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The CO2 desorption process from a CO2-saturated nonaqueous sorbent, 2-(2-aminoethoxy)ethanol (DGA) in diethylene glycol monomethyl ether (DEGMME), was investigated in the absence and presence of four different metal oxides, namely, V2O5, TiO2, WO3, and ZnO, aiming at identifying acid catalysts with the potential to reduce the energy demand for sorbent regeneration. The desorption performances of the DGA-DEGMME solutions with and without catalysts were evaluated in terms of CO2 desorption rate, overall CO2 desorbed, and thermal energy consumption. The desorption mechanism was understood by the 13C NMR speciation study of the solutions during the regeneration experiments. As a result, metal oxide catalysts, depending on the number and types of acidic sites on their surface, can accelerate the carbamate breakdown and the subsequent CO2 release. In particular, WO3 and TiO2 can be considered good candidates for implementation in CO2 capture processes with nonaqueous sorbents, as they greatly improved the desorption performance, and their structures remain unchanged before and after use. The combination of nonaqueous sorbents with catalysts, here reported for the first time, provides an effective strategy that could inspire the design of advanced sorbents for energy-efficient CO2 capture.

The new bimetallic [Ru2(mu-Cl)3(CAP)6]Cl (1) and monometallic cis,cis,trans-[RuCl2(dmso)2(CAP)2] (2) complexes, bearing the water soluble cage-like phosphine CAP (1,4,7-triaza-9-phosphatricyclo[5.3.2.1]tridecane), were synthesized and characterized in solution by NMR spectroscopy and ESI-MS spectrometry. The complexes, endowed with high solubility and stability in water, were applied as catalysts for the proof-of-concept hydration of benzonitrile to benzamide in neat water at 100 °C, achieving high conversions with only 1 mol% of catalyst, both in single runs and in catalyst recycling experiments.

The direct chemical reactivity between phosphorus and nitrogen was induced under high-pressure and high-temperature conditions (9.1 GPa and 2000-2500 K), generated by a laser-heated diamond anvil cell and studied by synchrotron X-ray diffraction, Raman spectroscopy, and DFT calculations. α-P

Bidimensional (2D) materials are nowadays being developed as outstanding candidates for electronic and optoelectronic components and devices. Targeted applications include sensing, energy conversion, and storage. Phosphorene is one of the most promising systems in this context, but its high reactivity under atmospheric conditions and its small-area/lab-scale deposition techniques have hampered the introduction of this material in real-world applications so far. However, phosphorene oxides in the form of low-dimensional structures (2D POx) should behave as an electroresponsive material according to recent theoretical studies. In the present work, we introduce electrospraying for the deposition of stoichiometric and large-area 2D POx nanoflakes starting from a suspension of liquid-phase-exfoliated phosphorene. We obtained 2D POx nanostructures with a mean surface area two orders of magnitude larger than phosphorene structures obtained with standard mechanical and liquid exfoliation techniques. X-ray spectroscopy and high-resolution electron microscopy confirmed the P2O5-like crystallographic structure of the electrosprayed flakes. Finally, we experimentally demonstrated for the first time the electromechanical responsivity of the 2D P2O5 nanoflakes, through piezoresponse force microscopy (PFM). This work sheds light on the possible implementation of phosphorus oxide-based 2D nanomaterials in the value chain of fabrication and engineering of devices, which might be easily scaled up for energy-harvesting/conversion applications.

Binary ruthenium-phosphorus nanoparticles (NPs) with different Ru/P ratio were prepared in mild conditions using white phosphorus (P4) as phosphorus source. Accurate study of both their morphology and structure at the atomic level by TEM and HAADF-STEM, respectively, showed that Ru2P and RuP have a narrow size distribution (ca. 3.3 nm) and are lacking an ordered ruthenium phosphide lattice. 31P Solid State NMR highlighted the existence of three different phosphorus species consistently with the lack of a metal phosphide lattice and finally XPS revealed that the true nature of these nanoparticles can be better described as a ruthenium-phosphorus alloy. As a benchmark test, the selective hydrogenation of nitroarenes to primary aromatic amines was studied and evidenced how the P-alloying imparts a surface modification resulting in a higher catalytic activity and excellent chemoselectivity of Ru2P in comparison to Ru(0) and RuP.

The catalytic reduction of carbon dioxide is a process of growing interest for the use of this simple and abundant molecule as a renewable building block in C1-chemical synthesis and for hydrogen storage. The well-defined, bench-stable alkylcarbonyl Mn(I) bis(phosphine) complex fac-[Mn(CH2CH2CH3)(dippe)(CO)3] [dippe = 1,2-bis(diisopropylphosphino)ethane] was tested as an efficient and selective non-precious-metal precatalyst for the hydrogenation of CO2 to formate under mild conditions (75 bar total pressure, 80 °C), in the presence of a Lewis acid co-catalyst (LiOTf) and a base (DBU). Mechanistic insight into the catalytic reaction is provided by means of density functional theory (DFT) calculations.

The reaction between basic [(PCP)Pd(H)] (PCP = 2,6-(CH2P(t-C4H9)2)2C6H4) and acidic [LWH(CO)3] (L = Cp (1a), Tp (1b); Cp = η5-cyclopentadienyl, Tp = κ3-hydridotris(pyrazolyl)borate) leads to the formation of bimolecular complexes [LW(CO)2(μ-CO)⋯Pd(PCP)] (4a, 4b), which catalyze amine-borane (Me2NHBH3, tBuNH2BH3) dehydrogenation. The combination of variable-temperature (1H, 31P{1H}, 11B NMR and IR) spectroscopies and computational (ωB97XD/def2-TZVP) studies reveal the formation of an η1-borane complex [(PCP)Pd(Me2NHBH3)]+[LW(CO3)]− (5) in the first step, where a BH bond strongly binds palladium and an amine group is hydrogen-bonded to tungsten. The subsequent intracomplex proton transfer is the rate-determining step, followed by an almost barrierless hydride transfer. Bimetallic species 4 are easily regenerated through hydrogen evolution in the reaction between two hydrides., Bimetallic complexes [LW(CO)2(μ-CO)⋯Pd(PCP)] cooperatively activate amine-boranes for their dehydrogenation via N–H proton tunneling at RDS and H2 evolution from two neutral hydrides.

High pressure reactivity of phosphorus and hydrogen is relevant to fundamental chemistry, energy conversion and storage, and materials science. Here we report the synthesis of (PH3)2H2, a crystalline van der Waals (vdW) compound (I4cm) made of PH3 and H2 molecules, in a Diamond Anvil Cell by direct catalyst-free high pressure (1.2 GPa) and high temperature (T ≲ 1000 K) chemical reaction of black phosphorus and liquid hydrogen, followed by room T compression above 3.5 GPa. Group 15 elements were previously not known to form H2-containing vdW compounds of their molecular hydrides. The observation of (PH3)2H2, identified by synchrotron X-ray diffraction and vibrational spectroscopy (FTIR, Raman), therefore represents the discovery of a previously missing tile, specifically corresponding to P for pnictogens, in the ability of non-metallic elements to form such compounds. Significant chemical implications encompass reactivity of the elements under extreme conditions, with the observation of the P analogue of the Haber-Bosch reaction for N, fundamental bond theory, and predicted high pressure superconductivity in P-H systems., Chemical elements at high pressure may behave more consistently with their periodic properties than they do at ambient conditions. The authors report the synthesis of PH3 from black phosphorous and hydrogen, and the crystallization of the van der Waals compound (PH3)2H2 which fills a gap in the chemistry of adjacent elements in the periodic table.

Direct air capture (DAC) is an emerging technology that can help limit the global temperature rises, as it has the potential to contrast the dispersed CO2 emissions coming from transport and heating that cannot be captured with traditional CCS methods. Although recent improvements are bringing DAC closer to commercial feasibility, an obstacle to its diffusion is the high regeneration energy required by the most common liquid sorbents, Na or K hydroxides. In order to develop efficient and more sustainable sorbents, in the present screening study several alkanolamines, particularly those already known for their utilization in CCS, were tested for DAC. The percentage of CO2 absorbed from compressed air of their 1.5 mol dm-3 aqueous solutions was evaluated in 24 h capture experiments and the species formed were identified and quantified by means of 13C-NMR spectroscopy. For selected amines, their performance in organic diluents was also evaluated. The correlations between aerial CO2 absorption, chemical structures of the different amine and species formed in solution have shown that a high yield production of amine carbamate is the decisive factor for an effective CO2 capture, and that aqueous primary unhindered amines are as efficient as aqueous alkali hydroxides, with the potential of a lower regeneration energy.

Well-defined Mn(I)-PNP pincer-type complexes were tested as non-precious transition metal catalysts for the selective reduction of CO2 to boryl-protected MeOH in the presence of hydroboranes (HBpin, 9-BBN) and borates as Lewis acids (LA) additives. The best performance was obtained under mild reaction conditions (1 bar CO2, 60 °C) in the presence of the hydridocarbonyl complex [MnH(PNPNH-iPr)(CO)2] and B(OPh)3 as co-catalyst. Preliminary mechanistic studies suggest that the initial activation step may occur by cationization of the metal center by the strong LA, and that both metal-catalyzed and metal-free steps are present in the overall catalytic system.

A comparison between the high-pressure (0.8 GPa) photo-induced reactivity of black and red phosphorus at ambient temperature in the presence of ammonia has been conducted in Diamond Anvil Cells (DAC), using spectroscopy (IR and Raman) and X-ray diffraction (XRD). Reactivity has been triggered exploiting the two-photon absorption of near-UV radiation by ammonia. The infrared characterization showed a very complex reactivity in the case of red phosphorus, proceeding to a much more extent with respect to the black allotrope. Furthermore, Raman spectra showed the formation of molecular hydrogen and phosphine besides of three different solid products. Whereas one of them is air sensitive, the other two are recoverable at ambient conditions. IR, Raman and XRD data for the obtained products have been compared to those acquired on known HxPyNz compounds: for one of the two stable products, a fair matching was found with the XRD pattern and the IR spectrum of P3N3(NH2)6 ·(NH3)0.5, whereas for the other one only the functional groups actually involved in the structure could be evinced from accurate Raman mapping of the sample, with no further information about composition or stoichiometry. High density conditions in combination with near-UV laser irradiation were thus proved to be effective in the formation of two stable reaction products featuring new P-N functionalities, both recoverable at ambient pressure. For the first time, a cyclic triphosphazene has been synthesized through the reaction of red phosphorus and ammonia triggered by UV light under moderate high pressure conditions, possibly opening new perspectives about this topic.

We study surface charge transfer doping of exfoliated black phosphorus (bP) flakes by copper using scanning tunneling microscopy (STM) and spectroscopy (STS) at room temperature. The tunneling spectra reveal a gap in correspondence of Cu islands, which is tentatively attributed to Coulomb blockade phenomena. Moreover, using line spectroscopic measurements across small copper islands, we exploit the potential of the local investigation, showing that the n-type doping effect of copper on bP is short-ranged. These experimental results are substantiated by first-principles simulations, which quantify the role of cluster size for an effective n-type doping of bP and show an electronic decoupling of the topmost bP layer from the underlying layers driven by the copper cluster, consistent with the Coulomb blockade interpretation. Our results provide novel understanding--difficult to retrieve by transport measurements--of the doping of bP by copper, which appears promising for the implementation of ultrasharp p-n junctions in bP.

Setting up strong Josephson coupling in van der Waals materials in close proximity to superconductors offers several opportunities both to inspect fundamental physics and to develop novel cryogenic quantum technologies. Here we show evidence of Josephson coupling in a planar few-layer black Phosphorus junction. The planar geometry allows us to probe the junction behavior by means of external gates, at different carrier concentrations. Clear signatures of Josephson coupling are demonstrated by measuring supercurrent flow through the junction at milli Kelvin temperatures. Manifestation of Fraunhofer pattern with a transverse magnetic field is also reported, confirming the Josephson coupling. These findings represent the first evidence of proximity Josephson coupling in a planar junction based on a van der Waals material beyond graphene and open the way to new studies, exploiting the peculiar properties of exfoliated black phosphorus thin flakes.

Aqueous blends of the three amines 2-aminoethanol (MEA), N-methyldiethanolamine (MDEA) and 2-amino-2-methyl-1-propanol (AMP) were tested as sorbents for CO2 capture processes. We formulated three different blends with the same overall amine concentration (5M) but with different amine molar ratio, namely blend-1 (2M MEA+2M MDEA+1M AMP), blend-2 (1M MEA+2M MDEA+2M AMP) and blend-3 (2M MEA+1M MDEA+2M AMP). Their CO2 absorption and desorption performances were investigated in batch experiments in terms of CO2 equilibrium solubility, CO2 absorption at 40 °C and CO2 desorption at 100 °C as a function of time, and energy consumption during the regeneration process. The results were compared to those obtained under the same operating conditions with 5M aqueous MEA, the benchmark sorbent for CO2 absorption processes. The effect of the different amino composition on the CO2 capture mechanism was evaluated by identifying and quantifying the species formed during the capture process through an accurate 13C NMR speciation study. The results obtained showed that all formulated sorbents have higher desorption performance and require less energy for regeneration than conventional aqueous MEA, confirming that blending different alkanolamines has the potential to improve CO2 capture. In particular, blend-2 can be regarded as a promising sorbent for implementation in commercial systems, as it performed a desorption rate up to 5 times higher than conventional aqueous MEA, combined with a significantly lower relative heat duty for regeneration (41.5%) and lower operating costs for CO2 capture.

Chemical reactivity between As and N2 , leading to the synthesis of crystalline arsenic nitride, is here reported under high pressure and high temperature conditions generated by laser heating in a Diamond Anvil Cell. Single crystal synchrotron X-ray diffraction at different pressures between 30 and 40 GPa provides evidence for the synthesis of a covalent compound of AsN stoichiometry, crystallizing in a cubic P213 space group, in which each of the two elements is single-bonded to three atoms of the other and hosts an electron lone pair, in a tetrahedral anisotropic coordination. The identification of characteristic structural motifs highlights the key role played by the directional repulsive interactions between non-bonding electron lone pairs in the formation of the AsN structure. Additional data indicate the existence of AsN at room temperature from 9.8 up to 50 GPa. Implications concern fundamental aspects of pnictogens chemistry and the synthesis of innovative advanced materials.

Heterostructures of single- and few-layer black phosphorus (2D bP) functionalized with gold nanoparticles (Au NPs) have been recently reported in the literature, exploiting their intriguing properties and biocompatibility for catalytic, therapeutical and diagnostic applications. However, a deeper insight on the structural and electronic properties at the interface of the 2D bP/Au NP heterostructure is still lacking. In this work, 2D bP is functionalized with Au nanoparticles (NPs) through in situ deposition–precipitation heterogeneous reaction. The smallest realized Au NPs have a diameter around 10 nm as revealed by atomic-force and scanning electron microscopy, and are partially positively charged as revealed by X-ray Photoelectron Spectroscopy (XPS). XPS, UV-vis and Raman spectroscopy, supported by density functional theory (DFT) calculations, confirmed that while the structural and electronic properties of 2D bP are overall preserved, a soft-pairing between P atoms at the surface of 2D bP and Au atoms at the surface of Au NPs occurs, leading to a partial charge transfer at the 2D bP/Au interface, with a positive charge being localized on the Au atoms directly bonded to 2D bP. DFT calculations also predicted a band gap lowering, by 0.8 eV, for phosphorene functionalized with a tetranuclear Au cluster. Larger effects are expected as the Au cluster nuclearity (and coverage) increases., Computational analysis and electronic, structural and morphological properties of a heterostructure of 2D bP with Au nanoparticles formed in situ.

Exfoliated black phosphorus (bP) embedded into a polymer is preserved from oxidation, is stable to air, light, and humidity, and can be further processed into devices without degrading its properties. Most of the examples of exfoliated bP/polymer composites involve a single polymer matrix. Herein, we report the preparation of biphasic polystyrene/poly(methyl methacrylate) (50/50 wt.%) composites containing few-layer black phosphorus (fl-bP) (0.6–1 wt.%) produced by sonicated-assisted liquid-phase exfoliation. Micro-Raman spectroscopy confirmed the integrity of fl-bP, while scanning electron microscopy evidenced the influence of fl-bP into the coalescence of polymeric phases. Furthermore, the topography of thin films analyzed by atomic force microscopy confirmed the effect of fl-bP into the PS dewetting, and the selective PS etching of thin films revealed the presence of fl-bP flakes. Finally, a block copolymer/fl-bP composite (1.2 wt.%) was prepared via in situ reversible addition–fragmentation chain transfer (RAFT) polymerization by sonication-assisted exfoliation of bP into styrene. For this sample, 31P solid-state NMR and Raman spectroscopy confirmed an excellent preservation of bP structure.

This work aims at characterizing for the first time the 31P spin interactions determining the nuclear magnetic resonance (NMR) properties of solid black phosphorus (bP) and of its few-layer exfoliated form (fl-bP). Indeed, the knowledge of these properties is still very poor, despite the great interest received by this layered phosphorus allotrope and its exfoliated 2D form, phosphorene. By combining density functional theory (DFT) calculations and solid-state NMR experiments on suspensions of fl-bP nanoflakes and on solid bP, it has been possible to characterize the 31P homonuclear dipolar and chemical shift interactions, identifying the network of 31P nuclei more strongly dipolarly coupled and highlighting two kinds of magnetically nonequivalent 31P nuclei. These results add an important missing piece of information to the fundamental chemico-physical knowledge of bP and support future extensive applications of NMR spectroscopy to the characterization of phosphorene-based materials.

The burgeoning interest in two-dimensional (2D) black phosphorus (bP) contributes to the expansion of its applications in numerous fields. In the present study, 2D bP is used as a support for homogeneously dispersed palladium nanoparticles directly grown on it by a wet chemical process. Electron energy loss spectroscopy-scanning transmission electron microscopy analysis evidences a strong interaction between palladium and P atoms of the bP nanosheets. A quantitative evaluation of this interaction comes from the X-ray absorption spectroscopy measurements that show a very short Pd-P distance of 2.26 Å, proving for the first time the existence of an unprecedented Pd-P coordination bond of a covalent nature. Additionally, the average Pd-P coordination number of about 1.7 reveals that bP acts as a polydentate phosphine ligand toward the surface of the Pd atoms of the nanoparticles, thus preventing their agglomeration and inferring with structural stability. These unique properties result in a superior performance in the catalytic hydrogenation of chloronitroarenes to chloroanilines, where a higher chemoselectivity in comparison to other heterogeneous catalyst based on palladium has been observed.

Well-defined Mn(I) hydrido carbonyl PNP pincer-type complexes were tested as efficient and selective nonprecious transition metal catalysts for the reduction of CO2 to MeOH in the presence of hydrosilanes. The choice of reaction temperature and type of silanes proved to be pivotal to achieve fast reactions and high selectivity to the methoxysilyl- vs silylformate derivatives in DMSO. The catalytic data are complemented by DFT calculations, highlighting a stepwise CO2 reduction mechanism centered on the Mn catalyst without metal-to-ligand cooperation.

Nowadays, prostate cancer is the most widespread tumour in worldwide male population. Actually, brachytherapy is the most advanced radiotherapy strategy for the local treatment of prostate cancer. It consists in the placing of radioactive sources closed to the tumour side thus killing cancer cells. However, brachytherapy causes the same adverse effects of external-beam radiotherapy. Therefore, alternative treatment approaches are required for enhancing radiotherapy effectiveness and reducing toxic symptoms. Nanostructured exfoliated black phosphorus (2D BP) may represent a strategic tool for local cancer therapy because of its capability to induce singlet oxygen production and act as photosensitizer. Hence, we investigated 2D BP in vitro effect on healthy and cancer prostate cell behavior. 2D BP was obtained through liquid exfoliation. 2D BP effect on healthy and cancer prostate cell behaviors was analyzed by investigating cell viability, oxidative stress and inflammatory marker expression. 2D BP inhibited prostate cancer cell survival, meanwhile promoted healthy prostate cell survival in vitro by modulating oxidative stress and immune response with and without near-infrared light (NIR)-irradiation. Nanostructured 2D BP is able to inhibit in vitro prostate cancer cells survival and preserve healthy prostate cell vitality through the control of oxidative stress and immune response, respectively.

Since its first reported exfoliation in 2014, the interest in 2D black phosphorus (2D BP) and its chemical functionalization has grown dramatically [1], though a satisfactory structural description of the modified materials is seldom achieved. Herein, the functionalization of 2D BP starting from molecular Pd precursors is presented, leading either to supported Pd NPs (Pd/BP) or to interlayer Pd-Pd discrete units (Pd2/BP). An in-depth solid-state characterization of the new materials was carried out by means of XPS, HAADF-STEM, XRD, NMR MAS and XAS. Remarkably, XAS analysis, backed up by DFT modelling, was crucial in revealing the existence of Pd2 moieties stacked amidst BP layers in Pd2/BP. The potential application of these heterogeneous systems as catalysts was demonstrated in distinct processes, namely the selective hydrogenation of chloronitrobenzene to chloroaniline and the hydrogen evolution reaction (HER) from acidic medium.

The Intergovernmental Panel on Climate Change (IPCC) has identified in human influence the dominant cause of the observed warming since the mid-20th century, and today there is a general consensus about the correlation between the anthropogenic greenhouse gas (GHG) emissions in the atmosphere and the rise of the Earth's temperature. The development of strategies aimed at reducing the anthropogenic CO2 emissions, the main component of GHGs, has become a worldwide priority. Amongst them, negative emission technologies (NETs) are gaining increasing interest and, in particular, the chemical capture of carbon dioxide from ambient air (Direct Air Capture - DAC) could play a decisive role in keeping the global temperature rise well below 2°C above pre-industrial levels. DAC is an emerging technology with the potential to contrast the dispersed emissions coming from transport and residential heating, that cannot be captured at their sparse sources and that represent approximately half of the annual anthropogenic CO2 emissions. Moreover, the capture of CO2 from air is suitable to supply pure CO2 wherever it is needed. Because of the extremely low concentrations of CO2 in the ambient air (approximatively 410 ppm), the most studied sorbents for DAC are based on aqueous solutions of sodium or calcium hydroxide. These sorbents show a very high CO2 capture efficiency, but unfortunately the energy required for their regeneration is very high (calcium carbonate, formed during the absorption, is calcinated at 900-1000 °C to release CO2) and despite some recent improvements, the whole process is still too expansive. In recent papers, we have reported some experimental studies on the CO2 capture from gas mixtures by different aqueous and nonaqueous amine-based sorbents [1]. Herein, we have evaluated the possibility of transferring our previous studies to DAC technology: with the objective of developing new absorbents combining an efficient capture of ultra-diluted aerial CO2 with a lower energy demand for their regeneration compared to NaOH or KOH solutions, we have decided to investigate the performance of some amine-based sorbents in DAC systems and to correlate the CO2 capture efficiency to the chemical properties of the amines themselves. In the present work we have studied 18 different amines, selected in order to cover a wide range of different chemical structures: primary, secondary and tertiary amines, alkylamines and alkanolamines, amines with steric hindrance and diamines. Their aqueous solutions (1.5 mol dm-3) have been screened as sorbents for the direct air capture in 24-hour batch absorption experiments, carried out in a thermostatted absorption column, kept at 25°C. The CO2 capture efficiencies have been measured as a function of the absorption time by analyzing the treated air with a gas chromatograph. The carbonated species formed in solution upon the CO2 uptake and their relative amounts were evaluated by 13C NMR spectroscopy, a powerful non-invasive analytical technique that can provide valuable information on the absorption mechanism. In addition, for some particular amines, we have evaluated also the performances of their solution in organic diluents, namely in diethylene glycol monoethyl ether (DEGMEE) or in a 1:1 (volume scale) mixture of ethylene glycol (EG) and 1-propanol (PrOH): as we verified in previous studies [2], the higher solubility of CO2 in organic diluents than in water, and the lower heat capacity and vapor pressure of organic diluents compared to water, could enhance the CO2 absorption and reduce the heat required for the sorbent regeneration. The correlations between aerial CO2 absorption efficiencies, chemical structures and species formed for the different amine solutions are presented and discussed. Moreover, the CO2 capture efficiencies of the different amine solutions were compared with those obtained in the same operational condition with aqueous NaOH, sodium carbonate and potassium glycinate, some of the most commonly proposed sorbents in DAC processes.

Black phosphorus (BP) exhibits a significant chemical reactivity toward transition metals, which is strongly dependent on its electronic and morphological features. Using as a case study metal Co atoms deposited by physical vapor deposition on chemically exfoliated BP thin films, we document that environmentally oxidized BP edges react immediately with the formation of Co(II)–POx species, but later also the basal plane strongly reacts, already at room temperature, to form an interfacial phosphide. Atomically resolved scanning tunneling microscopy data reveal the formation of a Co2P(112) layer, upon which the further growth of metal Co nanoparticles takes place. X-ray photoemission spectroscopy data show similar interfacial reactions also for atomic W, suggesting a quite general behavior. The electrochemical and photoelectrocatalytic properties of the resulting metal–BP nanohybrids are investigated by linear sweep voltammetry and electrochemical impedance spectroscopy. The Co–BP nanohybrid shows a marked stability in acid media and a significant increase of the electrocatalytic activity for the hydrogen evolution reaction with respect to bare BP, due to the formation of a very stable phosphide phase, and even an interesting photoactivity connected to the formation of p–n junction between BP and Co2P. On the other hand, the W–BP nanohybrid exhibits a modest performance in the electrocatalytic production of hydrogen because of the formation of less active oxide phases as a consequence of environmental oxidation.

Italy was a founding member of IUPAC in 1919. Italian participation is still vivid thanks to the proactive, collaborative spirit that motivated its initial support of the establishment of IUPAC. The National Research Council, CNR, the largest research institution for public research in the country, is the official representative of Italy at IUPAC through the National Commission operating as the IUPAC National Adhering Organization. The main operational objectives of the NAO-CNR are: strengthening the Italian presence in the Union and opening new collaboration opportunities; identifying Italian experts keen to bring about collaborations in existing areas; and increasing the relationship between NAO-CNR and the Scientific Divisions of IUPAC to plan and promote initiatives, congresses, and schools at international level. In general terms, the National Commission will take part in the challenge of global sustainable development, exploiting its know-how and methods of chemical sciences to meet the demands of society and markets for sustainable solutions. NAO-CNR also aims to participate in IUPAC to advance chemistry worldwide, the overall goal of all the IUPAC NAOs.

In the rapidly emerging field of layered two-dimensional functional materials, black phosphorus, the P-counterpart of graphene, is a potential candidate for various applications, e.g., nanoscale optoelectronics, rechargeable ion batteries, electrocatalysts, thermoelectrics, solar cells, and sensors. Black phosphorus has shown superior chemical sensing performance; in particular, it is selective for the detection of NO2, an environmental toxic gas, for which black phosphorus has highlighted high sensitivity at a ppb level. In this work, by applying a multiscale characterization approach, we demonstrated a stability and functionality improvement of nickel-decorated black phosphorus films for gas sensing prepared by a simple, reproducible, and affordable deposition technique. Furthermore, we studied the electrical behavior of these films once implemented as functional layers in gas sensors by exposing them to different gaseous compounds and under different relative humidity conditions. Finally, the influence on sensing performance of nickel nanoparticle dimensions and concentration correlated to the decoration technique and film thickness was investigated.

The chemical functionalization of 2D exfoliated black phosphorus (2D BP) continues to attract great interest, although a satisfactory structural characterization of the functionalized material has seldom been achieved. Herein, we provide the first complete structural characterization of 2D BP functionalized with rare discrete Pd2 units, obtained through a mild decomposition of the organometallic dimeric precursor [Pd(?3-C3H5)Cl]2. A multitechnique approach, including HAADF-STEM, solid-state NMR, XPS, and XAS, was used to study in detail the morphology of the palladated nanosheets (Pd2/BP) and to unravel the coordination of Pd2 units to phosphorus atoms of 2D BP. In particular, XAS, backed up by DFT modeling, revealed the existence of unprecedented interlayer Pd-Pd units, sandwiched between stacked BP layers. The preliminary application of Pd2/BP as a catalyst for the hydrogen evolution reaction (HER) in acidic medium highlighted an activity increase due to the presence of Pd2 units.

Functionalization is one of the most powerful tools in materials science for the development of new and innovative materials with tailored properties purposefully designed to enhance the overall stability of the system. This is particularly true for exfoliated black phosphorus, which suffers from easy decomposition by air and moisture, hampering its highly desirable applications, especially in electronics. The present work suggests an innovative approach to the functionalization process of this 2D-material based on the selective introduction of chalcogen atoms on the material surface through a reaction with suitable molecular precursors such as stibine chalcogenides (R3Sb(X), X = O or S; R = organyl group). These molecules may readily act as chalcogen-transfer agents and, upon releasing the chalcogen atom atop the bP surface, leave stable stibines (R3Sb) as byproducts, which may be easily removed from the functionalized bP surface. The work provides an overview of all the possible structural, electronic and energy aspects associated with the chalcogen-atom transfer from the stibine to phosphorus based compounds, exemplified by trialkyl phosphines and single layer exfoliated black phosphorus, i.e. phosphorene, Pn. In both cases the oxygen transfer is more exergonic than the sulfur transfer, with the associated free energy barrier for the phosphine process being higher. Although the sulfur transfer for the Pn is found to be endergonic (ca. +3.6 kcal mol-1), the process may surely occur at high temperature. The evolution of the band structure upon the chalcogen transfer has been depicted in detail.

Achieving good quality Ohmic contacts to van der Waals materials is a challenge, since at the interface between metal and van der Waals material different conditions can occur, ranging from the presence of a large energy barrier between the two materials to the metallization of the layered material below the contacts. In black phosphorus (bP), a further challenge is its high reactivity to oxygen and moisture, since the presence of uncontrolled oxidation can substantially change the behavior of the contacts. Here we study three of the most commonly used metals as contacts to bP, chromium, titanium, and nickel, and investigate their influence on contact resistance against the variability between different flakes and different samples. We investigate the gate dependence of the current-voltage characteristics of field-effect transistors fabricated with these metals on bP, observing good linearity in the accumulation regime for all metals investigated. Using the transfer length method, from an analysis of ten devices, both at room temperature and at low temperature, Ni results to provide the lowest contact resistance to bP and minimum scattering between different devices. Moreover, we observe that our best devices approach the quantum limit for contact resistance both for Ni and for Ti contacts.

Since its discovery, the environmental instability of exfoliated black phosphorus (2D bP) has emerged as a challenge that hampers its wide application in chemistry, physics, and materials science. Many studies have been carried out to overcome this drawback. Here we show a relevant enhancement of ambient stability in few-layer bP decorated with nickel nanoparticles as compared to pristine bP. In detail, the behavior of the Ni-functionalized material exposed to ambient conditions in the dark is accurately studied by Transmission Electron Microscopy (TEM), Raman Spectroscopy, and high resolution X-ray Photoemission and Absorption Spectroscopy. These techniques provide a morphological and quantitative insight of the oxidation process taking place at the surface of the bP flakes. In the presence of Ni nanoparticles (NPs), the decay time of 2D bP to phosphorus oxides is more than three time slower compared to pristine bP, demonstrating an improved structural stability within twenty months of observation.

International audience; Black phosphorus (bP) is a crystalline material which can be seen as an ordered stacking of two-dimensional layers, referred to as Phosphorene. The knowledge of the linear thermal expansion coefficients (LTEC) of bP is of great interest in the field of 2D materials for a better understanding of the anistropic thermal properties and exfoliation mechanism of this material. Despite several theoretical and experimental studies important uncertainties remain in the determination of the LTEC of bP. Here, we report accurate thermal expansion measurements along the three crystallographic axes using in-situ high temperature x-ray diffraction. From the progressive reduction of the diffracted intensities with temperature we monitored the loss of the crystal structure of bP across the investigated temperature range, evidencing two thermal expansion regimes at temperature below and above 706 K. Below 706 K, we observe a strong out-of-plane anisotropy, while at temperatures above 706 K a larger thermal expansion occurs along the a crystallographic direction. From our data and by taking advantage of ab-initio optimization, we propose a detailed anisotropic thermal expansion mechanism of bP, which leads to an inter- and intra-layer destabilization. An interpretation of it, based on the high T perturbation of the stabilizing sp orbital mixing effect, is provided, consistently with high pressure data.

The self-aggregation of neutral [RuCl2(eta6-p-cymene)(CAP)] (2; p-cymene = 1-methyl-4-(propan-2-yl)benzene) and ionic [RuCl(eta6-p-cymene)(L)(CAP)](PF6) (3, L = CAP; 4, L = MeCN) and [RuCl2(eta6-p-cymene)(CAP-H)](BPh4) (5; CAP-H = monoprotonated CAP) ruthenium(II) arene complexes, bearing the water-soluble phosphine CAP (1,4,7-triaza-9-phosphatricyclo[5.3.2.1]tridecane), in aprotic polar solvents, was investigated by means of PGSE (pulsed field gradient spin-echo) diffusion NMR. In addition, the analogous neutral [RuCl2(eta6-p-cymene)(PTA)] (1) and monoprotonated [RuCl2(eta6-p-cymene)(PTA-H)](BPh4) (6) PTA (1,3,5-triaza-7-phosphaadamantane) complexes were investigated in acetonitrile-d3. Complexes 1-4 do not exhibit any tendency to self-aggregate in acetonitrile-d3 and acetone-d6. In contrast, 5 and 6 monoprotonated complexes undergo a peculiar self-aggregation process, involving almost exclusively the cation, leading to the main formation of dicationic species held together by intermolecular hydrogen bonds. This has been clearly demonstrated by 1H diffusion NMR experiments, which allowed measurement of an average hydrodynamic volume for the cation that was more than double that expected, whereas that of the counterion is only slightly higher than that of the free anion. The trend of the aggregation number (N+) as a function of the concentration of 5 and 6 was fitted using the equation of the equal K indefinite model of association, leading to DeltaG°298 K = -3.1 and -3.0 kcal mol-1, respectively, for the formation of H-bonded dications. The critical role played by the protonated -NH unit in establishing hydrogen bonding was further supported by the detection of 6+2 dinuclear species in acetonitrile-d3 solutions containing equimolar mixtures of 2 and 6. The self-aggregation free energy of 2 (DeltaG°298 K = -3.1 kcal mol-1) and 6+ (DeltaG°298 K = -2.9 kcal mol-1) in such mixed solutions is practically identical with those of 5 and 6 in acetonitrile-d3.

We study the electrical characterization at room temperature (RT) of black phosphorus nanoflakes decorated with nickel nanoparticles (Ni/bP). The latter has been exposed to different concentrations of NO2 at RT in a dry air environment highlighting fast and stable response over the time. This latter characteristic is particularly relevant since environmental instability of exfoliated BP has been an issue so far, under ambient conditions few-layer BP degrades completely in less than a week, preventing its applications in several fields. Introduction In the rapidly emerging field of layered two-dimensional (2D) functional materials, bP, the all P-counterpart of graphene, is a potential candidate for various applications e.g., nanoscale optoelectronics, rechargeable ion batteries, electrocatalysts, thermoelectrics, solar cells, and sensors [1]. bP has been reported to exhibit superior chemical sensing performance. In particular, bP is selective for the detection of paramagnetic molecules, e.g., NO2, in addition to high sensitivity at a limit of detection (LOD) of ppb levels.[2] In this work, by applying a multiscale characterization approach we demonstrated a stability and functionality improvement of Nickel-decorated bP (Ni/bP) films for gas sensing prepared by a simple, reproducible and affordable deposition technique. Furthermore, we studied possible electrical activity of these films for their employment as functional layers in gas sensors by exposing them to different gaseous compounds (NO2, CO2, H2, NH3, CO, Benzene, etha-nol, ethylene, Formaldehyde) in different relative humidity (RH%) conditions. Moreover, the influence in sensing perfor-mance of nickel nanoparticle (NP) dimensions in related to the decoration technique and the film thickness were investigated. Materials and Methods Black phosphorus microcrystals were suspended in dimethylsulfoxide and kept under ultrasonication for several hours. The exfoliated bP nanosheets were decorated with nickel nanoparticles following two different procedures: 1) preformed Ni NPs were immobilized on bP, 2) Ni NPs were grown directly on bP flakes. Electrical conductance measurements have been performed on Ni/bP flakes deposited via spin coating on Al2O3 substrates with built-in interdigitated gold electrodes, in order to better control the film thickness. Electrical conductance measurements have been performed at RT (25±2°C) by exposing the sensing film to certified mixtures of NO2 diluted in dry air (20% O2 and 80% N2) with different NO2 concentration ranging from 200 ppb to 1 ppm. Results and Conclusions Exfoliated black phosphorus nanoflakes decorated with nickel nanoparticles (Ni/bP) have been prepared and characterized with particular attention to the role of Ni nanoparticle dimension in the sensing mechanism. Electrical activity towards different concentrations of NO2 at room temperature in a dry air environment highlighted fast and stable response over the time. This latter characteristic is particularly relevant since environmental instability of exfoliated BP has been an issue so far, under ambient conditions few-layer bP degrades completely in less than a week, preventing its applications in several fields. In situ grown Ni/bP (2) shows stable response during all the four weeks measurements period with no dependence of the response on the film thickness. Ni decoration effectively suppress ambient degradation, for at least 1 week in Ni/bP (1) and over 4 weeks in Ni/bP (2) in ambient conditions. This result highlighted that Ni/bP (2) sensor can be practically used under ambient conditions for a reasonable period without performance degradation of the devices.The obtained results pave the way for the use of chemically exfoliated bP flakes for gas sensing applications, avoiding the use of a time-consuming technique for the exfoliation and for the fabrication of the metallic contacts, like electron beam lithography, focused ion beam lithography, etc. References [1] Batmunkh, M.; Bat-Erdene, M.; Shapter, J. G. Phosphorene and Phosphorene-Based Materials - Prospects for Future Applications. Adv. Mater. 2016, 28, 8586– 8617. [2] Donarelli, M.; Ottaviano, L.; Giancaterini, L.; Fioravanti, G.; Perrozzi, F.; Cantalini, C. Exfoliated black phosphorus gas sensing properties at room temperature. 2D Mater. 2016, 3, 025002 Figure 1: (a) Electrical characterization at room temperature of bP, Ni/bP (1) and Ni/bP (2) devices in dry conditions with five different concentration of NO2. (b) Calibration curve of Ni/bP based sensors in dry condition. Figure 1

Among the novel class of mono-elemental two-dimensional (2D) materials, termed Xenes, phosphorene is emerging as a great promise for its peculiar chemical and physical properties. This review collects a selection of the recent breakthroughs that are related to the application of phosphorene in catalysis and electrocatalysis. Noteworthy, thanks to its intrinsic Lewis basic character, pristine phosphorene turned out to be more efficient and more selective than other non-metal catalysts, in chemical processes as the electroreduction of nitrogen to ammonia or the alkylation of nucleophiles with esters. Once functionalized with transition metals nanoparticles (Co, Ni, Pd, Pt, Ag, Au), its catalytic activity has been evaluated in several processes, mainly hydrogen and oxygen evolution reactions. Under visible light irradiation, it has shown a great improvement of the activity, demonstrating high potential as a photocatalyst.