Interlayer bond formation in black phosphorus at high pressure

Black phosphorus was compressed at room temperature across the A17, A7 and simple-cubic phases up to 30 GPa, using a diamond anvil cell and He as pressure transmitting medium. Synchrotron X-ray diffraction showed the persistence of two previously unreported peaks related to the A7 structure in the pressure range of the simple-cubic phase. The Rietveld refinement of the data demonstrates the occurrence of a two-step mechanism for the A7 to simple-cubic phase transition, indicating the existence of an intermediate pseudo simple-cubic structure. From a chemical point of view this study represents a deep insight on the mechanism of interlayer bond formation during the transformation from the layered A7 to the non-layered simple-cubic phase of phosphorus, opening new perspectives for the design, synthesis and stabilization of phosphorene-based systems. As superconductivity is concerned, a new experimental evidence to explain the anomalous pressure behavior of Tc in phosphorus below 30 GPa is provided

Lattice expansion of graphite oxide by pressure induced insertion of liquid ammonia

© 2015 Elsevier Ltd. All rights reserved. A pressure induced lattice expansion of Graphite Oxide (GO) in presence of NH3 was observed by X-ray diffraction during room temperature compression and decompression up to 7 GPa in a diamond anvil cell (DAC). A remarkable increase (∼11%) of the interlayer d-spacing of GO was observed between 0.2 and 1.1 GPa in the liquid phase of NH3, indicating the occurrence of molecular insertion between the GO layers. The expansion is reversible with the release of pressure, thus leading to a pressure induced breathing of the GO lattice. The presence of high density NH3 between the GO layers opens new perspectives for N-doping and chemical functionalization of GO and for designing new advanced carbon based nanostructured materials

High-Pressure Chemistry of Graphene Oxide in the Presence of Ar, N<inf>2</inf>, and NH<inf>3</inf>

© 2016 American Chemical Society.The high pressure structural and reactive beahvior of graphene oxide (GO) in the presence of Ar, N2, and NH3 was studied in diamond anvil cells (DAC) by X-ray diffraction (XRD) and vibrational spectroscopy (FTIR and Raman), with the purpose of investigating the use of pressure for N-doping and functionalization of GO in high-density conditions. The pressure evolution of the interlayer d-spacing of GO during room temperature compression and decompression indicates the pressure-induced insertion of the selected systems between the GO layers and the stability of the GO layered structure at high pressure. Thermal and photoinduced reactivity was studied in GO with N2 and in GO with NH3 in different pressure conditions. The comparison of the infrared spectra of the recovered samples at ambient conditions with respect to the starting GO provides evidence for the occurrence of chemical reactivity of N2 and NH3 with GO, leading to N incorporation and GO functionalization, as also confirmed by the Raman spectra. The observed reactivity opens new perspectives for the high-pressure chemistry of GO and carbon-based nanostructured systems

Chemical functionalization of N-doped carbon nanotubes: A powerful approach to cast light on the electrochemical role of specific N-functionalities in the oxygen reduction reaction

© 2016 The Royal Society of Chemistry.In this paper, we describe the combination of two different synthetic approaches to carbon nanotube N-decoration/doping: the chemical functionalization with tailored N-pyridinic groups and the classical Chemical Vapor Deposition (CVD) technique. Accordingly, CVD-prepared N-doped CNMs (NMWs) and their N-decorated (chemically functionalized) counterparts (NMW@N1,2) have been prepared and used as metal-free electrocatalysts for the oxygen reduction reaction (ORR). It has been demonstrated that chemical functionalization occurs on the NMW surface sites responsible for their inherent electrochemical properties and "switches them off". As a result, the ORR promoted by NMW@N1,2 is fully controlled by the appended N-heterocycles. A comparative analysis of N-functionalized samples and N-doped (CVD prepared) materials is used to foster the hypothesis of a unique N-configuration (N-pyridinic) responsible for the overall electrochemical performance in NMWs. In addition to that, original electrochemical insights unveiled during the study are discussed and the truly metal-free action of NMW in ORR catalysis is demonstrated

The self-organizing fractal theory as a universal discovery method: the phenomenon of life

A universal discovery method potentially applicable to all disciplines studying organizational phenomena has been developed. This method takes advantage of a new form of global symmetry, namely, scale-invariance of self-organizational dynamics of energy/matter at all levels of organizational hierarchy, from elementary particles through cells and organisms to the Universe as a whole. The method is based on an alternative conceptualization of physical reality postulating that the energy/matter comprising the Universe is far from equilibrium, that it exists as a flow, and that it develops via self-organization in accordance with the empirical laws of nonequilibrium thermodynamics. It is postulated that the energy/matter flowing through and comprising the Universe evolves as a multiscale, self-similar structure-process, i.e., as a self-organizing fractal. This means that certain organizational structures and processes are scale-invariant and are reproduced at all levels of the organizational hierarchy. Being a form of symmetry, scale-invariance naturally lends itself to a new discovery method that allows for the deduction of missing information by comparing scale-invariant organizational patterns across different levels of the organizational hierarchy

Probing high-pressure reactions in heterogeneous materials by Raman spectroscopy

International audienc

High-Pressure Chemistry of Graphene Oxide in the Presence of Ar, N<inf>2</inf>, and NH<inf>3</inf>

© 2016 American Chemical Society.The high pressure structural and reactive beahvior of graphene oxide (GO) in the presence of Ar, N2, and NH3 was studied in diamond anvil cells (DAC) by X-ray diffraction (XRD) and vibrational spectroscopy (FTIR and Raman), with the purpose of investigating the use of pressure for N-doping and functionalization of GO in high-density conditions. The pressure evolution of the interlayer d-spacing of GO during room temperature compression and decompression indicates the pressure-induced insertion of the selected systems between the GO layers and the stability of the GO layered structure at high pressure. Thermal and photoinduced reactivity was studied in GO with N2 and in GO with NH3 in different pressure conditions. The comparison of the infrared spectra of the recovered samples at ambient conditions with respect to the starting GO provides evidence for the occurrence of chemical reactivity of N2 and NH3 with GO, leading to N incorporation and GO functionalization, as also confirmed by the Raman spectra. The observed reactivity opens new perspectives for the high-pressure chemistry of GO and carbon-based nanostructured systems

High-Pressure Chemistry of Graphene Oxide in the Presence of Ar, N<inf>2</inf>, and NH<inf>3</inf>

© 2016 American Chemical Society.The high pressure structural and reactive beahvior of graphene oxide (GO) in the presence of Ar, N2, and NH3 was studied in diamond anvil cells (DAC) by X-ray diffraction (XRD) and vibrational spectroscopy (FTIR and Raman), with the purpose of investigating the use of pressure for N-doping and functionalization of GO in high-density conditions. The pressure evolution of the interlayer d-spacing of GO during room temperature compression and decompression indicates the pressure-induced insertion of the selected systems between the GO layers and the stability of the GO layered structure at high pressure. Thermal and photoinduced reactivity was studied in GO with N2 and in GO with NH3 in different pressure conditions. The comparison of the infrared spectra of the recovered samples at ambient conditions with respect to the starting GO provides evidence for the occurrence of chemical reactivity of N2 and NH3 with GO, leading to N incorporation and GO functionalization, as also confirmed by the Raman spectra. The observed reactivity opens new perspectives for the high-pressure chemistry of GO and carbon-based nanostructured systems

Lattice expansion of graphite oxide by pressure induced insertion of liquid ammonia

© 2015 Elsevier Ltd. All rights reserved. A pressure induced lattice expansion of Graphite Oxide (GO) in presence of NH3 was observed by X-ray diffraction during room temperature compression and decompression up to 7 GPa in a diamond anvil cell (DAC). A remarkable increase (∼11%) of the interlayer d-spacing of GO was observed between 0.2 and 1.1 GPa in the liquid phase of NH3, indicating the occurrence of molecular insertion between the GO layers. The expansion is reversible with the release of pressure, thus leading to a pressure induced breathing of the GO lattice. The presence of high density NH3 between the GO layers opens new perspectives for N-doping and chemical functionalization of GO and for designing new advanced carbon based nanostructured materials