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Wang Y, Collinson DW, Kwon H, Miller RD, Lionti K, Goodson KE, Dauskardt RH. Linking Interfacial Bonding and Thermal Conductivity in Molecularly-Confined Polymer-Glass Nanocomposites with Ultra-High Interfacial Density. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2023:e2301383. [PMID: 36971287 DOI: 10.1002/smll.202301383] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Indexed: 06/18/2023]
Abstract
Thermal transport in polymer nanocomposites becomes dependent on the interfacial thermal conductance due to the ultra-high density of the internal interfaces when the polymer and filler domains are intimately mixed at the nanoscale. However, there is a lack of experimental measurements that can link the thermal conductance across the interfaces to the chemistry and bonding between the polymer molecules and the glass surface. Characterizing the thermal properties of amorphous composites are a particular challenge as their low intrinsic thermal conductivity leads to poor measurement sensitivity of the interfacial thermal conductance. To address this issue here, polymers are confined in porous organosilicates with high interfacial densities, stable composite structure, and varying surface chemistries. The thermal conductivities and fracture energies of the composites are measured with frequency dependent time-domain thermoreflectance (TDTR) and thin-film fracture testing, respectively. Effective medium theory (EMT) along with finite element analysis (FEA) is then used to uniquely extract the thermal boundary conductance (TBC) from the measured thermal conductivity of the composites. Changes in TBC are then linked to the hydrogen bonding between the polymer and organosilicate as quantified by Fourier-transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopy. This platform for analysis is a new paradigm in the experimental investigation of heat flow across constituent domains.
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Affiliation(s)
- Yang Wang
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - David W Collinson
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Heungdong Kwon
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Robert D Miller
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
| | - Krystelle Lionti
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
- Hybrid Polymeric Materials, IBM Almaden Research Center, San Jose, CA, USA
| | - Kenneth E Goodson
- Department of Mechanical Engineering, Stanford University, Stanford, CA, USA
| | - Reinhold H Dauskardt
- Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA
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Water coordinated on Cu(I)-based catalysts is the oxygen source in CO 2 reduction to CO. Nat Commun 2022; 13:2577. [PMID: 35562192 PMCID: PMC9095693 DOI: 10.1038/s41467-022-30289-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 04/12/2022] [Indexed: 11/21/2022] Open
Abstract
Catalytic reduction of CO2 over Cu-based catalysts can produce various carbon-based products such as the critical intermediate CO, yet significant challenges remain in shedding light on the underlying mechanisms. Here, we develop a modified triple-stage quadrupole mass spectrometer to monitor the reduction of CO2 to CO in the gas phase online. Our experimental observations reveal that the coordinated H2O on Cu(I)-based catalysts promotes CO2 adsorption and reduction to CO, and the resulting efficiencies are two orders of magnitude higher than those without H2O. Isotope-labeling studies render compelling evidence that the O atom in produced CO originates from the coordinated H2O on catalysts, rather than CO2 itself. Combining experimental observations and computational calculations with density functional theory, we propose a detailed reaction mechanism of CO2 reduction to CO over Cu(I)-based catalysts with coordinated H2O. This study offers an effective method to reveal the vital roles of H2O in promoting metal catalysts to CO2 reduction. Understanding the underlying mechanisms for catalytic reduction of CO2 over Cu based catalysts remains challenging. Here, the authors develop an effective method to reveal the vital roles of H2O in promoting metal catalysts to CO2 reduction via a modified triple stage quadrupole mass spectrometer.
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Queiroz MH, Alves TV, Rivelino R. A theoretical screening of the O H⋅⋅⋅π interaction between water and benzene using density-functional approaches: Effects of nonlocal exchange and long-range dispersion corrections in the true minimum. COMPUT THEOR CHEM 2021. [DOI: 10.1016/j.comptc.2021.113464] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Elowitz M, Sivaraman B, Hendrix A, Lo JI, Chou SL, Cheng BM, Sekhar BNR, Mason NJ. Possible detection of hydrazine on Saturn's moon Rhea. SCIENCE ADVANCES 2021; 7:eaba5749. [PMID: 33523937 PMCID: PMC10670839 DOI: 10.1126/sciadv.aba5749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2019] [Accepted: 11/18/2020] [Indexed: 06/12/2023]
Abstract
We present the first analysis of far-ultraviolet reflectance spectra of regions on Rhea's leading and trailing hemispheres collected by the Cassini Ultraviolet Imaging Spectrograph during targeted flybys. In particular, we aim to explain the unidentified broad absorption feature centred near 184 nm. We have used laboratory measurements of the UV spectroscopy of a set of candidate molecules and found a good fit to Rhea's spectra with both hydrazine monohydrate and several chlorine-containing molecules. Given the radiation-dominated chemistry on the surface of icy satellites embedded within their planets' magnetospheres, hydrazine monohydrate is argued to be the most plausible candidate for explaining the absorption feature at 184 nm. Hydrazine was also used as a propellant in Cassini's thrusters, but the thrusters were not used during icy satellite flybys and thus the signal is believed to not arise from spacecraft fuel. We discuss how hydrazine monohydrate may be chemically produced on icy surfaces.
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Affiliation(s)
- Mark Elowitz
- Department of Physical Sciences, The Open University, Milton Keynes MK7 6AA, UK.
| | - Bhalamurugan Sivaraman
- Atomic Molecular and Optical Physics Division, Physical Research Laboratory, Ahmedabad 380 009, India.
| | | | - Jen-Iu Lo
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
| | - Sheng-Lung Chou
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
| | - Bing-Ming Cheng
- National Synchrotron Radiation Research Center, Hsinchu, Taiwan
| | - B N Raja Sekhar
- B-1, Indus-1, Atomic and Molecular Physics Division, Bhabha Atomic Research Centre at RRCAT, Indore, India
| | - Nigel J Mason
- School of Physical Sciences, The University of Kent, Canterbury CT2 7NH, UK
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James RL, Ioppolo S, Hoffmann SV, Jones NC, Mason NJ, Dawes A. Systematic investigation of CO 2 : NH 3 ice mixtures using mid-IR and VUV spectroscopy – part 2: electron irradiation and thermal processing. RSC Adv 2021; 11:33055-33069. [PMID: 35493573 PMCID: PMC9042239 DOI: 10.1039/d1ra05600j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 09/20/2021] [Indexed: 11/21/2022] Open
Abstract
Many experimental parameters determine the chemical and physical properties of interstellar ice analogues, each of which may influence the molecular synthesis that occurs in such ices. In part 1, James et al., RSC Adv., 2020, 10, 37517, we demonstrated the effects that the stoichiometric mixing ratio had on the chemical and physical properties of CO2 : NH3 mixtures and the impact on molecular synthesis induced by thermal processing. Here, in part 2, we extend this to include 1 keV electron irradiation at 20 K of several stoichiometric mixing ratios of CO2 : NH3 ices followed by thermal processing. We demonstrate that not all stoichiometric mixing ratios of CO2 : NH3 ice form the same products. Not only did the 4 : 1 ratio form a different residue after thermal processing, but O3 was observed after electron irradiation at 20 K, which was not observed in the other ratios. For the other ratios, the residue formed from a thermal reaction similar to the work shown in Part 1. However, conversion of ammonium carbamate to carbamic acid was hindered due to electron irradiation at 20 K. Our results demonstrate the need to systematically investigate stoichiometric mixing ratios to better characterise the chemical and physical properties of interstellar ice analogues to further our understanding of the routes of molecular synthesis under different astrochemical conditions. The stoichiometric mixing ratio of CO2 : NH3 ice mixtures determines the electron irradiation products at 20 K and the composition of residue material formed after thermal processing.![]()
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Affiliation(s)
- Rachel L. James
- School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, UK
| | - Sergio Ioppolo
- School of Electronic Engineering and Computer Science, Queen Mary University of London, Mile End Road, London, UK
| | - Søren V. Hoffmann
- ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
| | - Nykola C. Jones
- ISA, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
| | - Nigel J. Mason
- School of Physical Sciences, University of Kent, Canterbury, Kent, UK
| | - Anita Dawes
- School of Physical Sciences, The Open University, Walton Hall, Milton Keynes, UK
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Stubbing JW, McCoustra MRS, Brown WA. A new technique for determining the refractive index of ices at cryogenic temperatures. Phys Chem Chem Phys 2020; 22:25353-25365. [PMID: 33140768 DOI: 10.1039/d0cp02373f] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A reflection-absorption optical (RAO) spectrometer, operating across the ultra-violet/visible (UV/visible) wavelength region, has been developed that allows simultaneous measurements of optical properties and thickness of thin solid films at cryogenic temperatures in ultrahigh vacuum. The RAO spectrometer enables such measurements to be made after ice deposition, as opposed to most current approaches which make measurements during deposition. This allows changes in the optical properties and in the thickness of the film to be determined subsequent to thermal, photon or charged particle processing. This is not possible with current techniques. A data analysis method is presented that allows the wavelength dependent n and k values for ices to be extracted from the reflection-absorption spectra. The validity of this analysis method is shown using model data from the literature. New data are presented for the reflection UV/visible spectra of amorphous and crystalline single component ices of benzene, methyl formate and water adsorbed on a graphite surface. These data show that, for benzene and methyl formate, the crystalline ice has a larger refractive index than amorphous ice, reflecting changes in the electronic environment occurring in the ice during crystallisation. For water, the refractive index does not vary with ice phase.
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Affiliation(s)
- James W Stubbing
- Department of Chemistry, School of Life Sciences, University of Sussex, Falmer, Brighton, BN1 9QJ, UK.
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James RL, Ioppolo S, Hoffmann SV, Jones NC, Mason NJ, Dawes A. Systematic investigation of CO 2 : NH 3 ice mixtures using mid-IR and VUV spectroscopy - part 1: thermal processing. RSC Adv 2020; 10:37515-37528. [PMID: 35521284 PMCID: PMC9057146 DOI: 10.1039/d0ra05826b] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 09/25/2020] [Indexed: 12/24/2022] Open
Abstract
The adjustment of experimental parameters in interstellar ice analogues can have profound effects on molecular synthesis within an ice system. We demonstrated this by systematically investigating the stoichiometric mixing ratios of CO2 : NH3 ices as a function of thermal processing using mid-IR and VUV spectroscopy. We observed that the type of CO2 bonding environment was dependent on the different stoichiometric mixing ratios and that this pre-determined the NH3 crystallite structure after phase change. The thermal reactivity of the ices was linked to the different chemical and physical properties of the stoichiometric ratios. Our results provide new details into the chemical and physical properties of the different stoichiometric CO2 : NH3 ices enhancing our understanding of the thermally induced molecular synthesis within this ice system. The stoichiometric mixing ratio of CO2 : NH3 ices determines both the initial chemical and physical properties of the ices and their evolution through thermal processing including CO2 bonding environment, NH3 crystallite size and amount of residue.![]()
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Affiliation(s)
- Rachel L James
- School of Physical Sciences, The Open University Walton Hall Milton Keynes UK +44 (0)1908 654192 +44 (0)1908 332012
| | - Sergio Ioppolo
- School of Electronic Engineering and Computer Science, Queen Mary University of London Mile End Road London UK
| | - Søren V Hoffmann
- ISA, Department of Physics and Astronomy, Aarhus University Ny Munkegade 120 DK-8000 Aarhus C Denmark
| | - Nykola C Jones
- ISA, Department of Physics and Astronomy, Aarhus University Ny Munkegade 120 DK-8000 Aarhus C Denmark
| | - Nigel J Mason
- School of Physical Sciences, University of Kent Canterbury Kent UK
| | - Anita Dawes
- School of Physical Sciences, The Open University Walton Hall Milton Keynes UK +44 (0)1908 654192 +44 (0)1908 332012
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Halukeerthi SO, Shephard JJ, Talewar SK, Evans JSO, Rosu-Finsen A, Salzmann CG. Amorphous Mixtures of Ice and C 60 Fullerene. J Phys Chem A 2020; 124:5015-5022. [DOI: 10.1021/acs.jpca.0c03439] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Siriney O. Halukeerthi
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Jacob J. Shephard
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - Sukhpreet K. Talewar
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - John S. O. Evans
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - Alexander Rosu-Finsen
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
| | - Christoph G. Salzmann
- Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, United Kingdom
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James RL, Jones NC, Hoffmann SV, Dawes A. VUV spectroscopy of an electron irradiated benzene : carbon dioxide interstellar ice analogue. RSC Adv 2019; 9:5453-5459. [PMID: 35515951 PMCID: PMC9060755 DOI: 10.1039/c9ra00462a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 02/03/2019] [Indexed: 01/02/2023] Open
Abstract
We present the first vacuum ultraviolet spectroscopic study of an interstellar ice analogue of a benzene (C6H6) : carbon dioxide (CO2) (1 : 100) mixture which has been energetically processed with 1 keV electrons.
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Affiliation(s)
| | - Nykola C. Jones
- ISA
- Centre for Storage Ring Facilities
- Department of Physics and Astronomy
- Aarhus University
- Denmark
| | - Søren V. Hoffmann
- ISA
- Centre for Storage Ring Facilities
- Department of Physics and Astronomy
- Aarhus University
- Denmark
| | - Anita Dawes
- School of Physical Sciences
- The Open University
- UK
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