B18-Core EXAFS
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Hongman
Sun
,
Yu
Zhang
,
Chunfen
Wang
,
Mark A.
Isaacs
,
Ahmed I.
Osman
,
Yehong
Wang
,
David
Rooney
,
Youhe
Wang
,
Zifeng
Yan
,
Christopher M. A.
Parlett
,
Feng
Wang
,
Chunfei
Wu
Diamond Proposal Number(s):
[19850]
Abstract: Integrated carbon capture and utilization (ICCU) presents an ideal solution to address anthropogenic carbon dioxide (CO2) emissions from industry and energy sectors, facilitating CO2 capture and subsequent utilization through conversion into high-value chemicals, as opposed to current release into the atmosphere. Herein, we report the synergistic coupling of porous CaO, as a sorbent for CO2 capture, and Ni doped CeO2 nanorods, as catalytic sites for CO2 reduction. It is found that ceria is shown to possess the capacity for CO2 utilization, however, critically it only results in the generation of CO due to the weak CO-ceria bonding. The addition of Ni active sites gives rise to CH4 being the predominant product, via the strong interaction between Ni species and CO, which facilitates further reduction. Through tuning Ni loadings, we have evaluated the role of catalytic active site size, with a Ni loading of only 0.5 wt% providing optimal performance through the formation of sub-nanometer sized clusters. This near-atomic active site dispersion gives rise to CH4 productivity and selectivity of 1540 mmol g−1 Ni and 85.8%, respectively, with this optimal combination of catalyst and sorbent demonstrating high stability over 10 cycles of ICCU process. These observations in parallel with the synergistic coupling of earth-abundant, low-cost materials (CaO and Ni) will have broad implications on the design and implementation of high efficiency, cost-effective ICCU materials and processes.
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Jun 2022
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I03-Macromolecular Crystallography
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Alissa
Bleem
,
Eugene
Kuatsjah
,
Gerald N.
Presley
,
Daniel J.
Hinchen
,
Michael
Zahn
,
David C.
Garcia
,
William E.
Michener
,
Gerhard
König
,
Konstantinos
Tornesakis
,
Marco N.
Allemann
,
Richard J.
Giannone
,
John E.
Mcgeehan
,
Gregg T.
Beckham
,
Joshua K.
Michener
Abstract: Aryl-O-demethylation is a common rate-limiting step in the catabolism of lignin-related compounds, including guaiacol. Here we used randomly barcoded transposon insertion sequencing (RB-TnSeq) in the bacterium Novosphingobium aromaticivorans to identify a Rieske-type guaiacol O-demethylase, GdmA. Similarity searches identified GdmA homologs in other bacteria, along with candidate reductase partners, denoted GdmB. GdmAB combinations were biochemically characterized for activity with several lignin-related substrates. Structural and sequence comparisons of vanillate- and guaiacol-specific O-demethylase active sites revealed conserved hallmarks of substrate specificity. GdmAB combinations were also evaluated in Pseudomonas putida KT2440, which does not natively utilize guaiacol. GdmAB from Cupriavidus necator N-1 demonstrated the highest rate of guaiacol turnover in vitro and in engineered P. putida strains and notably higher catalytic efficiency than a cytochrome P450 system (GcoAB) and the vanillate Rieske-type O-demethylase from P. putida (VanAB). The GdmAB O-demethylases described here expand the suite of options for microbial conversion of a model lignin-derived substrate.
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May 2022
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I22-Small angle scattering & Diffraction
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Diamond Proposal Number(s):
[21663]
Open Access
Abstract: Atmospheric aerosols influence the climate via cloud droplet nucleation and can facilitate the long range transport of harmful pollutants. The lifetime of such aerosols can therefore determine their environmental impact. Fatty acids are found in organic aerosol emissions with oleic acid, an unsaturated fatty acid, being a large contributor to cooking emissions. As a surfactant, oleic acid can self-organise into nanostructured lamellar bilayers with its sodium salt, and this self-organisation can influence reaction kinetics. We developed a kinetic multi-layer model-based description of decay data we obtained from laboratory experiments of the ozonolysis of coated films of this self-organised system, demonstrating a decreased diffusivity for both oleic acid and ozone due to lamellar bilayer formation. Diffusivity was further inhibited by a viscous oligomer product forming in the surface layers of the film. Our results indicate that nanostructure formation can increase the reactive half-life of oleic acid by an order of days at typical indoor and outdoor atmospheric ozone concentrations. We are now able to place nanostructure formation in an atmospherically meaningful and quantifiable context. These results have implications for the transport of harmful pollutants and the climate.
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Apr 2022
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E01-JEM ARM 200CF
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Michael
Bowker
,
Naomi
Lawes
,
Isla
Gow
,
James
Hayward
,
Jonathan
Ruiz Esquius
,
Nia
Richards
,
Louise R.
Smith
,
Thomas J. A.
Slater
,
Thomas E.
Davies
,
Nicholas F.
Dummer
,
Lara
Kabalan
,
Andrew
Logsdail
,
Richard C.
Catlow
,
Stuart
Taylor
,
Graham J
Hutchings
Diamond Proposal Number(s):
[27530]
Open Access
Abstract: The rise in atmospheric CO2 concentration and the concomitant rise in global surface temperature have prompted massive research effort in designing catalytic routes to utilize CO2 as a feedstock. Prime among these is the hydrogenation of CO2 to make methanol, which is a key commodity chemical intermediate, a hydrogen storage molecule, and a possible future fuel for transport sectors that cannot be electrified. Pd/ZnO has been identified as an effective candidate as a catalyst for this reaction, yet there has been no attempt to gain a fundamental understanding of how this catalyst works and more importantly to establish specific design criteria for CO2 hydrogenation catalysts. Here, we show that Pd/ZnO catalysts have the same metal particle composition, irrespective of the different synthesis procedures and types of ZnO used here. We demonstrate that all of these Pd/ZnO catalysts exhibit the same activity trend. In all cases, the β-PdZn 1:1 alloy is produced and dictates the catalysis. This conclusion is further supported by the relationship between conversion and selectivity and their small variation with ZnO surface area in the range 6–80 m2g–1. Without alloying with Zn, Pd is a reverse water-gas shift catalyst and when supported on alumina and silica is much less active for CO2 conversion to methanol than on ZnO. Our approach is applicable to the discovery and design of improved catalysts for CO2 hydrogenation and will aid future catalyst discovery.
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Apr 2022
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I13-2-Diamond Manchester Imaging
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Diamond Proposal Number(s):
[18758]
Abstract: Natural surface gas seeps provide a significant input of greenhouse gas emissions into the Earth’s atmosphere and hydrosphere. The gas flux is controlled by the properties of underlying fluid-escape conduits, which are present within sedimentary basins globally. These conduits permit pressure-driven fluid flow, hydraulically connecting deeper strata with the Earth’s surface; however they can only be fully resolved at sub-seismic scale. Here, a novel ‘minus cement and matrix permeability’ method using three-dimensional X-ray micro-computed tomography imaging enables the improved petrophysical linkage of outcrop and sub-surface data. The methodology is applied to the largest known outcrop of an inactive fluid-escape system, the Panoche Giant Intrusion Complex in Central California, where samples were collected along transects of the 600 to 800 m stratigraphic depth range to constrain porosity and permeability spatial heterogeneity. The presence of silica cement and clay matrix within the intergranular pores of sand intrusions are the primary control of porosity (17 to 27%) and permeability (≤1 to ca 500 mD) spatial heterogeneity within the outcrop analogue system. Following the digital removal of clay matrix and silica (opal-CT and quartz) cement derived from the mudstone host strata, the sand intrusions have porosity-permeability ranges of ca 30 to 40% and 103 to 104 mD. These calculations are closely comparable to active sub-surface systems in sedimentary basins. Field observations revealed at decreasing depth, the connected sand intrusion network reduces in thickness and becomes carbonate cemented, terminating at carbonate mounds formed from methane escape at the seafloor. A new conceptual model integrates the pore-scale calculations and field-scale observations to highlight the key processes that control sand intrusion permeability, spatially and temporally. The study demonstrates the control of matrix and cement addition on the physical properties of fluid-escape conduits, which has significance for hydrocarbon reservoir characterization and modelling, as well as subsurface CO2 and energy storage containment assessment.
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Apr 2022
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B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
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Diamond Proposal Number(s):
[27121, 24584]
Open Access
Abstract: Palladium and palladium–platinum foils were analysed using temperature-programmed near-ambient pressure X-ray photoelectron spectroscopy (TP-NAP-XPS) under methane oxidation conditions. Oxidation of palladium is inhibited by the presence of water, and in oxygen-poor environments. Pt addition further inhibits oxidation of palladium across all reaction conditions, preserving metallic palladium to higher temperatures. Bimetallic foils underwent significant restructuring under reaction conditions, with platinum preferentially migrating to the bulk under select conditions.
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Apr 2022
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B07-B-Versatile Soft X-ray beamline: High Throughput
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Diamond Proposal Number(s):
[29340]
Abstract: The development of low-cost, robust and efficient non-noble metal electrocatalysts is still a pursuit for the hydrogen evolution reaction (HER). Herein, a self-standing electrocatalyst, Ni2P/CoP nanosheet, was fabricated directly on three-dimensional Ni foams by two facile steps, which illustrated both high activity and stability for HER in different electrolytes. Benefiting from the porous structures of nanosheets with large specific surface area and the hybrid Ni2P/CoP, the as-prepared electrocatalyst presented remarkable HER with overpotentials of 65.2 mV and 87.8 mV to reach a current density of -10 mA cm-2 in neutral and alkaline media, respectively. Density function theory calculations revealed a lower activation energy of water dissociation and efficient HER steps of hybrid Ni2P/CoP nanosheets compared with mono CoP. The self-standing electrocatalyst maintained excellent chemical stability. Additionally, the HER process in domestic wastewater was realized with more impressive performance by using Ni2P/CoP nanosheets compared with commercial Pt/C. Hydrogen was continuously generated for 20 h in mildly alkaline dishwashing wastewater. This work provides a feasible way to fabricate non-noble metal and self-standing hybrid bimetallic phosphides for HER in neutral and alkaline media, showing great potential for efficient hydrogen production by re-utilizing wastewater resources.
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Apr 2022
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I09-Surface and Interface Structural Analysis
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Matthew J.
Smiles
,
Thomas
Shalvey
,
Luke
Thomas
,
Theodore D. C.
Hobson
,
Leanne A. H.
Jones
,
Laurie
Phillips
,
Christopher
Don
,
Thomas
Beesley
,
Pardeep K.
Thakur
,
Tien-Lin
Lee
,
Ken
Durose
,
Jonathan D.
Major
,
Tim
Veal
Diamond Proposal Number(s):
[31170]
Open Access
Abstract: Germanium selenide (GeSe) bulk crystals, thin films and solar cells are investigated with a focus on acceptor-doping with silver (Ag) and the use of an Sb2Se3 interfacial layer. The Ag-doping of GeSe occurred by a stoichiometric melt growth technique that created Ag-doped GeSe bulk crystals. A combination of capacitance voltage measurements, synchrotron radiation photoemission spectroscopy and surface space-charge calculations indicate Ag-doping increases the hole density from 5.2×1015 cm-3 to 1.9×1016 cm-3. The melt-grown material is used as the source for thermally evaporated GeSe films within solar cells. The cell structure with the highest efficiency of 0.260% is FTO/CdS/Sb2Se3/undoped-GeSe/Au compared with solar cells without the Sb2Se3 interfacial layer or with the Ag-doped GeSe.
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Apr 2022
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I19-Small Molecule Single Crystal Diffraction
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Hannes
Michaels
,
Matthias Johannes
Golomb
,
Byeong
Kim
,
Tomas
Edvinsson
,
Fabio
Cucinotta
,
Paul G.
Waddell
,
Michael R.
Probert
,
Steven J.
Konezny
,
Gerrit
Boschloo
,
Aron
Walsh
,
Marina
Freitag
Diamond Proposal Number(s):
[22240]
Open Access
Abstract: Emerging technologies in solar energy will be critical in enabling worldwide society in overcoming the present energy challenges and reaching carbon net zero. Inefficient and unstable charge transport materials limit current emerging energy conversion and storage technologies. Low-dimensional coordination polymers represent an alternative, unprecedented class of charge transport materials, comprised of molecular building blocks. Here, we provide a comprehensive study of mixed-valence coordination polymers from an analysis of the charge transport mechanism to their implementation as hole conducting layers. CuII dithiocarbamate complexes afford morphology control of 1D polymer chains linked by (CuI2X2) copper halide rhombi. Concerted theoretical and experimental efforts identified the charge transport mechanism at the transition to band-like transport with an modeled effective hole mass of 6 me. The iodide-bridged coordination polymer showed an excellent conductivity of 1 mS cm-1 and a hole mobility of 5.8 10-4 cm2(Vs)-1 at room temperature. Nanosecond selective hole injection into coordination polymer thin films was captured by nanosecond photoluminescenceof halide perovskite films. The coordination polymers constitute a sustainable, tunable alternative to the current standard of heavily doped organic hole conductors.
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Mar 2022
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B18-Core EXAFS
E01-JEM ARM 200CF
E02-JEM ARM 300CF
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Runjia
Lin
,
Liqun
Kang
,
Tianqi
Zhao
,
Jianrui
Feng
,
Veronica
Celorrio
,
Guohui
Zhang
,
Giannantonio
Cibin
,
Anthony
Kucernak
,
Dan
Brett
,
Furio
Cora
,
Ivan P.
Parkin
,
Guanjie
He
Diamond Proposal Number(s):
[25410, 29207]
Open Access
Abstract: Electrocatalytic organic compound oxidation reactions (OCORs) have been intensively studied for energy and environmentally benign applications. However, relatively little effort has been devoted to developing a fundamental understanding of OCOR, including the detailed competition with side reactions and activity limitations, thus inhibiting the rational design of high-performance electrocatalysts. Herein, by taking NiWO4-catalysed urea oxidation reaction (UOR) in aqueous media as an example, the competition between the OCOR and the oxygen evolution reaction (OER) within a wide potential range is examined. It is shown that the root of the competition can be ascribed to insufficient surface concentration of dynamic Ni3+, an active site shared by both UOR and OER. Similar phenomenon are observed in other OCOR electrocatalysts and systems. To address the issue, a “controllable reconstruction of pseudo-crystalline bimetal oxides” design strategy is proposed to maximise the dynamic Ni3+ population and manipulate the competition between UOR and OER. The optimised electrocatalyst delivers best-in-class performance and a ~10-fold increase in current density at 1.6 V versus the reversible hydrogen electrode for alkaline urea electrolysis compared to that of the pristine materials.
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Mar 2022
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