I20-Scanning-X-ray spectroscopy (XAS/XES)
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Diamond Proposal Number(s):
[31504, 31559]
Open Access
Abstract: Lytic polysaccharide monooxygenases (LPMOs) play a critical role in the depolymerization of recalcitrant polysaccharides, such as chitin, making them of interest in biotechnological applications. These interfacial enzymes are also of great chemical interest because of their unique monocopper catalytic center and their ability to activate high energy C–H bonds. This report investigates the structural and electronic changes at the copper (Cu) site of an LPMO, SmAA10A, upon binding of its chitin substrate, utilizing a suite of spectroscopic and computational methods. Herein, we present the first reported X-ray Absorption (XAS) and Emission (XES) spectroscopic data on substrate-bound LPMO. By comparing the Cu(II) and Cu(I) states of SmAA10A in both the chitin-bound and unbound states, we provide insights into the structural adjustments facilitating substrate specificity and productive catalytic turnover. Our results indicate a substrate binding-induced conformational change in Cu(I) site geometry and concurrent modulations to the electronic structure, which prime the enzyme for targeted C–H activation with an H2O2 co-substrate. This work offers an atomistic understanding of interaction dynamics between the LPMO Cu site and the chitin substrate, advancing our knowledge of LPMO functionality and substrate specificity.
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Nov 2025
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E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[35866]
Open Access
Abstract: The catalytic hydrogenation of amides with molecular hydrogen (H2) is an appealing route for the synthesis of valuable amines entering in the preparation of countless organic compounds. Running effective amide hydrogenation under mild H2 pressures is challenging although desirable to preclude the need for specialized high-pressure technologies in research and industry. Here we show that magnetocatalysis with standard supported catalysts enables unprecedented amide hydrogenation at mild conditions. Widely available and commercial platinum on alumina (Pt/Al2O3) was functionalized with iron carbide nanoparticles (ICNPs) to allow for localized and rapid magnetic induction heating resulting in the activation of neighboring Pt sites by thermal energy transfer. Exposure of the ICNPs@Pt/Al2O3 catalyst to an alternating current magnetic field enables highly active and selective hydrogenation of a range of amides at a reactor temperature of 150 °C under 3 bar or even ambient pressure of H2. ICNPs@Pt/Al2O3 reacts adaptively to fluctuations in electricity supply mimicking the use of intermittent renewable energy sources. This work may pave the way toward a greatly enhanced practicability of amide hydrogenation at the laboratory and production scales, and demonstrates more generally the broad potential of the emerging field of magnetocatalysis for synthetic chemistry.
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Apr 2025
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E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[30716, 33118, 40768]
Open Access
Abstract: Extensive research has been conducted on carbon-supported single-atom catalysts (SACs) for electrochemical applications, owing to their outstanding conductivity and high metal atom utilization. The atomic dispersion of active sites provides an ideal platform to investigate the structure-performance correlations. Despite this, the development of straightforward and scalable synthesis methods, along with the tracking of the dynamic active sites under catalytic conditions, remains a significant challenge. Herein, we introduce a biomass-inspired coordination confinement strategy to construct a series of carbon-supported SACs, incorporating various metal elements, such as Fe, Co, Ni. We have systematically characterized their electronic and geometric structure using various spectroscopic and microscopic techniques. Through in situ X-ray absorption spectroscopy (XAS) and atomic scanning transmission electron microscopy (STEM) and electron paramagnetic resonance (EPR) analyses, it is demonstrated that the single atoms undergo structural rearrangement to form amorphous (oxy)hydroxide clusters during oxygen evolution reaction (OER), where the newly formed oxygen-bridged dual metal M-O-M or M-O-M’ (M/M’=Fe, Co, Ni) moieties within these clusters play key role in the OER performance. This work provides essential insights into tracking the actual active sites of SACs during electrochemical OER.
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Apr 2025
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E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[32035]
Open Access
Abstract: Bimetallic manganese–ruthenium nanoparticles of defined Mn:Ru ratios were prepared on an imidazolium-based supported ionic liquid phase. Characterization of the resulting MnxRu100–x@SILP materials by electron microscopy evidenced the formation of small (1.3–3.6 nm) and well-dispersed nanoparticles (NPs) containing Mn and Ru in the expected ratios. X-ray absorption spectroscopy (XAS) studies revealed that no significant levels of alloying occurred in these NPs that contain mainly oxidized Mn species and metallic Ru, consistent with the immiscibility of the two metals and the high oxophilicity of Mn. The hydrogenation performance of MnxRu100–x@SILP materials was probed using benzylideneacetone as model substrate containing three distinct reducible moieties. Albeit the two metals are present in distinct phases, the Mn:Ru ratio was found to have a strong impact on activity and selectivity with trends similar to what was previously reported for alloyed FexRu100–x@SILP and CoxRu100–x@SILP catalysts. In particular, a sharp switch of 6-membered aromatic ring hydrogenation between Mn15Ru85 (full ring hydrogenation) and Mn25Ru75 (no ring hydrogenation) was observed. These results demonstrate that alloying is not a requirement to observe synergistic effects from the combination of 3d metals and noble metals in NPs, opening new opportunities for the development of bimetallic catalysts for selective hydrogenation.
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Feb 2025
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B18-Core EXAFS
E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[33118, 35401]
Open Access
Abstract: An adaptive catalytic system for selective hydrogenation was developed exploiting the H2 + CO2
⇔
HCOOH equilibrium for reversible, rapid, and robust on/off switch of the ketone hydrogenation activity of ruthenium nanoparticles (Ru NPs). The catalyst design was based on mechanistic studies and DFT calculations demonstrating that adsorption of formic acid to Ru NPs on silica results in surface formate species that prevent C═O hydrogenation. Ru NPs were immobilized on readily accessible silica supports modified with guanidinium-based ionic liquid phases (Ru@SILPGB) to generate in situ sufficient amounts of HCOOH when CO2 was introduced into the H2 feed gas for switching off ketone hydrogenation while maintaining the activity for hydrogenation of olefinic and aromatic C═C bonds. Upon shutting down the CO2 supply, the C═O hydrogenation activity was restored in real time due to the rapid decarboxylation of the surface formate species without the need for any changes in the reaction conditions. Thus, the newly developed Ru@SILPGB catalysts allow controlled and alternating production of either saturated alcohols or ketones from unsaturated substrates depending on the use of H2 or H2/CO2 as feed gas. The major prerequisite for design of adaptive catalytic systems based on CO2 as trigger is the ability to shift the H2 + CO2
⇔
HCOOH equilibrium sufficiently to exploit competing adsorption of surface formate and targeted functional groups. Thus, the concept can be expected to be more generally applicable beyond ruthenium as the active metal, paving the way for next-generation adaptive catalytic systems in hydrogenation reactions more broadly.
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Sep 2024
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
B18-Core EXAFS
E02-JEM ARM 300CF
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Longxiang
Liu
,
Liqun
Kang
,
Jianrui
Feng
,
David G.
Hopkinson
,
Christopher S.
Allen
,
Yeshu
Tan
,
Hao
Gu
,
Iuliia
Mikulska
,
Veronica
Celorrio
,
Diego
Gianolio
,
Tianlei
Wang
,
Liquan
Zhang
,
Kaiqi
Li
,
Jichao
Zhang
,
Jiexin
Zhu
,
Georg
Held
,
Pilar
Ferrer
,
David
Grinter
,
June
Callison
,
Martin
Wilding
,
Sining
Chen
,
Ivan
Parkin
,
Guanjie
He
Diamond Proposal Number(s):
[30614, 32058, 32035, 32117, 33466, 29271]
Open Access
Abstract: Electrochemical hydrogen peroxide (H2O2) production (EHPP) via a two-electron oxygen reduction reaction (2e- ORR) provides a promising alternative to replace the energy-intensive anthraquinone process. M-N-C electrocatalysts, which consist of atomically dispersed transition metals and nitrogen-doped carbon, have demonstrated considerable EHPP efficiency. However, their full potential, particularly regarding the correlation between structural configurations and performances in neutral media, remains underexplored. Herein, a series of ultralow metal-loading M-N-C electrocatalysts are synthesized and investigated for the EHPP process in the neutral electrolyte. CoNCB material with the asymmetric Co-C/N/O configuration exhibits the highest EHPP activity and selectivity among various as-prepared M-N-C electrocatalyst, with an outstanding mass activity (6.1 × 105 A gCo−1 at 0.5 V vs. RHE), and a high practical H2O2 production rate (4.72 mol gcatalyst−1 h−1 cm−2). Compared with the popularly recognized square-planar symmetric Co-N4 configuration, the superiority of asymmetric Co-C/N/O configurations is elucidated by X-ray absorption fine structure spectroscopy analysis and computational studies.
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May 2024
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B18-Core EXAFS
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Diamond Proposal Number(s):
[31573]
Open Access
Abstract: Colloidal and supported manganese nanoparticles were synthesized following an organometallic approach and applied in the catalytic transfer hydrogenation (CTH) of aldehydes and ketones. Reaction parameters for the preparation of colloidal nanoparticles (NPs) were optimized to yield small (2-2.5 nm) and well-dispersed NPs. Manganese NPs were further immobilized on an imidazolium-based supported ionic phase (SILP) and characterized to evaluate NP size, metal loading, and oxidation states. Oxidation of the Mn NPs by the support was observed resulting in an average formal oxidation state of +2.5. The MnOx@SILP material showed promising performance in the CTH of aldehydes and ketones using 2-propanol as a hydrogen donor, outperforming previously reported Mn NPs-based CTH catalysts in terms of metal loading-normalized turnover numbers. Interestingly, MnOx@SILP were found to lose activity upon air exposure, which correlates with an additional increase in the average oxidation state of Mn as revealed by X-ray absorption spectroscopic studies.
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Feb 2024
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
B18-Core EXAFS
E01-JEM ARM 200CF
E02-JEM ARM 300CF
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Fangjia
Zhao
,
Jianwei
Li
,
Arunabhiram
Chutia
,
Longxiang
Liu
,
Liqun
Kang
,
Feili
Lai
,
Haobo
Dong
,
Xuan
Gao
,
Yeshu
Tan
,
Tianxi
Liu
,
Ivan P.
Parkin
,
Guanjie
He
Diamond Proposal Number(s):
[32905, 29340, 32058]
Open Access
Abstract: The design and synthesis of manganese oxide-based materials with high-rate performance and long cycle life is a major challenge for aqueous zinc-ion batteries (AZIBs). This research reports the presence of a synergistic collaboration between vacancies, lattice water and nickel ions on enhancing the hydrated protons hopping via the Grotthuss mechanism for high-performance zinc ion batteries. The Grotthuss mechanism allows for the efficient transfer of a proton charge without the actual movement of the molecule over long distances, resulting in high ionic conductivity. NiMn3O7·3H2O achieves a capacity of 318 mA h g−1 under 200 mA g−1 and 121 mA h g−1 under 5 A g−1 with a retention of 91% after 4000 cycles. The relationship between the remarkable performance and Grotthuss topochemistry is investigated using techniques including synchrotron X-ray absorption spectroscopy and density functional theory. Protons prefer to bond with O2− ions on the Mn–O layer, and proton transfer is favoured in the presence of vacancies. The continuous hopping of protons within the host material induces periodic, temporary local structural changes in the lattice. This dynamic behaviour alters the energy barriers for ions intercalation and deintercalation. Nickel ions facilitate the ongoing mobility of hydrated protons via Grotthuss hopping by preserving the system's electrical neutrality, which counterbalances the dynamic changes caused by proton migration. This study provides insight into the Grotthuss conduction mechanism for the development of high-performance cathode materials in AZIBs.
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Jan 2024
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E02-JEM ARM 300CF
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Jichao
Zhang
,
Jiexin
Zhu
,
Liqun
Kang
,
Qing
Zhang
,
Longxiang
Liu
,
Fei
Guo
,
Kaiqi
Li
,
Jianrui
Feng
,
Lixue
Xia
,
Lei
Lv
,
Wei
Zong
,
Paul R.
Shearing
,
Dan J. L.
Brett
,
Ivan P.
Parkin
,
Xuedan
Song
,
Liqiang
Mai
,
Guanjie
He
Diamond Proposal Number(s):
[32058, 33118]
Open Access
Abstract: Electrochemical urea splitting provides a sustainable and environmentally benign route for facilitating energy conversion. Nonetheless, the sustained efficiency of urea splitting is impeded by a scarcity of active sites during extended operational periods. Herein, an atomic heterostructure engineering strategy is proposed to promote the generation of active species via synthesizing unique Ru–O4 coordinated single atom catalysts anchored on Ni hydroxide (Ru1–Ni(OH)2), with ultralow Ru loading mass of 40.6 μg cm−2 on the nickel foam for commercial feasibility. Leveraging in situ spectroscopic characterizations, the structure-performance relationship in low and high urea concentrations was investigated and exhibited extensive universality. The boosted generation of dynamic Ni3+ active sites ensures outstanding activity and prominent long-term durability tests in various practical scenarios, including 100 h Zn–urea–air battery operation, 100 h alkaline urine electrolysis, and over 400 h stable hydrogen production in membrane electrode assembly (MEA) system under industrial-level current density.
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Nov 2023
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E02-JEM ARM 300CF
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Alexandre
Sodreau
,
Hooman Ghazi
Zahedi
,
Rıza
Dervişoğlu
,
Liqun
Kang
,
Julia
Menten
,
Johannes
Zenner
,
Nicole
Terefenko
,
Serena
Debeer
,
Thomas
Wiegand
,
Alexis
Bordet
,
Walter
Leitner
Diamond Proposal Number(s):
[33118]
Open Access
Abstract: Metal chloride complexes react with tris(trimethylsilyl)phosphine under mild condition to produce metal phosphide nanoparticles, and chlorotrimethylsilane as a byproduct. The formation of Si-Cl bonds that are stronger than the starting M-Cl bonds acts as a driving force for the reaction. The potential of this strategy is illustrated through the preparation of ruthenium phosphide nanoparticles using [RuCl2(cymene)] and tris(trimethylsilyl)phosphine at 35°C. Characterization with a combination of techniques including electron microscopy, X-ray absorption spectroscopy, and solid-state NMR spectroscopy, evidences the formation of small (diameter of 1.3 nm) and amorphous NPs with an overall Ru50P50 composition. Interestingly, these NPs can be easily immobilized on functional support materials, which is of great interest for potential applications in catalysis and electrocatalysis. Mo50P50 and Co50P50 NPs could also be synthesized following the same strategy. This approach is simple and versatile and paves the way toward the preparation of a wide range of transition metal phosphide nanoparticles under mild reaction conditions.
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Sep 2023
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