The oxygen evolution reaction (OER) on transition-metal electrodes involves dynamic surface reconstruction, but how the microstructure of metallic pre-catalysts controls this process remains insufficiently resolved. Here, polished polycrystalline Fe, Co, and Ni discs were investigated as alkaline OER anodes by tracking identical surface regions over 3000 activation cycles in 1 M KOH. Correlative identical-location scanning electron microscopy (IL-SEM) and electron backscatter diffraction (EBSD), including kernel average misorientation mapping (KAM), were complemented by energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectrometry (ToF-SIMS) to link OER activation-induced surface restructuring with local morphology, crystallography, stored deformation, and near-surface chemistry. The three metals exhibited markedly different reconstruction pathways. Fe rapidly deactivated and developed a heterogeneous passivation layer thin enough to preserve EBSD visibility, consistent with dissolution/etching and patchy, non-continuous oxide formation. Notably, low-KAM {101} grains were affected the least. Co underwent largely microstructure-independent roughening and developed oxygen-rich micrometre-scale hexagonal platelets, consistent with Co hydroxide/oxyhydroxide formation via dissolution–redeposition, while retaining the EBSD signal after activation. In contrast, Ni formed a relatively thick, porous, large-scale interlaced nanosheet layer of Ni-based oxyhydroxide that completely blocked the EBSD signal, with film growth promoted at grain boundaries and modulated by crystallographic orientation. After activation cycling, the OER activity followed the order Ni > Co > Fe, with overpotentials of 261, 331, and 489 mV at 5 mA cm⁻², respectively. These correlative identical-location electron microscopy observations demonstrate that alkaline OER activation of Fe, Co, and Ni metallic anodes proceeds through distinct electrochemical reconstruction pathways involving different contributions from local oxidation, dissolution/etching, precipitation or redeposition, and porous oxyhydroxide growth. The local progression of these pathways can be governed by crystallographic texture, grain boundaries, and processing-induced deformation.

The oxygen evolution reaction (OER) is a major bottleneck in electrochemical water splitting due to its sluggish kinetics and high overpotentials. Here, we report a single-step laser surface engineering approach to convert commercial Inconel 625 alloy into an active OER electrocatalyst. Pulsed laser treatment generates a hierarchical, "cauliflower-like" nanostructure that significantly enhances the electrochemically active surface area. Electrochemical testing in 1 M KOH shows that the laser-treated surface achieves an overpotential of 270 mV at 10 mA cm- 2, corresponding to a 30 mV cathodic shift relative to the untreated alloy. During electrochemical activation, selective dissolution of Mo and Cr produces a Ni-rich surface that facilitates the formation of catalytically active gamma-NiOOH species. Raman spectroscopy confirms gamma-NiOOH formation with characteristic bands at 470 and 548 cm- 1, while the shoulders at 493 and 539 cm- 1 suggest Fe incorporation into the oxyhydroxide structure. Under OER conditions, we also detect low-intensity bands in the spectral region between 800 and 1150 cm-1, which we ascribe to Ni-OO- species stabilized by cations. The Tafel slope decreases from 59.9 mV dec- 1 for pristine Inconel 625 to 39.2 mV dec- 1 after laser-treatment and electrochemical conditioning. Identical location SEM technique is used to follow how the hierarchical structure of the laser-treated sample partly coalesce and locally flatten after the electrochemical treatment. These results demonstrate that laser surface engineering provides a scalable and effective strategy to transform robust industrial alloys into functional OER electrocatalysts, offering new avenues for cost-effective water-splitting technologies.

Electrocatalysts are often assumed to be structurally stable; yet in practice, they continuously dissolve and restructure, directly affecting the number and nature of active sites and therefore performance. Although dissolution-redeposition-driven evolution is well recognized in some electrocatalysis communities, others still interpret activity and selectivity as properties of static surfaces. We argue that across electrocatalytic technologies, especially under demanding industrially relevant timescales, “static” electrocatalysts are a myth: even parts-per-billion metal fluxes can cumulatively change surface structure, poison membranes, degrade supports, and thus shift device performance. Controlling these changes requires a mechanistic understanding of when dissolution, transport, and redeposition are promoted or suppressed by, for instance, potential, pH, reactants, or local microenvironments. Here, we unify evidence for restructuring across metal and metal-derived catalysts under various electrochemical reactions, highlight common driving forces, and summarize the appropriate tools to quantify it. Ultimately, electrocatalysts should be evaluated, designed, and interpreted as dynamically stable materials and not as static electrochemical interfaces.

Medium entropy alloys (MEAs) have emerged as a promising class of materials for electro¬catalysis due to their tunable properties and exceptional catalytic performance. This study successfully functionalized a bulk FeCoNiCu alloy using a combined anodic oxidation (AO) and nitridation (NT) approach to produce a highly porous, thin-film catalyst. The hierarchical structure formed during the surface treatments enhances the material's specific surface area and alters the oxidation states of the constituent metals, creating abundant active sites. The electrocatalytic performance of the modified bulk FeCoNiCu electrode was evalu¬ated for both the oxygen evolution reaction (OER) and glycerol oxidation reaction (GOR) in an alkaline electrolyte. Remarkably, the AO-NT-treated catalyst exhibited superior activity for OER, surpassing commercial IrOx benchmarks with lower overpotential requirements. For GOR, the FeCoNiCu electrode demonstrated excellent performance by significantly reducing energy input compared to OER, highlighting its potential as a dual-purpose catalyst for alkaline water splitting. Post-reaction product analysis via NMR confirmed the formation of value-added chemicals, with formic acid identified as the main product. These results underline the feasibility of surface-modified MEAs for sustainable energy and chemical production applications, offering a cost-effective alternative to noble metal-based catalysts.

Understanding material transformations at the nano- and microscale is essential for advancing electrocatalysis, energy storage, and other applications. Conventional SEM imaging, which captures random locations before and after treatment, struggles to distinguish real transformations from inherent sample heterogeneity. Identical Location SEM (IL-SEM) overcomes this by enabling re-imaging of the exact same region, offering clear evidence of localized changes in morphology, structure, and composition. Despite its simplicity and wide applicability, IL-SEM remains underutilized. This article presents a detailed, practical guide to implementing IL-SEM reliably, including sample alignment, multiscale imaging, and consistent re-localization. Key methodological tips and solutions to common challenges are provided, making the approach accessible even for non-expert users. To showcase its versatility, we present case studies involving electrocatalysts, alloys, and nanostructured materials. Moreover, by integrating IL-SEM with energy-dispersive spectroscopy (EDS) and electron backscatter diffraction (EBSD), we demonstrate how compositional and crystallographic evolution can be tracked alongside morphological changes. This optimized workflow offers a powerful, non-destructive method for visualizing dynamic material behavior and provides a foundation for IL-SEM to become a standard technique for studying structural evolution across diverse materials research fields.

We report the first grain-resolved mapping of oxygen evolution reaction (OER) activation on a Ni-based superalloy using identical-location EBSD, complemented by IL-SEM, IL-EDS, and SECCM. NiFe (oxy)hydroxide film formation and OER activity are strongly influenced by grain size and orientation, with (111)-oriented and smaller grains undergoing pronounced structural, chemical, and electrochemical transformations. These findings reveal pronounced microstructure heterogeneity in OER and establish IL-EBSD as a powerful tool for the microstructure-guided design of advanced electrocatalysts.

The electrochemical CO2 reduction (ECO2R) on copper (Cu) remains one of the most promising pathways to convert CO2 into value-added products. However, it suffers from severe restructuring, resulting in the unknown structural identity of the ECO2R active catalyst. Here, we show that dissolution-redeposition is the universal early-stage restructuring mechanism in ECO2R, occurring across all the tested Cu morphologies, including foils, nanoparticles, oxide-derived films, and gas diffusion electrodes. Using identical location scanning electron microscopy, we directly visualize and confirm that this transformation begins at the reaction onset, reshaping catalyst morphology and complicating structure-activity interpretations. Our findings demonstrate that all the Cu catalysts act as precursors to their true, in situ-formed active phase, generated through the reduction of Cu oxides and electrolyte-driven dissolution-redeposition. Recognizing the universality of this transformation is essential for accurate mechanistic understanding and the rational design of future Cu-based ECO2R catalysts.

Bubble formation during gas-evolving electrochemical reactions disrupts potential control and obscures intrinsic catalyst-performance relationships. While conventional strategies to mitigate this issue have relied on surface engineering or cell design, here we introduce a dynamic internal resistance (IR) compensation approach that adapts to bubble-induced fluctuations in real time. This was achieved by employing (i) operando electrochemical impedance spectroscopy (EIS), which provided the electrolyte resistance (R Ohm) parameter continuously, and (ii) a Python control loop to extract EIS data and dynamically adjust the IR compensation. This self-correcting approach effectively suppressed bubble-induced artifacts during prolonged electrochemical CO2 reduction (ECO2R) on copper, enabling accurate performance evaluation and reliable assessment of catalyst instability under realistic operating conditions. We argue that such control is essential in ECO2R stability studies, where even minor potential shifts can obscure intrinsic catalyst-performance relationships and hinder mechanistic insight into degradation.

Electrochemical systems are inherently dynamic, often leading to unreliable performance assessments and even degradation. To address this challenge, we developed a self-correcting operando electrochemical impedance spectroscopy (EIS) method, regulated by a custom Python script, enabling non-destructive, real-time, and adaptive control over electrochemical processes. The methods' applicability was demonstrated on copper-catalyzed electrochemical CO2 reduction (ECO2R), a system known for its instability. By dynamically adjusting electrochemical parameters based on live EIS feedback, we effectively neutralized bubble-induced artifacts and achieved reliable tracking of activity and selectivity evolution. Additionally, the approach enabled direct observation of catalyst surface changes under true reaction conditions, yielding accurate operando insights into how interfacial alterations drive ECO2R performance shifts. Altogether, the results presented in this letter establish our method as a versatile operando framework to uncover, correct, and ultimately eliminate artifacts arising from the dynamic behavior of electrochemical systems.

This study demonstrates the transformation of commercially produced Inconel 625, a Ni-based superalloy, into a high-performance oxygen evolution reaction (OER) anode material through sequential nitridation and anodic oxidation treatments. Nitridation at 750 degrees C enriches surface NiFe content at the grain boundaries and scratches while reducing Cr concentration. Subsequent anodic oxidation further aggressively restructures the surface, introducing micrometer-scale cracks through aggressive intergranular corrosion, where the regions with smaller grains exhibit enhanced porosity. Through these surface modifications, an 8:1 NiFe ratio is established as an active OER oxyhydroxide film. Nano-to-microscale morphological and compositional insights are revealed through an advanced electrochemical characterization approach, utilizing identical location (IL) electron microscopy techniques, including IL-scanning electron microscopy and IL-energy dispersive spectroscopy mappings, along with time-of-flight secondary ion mass spectrometry, X-ray photoelectron spectroscopy and Fe and Ni K-edge X-ray absorption spectroscopy. The treated Inconel 625 exhibits a twofold increase in electrochemical surface area and outperforms both the untreated analog and iridium-based benchmark in OER performance. These findings establish Inconel 625 as a scalable and cost-effective material for alkaline water electrolyzers. Advanced surface engineering of complex alloys offers a promising route to address key electrocatalytic challenges and drive the hydrogen economy forward.

Compositionally complex materials (CCMs) have recently attracted great interest in electrocatalytic applications. To date, very few materials were systematically developed and tested due to the highly difficult preparation of high-surface-area CCMs. In this work, a surface of a compositionally complex FeCoNiCuZn alloy (CCA) was nitridated with subsequent anodization leading to morphological and compositional modifications. Notably, the electrochemical surface area and surface roughness as well as the electrocatalytic activity of the anodized material exhibit significant enhancement. Oxygen evolution reaction (OER) activity by the anodized CCN (CCN-AO) proceeds with remarkably small overpotential (233 mV) at 10 mA cm-2 in 1 M KOH. Experimental characterization indicates that the oxidation state of Co plays a critical role in the Fe-Co-Ni electrocatalyst. The developed approach and design strategy open up immense prospects in the preparation of a new, affordable, scalable and effective type of complex and high-performance electrocatalytic electrodes with tunable properties.

Aiming at speeding up the discovery and understanding of promising electrocatalysts, a novel experimental platform, i.e., the Nano Lab, is introduced. It is based on state-of-the-art physicochemical characterization and atomic-scale tracking of individual synthesis steps as well as subsequent electrochemical treatments targeting nanostructured composites. This is provided by having the entire experimental setup on a transmission electron microscopy (TEM) grid. Herein, the oxygen evolution reaction nanocomposite electrocatalyst, i.e., iridium nanoparticles dispersed on a high-surface-area TiOxNy support prepared on the Ti TEM grid, is investigated. By combining electrochemical concepts such as anodic oxidation of TEM grids, floating electrode-based electrochemical characterization, and identical location TEM analysis, relevant information from the entire composite's cycle, i.e., from the initial synthesis step to electrochemical operation, can be studied. We reveal that Ir nanoparticles as well as the TiOxNy support undergo dynamic changes during all steps. The most interesting findings made possible by the Nano Lab concept are the formation of Ir single atoms and only a small decrease in the N/O ratio of the TiOxNy-Ir catalyst during the electrochemical treatment. In this way, we show that the precise influence of the nanoscale structure, composition, morphology, and electrocatalyst's locally resolved surface sites can be deciphered on the atomic level. Furthermore, the Nano Lab's experimental setup is compatible with ex situ characterization and other analytical methods, such as Raman spectroscopy, X-ray photoelectron spectroscopy, and identical location scanning electron microscopy, hence providing a comprehensive understanding of structural changes and their effects. Overall, an experimental toolbox for the systematic development of supported electrocatalysts is now at hand.

Titania nanotubes are gaining prominence in the biomedical field as implant materials due to their mechanical durability, nano-rough properties, and positive influence on cellular response. This work aimed to synthesize titania and titanium oxynitride (Ti–O–N) nanotubular arrays on TiAl6V4 substrates using an anodic oxidation process followed by annealing in air or by additional nitridation in NH3 atmosphere. Different nanotubular layers of unique morphology and structure were fabricated and investigated using advanced surface analysis and biocompatibility tests. In-depth surface analysis was performed by field emission scanning electron microscopy (FE-SEM), atomic force microscopy (AFM), 3D profilometry, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). Cell testing using adipose-derived mesenchymal stem cells and human fetal osteoblasts demonstrated good cell viability, high proliferative capacity, and a favorable overall effect on cell morphology for the Ti–O–N nanotubes.

A versatile approach to the production of cluster- and single atom-based thin-film electrode composites is presented. The developed TiO x N y -Ir catalyst was prepared from sputtered Ti-Ir alloy constituted of 0.8 ± 0.2 at % Ir in α-Ti solid solution. The Ti-Ir solid solution on the Ti metal foil substrate was anodically oxidized to form amorphous TiO2-Ir and later subjected to heat treatment in air and in ammonia to prepare the final catalyst. Detailed morphological, structural, compositional, and electrochemical characterization revealed a nanoporous film with Ir single atoms and clusters that are present throughout the entire film thickness and concentrated at the Ti/TiO x N y -Ir interface as a result of the anodic oxidation mechanism. The developed TiO x N y -Ir catalyst exhibits very high oxygen evolution reaction activity in 0.1 M HClO4, reaching 1460 A g-1Ir at 1.6 V vs reference hydrogen electrode. The new preparation concept of single atom- and cluster-based thin-film catalysts has wide potential applications in electrocatalysis and beyond. In the present paper, a detailed description of the new and unique method and a high-performance thin film catalyst are provided along with directions for the future development of high-performance cluster and single-atom catalysts prepared from solid solutions.

Au/TiO2 photocatalysts were studied, characterized, and compared for CO2 photocatalytic gas-phase reduction. The impact of the nature of the TiO2 support was studied. It was shown that the surface area/porosity/TiO2 crystal phase/density of specific exposed facets and oxygen vacancies were the key factors determining CH4 productivity under solar-light activation. A 0.84 wt.% Au/TiO2 SG (Sol Gel) calcined at 400 °C exhibited the best performance, leading to a continuous mean CH4 production rate of 50 μmol.h−1.g−1 over 5 h, associated with an electronic selectivity of 85%. This high activity was mainly attributed to the large surface area and accessible microporous volume, high density of exposed TiO2 (101) anatase facets, and oxygen vacancies acting as reactive defects sites for CO2 adsorption/activation/dissociation and charge carrier transport.

Decreasing iridium loading in the electrocatalyst presents a crucial challenge in the implementation of proton exchange membrane (PEM) electrolyzers. In this respect, fine dispersion of Ir on electrically conductive ceramic supports is a promising strategy. However, the supporting material needs to meet the demanding requirements such as structural stability and electrical conductivity under harsh oxygen evolution reaction (OER) conditions. Herein, nanotubular titanium oxynitride (TiON) is studied as a support for iridium nanoparticles. Atomically resolved structural and compositional transformations of TiON during OER were followed using a task-specific advanced characterization platform. This combined the electrochemical treatment under floating electrode configuration and identical location transmission electron microscopy (IL-TEM) analysis of an in-house-prepared Ir-TiON TEM grid. Exhaustive characterization, supported by density functional theory (DFT) calculations, demonstrates and confirms that both the Ir nanoparticles and single atoms induce a stabilizing effect on the ceramic support via marked suppression of the oxidation tendency of TiON under OER conditions.

The reduction of Ir loading and thus its efficient utilization in proton exchange membrane water electrolyzers (PEM-WE) inevitably depends on the rational design of novel nanomaterials. This, however, is not possible without the understanding of structure-stability interrelations and underlying mechanisms. When pursuing the reduction of Ir amount by its dispersion on ceramic materials, the interactions between the catalytically active sites and their support further complicate the already understood processes. In the present study, we use our unique approach, where we employ an Ir/TiON-based TEM grid and use it as a support system for the investigation of structural transformations of Ir nanoparticles. This was achieved by utilizing both the modified floating electrode (MFE) apparatus, which enables efficient bubble management during electrochemical experiments and identical-location scanning transmission electron microscopy (IL-STEM) approach. The analysis of obtained high-resolution images with in-house developed computer algorithms for image analysis reveals several processes with surface roughening being the predominant degradation mechanism. Additionally, suppressed oxidation tendency of supported Ir was directly confirmed.

Pharmaceuticals are used every day in most parts of the world and great proportions of these substances are excreted unaltered or as active sub-products, posing a threat of pollution. To protect the aquatic ecosystems, innovative solutions such as photocatalysis, electrocatalysis and photoelectrocatalysis are required. In this article we provide a comprehensive review of photo-and electrocatalytic techniques for the removal of pharmaceuticals from water and wastewaters. The analytical and toxicity methods commonly used to study the degradation of pharmaceuticals are presented, and it is pointed high performance liquid chromatography analysis as the most common analytical method to evaluate the efficiency in the pharmaceutical's degradation. However, it is also highlighted that the evaluation of the toxicity is fundamental to ensure adequate treatment. The determination of the reactive species and the mechanistic evaluation of pharmaceuticals degradation are essential to understanding and enhancing the degradation process. A deep discussion of photocatalysis, electrocatalysis and photoelectrocatalysis principles and practical examples of their application in pharmaceuticals treatment is presented. The catalytic materials and the reactors used in these processes for the removal of pollutants are reviewed focusing on some representative examples. The reusability of catalysts is still restricted to a few reuse cycles. It was observed very limited results in the treatment of larger amounts of effluent and a lack of information about process costs, which were correlated to the difficulty of application of these techniques on real scale. Finally, the main advantages of photocatalysis, electrocatalysis and photoelectrocatalysis as high efficiency on pharmaceuticals degradation, and the main drawbacks, as the low quantum efficiency and/or high energetic consume are pointed out along with alternatives to overcome these limitations.