E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[35514]
Open Access
Abstract: The oxygen reduction reaction (ORR) is a central process in energy conversion and storage systems, such as fuel cells and metal–air batteries. To meet the urgent demand for efficient ORR catalysts, promising single-atom catalysts (SACs) with heteroatoms incorporated into a carbon matrix are a current research focus. However, the complex structure–function relationships between their metal coordination environments and the resulting ORR activity remain to be fully understood. Herein, three Cu-based SACs featuring S heteroatoms at different distances from the Cu center were synthesized by a ligand modification strategy. The short-range order of Cu-SACs was resolved by X-ray absorption spectroscopy (XAS), and the Gibbs adsorption energies (ΔG) of ORR intermediates were calculated by density functional theory (DFT). Using the correlation between ΔGOOH* and ΔGO* as a descriptor for the ORR activity linked to the O–O bond cleavage and Cu–S interatomic distances, we show that balanced *OOH adsorption occurs when S atoms are located in the second coordination shell around the Cu centers forming Cu–N4/S–C moieties. Combined operando Raman spectroscopy and operando XAS further unravel the dynamic role of sulfur incorporation in the optimization of the local coordination environment of Cu centers toward the facilitated generation of key ORR intermediates. When assembled into a rechargeable Zn–air battery (ZAB), the Cu–N4/S–C cathode displayed a peak power density of 138.9 mW cm–2 and sustained operation for 80 h. In a flexible ZAB, the Cu–N4/S–C air cathode revealed an open-circuit potential of 1.56 V and good bending tolerance. This work provides mechanistic insights on how dopant sites of heteroatomic species influence the catalytic activity of metal centers in SACs through their specific local coordination environments, thereby offering valuable atomic-level structure descriptors for performance optimization.
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Aug 2026
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E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[38966]
Open Access
Abstract: Mixed-cation lead mixed-halide perovskites are promising materials for applications in photovoltaics; however, it has been suggested that they exhibit instabilities linked to nanoscale heterogeneity. Directly probing the origins of this heterogeneity requires characterization with nanoscale spatial resolution, making transmission electron microscopy (TEM) an essential tool. However, characterizing these materials is challenging due to their extreme sensitivity to electron irradiation. Here, we develop a low-dose, concurrent methodology using four-dimensional scanning transmission electron microscopy (4D-STEM) and energy-dispersive x-ray spectroscopy (EDX) in order to map both the chemical and structural architecture of a (FA0.83Cs0.17)Pb(I0.8Br0.2)3 perovskite film without inducing damage. Our correlative analysis reveals a complex mosaic of coexisting crystal structures in this state-of-the-art LHP film. We establish a direct link between local chemical composition and crystal structure, showing that the formation of undesirable, photovoltaically inactive hexagonal polytypes is predominantly driven by local deficiencies in the stabilizing cesium cation. These findings provide crucial insight into one of the fundamental origins of structural instabilities in mixed composition perovskite thin-films, suggesting that achieving long-term device performance requires the development of fabrication routes that ensure compositional homogeneity at the nanoscale.
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Jul 2026
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E02-JEM ARM 300CF
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Leyuan
Zhang
,
Dongfang
Cheng
,
Pu
Zhang
,
David G.
Hopkinson
,
Zhaozong
Wang
,
Ao
Zhang
,
Chen
Li
,
Ran
Wang
,
Rongli
Liu
,
Christopher S.
Allen
,
Johanna
Nelson Weker
,
Yu
Huang
,
Philippe
Sautet
,
Xiangfeng
Duan
Diamond Proposal Number(s):
[32750]
Open Access
Abstract: Lithium–sulfur batteries are fundamentally constrained by the sluggish 16-electron sulfur reduction reaction. Electrocatalytic sulfur reduction reaction is inherently complex, involving multiple lithium polysulfide intermediates (Li2Sn, n = 2–8), each with distinct adsorption and activation requirements, leading to unbalanced polysulfide conversion and severe shuttle effect. Although cascade catalysis has been proposed as a potential solution, the precise pathway and its mechanistic role in regulating polysulfide conversion remain elusive. Here we elucidate and experimentally validate the complete cascade pathway of sulfur reduction on Fe,N,S-codoped holey graphene as a model catalyst. Density functional theory reveals that Fe sites preferentially bind and activate long-chain polysulfides, while N,S-C sites accelerate the conversion of Li2S4 to Li2S2/Li2S. Such site-specific synergy balances sulfur reduction kinetics and suppresses polysulfide accumulation. Combined kinetic analysis and operando Raman spectroscopy directly reveal how synergistic cascade catalysis governs the reaction pathway, modulates key intermediates, and enables balanced polysulfide conversion. Together, these results establish cascade catalysis as a mechanism-driven design strategy for lithium–sulfur battery electrodes, where regulation of the reaction pathway suppresses polysulfide shuttling and enables enhanced cycling stability.
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Jul 2026
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E02-JEM ARM 300CF
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Sam
Sullivan-Allsop
,
Nick
Clark
,
Wendong
Wang
,
Rongsheng
Cai
,
William
Thornley
,
David G.
Hopkinson
,
James G.
Mchugh
,
Ben
Davies
,
Samuel
Pattisson
,
Nicholas F.
Dummer
,
Rui
Zhang
,
Matthew
Lindley
,
Gareth
Tainton
,
Jack
Harrison
,
Hugo
De Latour
,
Joseph
Parker
,
Joshua
Swindell
,
Eli G.
Castanon
,
Amy
Carl
,
David J.
Lewis
,
Natalia
Martsinovich
,
Christopher S.
Allen
,
Mohsen
Danaie
,
Andrew J.
Logsdail
,
Vladimir
Fal’ko
,
Graham J.
Hutchings
,
Alex
Summerfield
,
Roman
Gorbachev
,
Sarah J.
Haigh
Diamond Proposal Number(s):
[33252, 35552]
Abstract: The structure and dynamics of adsorbed atoms (adatoms) at solid-liquid interfaces determine the performance of advanced catalysts, electrochemical devices, molecular separation technologies, and metal extraction from waste streams. However, in situ investigations of atomically dispersed metals in various chemical environments have been prevented by insufficient imaging resolution and solvent incompatibility. In this study, we combined a specimen design that provides atomic resolution in liquid-phase electron microscopy with deep learning–enabled analysis to explore the interactions between gold adatoms, graphite support, and the solvent collectively. We tracked the locations of >106 graphite-supported gold adatoms, dimers, and larger clusters in five solvents. Although their initial atomic dispersion was determined by the solvent polarity, fast drying kinetics at low temperature was required for optimizing catalytic performance.
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Apr 2026
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E02-JEM ARM 300CF
I05-ARPES
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Amy
Carl
,
Nicholas
Clark
,
David G.
Hopkinson
,
Matthew
Hamer
,
Matthew
Watson
,
Laxman
Nagireddy
,
James E.
Nunn
,
Alexei
Barinov
,
Yichao
Zou
,
William
Thornley
,
Casey
Cheung
,
Wendong
Wang
,
Sam
Sullivan-Allsop
,
Xiao
Li
,
Astrid
Weston
,
Eli G.
Castanon
,
Andrey V.
Kretinin
,
Cephise
Cacho
,
Neil R.
Wilson
,
Sarah J.
Haigh
,
Roman
Gorbachev
Diamond Proposal Number(s):
[21597, 21981, 24290, 24338]
Open Access
Abstract: Magnetic two-dimensional materials are a promising platform for novel nano-electronic device architectures. One such layered crystal is the ferromagnetic semiconductor chromium germanium telluride (Cr2Ge2Te6) which recently attracted interest due to its potential for spintronics and memory applications. Here we investigate its properties from the structural standpoint using atomic resolution Scanning Transmission Electron Microscopy (STEM) and present the first atomic resolution images down to its monolayer limit. We develop a novel technique that allows one to map the local tilt with unprecedented spatial resolution using only high-resolution images, enabling mapping of the topography and morphological variation of atomically thin crystals. Using it, we show that the Cr2Ge2Te6 monolayer has an unusually large out-of-plane rippling, with local tilt variation reaching 20° over few nm length scales. We hypothesize that such a strongly buckled structure originates from both point and extended lattice defects which are more prevalent in monolayer crystals. In addition, we correlate the structural observations with the band structure measurements using Angle-Resolved Photoemission Spectroscopy (ARPES). We believe that both the atomic scale insights we have gained on Cr2Ge2Te6 and our novel approach to nanoscale topography mapping will benefit the development of van der Waals heterostructures in both fundamental and applied research.
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Feb 2026
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E02-JEM ARM 300CF
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Wendong
Wang
,
Gareth R.
Tainton
,
Nicholas J.
Clark
,
James G.
Mchugh
,
Xue
Li
,
Sam
Sullivan-Allsop
,
David G.
Hopkinson
,
Oldrich
Cicvárek
,
Francisco
Selles
,
Rui
Zhang
,
Joshua D.
Swindell
,
Alex
Summerfield
,
David J.
Lewis
,
Vladimir I.
Fal'Ko
,
Zdenek
Sofer
,
Sarah
Haigh
,
Roman
Gorbachev
Diamond Proposal Number(s):
[39088]
Abstract: Transition metal diiodides such as FeI2, NiI2, and CoI2 are an emerging class of 2D magnets exhibiting rich and diverse magnetic behavior, but their study at the monolayer limit has been severely hindered by fabrication challenges due to their air-sensitivity. Here, we introduce a polymer-free method for clean, rapid, and high-yield assembly of hermetically encapsulated suspended samples of air-sensitive monolayers. Applied to diiodides, it enables atomic resolution characterization of thin samples down to the monolayer limit using transmission electron microscopy. Our imaging, combined with complementary first-principles calculations, reveals an unusually small energy barrier between alternate stable stacking polytypes in few-layer films, enabling extrinsic control of the stacking phase. We also observe stable isolated iodine vacancies that do not aggregate to form extended structures and identify and verify the stability of the various edge configurations of thin samples. These results establish the structural characteristics of these materials in the thin limit and more broadly demonstrate the utility of our transfer platform for creating atomically clean suspended van der Waals heterostructures.
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Jan 2026
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E01-JEM ARM 200CF
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Diamond Proposal Number(s):
[33481]
Open Access
Abstract: A novel heterostructured hexagonal-boron nitride (h-BN) flake-coating on multi-wall carbon nanotubes (MWCNT/BN) is reported and synthesized by chemical vapor deposition (CVD). Comprehensive characterization using X-ray photoelectron spectroscopy (XPS) and scanning transmission electron microscopy (STEM), combined with electron energy loss spectroscopy (EELS), revealed the atomic structure and growth mechanism, which is further validated by molecular dynamics simulations. The resulting MWCNT/BN structure comprises three distinct layers: an inner carbon nanotube (CNT) core, coaxial BN nanotubes (BNNTs) surrounding the CNT core, and outer BN flakes extending from the BNNTs. We propose that BN layers first form coaxial BNNTs on the CNT surface; as deposition proceeds, BN accumulation generate in-plane and out-of-plane compressive stresses in the h-BN layers. When these stresses exceed a critical threshold, local buckling or cracking occurs, BN flakes emerge and grow further. This work elucidates, for the first time, the formation mechanism of BN nanoflakes on MWCNTs and confirms that the structure is a van der Waals heterostructure. The approach also offers a new route for synthesizing coaxial MWCNT@BN with only a few h-BN layers. Notably, the BN flake coatings provide efficient phonon transport pathways and a large surface area, making this heterostructure highly promising for applications in thermal dissipation.
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Dec 2025
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E01-JEM ARM 200CF
E02-JEM ARM 300CF
I18-Microfocus Spectroscopy
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N.
Topping
,
J. C.
Bridges
,
L. J.
Hicks
,
L.
Petera
,
C. S.
Allen
,
J.
Ryu
,
D. G.
Hopkinson
,
M.
Danaie
,
L.
Blase
,
F. M.
Willcocks
,
G.
Douglas
,
H. G.
Changela
,
T.
Noguchi
,
T.
Matsumoto
,
A.
Miyake
Diamond Proposal Number(s):
[30752, 31953, 32874, 35976, 29615, 31641, 35046]
Open Access
Abstract: A correlative multi-technique approach, including electron microscopy and X-ray synchrotron work, has been used to obtain both structural and compositional information of a sulfur-bearing serpentine identified in several carbonaceous chondrites (Winchcombe CM2, Aguas Zarcas CM2, Ivuna CI, and Orgueil CI), and in Ryugu samples returned by the Hayabusa2 mission. S-K edge X-ray absorption spectroscopy was used to determine the oxidation state of sulfur in the serpentine in all samples except Ryugu. The abundance of this phase varies across these samples, with the largest amount in Winchcombe; ~12 vol% of phyllosilicates are identified as sulfur-bearing serpentine characterized by ~10 wt% SO3 equivalent. HRTEM studies reveal a d001-spacing range of 0.64–0.70 nm across all sulfur-bearing serpentine sites, averaging 0.68 nm, characteristic of serpentine. Sulfur-serpentine has variable S6+/ΣStotal values and different sulfur species dependent on specimen type, with CM sulfur-bearing serpentine having values of 0.1–0.2 and S2− as the dominant valency, and CIs having values of 0.9–1.0 with S6+ as the dominant valency. We suggest sulfur is structurally incorporated into serpentine as SH− partially replacing OH−, and trapped as SO42− ions, with an approximate mineral formula of (Mg Fe2+ Fe3+ Al)2-3(Si Al)2O5(OH)5-6(HS−)1-2(SO4)2−0.1-0.7. We conclude that much of the material identified in previous studies of carbonaceous chondrites as TCI-like or PCPs could be sulfur-bearing serpentine. The relatively high abundance of sulfur-bearing serpentine suggests that incorporation of sulfur into this phase was a significant part of the S-cycle in the early Solar System.
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Nov 2025
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B07-C-Versatile Soft X-ray beamline: Ambient Pressure XPS and NEXAFS
E01-JEM ARM 200CF
I20-Scanning-X-ray spectroscopy (XAS/XES)
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Lu
Chen
,
Xuze
Guan
,
Zhangyi
Yao
,
Shusaku
Hayama
,
Matthijs A.
Van Spronsen
,
Burcu
Karagoz
,
Georg
Held
,
David G.
Hopkinson
,
Christopher S.
Allen
,
June
Callison
,
Paul J.
Dyson
,
Feng Ryan
Wang
Diamond Proposal Number(s):
[30576, 31867, 32996]
Open Access
Abstract: Tuning the electronic properties of nanocatalysts via doping with monodispersed hetero-metal atoms is an effective method used to enhance catalytic properties. Doping CuO nanoparticles with monodispersed Co atoms using different reductants affords catalysts (CoBCu/Al2O3 and CoHCu/Al2O3) with strikingly different electronic structures. Compared to CoHCu/Al2O3, the CuO nanoparticles in CoBCu/Al2O3 have longer and weaker Cu-O bonds, with a lower 1s → 4pz antibonding transition and higher 4p → 1s bonding transition (as demonstrated from HERFD-XANES and valence-to-core X-ray emission spectroscopy). The weaker Cu-O bonds in CoBCu/Al2O3 lead to superior redox activity of the CuO nanoparticles, evidenced from operando XAFS and in-situ near ambient pressure-near edge X-ray absorption fine structures studies. Such superior redox properties of CuO in CoBCu/Al2O3 result in a much reduced activation energy of CoBCu/Al2O3 compared to CoHCu/Al2O3 (40.0 vs. 63.5 kJ/mol), thus leading to an enhancement in catalytic performance in the selective catalytic oxidation of NH3 to N2.
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Oct 2025
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E02-JEM ARM 300CF
I09-Surface and Interface Structural Analysis
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Benedikt P.
Klein
,
Matthew A.
Stoodley
,
Joel
Deyerling
,
Luke A.
Rochford
,
Dylan B.
Morgan
,
David G.
Hopkinson
,
Sam
Sullivan-Allsop
,
Henry
Thake
,
Fulden
Eratam
,
Lars
Sattler
,
Sebastian M.
Weber
,
Gerhard
Hilt
,
Alexander
Generalov
,
Alexei
Preobrajenski
,
Thomas
Liddy
,
Leon B. S.
Williams
,
Mhairi A.
Buchan
,
Graham A
Rance
,
Tien-Lin
Lee
,
Alex
Saywell
,
Roman
Gorbachev
,
Sarah J.
Haigh
,
Christopher S.
Allen
,
Willi
Auwärter
,
Reinhard
Maurer
,
David A.
Duncan
Diamond Proposal Number(s):
[25379, 30875, 31695, 31165, 33709]
Open Access
Abstract: Chemical vapour deposition enables large-domain growth of ideal graphene, yet many applications of graphene require the controlled inclusion of specific defects. We present a one-step chemical vapour deposition procedure aimed at retaining the precursor topology when incorporated into the grown carbonaceous film. When azupyrene, the molecular analogue of the Stone–Wales defect in graphene, is used as a precursor, carbonaceous monolayers with a range of morphologies are produced as a function of the copper substrate growth temperature. The higher the substrate temperature during deposition, the closer the resulting monolayer is to ideal graphene. Analysis, with a set of complementary materials characterisation techniques, reveals morphological changes closely correlated with changes in the atomic adsorption heights, network topology, and concentration of 5-/7-membered carbon rings. The engineered defective carbon monolayers can be transferred to different substrates, potentially enabling applications in nanoelectronics, sensorics, and catalysis.
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Sep 2025
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