Laboratoire Interfaces et Systèmes Électrochimiques

Well-crystallized ZnMn 2 O 4 thin films were fabricated via a facile single-step plasma process without calcination. These films showed excellent electrochemical performance and remarkable stability as cathode materials for zinc-ion batteries (ZIBs).

An improved understanding of the materials that will sustain the future of energy production, storage, and delivery calls for better characterization tools. Operando characterization methods have thus become essential for investigating electrocatalytic materials. Without their resulting insights, the study of highly performing catalysts post-mortem cannot viably facilitate the further development of functional catalysts. Herein, we present an operando electrochemical cell designed for hard X-ray absorption spectroscopy (XAS) and specifically adapted to the study of an electrocatalytically active Cu nanoparticle ensemble. So far, this nanocatalyst has proven to pose quite a challenge to characterize due to its unique structural dynamics. Adopting a design comparable to the H-cell employed for all activity testing, we report the satisfactory translation of the active site formation into an XAS-compatible cell. The simultaneous collection of CO2-derived products during XAS characterization enabled the operando characterization of this CO2-reducing active structure. We report a Cu–Cu coordination number of the first scattering path higher than suggested in our previous studies, highlighting the importance of monitoring metastable nanoelectrocatalysts in operando. This study illustrates important caveats for the electrocatalysis community when considering the application of operando XAS. Our results highlight that the sample size, homogeneity, and stability determine how to interpret the measured signal. Considering these parameters carefully, the operando EXAFS results confirm the exceptional undercoordinated character of the Cu nanoparticle ensemble during CO2 reduction to C2+ products.

ABSTRACT Binder‐free electrodes are critical for advancing supercapacitor performance. Here, we explore the development of multi‐wall carbon nanotubes (MWCNTs) electrodes for supercapacitors by replacing conventional non‐conductive polymer binders, such as poly(vinylidene fluoride‐ co ‐hexafluoropropylene) (PVDF‐HFP), with a conductive polymer, poly(3,4‐ethylenedioxythiophene) (PEDOT). PEDOT/MWCNT composite films were synthesized and characterized in an aqueous medium using an electrochemical quartz crystal microbalance (EQCM) and an advanced ac ‐electrogravimetric technique to investigate their charge storage mechanisms and ionic transfer kinetics. Compared to MWCNTs/PVDF‐HFP and pure PEDOT films, the PEDOT/MWCNT composite demonstrates enhanced electrochemical performance, with improved ion concentration and reduced interfacial resistance. The EQCM analysis reveals distinct mass transfer behaviors, highlighting the role of anions, cations, and free water molecules at the interface of electrodes. Ac‐electrogravimetry investigation further identifies the kinetics of ion transfer and the relative concentration of each species, showing that the composite film facilitates efficient charge storage. This work provides a new insight into understanding the interfacial behavior of binder‐free PEDOT/MWCNT electrode.

ABSTRACTThis study systematically investigated the effect of Mg content (0.5%, 1.8%, and 3.5%) on the microstructure, mechanical properties, and corrosion behavior of AlSi10 alloys fabricated via selective laser melting (SLM). Microstructural characterization via scanning electron microscopy and energy dispersive X‐ray spectroscopy (SEM/EDS) revealed that an increase in Mg content impairs the continuity of the Si network. The most severe disruption is observed in SLM AlSi10Mg3.5, accompanied by Mg aggregation. Tensile tests showed that higher Mg content improved yield strength (up to ~350 MPa in AlSi10Mg3.5) but reduced ductility. Electrochemical tests conducted in 3.5 wt.% NaCl solution demonstrated that SLM AlSi10Mg3.5 has the highest corrosion current density, whereas AlSi10Mg0.5 exhibited the best corrosion resistance. A kinetic model based on the univalent Mg (Mg+) was used to interpret the EIS data. Overall, a Mg content of 0.5% achieved an effective balance between mechanical properties and corrosion resistance.