High-yielding green hydrothermal synthesis of ruthenium nanoparticles and their characterization

Using hydrothermal techniques, a novel synthetic approach to prepare ruthenium nanoparticles has been developed. At 180 degrees C and under autogenous pressure, starting from an aqueous solution of ruthenium trichloride, the method yielded nanoparticles whose form and size both depended on the reducing agent: sodium citrate (hexagonal shaped nanocrystals, 1-20 nm), ascorbic acid (spherical nanoparticles, 3-5 nm) and succinic acid (spherical nanoparticles, 1-120 nm). Depending on the reaction variables, the nature and concentration of partially reduced species determines the characteristics of the final products. HRTEM image analysis along with the simulation techniques were stabilized preferential growth of nanoparticles on specific directions. Ruthenium samples have been investigated by Temperature-Programmed Reduction (TPR) showing that the reduction temperature of nanoparticles is correlated to their nanocrystalline size.Peer Reviewe

Thermal behavior of layered alpha-titanium phosphates: from the titanium(IV) bis(hydrogenphosphate) monohydrate to an europium(III)-phase via propylamine intercalation

Polycrystalline layered α-titanium phosphate, α-Ti(HPO4)2·H2O, has been obtained under H3PO4(aq) reflux conditions, and its intercalation compound with propylamine, α-Ti(HPO4)2·2C3H7NH2·H2O, was used for trapping luminescent Eu-centers in two-dimensional confined space. All materials were characterized by X-ray powder diffraction, scanning electron microscopy, solid-state nuclear magnetic resonance (SS-NMR, 31P MAS and 13C CPMAS) and thermogravimetric analysis coupled with mass spectrometry. Moreover, the activation energy of thermal decomposition has been calculated as a function of the extent of conversion, applying both a modified Friedman method developed in our laboratory and the advanced nonlinear method proposed by Vyazovkin.This work is supported by “Ministerio de Economía y Competitividad” (MAT2016-78155-C2-1-R, MAT2013-40950-R, MAT2011-27573-C04-02), “Gobierno del Principado de Asturias” (GRUPIN14-060), and FEDER.Peer reviewe

Selective photocatalytic oxidation of 5-hydroxymethylfurfural to 2,5-furandicarboxaldehyde by polymeric carbon nitride-hydrogen peroxide adduct

Polymeric carbon nitride-hydrogen peroxide adduct (PCN-H2O2) has been prepared, thoroughly characterised and its application for selective photocatalytic conversion of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxaldehyde (FDC) in aqueous suspension has been studied. The PCN-H2O2 adduct is stable in aqueous suspension under UV and solar irradiation up to 100 °C. It is also stable up to 200 °C if heated in air, while at temperatures close to 300 °C its decomposition takes place. Based on the obtained characterisation data it has been proposed that H2O2 attaches to the non-polymerised carbon nitride species and to the heptazine nitrogen atoms, thus producing strong hydrogen bonding within the PCN-H2O2 adduct. The blockage of the surface amino-groups in PCN-H2O2 by H2O2 hinders the interaction of HMF with these sites, which are responsible for unselective substrate conversion. PCN-H2O2, although being less active, possesses a superior selectivity in natural solar light assisted oxidation of HMF to FDC reaching 80% with respect to its thermally etched PCN counterpart, which gives rise to a 40–50% selectivity. We believe that the exceptional performance of the applied photocatalyst in the selective photocatalytic conversion of HMF to a high added value FDC in a green solvent under natural illumination makes a significant contribution to the development of environmentally friendly technologies for biomass valorisation.We gratefully acknowledge financial support from the Spanish MINECO (MAT2013-40950-R, MAT2016-78155-C2-1-R, CTQ2014-52956-C3-1-R, and Severo Ochoa PhD grant BP-14-029 to M.I.) and FEDER. IK acknowledges financial support from Ministry of Education and Science of the Russian Federation (grant No. 4.9722.2017/8.9) and grateful for the support by Act 211 Government of the Russian Federation, contract No. 02.A03.21.0011.Peer reviewe

Hydrothermal synthesis and characterization of a two-dimensional piperazinium cobalt-zinc phosphate via a metastable one-dimensional phase

A two-dimensional piperazinium cobalt–zinc phosphate, formulated as (C4N2H12)1.5(Co0.6Zn0.4)2(HPO4)2(PO4)·H2O (2D), was synthesized under hydrothermal conditions. The crystal structure was determined using single-crystal X-ray diffraction data (monoclinic P21/c, a=8.1165(3) Å, b=26.2301(10) Å, c=8.3595(4) Å, and β=110.930(5)°) and the hydrogen atom positions were optimized by DFT calculations. A single-crystal corresponding to one-dimensional metastable phase, (C4N2H12)Co0.3Zn0.7(HPO4)2·H2O (1D), was also isolated and the crystal structure was determined (monoclinic P21/c, a=8.9120(6) Å, b=14.0290(1) Å, c=12.2494(5) Å, and β=130.884(6)°). The bulk was characterized by chemical (C–H–N) analysis, powder X-ray diffraction (PXRD), powder X-ray thermodiffractometry (HT-XRD), transmission electron microscopy (STEM(DF)-EDX and EFTEM), and thermal analysis (TG/SDTA-MS), including activation energy data of its thermal decomposition. The magnetic susceptibility and magnetization measurements show no magnetic ordering down to 4 K.Financial support from Spanish Ministerio de Economía y Competitividad (MAT2010-15094, MAT2011-27573-C04, MAT2013-40950-R , Factoría de Cristalización—Consolider Ingenio 2010, and Técnicos de Infraestructuras Científico-Tecnológicas grants PTA2011-4903-I to ZA and PTA2011-4950-I to SAK) and FEDER funding is acknowledged.Peer Reviewe

Silicon Carbide with Uniformly Sized Spherical Mesopores from Butoxylated Silica Nanoparticles Template

A colloidal solution of uniformly sized butoxylated SiO₂ nanoparticles in <i>o</i>-xylene was prepared from Ludox HS-30 sol. Using these nanoparticles as a template for nanocasting and polycarbosilane (PCS) as a replica precursor, mesoporous SiC was produced by thermal decomposition of the PCS. More precisely, our synthesis allowed porous SiC to be obtained with uniformly sized (11 nm) spherical pores, high surface area (up to 800 m²/g), and large pore volume (up to 1.25 cm³/g). It is anticipated that such SiC with well-defined texture will find major applications as a mesoporous support for nanosized metal particles in exothermic catalytic reactions