The use of solar energy to produce valuable feedstocks and energy vectors, such as hydrogen, is a fascinating research field of utmost practical importance. Herein, we report a facile strategy to functionalize 2D black phosphorus nanosheets (BPNS) with mixed cobalt phosphide clusters of different stoichiometry, Co2P and CoP, with sub-nanometric sizes. The in-depth study at the atomic level by X-ray absorption spectroscopy and electron microscopy confirmed the nature and structure of the phosphides and revealed that Co2P/CoP functionalization effectively hindered the spontaneous degradation of BP under ambient conditions. Under simulated solar-light irradiation, the hydrogen evolution rate of BP@CoxP integrated with TiO2 reached 5.3 mmol g-1 h-1, almost 30-fold higher than that of TiO2. Electrochemical and photoluminescence investigations elucidated the electronic properties of the photocatalyst, showing that the mixed CoxP phases led to increased charge density across the heterostructure, a lower conduction band energy, which infers more reducing power, and the generation of multiple interfaces, which increase charge transfer and reduce electron-hole recombination.

We designed a high-performance photocatalyst by a selective in situ growth of Cu2O nanoparticles (NP) on the surface of black phosphorus (BP) nanosheets. Our ad-hoc procedure for generating Cu2O-BP nanohybrids, counting on a careful choice of the reducing agents and the reaction conditions, ensured the unaltered integrity of BP nanosheets and prevented the over-oxidation to Cu(II) or the reduction to Cu(0). Additionally, an improved ambient stability of BP was ascertained once embedded in the Cu2O-BP nanohybrid. By integrating the latter with TiO2 NPs, a new ternary photocatalyst was obtained, outperforming pristine TiO2 in the photocatalytic hydrogen production rate more than one hundred times. Next to the characterization of the materials, an indepth study of the newly created interfaces, Cu2O-BP and TiO2-Cu2O-BP, was carried out at the multiscale atomistic level by joining quantum chemistry and classical reactive molecular dynamics simulations, allowing an explicit evaluation of the electronic band alignment and the investigation of Cu2O NPs formation and interfacial H2 evolution.

Electron distribution and bonding in square planar gold complexes, traditionally classified as gold(III), have been investigated through DFT calculations. Molecular orbital (MO) and band structure analyses, used as diagnostic tools, indicate that the metal center, upon coordination with halide, retains d fully occupied orbitals, with a two-electron vacancy localized on ligand-based orbital combinations, consistent with the inverted ligand field (ILF) theory. The only exception is found in tetrafluoroaurate complex containing four fluoride ligands in the coordination sphere, for which a covalent bonding model appears to be more appropriate. Linear correlations were observed between halide electronegativity and the percentage contribution of gold to the LUMO or the bottom of the conduction band in the solidstate calculations. This trend is also reflected in mixed square planar halide-gold complexes. Electronegatvity of the ligands can be used as a predicting tool not only of the metal contribution to the LUMO but also to classify Au-L bonding nature. The results provide a valuable basis for a critical and constructive reassessment of the bonding and electronic description of square planar gold halide compounds with meaningful consequences in the representation of both spectroscopic and reactivity features in gold chemistry

ConspectusNitrides represent a class of chemical compounds of high scientific and technological relevance. Nevertheless, due to the challenging synthetic conditions, essentially related to the stability of the N2 molecule, nitrides have remained largely unexplored compared with the corresponding oxides.The laser-heated diamond anvil cell (LH-DAC), providing access to the GPa pressure range and temperatures as high as several thousands of K, has dramatically changed the rules of the game, unveiling thermodynamic conditions in which N2 becomes unstable and polymerizes into extended crystalline phases. A variety of N-compounds have been indeed synthesized by laser-heating the corresponding elements in a N2 environment under high-pressure (HP) conditions.Nevertheless, only recently group 15 elements heavier than N have been targeted by this method, and excluding α-P3N5 and γ-P3N5, crystalline pnictogen nitrides have remained essentially unknown.Since the discovery of phosphorene, while the quest for 2D materials has raised the interest for group 15 xenes and their N-doping as a key development, the inherent tendency of pnictogens to adopt crystalline layered structures persisting at high pressure has increased focus on binary N-compounds with heavier pnictogens, with implications for fundamental chemistry and potential applications.In this scenario, the discovery of the pseudo simple-cubic (p-sc) structure in the phase diagram of P, and, a few years later, the high-pressure-high-temperature (HP-HT) synthesis of PH3 from the elements and the discovery of the crystalline van der Waals (vdW) compound (PH3)2H2 have further reconnected the HP behavior of P to that of lighter N.These experimental studies, highlighting consistency in the structural and reactive properties of group 15 elements at high pressure, together with additional theoretical and computational insights, have opened new perspectives and motivated further investigations about the existence of crystalline pnictogen nitrides.Indeed, not only α- and γ-P3N5, but also three other crystalline polymorphs of phosphorus nitride (δ-P3N5, PN2, and α'-P3N5), have been synthesized by the direct HP-HT chemical reaction of P and N2 in a LH-DAC.Moving down in group 15, the same method has led to the discovery of the first crystalline nitrides of arsenic (AsN) and antimony (Sb3N5), whose existence has always represented an open question in inorganic chemistry, and to the structural characterization of two crystalline polymorphs of bismuth nitride (BiN).This Account provides an overview of the recent progress in the high-pressure and high-temperature synthesis of crystalline pnictogen nitrides, demonstrating the effective activation of a direct chemistry between N and heavier pnictogens. The presented results mark fundamental advancements in the chemistry of group 15 elements and pioneer the discovery of new advanced pnictogen-based materials of energetic and technological relevance, potentially recoverable under ambient conditions as stable or metastable systems.

The reversible decomposition of ammonium carbamate (AC) shows significant potential for application in chemical heat pumps. While AC is typically dissolved in a solvent and used in solution form, the impact of dissolution on its reaction reversibility remains insufficiently understood. To address this, the effects of commonly used solvents, namely ethylene glycol (EG), propylene glycol (PG), and monoethanolamine (MEA), on the decomposition reaction of AC were investigated using 13C NMR spectroscopy. A quantitative method was developed to better interpret the spectra of AC solutions. The results reveal that AC reacts with the glycol solvents EG and PG during dissolution generating the corresponding alkyl carbonates. These latter species can decompose synchronously with the dissolved AC, indicating minimal impact on the reaction reversibility. In contrast, the generated MEA-carbamate requires temperature above 120 degrees C for decomposition. Corrosivity experiments demonstrated that AC is non-corrosive towards stainless steel 316 and aluminum, but exhibits high corrosivity toward copper.

Cancer, a significant threat to human lives, has been the target of research for several decades. Although conventional therapies have drawbacks, such as side effects, low efficacy, and weak targeting, they have been applied extensively due to a lack of effective alternatives. The emergence of nanotechnology in medicine has opened up new possibilities and offered promising solutions for cancer therapy. In recent years, 2D nanomaterials have attracted enormous attention in nanomedicine due to their large surface-to-volume ratio, photo-responsivity, excellent electrical conductivity, etc. Among them, black phosphorus (BP) is a 2D nanomaterial consisting of multiple layers weakly bonded together through van der Waals forces. Its distinct structure makes BP suitable for biomedical applications, such as drug/gene carriers, PTT/PDT, and imaging agents. BP has demonstrated remarkable potential since its introduction in cancer therapy in 2015, particularly due to its selective anticancer activity even without the aid of near-infrared (NIR) or anticancer drugs. The present review makes efforts to cover and discuss studies published on the anticancer activity of BP. Based on the type of cancer, the subcategories are organized to shed light on the potential of BP nanosheets and BP quantum dots (BPQDs) against breast, brain, skin, prostate, and bone cancers, and a section is devoted to other cancer types. Since extensive attention has been paid to breast cancer cells and in vivo models, various subsections, including mono-, dual, and triple therapeutic approaches are established for this cancer type. Furthermore, the review outlines various synthesis approaches employed to produce BP nanomaterials, providing insights into key synthesis parameters. This review provides an up-to-date platform for the potential reader to understand what has been done about BP cancer therapy based on each disease, and the conclusions and outlook cover the directions in which this approach is going to proceed in the future.

Black phosphorus (bP) is a crystalline material that can be seen as ordered stackings of two-dimensional layers, which lead to outstanding anisotropic physical properties. The knowledge of its pressure-temperature (P-T) phase diagram, and in particular, the slope and location of its melting curve is fundamental for better understanding the synthesis and stability conditions of this important material. Despite several experimental studies, important uncertainties remain in the determination of this melting curve. Here we report accurate melting points measurements, using in situ high-temperature and high-pressure high-resolution synchrotron x-ray diffraction. In particular, we have employed an original and accurate pressure and temperature metrology based on the unique anisotropic P-T response of bP, that we used as sensor for the simultaneous determination of pressure and temperature up to 5 GPa and 1700 K. We confirmed the existence of and located a solid-liquid-liquid triple point at the intersection of the low- and high-pressure melting curves. Finally, we have characterized the irreversibility of the transformation in the low-pressure regime below 1 GPa, as the low-density liquid does not crystallize back to bP but into red phosphorus on temperature quenching.

Among 2D materials, exfoliated black phosphorus (or phosphorene) shows great promise for applications in biological domains. However, despite its performances, little is known about the intricate and dynamic interactions that this material can form with proteins. This increases the risk of off-target effects and adds complexity in designing phosphorene-based devices with tailored properties. In this study, we present a straightforward and easily implementable pipeline that integrates spectroscopies with Molecular Dynamics simulations to explore the dynamic interplay between phosphorene and a protein system. Using lysozyme as a deeply investigated reference protein, we employed two theoretical protein models with unique secondary structure folds to increase the descriptive power of the approach and disentangle the complexity and variability of experimental data into a few primary drivers of protein-phosphorene interactions. Our results show that the 2D material does not significantly alter the protein structure, but the observed conformational changes are influenced by the secondary fold. Indeed, while the beta structure interacts mainly through unfolded regions, the alpha fold favours phosphorene binding through structured clusters of residues, leading to more significant structural and dynamic perturbations. By utilizing this pipeline, we have gained valuable insights into the molecular recognition mechanism of phosphorene, enhancing the development of improved phosphorenebased devices. In addition, our methodology offers potential for further applications in biomedicine to characterise interfaces between other 2D (nano)materials and biological entities.

With a production exceeding 200 million tons per year, urea and its derivatives currently represent the most important class of commercial derivatives originating from the CO 2 utilization, but their synthesis is still mainly based on high energy demanding processes which, in addition, use often chemicals threatening both human health and environment. Recently, the development of innovative catalytic processes for the conversion of CO 2 , recovered from industrial emissions, into urea and derivatives, is receiving increasing attention; the use of simple metal salts or their complexes has made it possible to obtain some of these valuable products under mild operating conditions. Moreover, by using safer chemicals and harmless procedures, it allows the definition of new synthetic routes that are more sustainable from both energy and environmental perspectives.

A chemical reaction between Sb and N 2 was induced under high-pressure (32–35 GPa) and high-temperature (1600–2200 K) conditions, generated by a laser heated diamond anvil cell. The reaction product was identified by single crystal synchrotron X-ray diffraction at 35 GPa and room temperature as crystalline antimony nitride with Sb 3 N 5 stoichiometry and structure belonging to orthorhombic space group Cmc 2 1 . Only Sb−N bonds are present in the covalent bonding framework, with two types of Sb atoms respectively forming SbN 6 distorted octahedra and trigonal prisms and three types of N atoms forming NSb 4 distorted tetrahedra and NSb 3 trigonal pyramids. Taking into account two longer Sb−N distances, the SbN 6 trigonal prisms can be depicted as SbN 8 square antiprisms and the NSb 3 trigonal pyramids as NSb 4 distorted tetrahedra. The Sb 3 N 5 structure can be described as an ordered stacking in the bc plane of bi- layers of SbN 6 octahedra alternated to monolayers of SbN 6 trigonal prisms (SbN 8 square antiprisms). The discovery of Sb 3 N 5 finally represents the long sought-after experimental evidence for Sb to form a crystalline nitride, providing new insights about fundamental aspects of pnictogens chemistry and opening new perspectives for the high-pressure chemistry of pnictogen nitrides and the synthesis of an entire class of new materials.

The thermochemical reaction of ammonium carbamate (AC) holds significant potential for low-grade heat utilization. However, the insufficient understanding of reaction kinetics limits its further applications. Therefore, a detailed study on the kinetic mechanism of AC decomposition was conducted using both the model-free and model-fitting thermal analysis methods with kinetic data from multiple heating program experiments. The results obtained from various methods are consistent, supporting the concept that AC decomposition is a single-step controlled multi-step reaction. The activation energy E, preexponential factor A, and most probable reaction model were determined to be 56.38 kJ center dot mol(-1), 2.75 x 10(6) s(-1), f(alpha)=(1-alpha)(0.7811), respectively. The reaction mechanism can be hypothesized as involving the rapid generation of numerous nucleation sites on the surface of solid AC, where surface reactions occur, with the movement of reaction interface governing the reaction rate. Consequently, a kinetic equation accounting for the AC decomposition was developed and evaluated, and the heat absorption specific power under different temperature conditions was predicted.

The covalent bonding framework of crystalline single-bonded cubic AsN, recently synthesized under high pressure and high temperature conditions in a laser-heated diamond anvil cell, is here studied by means of density functional theory calculations and compared to single crystal X-ray diffraction data. The precise localization of the nonbonding electron lone pairs and the determination of their distances and orientations are related to the presence of characteristic structural motifs and space regions of the unit cell dominated by repulsive electronic interactions, with the relative orientation of the electron lone pairs playing a key role in minimizing the energy of the structure. We find that the vibrational modes associated with the expression of the lone pairs are strongly localized, an observation that may have implications for the thermal conductivity of the compound. The results indicate the thermodynamic stability of the experimentally observed structure of AsN above ∼17 GPa, provide a detailed insight into the nature of the chemical bonding network underlying the formation of this compound, and open new perspectives to the design and high pressure synthesis of new pnictogen-based advanced materials for potential applications of energetic and technological relevance.

Global Conversation on Sustainability (GCS) 2023 was enthusiastically welcomed by researchers of the National Research Council of Italy (CNR). Highly committed to international organizations such as IUPAC and ISC, the promoters participated to the 2023 edition of the Global Conversation on Sustainability hosting a local in person event held in one of the major CNR institute for chemistry research. The format was a round-table discussion involving colleagues of different age, gender, experience, and area of expertise, who participated to an informal dialogue with the aim of reflecting and sharing aspects of the respective research activities contributing to sustainable development goals. From many chemistry research areas, it emerged a wide range of subjects, which stimulated an interesting and purpose-oriented discussion. Therefore, GCS 2023 at CNR prompted a reflection on how improving chemists' impact on sustainability including laboratories' practises and on considering communication becoming part of scientific process. Transformation requires continuous investment in research and innovation and evolving scientific activities, but also requires synergies, collaborations and policy making on cross-cutting issues that can make this successful. Global initiatives as GCS, in the framework of international scientific organizations, represent a key global vehicle for enhancing the big area of science communication. Overcoming time and spatial limitations, these initiatives enable to link global and locally tailored in person events.

Direct Air Capture (DAC) of carbon dioxide from ambient air is recognized as a pivotal technology for reducing atmospheric CO2 levels and limiting global temperature rise to less than 2°C above pre-industrial levels. In pursuit of developing novel sorbents that can efficiently capture ultra-diluted CO2 from the air while minimizing regeneration energy requirements, we present a comprehensive screening study evaluating the performance of various aqueous amine-based solutions in DAC systems. This study aims to correlate CO2 capture efficiency with the physical and chemical properties of the amines. A range of amine types were investigated, including primary, secondary and tertiary amines, alkylamines, alkanolamines, sterically hindered amines, and diamines. These amines were assessed both individually and in binary or ternary blends to combine the optimal properties of each species. Additionally, selected amines were studied in non-aqueous solutions, where the higher solubility of CO2 in organic diluents, coupled with their lower heat capacity and vapor pressure compared to water, offers the potential for enhanced CO2 absorption efficiency and reduced regeneration energy requirements. The CO2 capture efficiencies of the formulated amine sorbents were measured over time in batch experiments at 25°C using a custom-built DAC system. These results were compared to those obtained under identical conditions with aqueous NaOH, sodium carbonate, and potassium glycinate, which are among the most commonly proposed sorbents for DAC processes. The carbonated species formed during the capture process were identified and quantified using 13C NMR spectroscopy, offering key insights into the capture mechanisms across different liquid sorbents. This screening study provides valuable correlations between CO2 absorption efficiency, amine chemical structure, and the species formed during the process, offering guidelines for the formulation of optimized sorbents for DAC applications.

The utilization of water-lean and non-aqueous amine sorbents is regarded as an appealing approach to reduce the energy costs of CO2 capture via liquid sorbents. However, significant research is still needed to achieve the technological maturity required for industrial-scale implementation. Here, we present a detailed experimental and computational analysis at the molecular level of CO2 capture by dipropylamine (DPA) as a case study to deepen our understanding of the mechanisms governing CO2 absorption by liquid secondary amines that can be used without any additional diluent. CO2 uptake with pure DPA was investigated, and the species produced over time were determined by NMR and FT-IR spectroscopy. In particular, the NMR analysis revealed the formation of carbamic acid at high CO2/DPA ratios. A detailed DFT investigation explained the mechanism of the reaction revealing a dynamic evolution in product distribution as CO2 loading increases. At low CO2 loadings, adducts with at least four DPA molecules are formed, ultimately leading to the carbamate/ammonium ionic pair stabilized through H-bonding interactions with DPA moieties. Conversely, at higher CO2 levels some stabilizing DPA molecules of ionic pair are required for the CO2 activation, resulting in the formation of carbamic acid. A reasonable mechanism for the evolution of product distribution is provided, and the main steps of the mechanistic picture are depicted and commented on. The dependence of carbamate and carbamic acid on the availability of hydrogen bond donors and acceptors in solution is also highlighted.

Hexagonal boron nitride (hBN) and black phosphorus (bP) are crystalline materials that can be seen as ordered stackings of two-dimensional layers, which lead to outstanding anisotropic physical properties. The knowledge of the thermal equations of state of hBN and bP is of great interest in the field of 2D materials for a better understanding of the anisotropic thermo-mechanical properties and exfoliation mechanism of these materials. Despite several theoretical and experimental studies, important uncertainties remain in the determination of the thermoelastic parameters of hBN and bP. Here, we report accurate thermal expansion and compressibility measurements along the individual crystallographic axes, using in situ high-temperature and high-pressure high-resolution synchrotron X-ray diffraction. In particular, we have quantitatively determined the subtle variations of the in-plane thermo-mechanical parameters by subjecting these materials to hydrostatic pressure conditions and collecting a large number of data points in small pressure and temperature increments. Based on the anisotropic behavior of bP, we propose the use of this material as sensor for the simultaneous determination of pressure and temperature in the range 0-5 GPa, 298-1700 K.

Chemical heat pump based on ammonium carbamate (AC) is a promising low-grade heat utilization technology. It is essential to know the chemical equilibrium properties in the application of AC-based technologies. AC is usually mixed with solvents to realize circulation. However, the existing studies mainly focus on AC in the solid phase. Therefore, the influence of solvents on the chemical equilibrium of AC was experimentally investigated in this work. The results confirm the solvent effect on the equilibrium pressure of AC in the range of 10 similar to 90 degrees C. For solvents capable of dissolving AC, the equilibrium pressure increases with both AC concentration and temperature. The solvent effect is mainly due to the influence on both the reaction enthalpy and entropy change terms. An equilibrium pressure-temperature-concentration relationship of AC solution is established. These results provide essential parameters for the design and operation of low-grade heat management and utilization systems based on AC.

Chemical absorption of CO2 from flue gases by using aqueous amine sorbents is regarded as the most mature and effective technology for reducing CO2 emissions, but the high energy cost of sorbent regeneration has so far greatly limited its industrial application. One of the best strategies developed by researchers in recent years to reduce energy requirements is to improve CO2 desorption kinetics by adding catalysts during sorbent regeneration. Moreover, non-aqueous sorbents have recently been gaining increasing attention as alternatives to conventional aqueous amines as they have the potential to lower the energy demand for sorbent regeneration. In this paper, we propose an innovative technique that combines and further develops these two emerging technologies, nonaqueous absorbent and catalyst-assisted regeneration, to enable less energy-intensive CO2 capture processes. In particular, in this screening study, we evaluate the regeneration behaviour of a CO2 -saturated solution of 2-(2-aminoethoxy)ethanol (DGA) in diethylene glycol monomethyl ether (DEGMME) when heated to 85 degrees C in the absence and presence of different types of solid acid catalysts. In order to assess the potential benefits of this innovative technique over conventional systems, the results obtained were compared with the desorption performance of an aqueous solution of DGA under the same operating conditions and with the same catalysts, which highlighted the possibility of obtaining rapid desorption at relatively low temperatures when conducted with suitable acid catalysts using amines in organic diluents.

Layered black phosphorus (BP) is endowed with peculiar chemico-physical properties that make it a highly promising candidate in the field of electronics. Nevertheless, as other 2D materials with atomic scale thickness, it suffers from easy degradation under ambient conditions. Herein, it is shown that the functionalization of BP with preformed and in situ grown Ni NPs, affects the electronic properties of the material. In particular, Ni functionalization performed in situ leads to a narrowing of the average BP band gap from 1.15 to 0.95 eV and to a marked shift in the conduction band maximum from -0.33 V to -0.07 V, which, in turn, improve the ambient stability. Structural studies carried out by XAS can well distinguish the two nanohybrids and reveal that once Ni NPs are grown on BP nanosheets, a Ni-P coordinative bond is formed, featuring a short Ni-P distance of 2.27 Å, which is not observed when preformed Ni NPs are immobilized on BP. Comparing the XANES and EXAFS spectra of fresh and aged samples of both nanohybrids, suggests that the interaction between Ni and P atoms results in a stabilization effect exerted via a dual electronic and redox mechanism, that infers a much superior ambient stability to BP, even if the surface functionalization is far to achieve a full coverage.

The extraordinary invention of the "voltaic" battery, published by the great and creative Italian scientist Alessandro Volta in 1800, opened the way to electrochemistry, a lively branch of chemistry that is extremely relevant today to face the challenges of sustainability.The intense and multifaceted history of electrochemistry, from its origin to the most promising developments, have been the focus of an open educational event held in Como, the birthplace of Alessandro Volta, on