Phosphorus is a nonmetal with several allotropes, from the highly reactive white phosphorus to the thermodynamically stable black phosphorus (BP) with a puckered orthorhombic layered structure. The ...bulk form of BP was first synthesized in 1914, but received little attention until it was rediscovered in 2014 as a member of the new wave of 2D layered nanomaterials. BP can be exfoliated to a single sheet that acts as a semiconductor with a tunable direct band gap, a high carrier mobility at room temperature, and an in‐plane anisotropy. The development of BP applications is hampered by surface degradation, thus efforts to achieve effective BP passivation are ongoing, such as its integration in van der Waals heterostructures. BP has been tested as a novel nanomaterial in batteries, transistors, sensors, and photonics. This Review begins with the origin of the BP story, following the path from a bulk material to modern few/single layers. The physical and chemical properties are summarized, and the state‐of‐the‐art of BP applications highlighted.
Back to black: Black phosphorus (BP) is thermodynamically stable and has a puckered orthorhombic layered structure. It can be exfoliated to a single sheet with a tunable direct band gap, semiconducting properties, high carrier mobility at room temperature, and in‐plane anisotropy. BP is promising as a new nanomaterial for batteries, transistors, sensors, and photonics.
Two-dimensional (2D) layered materials have proven to be crucial platforms for anchored individual and isolated metal atoms acting as active single atom catalysts (SACs). Therefore, an accurate ...location of single atoms is essential for understanding the reaction mechanism and design of SACs anchored at 2D layered materials. However, the preparation of SACs with a precise location remains a great challenge. This review highlights recent advances in the preparation, characterization, and catalytic performance of SACs, focusing on single atoms anchored at 2D layered materials beyond graphene. These 2D materials include transitional metal dichalcogenides, layered double hydroxides, and MXenes. Importantly, the topic of impurities is discussed because these can be present at an even higher percentage than the single atoms at 2D layered materials. A variety of electrochemical energy applications are discussed in which SACs have a crucial role, including water splitting and carbon dioxide reduction. Finally, this review provides the latest applications and developments perspective of single metal atoms on 2D surfaces, which offers a unique opportunity to tune active sites and optimize the activity, selectivity, and stability of electrocatalysts.
Owing to their unique physical and chemical properties, layered two‐dimensional (2D) materials have been established as the most significant topic in materials science for the current decade. This ...includes layers comprising mono‐element (graphene, phosphorene), di‐element (metal dichalcogenides), and even multi‐element. A distinctive class of 2D layered materials is the metal phosphorous trichalcogenides (MPCh3, Ch=S, Se), first synthesized in the late 1800s. Having an unusual intercalation behavior, MPCh3 were intensively studied in the 1970s for their magnetic properties and as secondary electrodes in lithium batteries, but fell from scrutiny until very recently, being 2D nanomaterials. Based on their synthesis and most significant properties, the present surge of reports related to water‐splitting catalysis and energy storage are discussed in detail. This Minireview is intended as a baseline for the anticipated new wave of researchers who aim to explore these 2D layered materials for their electrochemical energy applications.
MPCh3 player: A new era for metal phosphorous trichalcogenides (MPCh3), a distinctive class of 2D layered materials, first synthesized in the late 1800s, is beginning. With an unusual intercalation behavior, MPCh3 were intensively studied in the 1970s for lithium batteries. Presently rediscovered as 2D nanomaterials for water splitting catalysis and energy storage applications.
Layered materials are of high importance because of their anisotropy and as a source of 2D materials. Whilst there is a plethora of multi‐elemental 2D materials, the number mono‐elemental 2D ...materials is rather limited. Herein, we demonstrate that aqueous shear exfoliation can be used to obtain As, Sb, and Bi exfoliated nanosheets. Morphological and chemical characterization of the exfoliated materials shows a decrease in thickness, sheet‐to‐nanosheet scale, and partial oxidation owing to a higher surface area. The electrochemical performance is tested in terms of inherent electrochemistry, electron transfer, and sensing applications as demonstrated with ascorbic acid. Potential energy‐related applications are evaluated in the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR), with shear‐exfoliated Sb having the best electrochemical performance overall. These findings will have a profound impact on the preparation and application of 2D mono‐elemental materials.
Will it blend? The aqueous shear exfoliation of pnictogens using household kitchen blenders to obtain As, Sb, and Bi exfoliated nanosheets is reported. Electrochemical performance is improved, with shear‐exfoliated Sb having the best electrocatalytic performance overall.
Layered metal trichalcogen phosphites, also entitled as metal phosphorus chalcogenides (MPX3), have regained abundant interest, not only due to their magnetic properties, but also due to promising ...performances in energy storage and conversion. Herein, two different layered manganese trichalcogen phosphites, MnPX3 (X = S, Se), are synthetized and submitted to shear force exfoliation. Structural and morphological characterization point to the fact that exfoliated MPX3 (exf‐MnPX3) undergo mainly a downsizing process, alongside with delamination. Layered exf‐MnPSe3 has the lowest onset potential for hydrogen evolution reaction (HER) in both media. In acidic media, a comparative improvement of 350 mV is observed for exf‐MnPSe3 relative to the bulk MnPSe3. The materials stability as electrocatalysts is also tested for HER in a wide pH range, in which exf‐MnPSe3 has a good stability after 100 cycles. The improved performance of exf‐MnPSe3 can be correlated with the lower relative abundance of Mn and P oxides detected in the Mn 2p and P 2p core levels. Such materials show a great promise for future in a hydrogen‐based economy.
Metal phosphorus chalcogenides (MPX3) have reclaimed ample interest as 2D layered materials, due to favorable performances in energy storage and conversion. Herein, MnPX3 (X = S, Se) are synthetized and submitted to shear force exfoliation. Exfoliated MnPSe3 has the lowest onset potential and best stability for hydrogen evolution. Such materials show a great promise for future in a hydrogen‐based economy.
Two-dimensional (2D) layered materials assume a central role in efforts to address the challenges associated with electromagnetic interference (EMI) due to undesirable effects of continuous exposure ...to electromagnetic fields. Recent progress on EMI shielding effectiveness (EMI SE) of 2D layered materials is highlighted, such as black phosphorus, hexagonal boron nitride, layered double hydroxides, and transition metal dichalcogenides, with a focus on the significant volume of work done with MXenes. The 2D structures yield large surface area and low density, and their unique electrical properties confer them a high potential for developing superior EMI shielding materials. Commercial products of EMI shielding materials are analyzed, and we discuss how these 2D materials could reach the market.
3D-printing (or additive manufacturing) is presently an emerging technology that promises to reshape traditional manufacturing processes. The electrochemistry field can certainly take advantage of ...this fabrication tool for sensing and energy-related applications. Polymer/graphene filaments commonly used for the fabrication of 3D-printed electrodes show poor electrochemistry in the native state, requiring post-fabrication activation procedures. In the present work, solvent activation of graphene/polymer-based 3D-printed electrodes was investigated, using both polar aprotic solvents (DMF and acetone) and polar protic solvents (EtOH, MeOH, and H2O). Differences were noted with respect to the weight loss and surface morphologies of the activated electrodes prior to their use, depending the solvent used. The electrodes activated in polar aprotic solvents exhibit a dramatic increase in heterogeneous electron transfer rate using the Fe(CN6)4−/3− redox couple. Moreover, the activation medium has a crucial influence on the electrochemical double layer. We wish to provide meaningful insight to researchers by comparing results obtained with 3D-printed electrodes fabricated from graphene/polymer filaments and drawing attention to the influence of the solvents used in their activation.
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•Cheap and quick 3D printing and activation of 3D Printed Graphene/PLA electrodes.•Solvent activation improves the capacitance and electron transfer properties.•Polar aprotic solvents have better activation capabilities than polar protic solvents.
The experimental achievement of phosphorene, which exhibits superior electronic, physical, and optical properties has spurred recent interest in other Group 15 elemental 2D nanomaterials such as ...arsenene, antimonene, and bismuthene. These unique and superior properties of the pnictogen nanosheets have spurred intensive research efforts and led to the discovery of their diversified potential applications; for instance, optical Kerr material, photonic devices, pnictogen‐decorated microfibers, high‐speed transistors, and flexible 2D electronics. Previous studies have mainly been dedicated to study the synthesis, properties, and applications of the heavy pnictogens nanosheets; however, the toxicological behaviour of these nanosheets has yet to be established. Herein, the cytotoxicity study of pnictogen nanosheets (As, Sb, and Bi) was conducted over 24 h of incubation with various concentrations of test materials and adenocarcinoma human lung epithelial A549 cells. After the treatment period, the remaining cell viabilities were obtained through absorbance measurements with WST‐8 and MTT assays. These findings demonstrate that the toxicity of pnictogen nanosheets decreases down Group 15, whereby arsenic nanosheets are considered to be the most toxic, whereas bismuth nanosheets induce low cytotoxicity. The findings of this study constitute an important initial step towards enhancing our understanding of the toxicological effects of pnictogen nanosheets in light of their prospective commercial applications.
A cytotoxicity study of shear exfoliated pnictogen nanosheets with human lung epithelial carcinoma A549 cells by WST‐8 and MTT assay, which reveal that the arsenic nanosheets are the most toxic while bismuth nanosheets are the least toxic.
Two-dimensional (2D) layered materials are currently one of the most explored materials for developing efficient and stable electrocatalysts in energy conversion applications. Some of the 2D metal ...phosphorous trichalcogenides (M2P2X6 or MPX3 in its simplified form) have been reported to be useful catalysts for water splitting, although results have been less promising for the sluggish oxygen evolution reaction (OER) due to insufficient activity or compromised stability. Herein, we report the OER catalysis of a series of M2P2X6 (M2+ = Mn, Fe, Co, Zn, Cd; X = S, Se). From the series of MPX3, CoPS3 yields the best results with an overpotential within the range of values usually obtained for IrO2 or RuO2 catalysts. The liquid-phase exfoliation of CoPS3 even improves the OER activity due to abundant active edges of the downsized sheets, accompanied by the presence of surface oxides. The influence of the OER medium and underlying substrate electrode is studied, with the exfoliated CoPS3 reaching the lowest overpotential at 234 mV at a current density of 10 mA/cm2, also able to sustain high current densities, with an overpotential of 388 mV at a current density of 100 mA/cm2, and excellent stability after multiple cycles or long-term operation. Quantum chemical models reveal that these observations are likely tied to moieties on CoPS3 edges, which are responsible for low overpotentials through a two-site mechanism. The OER performance of exfoliated CoPS3 reported herein yields competitive values compared to those reported for other Co-based and MPX3 in the literature, thus holding substantial promise for use as an efficient material for the anodic water-splitting reaction.
Few and monolayer black phosphorus (phosphorene) is currently an intensively researched material. Shear exfoliated black phosphorus (BPSE) nanosheets were functionalized with the redox active ...antraquinone (AQ) that can provide additional charge storage capacity. The noncovalent interaction of BP with AQ occurs due to van der Waals interactions. X-ray photoelectron spectroscopy results show that AQ coverage of BPSE nanosheets led to a stabilization against BPSE degradation. Electrochemistry of the BPSE-AQ shows that AQ is stably anchored onto BPSE and exhibits redox peaks stable for more than 100 cycles. The surface coverage by AQ on BPSE is estimated to be 1.25 nmol AQ/mg BP and electron-transfer rate constant (k ET) of 33 s–1. Furthermore, the proposed modification greatly increases the gravimetric capacitance of BPSE-AQ with respect to the starting BPbulk. Such coating of BP not only protects BP from degradation but also brings electroactive functionality to this two-dimensionally layered material.
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