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Open Access
Abstract: Herein, the alcoholysis of furfuryl alcohol in a series of SBA-15-pr-SO3H catalysts with different pore sizes is reported. Elemental analysis and NMR relaxation/diffusion methods show that changes in pore size have a significant effect on catalyst activity and durability. In particular, the decrease in catalyst activity after catalyst reuse is mainly due to carbonaceous deposition, whereas leaching of sulfonic acid groups is not significant. This effect is more pronounced in the largest-pore-size catalyst C3, which rapidly deactivates after one reaction cycle, whereas catalysts with a relatively medium and small average pore size (named, respectively, C2 and C1) deactivate after two reaction cycles and to a lesser extent. CHNS elemental analysis showed that C1 and C3 experience a similar amount of carbonaceous deposition, suggesting that the increased reusability of the small-pore-size catalyst can be attributed to the presence of SO3H groups mostly present on the external surface, as corroborated by results on pore clogging obtained by NMR relaxation measurements. The increased reusability of the C2 catalyst is attributed to a lower amount of humin being formed and, at the same time, reduced pore clogging, which helps to maintain accessible the internal pore space.
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May 2023
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NONE-No attached Diamond beamline
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Chung-Che
Huang
,
He
Wang
,
Yameng
Cao
,
Ed
Weatherby
,
Filipe
Richheimer
,
Sebastian
Wood
,
Shan
Jiang
,
Daqing
Wei
,
Yongkang
Dong
,
Xiaosong
Lu
,
Pengfei
Wang
,
Tomas
Polcar
,
Daniel W.
Hewak
Open Access
Abstract: The fabrication process for the uniform large-scale MoS2, WS2 transition-metal dichalcogenides (TMDCs) monolayers, and their heterostructures has been developed by van der Waals epitaxy (VdWE) through the reaction of MoCl5 or WCl6 precursors and the reactive gas H2S to form MoS2 or WS2 monolayers, respectively. The heterostructures of MoS2/WS2 or WS2/MoS2 can be easily achieved by changing the precursor from WCl6 to MoCl5 once the WS2 monolayer has been fabricated or switching the precursor from MoCl5 to WCl6 after the MoS2 monolayer has been deposited on the substrate. These VdWE-grown MoS2, WS2 monolayers, and their heterostructures have been successfully deposited on Si wafers with 300 nm SiO2 coating (300 nm SiO2/Si), quartz glass, fused silica, and sapphire substrates using the protocol that we have developed. We have characterized these TMDCs materials with a range of tools/techniques including scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), micro-Raman analysis, photoluminescence (PL), atomic force microscopy (AFM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), and selected-area electron diffraction (SAED). The band alignment and large-scale uniformity of MoS2/WS2 heterostructures have also been evaluated with PL spectroscopy. This process and resulting large-scale MoS2, WS2 monolayers, and their heterostructures have demonstrated promising solutions for the applications in next-generation nanoelectronics, nanophotonics, and quantum technology.
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Sep 2022
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B18-Core EXAFS
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Diamond Proposal Number(s):
[19850]
Abstract: Anthropogenic carbon dioxide (CO2) emission is soaring day by day due to fossil fuel combustion to fulfill the daily energy requirements of our society. The CO2 concentration should be stabilized to evade the deadly consequences of it, as climate change is one of the major consequences of greenhouse gas emission. Chemical fixation of CO2 to other value-added chemicals requires high energy due to its stability at the highest oxidation state, creating a tremendous challenge to the scientific community to fix CO2 and prevent global warming caused by it. In this work, we have introduced a novel monomer-assembly-directed strategy to design va isible-light-responsive conjugated Zn-metalated porous organic polymer (Zn@MA-POP) with a dynamic covalent acyl hydrazone linkage, via a one-pot condensation between the self-assembled monomer 1,3,5-benzenetricarbohydrazide (TPH) and a Zn complex (Zn@COM). We have successfully explored as-synthesized Zn@MA-POP as a potential photocatalyst in visible-light-driven CO2 photofixation with styrene epoxide (SE) to styrene carbonate (SC). Nearly 90% desired product (SC) selectivity has been achieved with our Zn@MA-POP, which is significantly better than that for the conventional Zn@TiO2 (∼29%) and Zn@gC3N4 (∼26%) photocatalytic systems. The excellent light-harvesting nature with longer lifetime minimizes the radiative recombination rate of photoexcited electrons as a result of extended π-conjugation in Zn@MA-POP and increased CO2 uptake, eventually boosting the photocatalytic activity. Local structural results from a first-shell EXAFS analysis reveals the existence of a Zn(N2O4) core structure in Zn@MA-POP, which plays a pivotal role in activating the epoxide ring as well as capturing the CO2 molecules. An in-depth study of the POP–CO2 interaction via a density functional theory (DFT) analysis reveals two feasible interactions, Zn@MA-POP-CO2-A and Zn@MA-POP-CO2-B, of which the latter has a lower relative energy of 0.90 kcal/mol in comparison to the former. A density of states (DOS) calculation demonstrates the lowering of the LUMO energy (EL) of Zn@MA-POP by 0.35 and 0.42 eV, respectively, for the two feasible interactions, in comparison to Zn@COM. Moreover, the potential energy profile also unveils the spontaneous and exergonic photoconversion pathways for the SE to SC conversion. Our contribution is expected to spur further interest in the precise design of visible-light-active conjugated porous organic polymers for CO2 photofixation to value-added chemicals.
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Aug 2022
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B16-Test Beamline
E01-JEM ARM 200CF
I12-JEEP: Joint Engineering, Environmental and Processing
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Zifan
Wang
,
Jingwei
Chen
,
Radim
Kocich
,
Samuel
Tardif
,
Igor P.
Dolbnya
,
Lenka
Kunčická
,
Jean-Sébastien
Micha
,
Konstantinos
Liogas
,
Oxana
Magdysyuk
,
Ivo
Szurman
,
Alexander M.
Korsunsky
Diamond Proposal Number(s):
[25467, 28397, 28418]
Open Access
Abstract: To explore an effective route of customizing the superelasticity (SE) of NiTi shape memory alloys via modifying the grain structure, binary Ni55Ti45 (wt) alloys were fabricated in as-cast, hot swaged, and hot-rolled conditions, presenting contrasting grain sizes and grain boundary types. In situ synchrotron X-ray Laue microdiffraction and in situ synchrotron X-ray powder diffraction techniques were employed to unravel the underlying grain structure mechanisms that cause the diversity of SE performance among the three materials. The evolution of lattice rotation, strain field, and phase transformation has been revealed at the micro- and mesoscale, and the effect of grain structure on SE performance has been quantified. It was found that (i) the Ni4Ti3 and NiTi2 precipitates are similar among the three materials in terms of morphology, size, and orientation distribution; (ii) phase transformation happens preferentially near high-angle grain boundary (HAGB) yet randomly in low-angle grain boundary (LAGB) structures; (iii) the smaller the grain size, the higher the phase transformation nucleation kinetics, and the lower the propagation kinetics; (iv) stress concentration happens near HAGBs, while no obvious stress concentration can be observed in the LAGB grain structure during loading; (v) the statistical distribution of strain in the three materials becomes asymmetric during loading; (vi) three grain lattice rotation modes are identified and termed for the first time, namely, multi-extension rotation, rigid rotation, and nondispersive rotation; and (vii) the texture evolution of B2 austenite and B19′ martensite is not strongly dependent on the grain structure.
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Jun 2022
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I15-1-X-ray Pair Distribution Function (XPDF)
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Diamond Proposal Number(s):
[28223]
Open Access
Abstract: The metal-organic framework MOF-808 contains Zr6O8 nodes with a high density of vacancy sites, which can incorporate carboxylate-containing functional groups to tune chemical reactivity. Although the postsynthetic methods to modify the chemistry of the Zr6O8 nodes in MOFs are well known, tackling these alterations from a structural perspective is still a challenge. We have combined infrared spectroscopy experiments and first-principles calculations to identify the presence of node vacancies accessible for chemical modifications within the MOF-808. We demonstrate the potential of our approach to assess the decoration of MOF-808 nodes with different catechol–benzoate ligands. Furthermore, we have applied advanced synchrotron characterization tools, such as pair distribution function analyses and X-ray absorption spectroscopy, to resolve the atomic structure of single metal sites incorporated into the catechol groups postsynthetically. Finally, we demonstrate the catalytic activity of these MOF-808 materials decorated with single copper sites for 1,3-dipolar cycloadditions.
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May 2022
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DL-SAXS-Offline SAXS and Sample Environment Development
I22-Small angle scattering & Diffraction
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Arindam
Pramanik
,
Zexi
Xu
,
Shazana H.
Shamsuddin
,
Yazan S.
Khaled
,
Nicola
Ingram
,
Thomas
Maisey
,
Darren
Tomlinson
,
P. Louise
Coletta
,
David
Jayne
,
Thomas A.
Hughes
,
Arwen
Tyler
,
Paul A.
Millner
Diamond Proposal Number(s):
[16566, 26258, 28627]
Abstract: Nanomedicines, while having been approved for cancer therapy, present many challenges such as low stability, rapid clearance, and nonspecificity leading to off-target toxicity. Cubosomes are porous lyotropic liquid crystalline nanoparticles that have shown great premise as drug delivery vehicles; however, their behavior in vivo is largely underexplored, hindering clinical translation. Here, we have engineered cubosomes based on the space group Im3m that are loaded with copper acetylacetonate as a model drug, and their surfaces are functionalized for the first time with Affimer proteins via copper-free click chemistry to actively target overexpressed carcinoembryonic antigens on LS174T colorectal cancer cells. Unlike nontargeted cubosomes, Affimer tagged cubosomes showed preferential accumulation in cancer cells compared to normal cells not only in vitro (2D monolayer cell culture and 3D spheroid models) but also in vivo in colorectal cancer mouse xenografts, while exhibiting low nonspecific absorption and toxicity in other vital organs. Cancerous spheroids had maximum cell death compared to noncancerous cells upon targeted delivery. Xenografts subjected to targeted drug-loaded cubosomes showed a 5–7-fold higher drug accumulation in the tumor tissue compared to the liver, kidneys, and other vital organs, a significant decrease in tumor growth, and an increased survival rate compared to the nontargeted group. This work encompasses the first thorough preclinical investigation of Affimer targeted cubosomes as a cancer therapeutic.
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Feb 2022
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B18-Core EXAFS
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Diamond Proposal Number(s):
[21533]
Open Access
Abstract: The electrochemical conversion of carbon dioxide (CO2) to useful chemical fuels is a promising route toward the achievement of carbon neutral and carbon negative energy technologies. Copper (Cu)- and Cu oxide-derived surfaces are known to electrochemically convert CO2 to high-value and energy-dense products. However, the nature and stability of oxidized Cu species under reaction conditions are the subject of much debate in the literature. Herein, we present the synthesis and characterization of copper-titanate nanocatalysts, with discrete Cu–O coordination environments, for the electrochemical CO2 reduction reaction (CO2RR). We employ real-time in situ X-ray absorption spectroscopy (XAS) to monitor Cu species under neutral-pH CO2RR conditions. Combination of voltammetry and on-line electrochemical mass spectrometry with XAS results demonstrates that the titanate motif promotes the retention of oxidized Cu species under reducing conditions for extended periods, without itself possessing any CO2RR activity. Additionally, we demonstrate that the specific nature of the Cu–O environment and the size of the catalyst dictate the long-term stability of the oxidized Cu species and, subsequently, the product selectivity.
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Jan 2022
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B21-High Throughput SAXS
I22-Small angle scattering & Diffraction
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Diamond Proposal Number(s):
[17972, 16970]
Abstract: Catalytically active materials for the enhancement of personalized protective equipment (PPE) could be advantageous to help alleviate threats posed by neurotoxic organophosphorus compounds (OPs). Accordingly, a chimeric protein comprised of a supercharged green fluorescent protein (scGFP) and phosphotriesterase from Agrobacterium radiobacter (arPTE) was designed to drive the polymer surfactant (S–)-mediated self-assembly of microclusters to produce robust, enzymatically active materials. The chimera scGFP-arPTE was structurally characterized via circular dichroism spectroscopy and synchrotron radiation small-angle X-ray scattering, and its biophysical properties were determined. Significantly, the chimera exhibited greater thermal stability than the native constituent proteins, as well as a higher catalytic turnover number (kcat). Furthermore, scGFP-arPTE was electrostatically complexed with monomeric S–, driving self-assembly into [scGFP-arPTE][S–] nanoclusters, which could be dehydrated and cross-linked to yield enzymatically active [scGFP-arPTE][S–] porous films with a high-order structure. Moreover, these clusters could self-assemble within cotton fibers to generate active composite textiles without the need for the pretreatment of the fabrics. Significantly, the resulting materials maintained the biophysical activities of both constituent proteins and displayed recyclable and persistent activity against the nerve agent simulant paraoxon.
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Dec 2021
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B18-Core EXAFS
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Diamond Proposal Number(s):
[14239]
Abstract: Bulk isocubanite (CuFe2S3) was synthesized via a multistep high-temperature synthesis and was investigated as an anode material for sodium-ion batteries. CuFe2S3 exhibits an excellent electrochemical performance with a capacity retention of 422 mA h g–1 for more than 1000 cycles at a current rate of 0.5 A g–1 (0.85 C). The complex reaction mechanism of the first cycle was investigated via PXRD and X-ray absorption spectroscopy. At the early stages of Na uptake, CuFe2S3 is converted to form crystalline CuFeS2 and nanocrystalline NaFe1.5S2 simultaneously. By increasing the Na content, Cu+ is reduced to nanocrystalline Cu, followed by the reduction of Fe2+ to amorphous Fe0 while reflections of nanocrystalline Na2S appear. During charging up to −5 Na/f.u., the intermediate NaFe1.5S2 appears again, which transforms in the last step of charging to a new unknown phase. This unknown phase together with NaFe1.5S2 plays a key role in the mechanism for the following cycles, evidenced by the PXRD investigation of the second cycle. Even after 400 cycles, the occurrence of nanocrystalline phases made it possible to gain insights into the alteration of the mechanism, which shows that CuxS phases play an important role in the region of constant specific capacity.
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Nov 2021
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B18-Core EXAFS
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Diamond Proposal Number(s):
[20060]
Abstract: Electrochemical performance of the layered compound CrPS4 for the usage as anode material in sodium-ion batteries (SIBs) was examined and exceptional reversible long-term capacity and capacity retention were found. After 300 cycles, an extraordinary reversible capacity of 687 mAh g–1 at a current rate of 1 A g–1 was achieved, while rate capability tests showed an excellent capacity retention of 100%. Detailed evaluation of the data evidence a change of the electrochemical reaction upon cycling leading to the striking long-term performance. Further investigations targeted the reaction mechanism of the first cycle by applying complementary techniques, i.e., powder X-ray diffraction (XRD), pair distribution function (PDF) analysis, X-ray absorption spectroscopy (XAS), and 23Na/31P magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The results indicated an unexpectedly complex reaction pathway including formation of several intercalation compounds, depending on the amount of Na inserted at the early discharge states and subsequent conversion to Na2S and strongly disordered metallic Cr at the completely discharged state. While XAS measurements suggest no further presence of intermediates after formation of Na intercalation compounds, several different phases are detected via MAS NMR upon continued discharging. Especially the data obtained from the MAS NMR investigations therefore point toward a very complex reaction pathway. Furthermore, solid electrolyte interphase (SEI) formation, resulting in the presence of NaF, was observed. After recharging the anode material, no structural long-range order occurred, but short-range order indeed resembled the local environment of the starting material, to a certain extent.
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Nov 2021
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