Bimetallic Intersection in PdFe@FeOx-C Nanomaterial for Enhanced Water Splitting Electrocatalysis

Supported Fe-doped Pd-nanoparticles (NPs) are prepared via soft transfor-mation of a PdFe-metal oraganic framework (MOF). The thus synthesized bimetallic PdFe-NPs are supported on FeOx@C layers, which are essential for developing well-defined and distributed small NPs, 2.3 nm with 35% metal loading. They are used as bifunctional nanocatalysts for the electro-catalytic water splitting process. They display superior mass activity for the oxygen evolution reaction (OER) and the hydrogen evolution reaction (HER), both in alkaline and acid media, compared with those obtained for benchmarking platinum HER catalyst, and ruthenium, and iridium oxide OER catalysts. PdFe-NPs also exhibit outstanding stability against sintering that can be explained by the protecting role of graphitic carbon layers provided by the organic linker of the MOF. Additionally, the superior electrocatalytic performance of the bimetallic PdFe-NPs compared with those of monometallic Pd/C NPs and FeOx points to a synergetic effect induced by Fe-Pd interactions that facilitates the water splitting reaction. This is supported by additional characterization of the PdFe-NPs prior and post electrolysis by TEM, XRD, X-ray photoelectron spectroscopy, and Raman revealing that dispersed PdFe NPs on FeOx@C promote interactions between Pd and Fe, most likely to be Pd-O-Fe active centers

MOF-mediated synthesis of supported Fe-doped Pd nanoparticles under mild conditions for magnetically recoverable catalysis

Metal-organic framework (MOF)-driven synthesis is considered as a promising alternative for the development of new catalytic materials with well-designed active sites. This synthetic approach is used here to gradually transform a new bimetallic MOF, with Pd and Fe as the metal components, by the in situ generation of aniline under mild conditions. This methodology results in a compositionally homogeneous nanocomposite formed by Fe-doped Pd nanoparticles that, in turn, are supported on iron oxide-doped carbon. The nanocomposite has been fully characterized by several techniques such as IR and Raman spectroscopy, TEM, XPS, and XAS. The performance of this nanocomposite as an heterogeneous catalyst for hydrogenation of nitroarenes and nitrobenzene coupling with benzaldehyde has been evaluated, proving it to be an efficient and reusable catalyst

Spectroscopic, calorimetric, and catalytic evidences of hydrophobicity on Ti-MCM-41 silylated materials for olefin epoxidations

tHydrophobic Ti-MCM-41 samples prepared by post-synthesis silylation treatment demonstrate to behighly active and selective catalysts in olefins epoxidation by using organic hydroperoxides as oxidizingagents in liquid phase reaction systems. Epoxide yields show important enhancements with increasedsilylation degrees of the Ti-mesoporous samples. Catalytic studies are combined and correlated withspectroscopic techniques (e.g. XRD, XANES, UV-Visible,29Si MAS-NMR) and calorimetric measurementsto better understand the changes in the surface chemistry of Ti-MCM-41 samples due to the post-synthesis silylation treatment and to ascertain the role of these trimethylsilyl groups incorporated inolefin epoxidation. In such manner, the effect of the organic moieties on solids, and both water and gly-col molecules contents on the catalytic activity and selectivity are analyzed in detail. Results show thatthe hydrophobicity level of the samples is responsible for the decrease in water adsorption and, conse-quently, the negligible formation of the non-desired glycol during the catalytic process. Thus, catalystdeactivation by glycol poisoning of Ti active sites is greatly diminished, this increasing catalyst stabilityand leading to practically quantitative production of the corresponding epoxide. The extended use ofthese hydrophobic Ti-MCM-41 catalysts together with organic hydroperoxides for the highly efficientand selective epoxidation of natural terpenes is also exemplified.The authors gratefully acknowledge financial support of Spanish Government (MAT2012-38567-C02-01, Consolider-Ingenio 2010-Multicat CSD-2009-00050 and Severo Ochoa SEV-2012-0267) and Generalitat Valenciana (Project Prometeo). M.E.D. also thanks funds from Spanish Government (CTQ-2011-27550) and CSIC (PIE 2009801063). J.S.A. and F.R.R. acknowledge financial support from MINECO (Projects MAT2013-45008-p and CONCERT Project-NASEMS (PCIN-2013-057), and from Generalitat Valenciana (PROMETEO2009/002).Silvestre Albero, J.; Domine ., ME.; Jorda Moret, JL.; Navarro Villalba, MT.; Rey Garcia, F.; Rodriguez-Reinoso, F.; Corma Canós, A. (2015). Spectroscopic, calorimetric, and catalytic evidences of hydrophobicity on Ti-MCM-41 silylated materials for olefin epoxidations. Applied Catalysis A: General. 507:14-25. https://doi.org/10.1016/j.apcata.2015.09.029S142550

MOF-Mediated Synthesis of Supported Fe-doped Pd Nanoparticles under Mild Conditions for Magnetically Recoverable Catalysis

MOF-driven synthesis is considered as a promising alternative for the development of new catalytic materials with well-designed active sites. This synthetic approach is used here to gradually transform a new bimetallic MOF, composed of Pd and Fe as metal components, via the in situ generation of aniline under mild conditions. This methodology results in a compositionally homogeneous nanocomposite formed by Fedoped Pd nanoparticles and these, in turn, supported on an iron oxide-doped carbon. The nanocomposite has been fully characterized by several techniques such as IR, Raman, TEM, XPS, XAS, among others. The performance of this nanocomposite as an heterogeneous catalyst for hydrogenation of nitroarenes and nitrobenzene coupling with benzaldehyde has been evaluated, proving it to be an efficient and reusable catalyst

Redox Tuning and Species Distribution in Maya Blue-Type Materials: A Reassessment

Maya Blue-type specimens prepared from indigo (1 wt %) plus kaolinite, montmorillonite, palygorskite, sepiolite, and silicalite are studied. Liquid chromatography with diode array detection, ultra-performance liquid chromatography coupled with mass spectrometry, and pyrolysis-silylation gas chromatography–mass spectrometry analyses of the extracts from these specimens combined with spectral and solid-state voltammetry, electrochemical impedance spectroscopy, and scanning electrochemical microscopy techniques provide evidence for the presence of a significant amount of dehydroindigo and isatin accompanying indigo and other minority organic compounds in all samples. Solid-state electrochemistry data permits the estimatation of indigo loading in archeological Maya Blue, which is in the range of 0.2 to 1.5 wt %. These results support a view of ‘genuine’ Maya Blue-type materials as complex polyfunctional organic–inorganic hybrids

Deep Underground Neutrino Experiment (DUNE), Far Detector Technical Design Report, Volume II: DUNE Physics

The preponderance of matter over antimatter in the early universe, the dynamics of the supernovae that produced the heavy elements necessary for life, and whether protons eventually decay -- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our universe, its current state, and its eventual fate. DUNE is an international world-class experiment dedicated to addressing these questions as it searches for leptonic charge-parity symmetry violation, stands ready to capture supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the standard model. The DUNE far detector technical design report (TDR) describes the DUNE physics program and the technical designs of the single- and dual-phase DUNE liquid argon TPC far detector modules. Volume II of this TDR, DUNE Physics, describes the array of identified scientific opportunities and key goals. Crucially, we also report our best current understanding of the capability of DUNE to realize these goals, along with the detailed arguments and investigations on which this understanding is based. This TDR volume documents the scientific basis underlying the conception and design of the LBNF/DUNE experimental configurations. As a result, the description of DUNE's experimental capabilities constitutes the bulk of the document. Key linkages between requirements for successful execution of the physics program and primary specifications of the experimental configurations are drawn and summarized. This document also serves a wider purpose as a statement on the scientific potential of DUNE as a central component within a global program of frontier theoretical and experimental particle physics research. Thus, the presentation also aims to serve as a resource for the particle physics community at large