B18-Core EXAFS
E02-JEM ARM 300CF
|
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
|
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
|
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
|
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
|
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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I20-Scanning-X-ray spectroscopy (XAS/XES)
|
Yue
Pang
,
Nils
Nöthling
,
Markus
Leutzsch
,
Liqun
Kang
,
Eckhard
Bill
,
Maurice
Van Gastel
,
Edward
Reijerse
,
Richard
Goddard
,
Lucas
Wagner
,
Daniel
Santalucia
,
Serena
Debeer
,
Frank
Neese
,
Josep
Cornella
Diamond Proposal Number(s):
[30449]
Abstract: Large Spin-Orbit Coupling (SOC) is an intrinsic property of the heavy-elements that directly affects the electronic structures of the compounds. Herein we report the synthesis and characterization of a mono-coordinate bismuthinidene featuring a rigid and bulky ligand. All magnetic measurements (SQUID, NMR) point to a diamagnetic compound. However, multiconfigurational quantum chemical calculations predict the ground state of the compound to be dominated (76%) by a spin-triplet. The apparent diamagnetism is explained by an extremely large SOC induced positive zero-field-splitting of more than 4500 cm−1 that leaves the MS = 0 magnetic sublevel thermally isolated in the electronic ground state.
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May 2023
|
|
B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
E02-JEM ARM 300CF
|
Longxiang
Liu
,
Liqun
Kang
,
Arunabhiram
Chutia
,
Jianrui
Feng
,
Martyna
Michalska
,
Pilar
Ferrer
,
David
Grinter
,
Georg
Held
,
Yeshu
Tan
,
Fangjia
Zhao
,
Fei
Guo
,
David
Hopkinson
,
Christopher
Allen
,
Yanbei
Hou
,
Junwen
Gu
,
Ioannis
Papakonstantinou
,
Paul
Shearing
,
Dan
Brett
,
Ivan P.
Parkin
,
Guanjie
He
Diamond Proposal Number(s):
[29340, 32501, 30614, 29809, 32058]
Open Access
Abstract: The electrochemical synthesis of hydrogen peroxide (H2O2) via a two-electron (2e-) oxygen reduction reaction (ORR) process provides a promising alternative to replace the energy-intensive anthraquinone process. However, the development of efficient electrocatalysts is still facing lots of challenges like insufficient understanding of active sites. Herein, we develop a facile template-protected strategy to synthesize a highly active quinone-rich porous carbon catalyst (PCC) for H2O2 electrochemical production. The optimized PCC900 exhibits unprecedented activity and selectivity, of which the onset potential reaches 0.83 V vs. reversible hydrogen electrode in 0.1 M KOH and the H2O2 selectivity is over 95 % in a wide potential range. Comprehensive synchrotron-based near-edge X-ray absorption fine structure (NEXAFS) spectroscopy combined with electrocatalytic characterizations reveals the positive correlation between quinone content and 2e- ORR performance. The effectiveness of chair-form quinone groups as the most efficient active sites is highlighted by the molecule-mimic strategy and theoretical analysis.
|
Mar 2023
|
|
E01-JEM ARM 200CF
E02-JEM ARM 300CF
I20-Scanning-X-ray spectroscopy (XAS/XES)
|
Runjia
Lin
,
Liqun
Kang
,
Karolina
Lisowska
,
Weiying
He
,
Siyu
Zhao
,
Shusaku
Hayama
,
Dan
Brett
,
Graham
Hutchings
,
Furio
Corà
,
Ivan
Parkin
,
Guanjie
He
Diamond Proposal Number(s):
[29254, 29207]
Open Access
Abstract: Electrocatalytic oxygen reduction reaction (ORR) has been intensively studied for efficient and environmentally benign energy conversion processes. However, insufficient understanding of ORR 2e--pathway mechanism at the atomic level inhibits rational design of electrocatalysts with both high activity and selectivity, causing concerns including catalyst degradation due to Fenton reaction or poor efficiency of H2O2 electrosynthesis. Herein we show that the generally accepted ORR electrocatalyst design based on a Sabatier volcano plot argument optimises activity but is unable to account for the 2e--pathway selectivity; an extended “dynamic active site saturation” model that examines in addition the hydrogenation kinetics linked to the OOH* adsorption energy enables us to resolve the activity-selectivity compromise. Through electrochemical and operando spectroscopic studies on the ORR process governed by a series of Co-N x /carbon nanotube hybrids, a construction-driven approach that aims to create the maximum number of 2e- ORR sites by directing the secondary ORR electron transfer step towards the 2e- intermediate is proven to be attainable by manipulating O2 hydrogenation kinetics. Control experiments reveal the O2 hydrogenation chemistry is related to a catalyst reconstruction with lower symmetry around the Co active centre induced by the application of a cathodic potential. The optimised catalyst exhibits a ~100% H2O2 selectivity and an outstanding activity with an ORR potential of 0.82 V versus the reversible hydrogen electrode to reach the ring current density of 1 mA cm-2 by using rotating ring-disk electrode measurement, which is the best-performing 2e- ORR electrocatalyst reported to date, and approaches the thermodynamic limit.
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Mar 2023
|
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E02-JEM ARM 300CF
|
Haobo
Dong
,
Ruirui
Liu
,
Xueying
Hu
,
Fangjia
Zhao
,
Liqun
Kang
,
Longxiang
Liu
,
Jianwei
Li
,
Yeshu
Tan
,
Yongquan
Zhou
,
Dan J. L.
Brett
,
Guanjie
He
,
Ivan
Parkin
Diamond Proposal Number(s):
[30614, 29809]
Open Access
Abstract: A stable cathode–electrolyte interface (CEI) is crucial for aqueous zinc-ion batteries (AZIBs), but it is less investigated. Commercial binder poly(vinylidene fluoride) (PVDF) is widely used without scrutinizing its suitability and cathode-electrolyte interface (CEI) in AZIBs. A water-soluble binder is developed that facilitated the in situ formation of a CEI protecting layer tuning the interfacial morphology. By combining a polysaccharide sodium alginate (SA) with a hydrophobic polytetrafluoroethylene (PTFE), the surface morphology, and charge storage kinetics can be confined from diffusion-dominated to capacitance-controlled processes. The underpinning mechanism investigates experimentally in both kinetic and thermodynamic perspectives demonstrate that the COO− from SA acts as an anionic polyelectrolyte facilitating the adsorption of Zn2+; meanwhile fluoride atoms on PTFE backbone provide hydrophobicity to break desolvation penalty. The hybrid binder is beneficial in providing a higher areal flux of Zn2+ at the CEI, where the Zn-Birnessite MnO2 battery with the hybrid binder exhibits an average specific capacity 45.6% higher than that with conventional PVDF binders; moreover, a reduced interface activation energy attained fosters a superior rate capability and a capacity retention of 99.1% in 1000 cycles. The hybrid binder also reduces the cost compared to the PVDF/NMP, which is a universal strategy to modify interface morphology.
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Dec 2022
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