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NiFe and CoFe (MFe) layered double hydroxides (LDHs) are among the most active electrocatalysts for the alkaline oxygen evolution reaction (OER). Herein, we combine electrochemical measurements, operando X-ray scattering and absorption spectroscopy, and density functional theory (DFT) calculations to elucidate the catalytically active phase, reaction center and the OER mechanism. We provide the first direct atomic-scale evidence that, under applied anodic potentials, MFe LDHs oxidize from as-prepared α-phases to activated γ-phases. The OER-active γ-phases are characterized by about 8% contraction of the lattice spacing and switching of the intercalated ions. DFT calculations reveal that the OER proceeds via a Mars van Krevelen mechanism. The flexible electronic structure of the surface Fe sites, and their synergy with nearest-neighbor M sites through formation of O-bridged Fe-M reaction centers, stabilize OER intermediates that are unfavorable on pure M-M centers and single Fe sites, fundamentally accounting for the high catalytic activity of MFe LDHs. NiFe and CoFe layered double hydroxides are among the most active electrocatalysts for the alkaline oxygen evolution reaction. Here, by combining operando experiments and rigorous DFT calculations, the authors unravel their active phase, the reaction center and the catalytic mechanism.

Tuning the surface structure at the atomic level is of primary importance to simultaneously meet the electrocatalytic performance and stability criteria required for the development of low-temperature proton-exchange membrane fuel cells (PEMFCs). However, transposing the knowledge acquired on extended, model surfaces to practical nanomaterials remains highly challenging. Here, we propose ‘surface distortion’ as a novel structural descriptor, which is able to reconciliate and unify seemingly opposing notions and contradictory experimental observations in regards to the electrocatalytic oxygen reduction reaction (ORR) reactivity. Beyond its unifying character, we show that surface distortion is pivotal to rationalize the electrocatalytic properties of state-of-the-art of PtNi/C nanocatalysts with distinct atomic composition, size, shape and degree of surface defectiveness under a simulated PEMFC cathode environment. Our study brings fundamental and practical insights into the role of surface defects in electrocatalysis and highlights strategies to design more durable ORR nanocatalysts.

Lithiation dynamics and phase transition mechanisms in most battery cathode materials remain poorly understood, because of the challenge in differentiating inter- and intra-particle heterogeneity. In this work, the structural evolution inside Li 1− x Mn 1.5 Ni 0.5 O 4 single crystals during electrochemical delithiation is directly resolved with operando X-ray nanodiffraction microscopy. Metastable domains of solid-solution intermediates do not appear associated with the reaction front between the lithiated and delithiated phases, as predicted by current phase transition theory. Instead, unusually persistent strain gradients inside the single crystals suggest that the shape and size of solid solution domains are instead templated by lattice defects, which guide the entire delithiation process. Morphology, strain distributions, and tilt boundaries reveal that the (Ni 2+ /Ni 3+ ) and (Ni 3+ /Ni 4+ ) phase transitions proceed through different mechanisms, offering solutions for reducing structural degradation in high voltage spinel active materials towards commercially useful durability. Dynamic lattice domain reorientation during cycling are found to be the cause for formation of permanent tilt boundaries with their angular deviation increasing during continuous cycling. Lithiation dynamics and phase transition mechanisms in battery materials remain poorly understood. Here authors use operando X-ray nanodiffraction microscopy to reveal how domains relate to defects and how cycling affects the lattice domain reorientation in LiMn 1.5 Ni 0.5 O 4 single crystals.

The long-term stability of Pt-based catalysts is critical to the reliability of proton exchange membrane fuel cells (PEMFCs), and receives constant attention. However, the current knowledge of Pt oxidation is restricted to unrealistic PEMFC cathode environment or operation, which questions its practical relevance. Herein, Pt oxidation is investigated directly in a PEMFC with stroboscopic operando high energy X-ray scattering. The onset potential for phase transition of the nanoparticles surface from metallic to amorphous electrochemical oxide is observed far below previously reported values, and most importantly, below the open-circuit potential of PEMFC cathode. Such phase transition is shown to impact PEMFC performance and its role on Pt transient dissolution is verified by electrochemical on-line inductively coupled plasma mass spectrometry. By further demonstrating and resolving the limitations of currently employed accelerated stress test protocols in the light of metal-oxide phase transitions kinetics, this picture of Pt oxidation enables new mitigation strategies against PEMFC degradation. The stability of Pt-based catalysts is critical to the reliability of proton exchange membrane fuel cells. Here, the authors use stroboscopic operando high energy X-ray scattering to reveal Pt nanocatalysts experience a metal-oxide phase transition during conventional fuel cell operation.

Platinum dissolution and restructuring due to surface oxidation are primary degradation mechanisms that limit the lifetime of platinum-based electrocatalysts for electrochemical energy conversion. Here, we have studied well-defined Pt(100) and Pt(111) electrode surfaces by in situ high-energy surface X-ray diffraction, online inductively coupled plasma mass spectrometry and density functional theory calculations to elucidate the atomic-scale mechanisms of these processes. The locations of the extracted platinum atoms after Pt(100) oxidation reveal distinct differences from the Pt(111) case, which explains the different surface stability. The evolution of a specific oxide stripe structure on Pt(100) produces unstable surface atoms that are prone to dissolution and restructuring, leading to one order of magnitude higher dissolution rates. Platinum dissolution and restructuring due to surface oxidation are primary degradation mechanisms of platinum-based electrocatalysts. Now, stark differences are reported in the mechanism for the oxidative extraction of platinum atoms on (111) and (100) single crystals, providing a detailed explanation for the enhanced dissolution on the latter surface.

A porous Co‐based metal‐oxide foam catalyst is fabricated via the dynamic hydrogen bubble template electrodeposition method followed by calcination (6 h at 300 °C thermal treatment). Electrolysis results demonstrate excellent performance of this catalyst in the electrochemical nitrate reduction reaction (NO3−RR ${\\mathrm{NO}}_3^ - {\\mathrm{RR}}$ ), attaining near‐unity Faradaic efficiency (97.8% ± 3.6% at jNH3,lim = –59.5 ± 2.3 mA cm−2) at a low (over)potential of –0.2 V vs RHE, which represents maximum achievable performance in 0.1 mol L−1 nitrate solutions (pH 13.7) under transport‐limiting conditions in the absence of extra convection. Digital simulations show that, without forced convection, the catalyst's electrochemically active surface area changes dynamically due to rapid nitrate depletion inside the 3D foam. Electrolyte replenishment, triggered by vigorous hydrogen evolution, is shown to restore the active surface in the foam interior. This self‐convection enables high ammonia partial current densities exceeding hundreds of mA cm−2 (e.g., jNH3 = –220 ± 18 mA cm−2 at –0.6 V vs RHE, with FENH3 = 80.2% ± 2.2%). Operando XAS, XRD, Raman spectroscopy, and electrochemical analysis reveal the in situ evolution of a “tandem” composite catalyst during electrolysis, where β‐Co(OH)2 and metallic Co function both as the active phases for NO3−RR ${\\mathrm{NO}}_3^ - {\\mathrm{RR}}$ , with β‐Co(OH)2 remaining kinetically stabilized under the cathodic operating conditions. A porous cobalt‐based metal‐oxide foam catalyst is synthesized using the DHBT technique, followed by calcination. It demonstrates exceptional activity for e‐NO3RR, reaching near‐unity ammonia selectivity at low overpotentials. Dynamic surface area changes due to NO3‐ depletion are mitigated by “self‐convection” during hydrogen evolution. Operando analyses reveal the formation of highly active “tandem catalyst”— β‐Co(OH)2 and metallic Co serving as a stable active phase under reaction conditions.

Surface X-ray Diffraction was used to study the transformation of a carbon-supersaturated carbidic precursor toward a complete single layer of graphene in the temperature region below 703 K without carbon supply from the gas phase. The excess carbon beyond the 0.45  monolayers of C atoms within a single Ni 2 C layer is accompanied by sharpened reflections of the |4772| superstructure, along with ring-like diffraction features resulting from non-coincidence rotated Ni 2 C-type domains. A dynamic Ni 2 C reordering process, accompanied by slow carbon loss to subsurface regions, is proposed to increase the Ni 2 C 2D carbide long-range order via ripening toward coherent domains, and to increase the local supersaturation of near-surface dissolved carbon required for spontaneous graphene nucleation and growth. Upon transformation, the intensities of the surface carbide reflections and of specific powder-like diffraction rings vanish. The associated change of the specular X-ray reflectivity allows to quantify a single, fully surface-covering layer of graphene (2 ML C) without diffraction contributions of rotated domains. The simultaneous presence of top-fcc and bridge-top configurations of graphene explains the crystal truncation rod data of the graphene-covered surface. Structure determination of the |4772| precursor surface-carbide using density functional theory is in perfect agreement with the experimentally derived X-ray structure factors.

Understanding the mechanisms of Pt dissolution with well‐defined surfaces is vital for developing stable catalysts for electrochemical energy conversion devices such as fuel cells. This work investigates Pt dissolution from low‐index single crystals in perchlorate, sulfate, and methanesulfonate acid solutions by on‐line inductively coupled plasma mass spectrometry (ICP‐MS), and the results are correlated with surface X‐ray diffraction (SXRD) studies. The previously reported stability trend Pt(111)>Pt(100)>Pt(110) in HClO4 was confirmed for the other acids. The application of electrochemical protocols up to high potential values demonstrated that dissolution for Pt(100) increases to a lower extent than for the other planes. Dissolution is affected by the nature of the anion, especially for Pt(111), with the dissolution rate increasing in the order H2SO4>MSA>HClO4. This influence could be due to the interaction strength of the anion with Pt and its complexing ability or different ratios of the surface coverage of different oxide species. For Pt(111), SXRD measurements show different onset potentials for extraction in HClO4 and H2SO4, which can influence the dissolution processes. These results demonstrate that fundamental studies are necessary to improve the current knowledge about Pt dissolution and how to hinder it to a practical extent. Pt dissolution from the low‐index planes in acidic solutions with perchlorate, sulfate, and methanesulfonate is investigated by on‐line inductively coupled plasma mass spectrometry (ICP‐MS) and surface X‐ray diffraction (SXRD) studies. Dissolution is affected by the nature of the anion, probably due to its interaction strength and complexing ability or different ratios of the surface coverage of different oxide species.

Controlling material functionalities via external stimuli is a cornerstone of modern science and technology. One effective strategy involves tuning mechanical strain, which can be induced through lattice mismatch, electric fields, or applied mechanical force. Recent advances in fabricating freestanding single‐crystalline complex oxide membranes have opened new opportunities for integrating these materials onto previously incompatible platforms such as metals and flexible polymers for next‐generation device applications. A key step in strain engineering is understanding and controlling the integration of such materials with flexible substrates. In this study, the integration and adhesion of freestanding single‐crystalline La0.7Sr0.3MnO3 (LSMO(001)) membranes onto metallic surfaces (Au, Pt, and TiN) coated on flexible polymer substrates is demonstrated. It is found that the choice of metal underlayer significantly influences the ability to strain the membrane. Using TiN‐coated polymer support, a uniform strain of ≈1% in LSMO membranes, along with strong adhesion between the membrane and substrate, is achieved. Theoretical calculations reveal that strong Ti─O bonding and compact in‐plane lattice matching at the LSMO(001)/TiN(111) interface lower the interface formation energy compared to noble metals. These findings offer valuable insights for selecting suitable platforms to apply external mechanical stress to freestanding oxide membranes, facilitating their integration into flexible electronic systems. Integrating freestanding complex oxides on flexible platforms holds great promise for next‐generation electronics. The successful integration and adhesion of freestanding single‐crystalline La0.7Sr0.3MnO3 membranes onto metal‐coated polymer substrates (Au, Pt, TiN) is demonstrated. Strong interfacial adhesion of the oxide membrane with TiN allows for ≈1% uniform strain, offering crucial insights for selecting suitable platforms to apply mechanical stress and advance flexible oxide device integration.

Breakthroughs in battery research are imperative to provide society with batteries that are safe and sustainable, have a high energy density, and have a long cycle life at low cost. Recent advances in research methodologies, the emergence of new market opportunities, and strategic funding schemes have allowed not only large, but also small companies, universities, and public research organizations to play an increasingly significant role in the advancement of battery technology. Challenges in battery technology development are multifaceted; therefore, a collaborative approach is crucial to bring together various stakeholders and ensure access to the full range of technical and scientific expertise. To grasp the core properties of electrode materials, electrolytes, and interfaces and to identify the mechanisms of battery degradation and failure, a multidisciplinary analytical approach is crucial. This strategy relies on the unique and complementary potential of advanced characterization techniques available at synchrotron and x-ray free electron laser facilities. Science-to-industry interactions are expected to increase the development of new standardized setups to approach realistic operando conditions. Therefore, rapid access to instruments, including high-throughput ex-situ , in-situ and operando capabilities, is key to accelerating the development of safe and sustainable batteries. The purpose of this paper is to discuss how the characterization needs of the battery community can be met by establishing a collaboration network based on a meta-infrastructure model, where the emphasis will be on collaboration and the sharing of experience and data. The proposed methodology considers the urgency in the battery community and the necessary technical developments to reach the scope of collaboration and focuses in particular on the needs for standardization, big data challenges, and open data approaches.