E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[35866]
Open Access
Abstract: NiFe-based compounds are among the most promising catalysts for the oxygen evolution reaction (OER). However, the structural reconstruction of NiFe catalysts during OER is not fully understood. Most existing studies implicitly assume the formation of a homogeneous NiFe (oxy)hydroxide lattice; however, the actual reconstruction process is more likely to generate structurally heterogeneous (oxy)hydroxide phases with local distortions due to the intrinsic mismatch between Fe3+–O and Ni3+–O bond lengths in the bulk NiFe compounds. By constructing atomically dispersed Ni and Fe active sites as precatalysts and combining them with operando spectroelectrochemical studies, we observed an unusual reconstruction pathway in which isolated Ni2+ and Fe atoms can adaptively evolve into a short-range mixed NiFe (oxy)hydroxide local structure through the formation of interconnected M-O-M′ (M/M′ = Ni3+δ, Fe3+) motifs during the OER. At 1.6 V vs RHE, the reconstructed γ-Fe3+OOH clusters are induced to integrate into the high-valent γ-Ni3+δOOH lattice, resulting in a short-range mixed NixFe1–xOOH structure. This new structure is characterized by an unusually short Fe3+–Ni3+δ distance of ∼2.86 Å, which is significantly shorter than the typical Fe3+-Fe3+ distance in Fe3+ (oxy)hydroxides (2.95–3.25 Å). Interestingly, this “induction effect” is absent in Co3+–Fe3+ catalysts, as atomically dispersed Co3+ sites directly transition into γ-Co3+OOH, which lacks structural compatibility with γ-Fe3+OOH. DFT calculations reveal that the unusually short Fe3+-O bond leads to a moderate *O adsorption strength at the Fe site in the catalyst, thereby creating the most favorable conditions for the oxygen evolution reaction (OER).
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Jul 2026
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
E01-JEM ARM 200CF
E02-JEM ARM 300CF
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Diamond Proposal Number(s):
[29340]
Open Access
Abstract: Ruthenium oxide is a well-known electrocatalyst for water splitting. Despite many advantages, the reaction mechanism and the structure changes of ruthenium oxide are unclear during catalysis, and the catalytic efficiency of ruthenium oxides remains a concern. In this paper, a needle-shaped copper substrate was synthesized, and the performance of RuOx was optimized. Reversible in situ Raman signals were found during the reaction process, which confirmed from the reversible surface reconstruction of RuOx. Density Functional Theory calculations found that the actual catalytic species is Ru(II)O. A detailed reaction mechanism of the Volmer step on the surface of ruthenium oxide was proposed based on the findings. The results indicate that the needles can lower the overpotentials of RuOx. At a current density of 10
, the overpotential of RuOx@ndl. was 68% lower than that of RuOx@b. f., which is much lower than the overpotential of commercial Pt(20wt.%)/C. This research provides a fundamental understanding of ruthenium oxide's reaction mechanism and gives insight into the design of the hydrogen evolution reaction catalysts.
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Jun 2026
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B18-Core EXAFS
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Fei
Guo
,
Manxi
Gong
,
Longxiang
Liu
,
Bochen
Li
,
Ruwei
Chen
,
Mengjun
Gong
,
Wei
Zong
,
Jianuo
Chen
,
Qi
Li
,
Jing
Li
,
Yunpeng
Zhong
,
Zeyi
Zhang
,
Jianrui
Feng
,
Rhodri
Jervis
,
Guanjie
He
Diamond Proposal Number(s):
[34632]
Open Access
Abstract: Platinum–transition metal (PtM) alloys are among the most promising oxygen reduction reaction (ORR) catalysts, yet their practical deployment in proton-exchange membrane fuel cells (PEMFCs) is hindered by transition-metal dissolution, particle coarsening, and insufficient durability. Moreover, conventional alloying or intermetallic ordering strategies often aggravate these issues by inducing severe nanoparticle aggregation and instability. Here we report a controllable alloying–dealloying strategy to construct PtNi nanoparticles confined in an N-doped carbon framework (Pt1Ni1-x@Nix_NC). Ammonia-assisted dealloying produces a Pt-rich shell with an alloyed core, while the N-doped carbon anchors the released Ni atoms form Ni–N/C moieties, thereby suppressing agglomeration and strengthening metal–support interactions. This coordination–support coupling optimizes Pt 5d orbital occupation, weakens oxygen adsorption, and accelerates ORR kinetics. Consequently, Pt1Ni1-x@Nix_NC exhibits a half-wave potential of 0.932 V and an ultrahigh mass activity of 2.028 A mgPt−1, which is 8.75-fold higher than commercial Pt/C and among the best values reported to date for PtNi-based catalysts. Remarkably, it shows only a 6 mV half-wave potential loss after 30,000 cycles, demonstrating exceptional durability. In PEMFCs, the fuel cell delivers 975 mW cm−2 peak power density and retains 91.9% of initial performance, underscoring a generalizable approach for designing durable, high-performance low-PGM catalysts for next generation PEMFCs.
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Feb 2026
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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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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
B18-Core EXAFS
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Abstract: The energy density of layered oxides of Li-ion batteries can be enhanced by inducing oxygen redox through replacing transition metal (TM) ions with Li ions in the TM layer. Undesirably, the cathodes always suffer from unfavorable structural degradation, which is closely associated with irreversible TM migration and slab gliding, resulting in continuous capacity and voltage decay. Herein, attention is paid to the Li ions in the TM layer (LiTM) and find their extra effects beyond inducing oxygen redox, which has been rarely mentioned. With the aid of 7Li solid-state NMR and density functional theory (DFT) calculations, the controllable migration of LiTM is verified. The mystery is uncovered that the preferential migration of LiTM plays an imperative role in preventing the structural transformation by postponing the slab gliding of the layered structure. Integrated with the inhibited TM migration, the structural robustness and reversibility of Li2RuO3 can be drastically improved after Zr-substitution, providing a solid foundation for achieving ultra-stable electrochemical performance even after thousands of cycles (2500 cycles). The discovery highlights the significance of LiTM with respect to the structural robustness and provides a potential route toward high-energy-density Li-ion batteries.
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Jan 2025
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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
B18-Core EXAFS
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Diamond Proposal Number(s):
[33466, 35401]
Abstract: O3-type layered oxides for sodium-ion batteries (SIBs) have attracted extensive attention due to their inherently sufficient Na content, which have been considered as one of the most promising candidates for practical applications. However, influenced by the irreversible oxygen loss and the phase transition of O3–P3, the O3-type cathodes are always limited by low cutoff voltages (typically <4.2 V), restraining the full release of the capacity. In this study, we originally propose a dual-reductive coupling mechanism in a novel O3-type Na0.8Li0.2Fe0.2Ru0.6O2 cathode with the suppressed O3–P3 phase transition, aiming at improving the reversibility of oxygen redox at high voltage regions. Consequently, thanks to the formation of the strong covalent Fe/Ru–(O–O) bonding and inhibited slab gliding from the O to P phase, the cathode delivers the preeminent cyclic stability among the numerous O3-type cathodes within a high voltage of 4.5 V (a capacity retention of 95.4% after 100 cycles within 1.5–4.5 V). More importantly, HAADF-STEM and 7Li solid-state NMR results reveal the absence of transition metal migration and the presence of reversible Li migration during cycling, which further contributes to the improved structural robustness of the cathode. This study proposes an innovative strategy to boost the reversibility of anionic redox and to achieve stable high-voltage O3-type layered oxides, promoting the further development of SIBs.
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May 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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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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B07-B1-Versatile Soft X-ray beamline: High Throughput ES1
E02-JEM ARM 300CF
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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.
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Mar 2023
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