B18-Core EXAFS
E01-JEM ARM 200CF
I09-Surface and Interface Structural Analysis
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Thomas J.
Liddy
,
Benjamin J.
Young
,
Emerson C.
Kohlrausch
,
Andreas
Weilhard
,
Gazi N.
Aliev
,
Yifan
Chen
,
Manfred E.
Schuster
,
Mohsen
Danaie
,
Luke L.
Keenan
,
Donato
Decarolis
,
Diego
Gianolio
,
Siqi
Wang
,
Mingming
Zhu
,
Graham J.
Hutchings
,
David M.
Grant
,
Wolfgang
Theis
,
Tien-Lin
Lee
,
David A.
Duncan
,
Alberto
Roldan
,
Andrei N.
Khlobystov
,
Jesum
Alves Fernandes
Diamond Proposal Number(s):
[38764]
Open Access
Abstract: Ammonia is an attractive hydrogen carrier, yet its practical use is limited by the need for efficient catalytic decomposition. We demonstrate that in-situ N-doping of Ru nanoparticles and graphitized carbon nanofiber supports during reaction produces a sharp increase in hydrogen production during the first 40 h, followed by stable activity. Spectroscopic and microscopic analyses, together with density functional theory simulations, reveal that Ru nitridation is rapid and support-independent, resulting in a mechanistic shift from the traditional Langmuir–Hinshelwood to a Mars–van Krevelen pathway, further confirmed by isotopic labelling experiments. In contrast, the progressive nitridation of the carbon support, observed via X-ray photoelectron spectroscopy, modulates the electronic environment of Ru and functions as a dynamic nitrogen reservoir that enables reversible N atoms exchange with the Ru particles, facilitating N desorption from the Ru surface and thereby governing the catalytic activity enhancement. These new findings provide new mechanistic insight into ammonia decomposition and establish progressive nitrogen doping of carbon supports as a strategy for designing efficient metal-based catalysts for hydrogen production.
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Dec 2025
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E01-JEM ARM 200CF
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Emerson C.
Kohlrausch
,
Sadegh
Ghaderzadeh
,
Gazi N.
Aliev
,
Ilya
Popov
,
Fatmah
Saad
,
Eman
Alharbi
,
Quentin M.
Ramasse
,
Graham A.
Rance
,
Mohsen
Danaie
,
Madasamy
Thangamuthu
,
Mathew
Young
,
Richard
Plummer
,
David J.
Morgan
,
Wolfgang
Theis
,
Elena
Besley
,
Andrei N.
Khlobystov
,
Jesum
Alves Fernandes
Diamond Proposal Number(s):
[37379, 38763]
Open Access
Abstract: 2D metal clusters maximize atom–surface interactions, making them highly attractive for energy and electronic technologies. However, their fabrication remains extremely challenging because they are thermodynamically unstable. Current methods are limited to element-specific binding sites or confinement of metals between layers, with no universal strategy achieved to date. Here, a general approach is presented that uses vacancy defects as universal binding sites to fabricate single-layer metal clusters (SLMC). It is demonstrated that the density of these vacancies governs metal atom diffusion and bonding to the surface, overriding the metal's physicochemical properties. Crucially, the reactivity of vacancy sites must be preserved prior to metal deposition to enable SLMC formation. This strategy is demonstrated across 21 elements and their mixtures, yielding SLMC with areal densities up to 4.3 atoms∙nm⁻2, without heteroatom doping, while maintaining high thermal, environmental, and electrochemical stability. These findings provide a universal strategy for stabilizing SLMC, eliminating the need for element-specific synthesis and metal confinement protocols and offering a strategy for efficiently utilizing metals.
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Jul 2025
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B18-Core EXAFS
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Diamond Proposal Number(s):
[19850, 17198]
Open Access
Abstract: In this work, we demonstrate that the synergistic effect of PdAu nanoparticles (NPs) in hydrogenation reactions is not only related to high activity but also to their stability when compared to Pd mono-metallic NPs. To demonstrate this, a series of mono- and bi-metallic NPs; Pd, Pd0.75Au0.25, Pd0.5Au0.5, Pd0.25Au0.75 and Au in ionic liquid [C4C1Im][NTf2] have been fabricated via magnetron sputtering process. Bi-metallic NPs possess external shells enriched with Pd atoms that interact with [NTf2]- of the ionic liquid resulting in enhanced catalytic performance in hydrogenation of cinnamanaldehyde compared to their mono-metallic counterparts. This is ascribed to their higher stability over 24 h reaction, whilst the catalytic activity and selectivity are comparable for both catalysts. Using a bespoke kinetic model for in situ catalyst deactivation investigations and electron microscopy imaging at nanoscale, we have shown that PdAu has a deactivation rate constant of 0.13 h-1, compared to 0.33 h-1 for Pd NPs, leaving 60 % and 40 % of available sites after the reaction, respectively. Beyond that, the kinetic model demonstrates that the reaction product has a strong stabilizing factor for bimetallic NPs against coarsening and deactivation, which is not the case for Pd NPs. In summary, our kinetic model enables the evaluation of the catalyst performance over the entire chemical reaction space, probing the contribution of each individual components of the reaction mixture and allowing the design of high-performance catalysts.
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Jun 2023
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B18-Core EXAFS
E01-JEM ARM 200CF
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Emerson Cristofer
Kohlrausch
,
Higor A.
Centurion
,
Rhys
Lodge
,
Xuanli
Luo
,
Thomas
Slater
,
Marcos J. L.
Santos
,
Sanliang
Ling
,
Valmor R.
Mastelaro
,
Matthew J.
Cliffe
,
Renato
Vitalino Goncalves
,
Jesum
Alves Fernandes
Diamond Proposal Number(s):
[25120, 17198, 24914]
Open Access
Abstract: Atomically-dispersed metal catalysts (ADMCs) on surfaces have demonstrated
high activity and selectivity in many catalytic reactions. However, dispersing and stabilising
individual atoms in support materials in an atom/energy-efficient scalable way still presents a
significant challenge. Currently, the synthesis of ADMCs involves many steps and further
filtration procedures, creating a substantial hurdle to their production at industrial scale. In this
work, we develop a new pathway for producing ADMCs in which Pt atoms are stabilised in the
nitrogen-interstices of a graphitic carbon nitride (g-C3N4) framework using scalable, solvent-free,
one-pot magnetron sputtering deposition. Our approach has the highest reported rate of ADMC
production of 4.8 mg h-1 and generates no chemical waste. Deposition of only 0.5 weight percent
of Pt onto g-C3N4 led to improved hydrogen production by factor of ca. 3333 ± 450 when compared to bare g-C3N4. PL analysis showed that the deposition of Pt atoms onto g-C3N4 suppressed the
charge carrier recombination from the photogenerated electron-hole pairs of Pt/g-C3N4 thereby
enhance hydrogen evolution. Scanning transmission electron microscope imaging before and after
the hydrogen evolution reaction revealed that the Pt atoms stabilised in g-C3N4 have a high
stability, with no agglomeration observed. Herein, it is shown that this scalable and clean approach
can produce effective ADMCs with no further synthetic steps required, and that they can be readily
used for catalytic reactions.
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Nov 2021
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B18-Core EXAFS
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Israel
Cano
,
Andreas
Weilhard
,
Carmen
Martin
,
Jose
Pinto
,
Rhys W.
Lodge
,
Ana R.
Santos
,
Graham A.
Rance
,
Elina Harriet
Åhlgren
,
Erlendur
Jónsson
,
Jun
Yuan
,
Ziyou Y.
Li
,
Peter
Licence
,
Andrei N.
Khlobystov
,
Jesum
Alves Fernandes
Diamond Proposal Number(s):
[19850, 17198]
Open Access
Abstract: Using a magnetron sputtering approach that allows size-controlled formation of nanoclusters, we have created palladium nanoclusters that combine the features of both heterogeneous and homogeneous catalysts. Here we report the atomic structures and electronic environments of a series of metal nanoclusters in ionic liquids at different stages of formation, leading to the discovery of Pd nanoclusters with a core of ca. 2 nm surrounded by a diffuse dynamic shell of atoms in [C4C1Im][NTf2]. Comparison of the catalytic activity of Pd nanoclusters in alkene cyclopropanation reveals that the atomically dynamic surface is critically important, increasing the activity by a factor of ca. 2 when compared to compact nanoclusters of similar size. Catalyst poisoning tests using mercury and dibenzo[a,e]cyclooctene show that dynamic Pd nanoclusters maintain their catalytic activity, which demonstrate their combined features of homogeneous and heterogeneous catalysts within the same material. Additionally, kinetic studies of cyclopropanation of alkenes mediated by the dynamic Pd nanoclusters reveal an observed catalyst order of 1, underpinning the pseudo-homogeneous character of the dynamic Pd nanoclusters.
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Aug 2021
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I22-Small angle scattering & Diffraction
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Ryan R.
Larder
,
Thomas
Bennett
,
L. Scott
Blankenship
,
Jesum A.
Fernandes
,
Bethany K.
Husband
,
Rachel L.
Atkinson
,
Matthew J.
Derry
,
Daniel T. W.
Toolan
,
Higor A.
Centurion
,
Paul D.
Topham
,
Renato V.
Goncalves
,
Vincenzo
Taresco
,
Steven M.
Howdle
Diamond Proposal Number(s):
[23501]
Open Access
Abstract: Reversible addition–fragmentation chain transfer (RAFT) mediated dispersion polymerisation in supercritical carbon dioxide (scCO2) is an efficient and green method for synthesising block copolymer microparticles with internal nanostructures. Here we report for the first time the synthesis of phase separated poly(methyl methacrylate-block-styrene-block-4-vinylpyridine) (PMMA-b-PS-b-P4VP) triblock terpolymer microparticles using a simple two-pot sequential synthesis procedure in scCO2, with high monomer conversions and no purification steps. The microparticles, produced directly and without further processing, show a complex internal nanostructure, appearing as a “lamellar with spheres” [L + S(II)] type morphology. The P4VP block is then exploited as a structure-directing agent for the fabrication of TiO2 microparticles. Through a simple and scalable sol–gel and calcination process we produce hollow TiO2 microparticles with a mesoporous outer shell. When directly compared to porous TiO2 particles fabricated using an equivalent PMMA-b-P4VP diblock copolymer, increased surface area and enhanced photocatalytic efficiencies are observed.
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Apr 2021
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B18-Core EXAFS
E01-JEM ARM 200CF
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Diamond Proposal Number(s):
[23723, 17198]
Abstract: The general and cost-effective synthesis of single atom electrocatalysts (SAECs) still remains a great challenge. Herein, we report a general synthetic protocol for the synthesis of SAECs via a simple condensation–carbonization process, in which furfural and cyanamide were condensation polymerized in the presence of polystyrene nanospheres and metal ions, followed by a pyrolysis to N-doped carbon nanosheet (NCNS) supported SAECs. Six types of SAECs containing platinum, palladium, gold, nickel, cobalt and iron were synthesized to demonstrate the generality of the synthesis protocol. This methodology affords a facile solution to the trade-off between support conductivity and metal loading of SAECs by optimizing the ratio of carbon/nitrogen precursors, i.e., furfural and cyanamide. The presence of single metal atoms was confirmed by high-angle annular dark field scanning transmission electron microscopy and X-ray absorption fine structure measurements. The three-dimensional distribution of single platinum atoms was vividly revealed by depth profile analysis using a scanning transmission electron microscope. The resulting SAECs showed excellent performance for glycerol electro-oxidation and water splitting in alkaline solutions. Notably, Pt/NCNSs possessed an unprecedent mass-normalized current density of 5.3 A per milligram of platinum, which is 32 times that of the commercial Pt/C catalyst. Density functional theory calculations were conducted to reveal the adsorption behavior of glycerol over the SAECs. Using Ni/NCNSs and Co/NCNSs as anodic and cathodic electrocatalysts, we constructed a solar panel powered electrolytic cell for overall water splitting, leading to an overall energy efficiency of 8.8%, which is among the largest solar-to-hydrogen conversion efficiencies reported in the literature.
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Nov 2020
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I20-Scanning-X-ray spectroscopy (XAS/XES)
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Diamond Proposal Number(s):
[15151]
Open Access
Abstract: We report the design and preparation of multifunctional hybrid nanomaterials through the stabilization of gold nanoparticles with thiol‐functionalised hybrid organic–inorganic polyoxometalates (POMs). The covalent attachment of the hybrid POM forms new nanocomposites that are stable at temperatures and pH values which destroy analogous electrostatically functionalised nanocomposites. Photoelectrochemical analysis revealed the unique photochemical and redox properties of these systems.
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Aug 2020
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B18-Core EXAFS
E01-JEM ARM 200CF
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Diamond Proposal Number(s):
[23723, 17198]
Abstract: Herein, we report a facile route to synthesize isolated single iron atoms on nitrogen-sulfur-codoped carbon matrix via a direct pyrolysis process in which hemoglobin, a by-product of the meat industry, was utilized as a precursor for iron, nitrogen and sulfur while bamboo-shaped carbon nanotubes served as a support owing to their excellent conductivity and numerous defects. The resulting metal-nitrogen complexed carbon showed outstanding catalytic performance for the oxygen evolution reaction (OER) in alkaline solutions. At an overpotential of 380 mV, the optimal sample yielded a current density of 83.6 mA cm−2, which is 2.5 times that of benchmark IrO2 (32.8 mA cm−2), rendering it as one of the best OER catalysts reported so far. It also showed negligible activity decay in alkaline solutions during long-term durability tests. Control experiments and X-ray absorption fine structure analyses revealed that Fe-Nx species in the samples are the active sites for OER. Further density functional theory calculations indicated that the presence of sulfur in the carbon matrix modified the electronic structures of active species, thereby leading to the superior activity of the sample.
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Jun 2020
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