Corina Andronescu

Anion exchange membrane water electrolysis (AEMWE) is a promising technology for sustainable hydrogen production but currently relies on highly purified water. Its large‐scale implementation would benefit from alternative water sources. However, the effects of dissolved contaminants, particularly organic compounds such as aromatic amines, remain poorly understood. We therefore investigated structurally distinct aromatic amines as model contaminants to evaluate their effects on the water splitting performance of nickel electrodes. Electrochemical measurements, product analysis, and operando interfacial characterization were combined to identify structure‐dependent effects and mechanisms of catalyst deactivation and recovery. Aniline severely suppressed the oxygen evolution reaction, whereas its methyl‐substituted derivatives had negligible effects. Complementary analyses attributed this inhibition to the potential‐dependent accumulation of an aniline‐derived, polyaniline‐like surface layer. This layer progressively modified the NiOOH/electrolyte interface, impeded interfacial charge transfer, and reduced oxygen evolution. These findings contribute to fundamental insights into how organic contaminants originating from feedwater or the degradation of polymeric electrolyzer components interact with nickel‐based electrodes, providing valuable guidance for defining feedwater‐quality requirements of future AEMWE systems.

The development of efficient oxygen evolution reaction (OER) catalysts requires a detailed understanding of how structural and compositional modifications influence the catalytic performance. Here, we present a high-throughput platform to induce structural and chemical modifications in Co ₃ O ₄ thin films by combining direct laser interference patterning (DLIP) with picosecond-pulsed laser defect engineering in liquids (PUDEL) and spatially resolved electrochemical screening via scanning electrochemical cell microscopy (SECCM). This approach enables the generation of spatially varying surface modifications within a single experiment, including controlled film restructuring, defect formation, and compositional changes. Localized measurements reveal that the OER activity is maximized at moderate laser fluence, where film restructuring and compositional changes occur, while excessive fluence leads to ablation and reduced performance. Despite the detectable Fe incorporation, activity trends are primarily governed by structural changes of the Co ₃ O ₄ film. This work establishes DLIP-PUDEL combined with SECCM as a platform for rapid structure–activity correlations and accelerated electrocatalyst development.

Epitaxial films are a model platform to investigate compositionally complex solid solutions (CCSSs). This work demonstrates how epitaxial CCSS films are grown and how correlative structure–activity mapping reveals their electrocatalytic behavior.

It has been shown that the incorporation of silver into the surface of a titanium alloy (Ti6Al4V) by powder mixed electrical discharge machining (PMEDM) exhibits an antiadhesive effect against Staphylococcus spp.. This study aims to investigate the electrochemical performance of this modified surface under simulated physiological conditions, mimicking in vivo corrosion-inducing conditions. Electrochemical behavior was analyzed using potentiodynamic polarization measurements, Kelvin probe fore microscope (KPFM) measurements and ion release quantification, while crevice-corrosion mechanisms were evaluated retrospectively by scanning electron microscopy and energy-dispersive X-ray spectroscopy.Corrosion current density showed an inverse association with PMEDM discharge energy, while neither silver content in the modified zone nor the open-circuit potential exhibited a significant association with corrosion activity. Crevice exposure led to Ti-rich, O-poor deposits at the inner end consistent with hydride formation and localized Ag-associated microgalvanic pitting corrosion were observed; which could be confirmed by local Volta potential differences in KPFM measurements. However, no widespread material degradation or propagating crevice corrosion was observed under the investigated conditions. Metal quantification revealed higher absolute release of alloying elements from the rougher PMEDM surfaces and an increase in the Ag release with the Ag content on the surface; the measured released Ag levels were within ranges regarded as antibacterial.Together, these findings indicate that PMEDM processing parameters influence the global electrochemical response, whereas Ag (particles) primarily affect localized surface mechanisms and Ag ion release. Under the investigated conditions, no correlation between Ag and corrosion current nor widespread surface degradation was detected, which could be translated into independent adaptation options for both electrochemical performance (based on discharge energy) and antibacterial properties (based on Ag content).

Strain has emerged as a promising approach for tuning electrocatalytic properties, yet its role in sputter-deposited thin films remains poorly understood. In this work, magnetron-sputtered platinum (Pt) thin films with different stress states were prepared by varying the sputter pressure. The resulting changes in microstructure, residual strain, and hydrogen evolution reaction (HER) activity were investigated using complementary characterization techniques and density functional theory (DFT) calculations. Structural analysis reveals a transition of (111)-textured Pt thin films from dense and smooth films at low pressures to more porous microstructures with increased roughness at higher pressures. Electrochemical measurements show that films deposited at a low sputter pressure exhibit the highest HER activity, while higher sputter pressures lead to reduced activity despite the increased surface area. DFT calculations demonstrate that lattice strain alters hydrogen adsorption energetics and surface coverage on Pt(111), providing a mechanistic explanation for the observed activity trends. Overall, the results highlight that HER activity in sputtered Pt thin films is governed by the interplay of residual strain, microstructure, and hydrogen coverage.

The potential of zero charge (PZC) is a key descriptor of the electrochemical interface, influencing ion distributions, mass transport, and reaction thermodynamics. It depends on the local surface structure, including grain orientation and atomic steps, making spatially resolved measurements essential. Scanning electrochemical cell microscopy (SECCM) enables local probing of electrochemical properties, including PZC. However, PZC probing via SECCM has been limited to pipette diameters above 1 µm due to low transient charging currents near the PZC, often at the instrumental detection limit. Here, PZC measurements on a Pt (111) thin film are demonstrated using submicron pipettes (~500 and ~250 nm diameters). Under conditions where the interfacial response is dominated by double‐layer charging, the measured PZC is consistent with macroscale results, with values of ~0.30 V versus standard hydrogen electrode (SHE). The study reveals the impact of preconditioning, electrolyte pH, and gas atmosphere used during SECCM measurements on the recorded PZC at the nanoscale on Pt (111). In particular, variations in preconditioning potential lead to systematic shifts in both PZC and hydrogen evolution reaction (HER) activity, reflecting the correlation between both properties. Overall, this work establishes a robust experimental protocol for PZC mapping at the submicron scale using SECCM.

The development of efficient oxygen evolution reaction (OER) catalysts requires a detailed understanding of how structural and compositional modifications influence the catalytic performance. Here, we present a high-throughput platform to induce structural and chemical modification in Co3O4 thin films by combining direct laser interference patterning (DLIP) with picosecond-pulsed laser defect engineering in liquids (PUDEL) and spatially resolved electrochemical screening via scanning electrochemical cell microscopy (SECCM). This approach enables the generation of spatially varying surface modifications within a single experiment, including controlled film restructuring, defect formation, and compositional changes. Localized measurements reveal that the OER activity is maximized at moderate laser fluence, where film restructuring and compositional changes occur, while excessive fluence leads to ablation and reduced performance. Despite detectable Fe incorporation, activity trends are primarily governed by structural changes of the Co3O4 film. This work establishes DLIP-PUDEL combined with SECCM as a platform for rapid structure–activity correlation and accelerated electrocatalyst development.

The tedious and time-consuming solvent exchange during aerogel production was sped up using a standard Soxhlet extractor. Optimizing the setup with a vent and molecular sieve allowed to save up to 80% of the production time compared to batchwise extractions while maintaining state-of-the-art samples of silica and polyurethane aerogels, i.e. MTMS aerogels with a thermal conductivity of 15 mW m⁻¹ K⁻¹ and PU aerogels with 17 mW m⁻¹ K⁻¹ and good mechanical properties even after freeze-drying, which is generally more stressful than supercritical drying. The syntheses had to be carried out in high-boiling solvents, but adaptation and optimisation were made possible rapidly due to the method developed.

Compositionally complex solid solutions provide a unique route for engineering high-performance electrocatalysts, where the polyelemental surface composition can be seamlessly tuned to optimize activity, selectivity, and stability. However, the mechanistic understanding of these electrocatalysts remains limited by the lack of a model system with a crystallographically-defined surface that is compatible with correlative, multi-scale characterization. Here, we present epitaxial films as a model platform for studying compositionally complex electrocatalysts. Using magnetron sputtering, we realize (111) epitaxial Ir-Pd-Pt-Rh-Ru films on (0001) sapphire substrate via a (111) Pt buffer layer, confirmed by X-ray diffraction and transmission electron microscopy. The growth approach is applicable across a broad composition range and produces smooth surfaces (root mean square roughness < 1 nm) with micrometer-sized grains in the nanoscale films. With these films, we demonstrate direct structure-activity mapping at the nanoscale through precise co-localization using micro-indents and performing correlative atomic force microscopy, electron backscatter diffraction, and scanning electrochemical cell microscopy. Our work establishes a model platform for fundamental scalebridging characterization and paves the way for rational design of compositionally complex electrocatalysts.