbon. The versatility of penta-graphene and its derivatives are expected to have broad applications in nanoelectronics and nanomechanics. Significance Carbon has many faces––from diamond and graphite to graphene, nanotube, and fullerenes. Whereas hexagons are the primary building blocks of many of these materials, except for C ₂₀ fullerene, carbon structures made exclusively of pentagons are not known. Because many of the exotic properties of carbon are associated with their unique structures, some fundamental questions arise: Is it possible to have materials made exclusively of carbon pentagons and if so will they be stable and have unusual properties? Based on extensive analyses and simulations we show that penta-graphene, composed of only carbon pentagons and resembling Cairo pentagonal tiling, is dynamically, thermally, and mechanically stable. It exhibits negative Poisson's ratio, a large band gap, and an ultrahigh mechanical strength.

Twenty-five years on from the discovery of C 60 , the outstanding properties and potential applications of the synthetic carbon allotropes — fullerenes, nanotubes and graphene — overwhelmingly illustrate their unique scientific and technological importance.

Zinc has been demonstrated to boost immune response during SAR-CoV-2 infection, where it prevents coronavirus multiplication. Clinical investigations have testified to its beneficial effects on respiratory health and its deficiency may reduce immune function. A highly sensitive detection of Zn(II) ion via differential pulse voltammetry (DPV) utilizing an environmentally friendly modified screen-printed carbon electrode (SPCE) of electrochemically reduced graphene oxide (ErGO) embedded with carboxylated-8-carboxamidoquinoline (CACQ) as Zn(II) chelating ligand. The green CACQ/ErGO-modified SPCE was characterized by spectroscopy techniques, such as Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, and field-emission scanning electron microscopy with energy dispersive X-ray (FESEM-EDX). The modified electrode-solution interface was studied by electrochemical cyclic voltammetry (CV) and DPV methods. The CACQ-modified wrinkled ErGO electrode conferred a large surface-to-volume ratio with multiple binding sites resulting in greater opportunity for multiple dative covalent binding events with Zn(II) via coordination chemistry, and considerably accelerated the electron transfer rate at the electrode surface. The green Zn(II) sensor demonstrated a quick response time (60 s), broad linear range [1 pM-1 [mu]M Zn(II) ion], a limit of detection (LOD) of 0.53 pM, 35 days of storage period ([greater than or equal to]80% of its initial response retained), good reproducibility [relative standard deviation (RSD) = 3.4%], and repeatability (RSD = 4.4%). The developed electrode was applied to determine Zn(II) ion concentration in dietary supplement samples, and the results were in good agreement with those obtained from inductively coupled plasma-mass spectrometry (ICP-MS).

The quest to model carbyne has been largely tackled through increasingly longer polyynes. [ n ]Cumulenes are an alternative class of molecules to model carbyne. The major difference between polyynes and cumulenes is that polyynes maintain strong bond length alternation (BLA) while cumulenes do not. The development of longer [ n ]cumulenes is challenged by decreased stability relative to oligoynes. This study compares the persistence of tetraaryl[ n ]cumulenes based on ortho ‐substituent(s) of aryl endgroups. A trend emerges in which bulkier ortho ‐substituents offer more persistent [ n ]cumulenes. The enhanced stability is consistent with a combination of steric shielding and disrupted electronic communication between the endgroups and cumulenic framework. Kinetically stabilized [ n ]cumulenes [ n ] ot Bu ( n = 5, 7, 9, 11, 13) are successfully synthesized. The longest derivatives, [11] ot Bu and [13] ot Bu , are studied in solution, and the electronic absorption properties are compared experimentally and computationally. The terminal alkylidene groups of [ n ]cumulenes have significant effects on the optical properties and result in an additional optical state, S 1 , relative to oligoynes. The S 1 state gives a lower fundamental optical energy gap ( E g ) in [ n ]cumulenes relative to oligoynes and decreases as the molecules transition from D 2 to D ∞h symmetry. The highest energy state ( S 4 ) is allowed by symmetry at any length and shows remarkable similarity to the analogous absorptions of polyynes.

In recent years, an increasing number of nanomaterials have been explored for their applications in biomedical diagnostics, making their applications in healthcare biosensing a rapidly evolving field. Nanomaterials introduce versatility to the sensing platforms and may even allow mobility between different detection mechanisms. The prospect of a combination of different nanomaterials allows an exploitation of their synergistic additive and novel properties for sensor development. This paper covers more than 290 research works since 2015, elaborating the diverse roles played by various nanomaterials in the biosensing field. Hence, we provide a comprehensive review of the healthcare sensing applications of nanomaterials, covering carbon allotrope-based, inorganic, and organic nanomaterials. These sensing systems are able to detect a wide variety of clinically relevant molecules, like nucleic acids, viruses, bacteria, cancer antigens, pharmaceuticals and narcotic drugs, toxins, contaminants, as well as entire cells in various sensing media, ranging from buffers to more complex environments such as urine, blood or sputum. Thus, the latest advancements reviewed in this paper hold tremendous potential for the application of nanomaterials in the early screening of diseases and point-of-care testing.