B18-Core EXAFS
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Diamond Proposal Number(s):
[36104]
Abstract: Seawater splitting has been considered an environmentally friendly and cost-effective method for hydrogen production. However, developing efficient electrocatalysts capable of enduring the severe corrosive conditions of natural seawaters for extended durations remains a notable technical challenge. Herein, the Ni3S2 supported NiFe oxalate ((NiFe)C2O4/Ni3S2) nanorod arrays were synthesised through hydrothermal and impregnation precipitation methods. Structural and spectroscopic analyses revealed that the (NiFe)C2O4/Ni3S2 catalyst formed an integrated oxide-sulfide interface with coexisting Ni–O/Ni–S coordination. This dual coordination environment, coupled with the presence of Fe in a higher oxidation state, confirmed interfacial electronic reorganization characterized by directional electron transfer from Ni to Fe. The resulting charge transfer pathway enhanced the electron delocalisation between active centers, thereby improving active site utilization. The obtained (NiFe)C2O4/Ni3S2 demonstrated remarkable catalytic activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in a simulated alkaline seawater solution (NaCl + KOH), with overpotentials of 363 mV (HER) and 295 mV (OER) at a current density of 500 mA cm−2 for industrial electrolysis requirements and remarkable stability over 100 h of durability testing. Additionally, the (NiFe)C2O4/Ni3S2 electrode pairs only required a cell voltage of 1.81 V to achieve 100 mA cm−2 with Faradaic efficiency of 98 % in 1.0 M KOH + seawater. This study presents a novel approach for fabricating multifunctional electrocatalysts, providing a promising pathway for advancing seawater electrolysis and supporting the development of cost-effective green hydrogen production technologies.
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Nov 2025
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I12-JEEP: Joint Engineering, Environmental and Processing
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Diamond Proposal Number(s):
[26730]
Open Access
Abstract: Hydrogen (H2) storage in porous geological formations offers a promising means to balance supply and demand in the renewable energy sector, supporting the energy transition. Important unknowns to this technology include the H2 fluid flow dynamics through the porous medium which affect H2 injectivity and recovery. We used time-resolved X-ray computed microtomography to image real-time unsteady and steady state injections of H2 and brine (2 M KI) into a Clashach sandstone core at 5 MPa and ambient temperature. In steady state injections, H2 entered the brine-saturated rock within seconds, dispersing over several discrete pores. Over time, some H2 ganglia connected, disconnected and then reconnected from each other (intermittent flow), indicating that the current presumption of a constant connected flow pathway during multiphase fluid flow is an oversimplification. Pressure oscillations at the sample outlet were characterized as red noise, supporting observations of intermittent pore-filling. At higher H2 fractional flow the H2 saturation in the pore space increased from 20-22 % to 28 %. Average Euler characteristics were generally positive over time at all H2 flow fractions, indicating poorly connected H2 clusters and little control of connectivity on the H2 saturation. In unsteady state injections, H2 displaced brine in sudden pore-filling events termed Haines jumps, which are key to understanding fluid dynamics in porous media. Our results suggest a lower H2 storage capacity in sandstone aquifers with higher injection-induced hydrodynamic flow and suggest a low H2 recovery. For more accurate predictions of H2 storage potential and recovery, geological models should incorporate energy-dissipating processes such as Haines jumps.
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Apr 2025
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B21-High Throughput SAXS
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Diamond Proposal Number(s):
[28659]
Abstract: In this research, we studied two novel lipopeptide sequences containing the amino acid serine (SPRWG) with one (compound 1) or two aliphatic tails (compound 2) to optimize the detection capabilities for organophosphate pesticides, specifically glyphosate. The study comprehensively explored how the incorporation of serine influences the physicochemical properties and supramolecular assembly of the lipopeptides, leading to enhanced interactions with glyphosate. Advanced analytical methods were employed to investigate these modifications, including fluorescence spectroscopy, circular dichroism, and small-angle X-ray scattering (SAXS). The results showed that serine significantly reduces the critical aggregation concentration, increases the hydrophilicity of the lipopeptides, and promotes the formation of distinct secondary structures—-turns in compound 1 and -sheets in compound 2. Moreover, isothermal titration calorimetry (ITC) and molecular dynamics confirmed the improved binding affinity with glyphosate strongly modulated by pH and pesticide load. Compound 1, with one alkyl chain, demonstrated notably higher catalytic activity and sensitivity linked to its pH equilibrium and structural features, marking it as particularly effective for acetylcholinesterase mimicry in pesticide detection. Density functional theory and molecular dynamics calculations showed that, when compared to the PRWG sequence, SPRWG has more unprotonated N-terminal sites due to a lower pKa, more beta-turn-like structures that improve stabilization, and more hydrogen bonds between N-(phosphonomethyl)glycine (PNG, commonly known as glyphosate) and aggregates across a wide pH range and P/L, which explains its enhanced reactivity in Ellman’s test and better inhibitory effects under the influence of PNG. Our results suggest that serine-functionalized lipopeptides have great potential as biomimetic sensors in environmental monitoring.
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Mar 2025
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I20-Scanning-X-ray spectroscopy (XAS/XES)
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Diamond Proposal Number(s):
[19223]
Abstract: High-charge micas exhibit improved adsorption properties and are a promising alternative clay material for the engineered barrier in deep geological repositories. When combined with Eu3+ cations, they serve as an in situ luminescent probe for tracking the physical–chemical changes occurring in this engineered barrier over the long term. Therefore, a better understanding of the local environment of the lanthanide is highly desirable to comprehend the specific behavior of these systems. A combination of different techniques, (X-ray diffraction, thermogravimetry, fluorescence, and X-ray absorption spectroscopy), has allowed the study of the local environment of two luminescent lanthanide cations, Eu3+ and Gd3+, embedded in the galleries of two high-charge micas with different Si/Al tetrahedral ratio. The results show that the hydration state of these cations is primarily influenced by the layer charge of the aluminosilicate, and secondarily by the cation’s hydration enthalpy. High-charge micas doped with trivalent lanthanide cations are more hydrated compared to the original clays with Na+ in the interlayer. Nevertheless, both Eu3+ and Gd3+ are adsorbed as inner-sphere complexes in the galleries of high-charge micas. They are located inside the distorted hexagonal cavity in all cases, coordinated by 3 oxygens from the tetragonal sheet, one fluorine from the octahedral sheet, and by 2–4 oxygens from water molecules, all at distances around 2.4 Å. An additional oxygen atom at a distance of 3.45–3.50 Å, is proposed from an H2O molecule in the second coordination shell.
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Jan 2025
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B18-Core EXAFS
E01-JEM ARM 200CF
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Diamond Proposal Number(s):
[23723, 17198]
Abstract: Electrochemical nitrate (NO3−) reduction reaction (NO3−RR) to ammonium (NH4+) or nitrogen (N2) provides a green route for nitrate remediation. However, nitrite generation and hydrogen evolution reactions hinder the feasibility of the process. Herein, dual single atom catalysts were rationally designed by introducing Ag/Bi/Mo atoms to atomically dispersed Nisingle bondNsingle bondC moieties supported by nitrogen-doped carbon nanosheet (NCNS) for the NO3−RR. Ni single atoms loaded on NCNS (Ni/NCNS) tend to reduce NO3− to valuable NH4+ with a high selectivity of 77.8 %. In contrast, the main product of NO3−RR catalyzing by NiAg/NCNS, NiBi/NCNS, and NiMo/NCNS was changed to N2, giving rise to N2 selectivity of 48.4, 47.1 and 47.5 %, respectively. Encouragingly, Ni/NCNS, NiBi/NCNS, and NiAg/NCNS showed excellent durability in acidic electrolytes, leading to nitrate conversion rates of 70.3, 91.1, and 93.2 % after a 10-h reaction. Simulated wastewater experiments showed that NiAg/NCNS could remove NO3− up to 97.8 % at −0.62 V after 9-h electrolysis. This work afforded a new strategy to regulate the reaction pathway and improve the conversion efficiency of the NO3−RR via engineering the dual atomic sites of the catalysts.
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Aug 2024
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B21-High Throughput SAXS
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Open Access
Abstract: Achieving a controlled preparation of nanoparticle superstructures with spatially periodic arrangement, also called superlattices, is one of the most intriguing and open questions in soft matter science. The interest in such regular superlattices originates from the potentialities in tailoring the physicochemical properties of the individual constituent nanoparticles, eventually leading to emerging behaviors and/or functionalities that are not exhibited by the initial building blocks. Despite progress, it is currently difficult to obtain such ordered structures; the influence of parameters, such as size, softness, interaction potentials, and entropy, are neither fully understood yet and not sufficiently studied for 3D systems. In this work, we describe the synthesis and characterization of spatially ordered hierarchical structures of coated cerium oxide nanoparticles in water suspension prepared by a bottom-up approach. Covering the CeO2 surface with amphiphilic molecules having chains of appropriate length makes it possible to form ordered structures in which the particles occupy well-defined positions. In the present case superlattice arrangement is accompanied by an improvement in photoluminescence (PL) efficiency, as an increase in PL intensity of the superlattice structure of up to 400 % compared with that of randomly dispersed nanoparticles was observed. To the best of our knowledge, this is one of the first works in the literature in which the coexistence of 3D structures in solution, such as face-centered cubic (FCC) and Frank-Kasper (FK) phases, of semiconductor nanoparticles have been related to their optical properties.
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Apr 2024
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B21-High Throughput SAXS
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Diamond Proposal Number(s):
[28287]
Abstract: A library of composite polymer networks (CPNs) were formed by combining Pluronic F127, as the primary gelator, with a range of di-acrylate functionalised PEG polymers, which tune the rheological properties and provide UV crosslinkability. A coarse-grained sol–gel room temperature phase diagram was constructed for the CPN library, which identifies PEG-dependent disruption of micelles as leading to liquefication. Small angle X-ray scattering and rheological measurements provide detailed insight into; (i) micelle-micelle ordering; (ii) micelle-micelle disruption, and; (iii) acrylate-micelle disruption; with contributions that depend on composition, including weak PEG chain length and end group effects. The influence of composition on 3D extrusion printability through modulation of the cohesive/hydrophobic interactions was assessed. It was found that only micelle content provides consistent changes in printing fidelity, controlled largely by printing conditions (pressure and feed rate). Finally, the hydrogels were shown to be UV photo-crosslinkable, which further improves fidelity and structural integrity, and usefully reduces the mesh size. Our results provide a guide for design of 3D-printable CPN inks for future biomedical applications.
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Jan 2024
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I07-Surface & interface diffraction
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Diamond Proposal Number(s):
[26893]
Open Access
Abstract: Whilst bottlebrush polymers have been studied in aqueous media for their conjectured role in biolubrication, surface forces and friction mediated by bottlebrush polymers in nonpolar media have not been previously reported. Here, small-angle neutron scattering (SANS) showed that a diblock bottlebrush copolymer (oligoethyleneglycol acrylate/ethylhexyl acrylate; OEGA/EHA) formed spherical core–shell aggregates in n-dodecane (a model oil) in the polymer concentration range 0.1–2.0 wt%, with a radius of gyration Rg ∼ 7 nm, comprising 40–65 polymer molecules per aggregate. The surface force apparatus (SFA) measurements revealed purely repulsive forces between surfaces bearing inhomogeneous polymer layers of thickness L ∼ 13–23 nm, attributed to adsorption of a mixture of polymer chains and surface-deformed micelles. Despite the surface inhomogeneity, the polymer layers could mediate effective lubrication, demonstrating superlubricity with the friction coefficient as low as µ ∼ 0.003. The analysis of velocity-dependence of friction using the Eyring model shed light on the mechanistic insights on the frictional process. That is, the friction mediation was consistent with the presence of nanoscopic surface aggregates, with possible contributions from a gel-like network formed by the polymer chains on the surface. These unprecedented results, correlating self-assembled polymer micelle structure with the surface forces and friction the polymer layers mediate, highlight the potential of polymers with the diblock bottlebrush architecture widespread in biological living systems, in tailoring desired surface interactions in nonpolar media.
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Dec 2023
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I07-Surface & interface diffraction
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Diamond Proposal Number(s):
[22995]
Open Access
Abstract: Hypothesis: The attractive interaction between a cationic surfactant monolayer at the air–water interface and vesicles, incorporating anionic lipids, is sufficient to drive the adsorption and deformation of the vesicles. Osmotic rupture of the vesicles produces a continuous lipid bilayer beneath the monolayer. Experimental: Specular neutron reflectivity has been measured from the surface of a purpose-built laminar flow trough, which allows for rapid adsorption of vesicles, the changes in salt concentration required for osmotic rupture of the adsorbed vesicles into a bilayer, and for neutron contrast variation of the sub-phase without disturbing the monolayer. Findings: The neutron reflectivity profiles measured after vesicle addition are consistent with the adsorption and flattening of the vesicles beneath the monolayer. An increase in the buffer salt concentration results in further flattening and fusion of the adsorbed vesicles, which are ruptured by a subsequent decrease in the salt concentration. This process results in a continuous, high coverage, bilayer suspended 11 Å beneath the monolayer. As the bilayer is not constrained by a solid substrate, this new mimetic is well-suited to studying the structure of lipid bilayers that include transmembrane proteins.
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Mar 2023
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B21-High Throughput SAXS
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Diamond Proposal Number(s):
[12411]
Abstract: The mixing of conventional and pH-sensitive lipids was exploited to design novel stimuli-responsive liposomes (fliposomes) that could be used for smart drug delivery. We deeply investigated the structural properties of the fliposomes and revealed the mechanisms that are involved in a membrane transformation during a pH change. From ITC experiments we observed the existence of a slow process that was attributed to lipid layers arrangement with changing pH. Moreover, we determined for the first time the pKa value of the trigger-lipid in an aqueous milieu that is drastically different from the methanol-based values reported previously in the literature. Furthermore, we studied the release kinetics of encapsulated NaCl and proposed a novel model of release that involves the physical fitting parameters that could be extracted from the release curves fitting. We have obtained for the first time, the values of pores self-healing times and were able to trace their evolution with changing pH, temperature, the amount of lipid-trigger.
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Feb 2023
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