A robust and efficient route to modify the chemical and physical properties of polycrystalline copper (Cu) wires via versatile plasma electrolysis is presented. Silica (SiO₂) nanoparticles (11 nm) are introduced during the electrolysis to tailor the surface structure of the Cu electrode. The influence of these SiO₂ nanoparticles on the structure of the Cu electrodes during plasma electrolysis over a wide array of applied voltages and processing time is investigated systematically. Homogeneously distributed 3D coral‐like microstructures are observed by scanning electron microscopy on the Cu surface after the in‐liquid plasma treatment. These 3D microstructures grow with increasing plasma processing time. Interestingly, the microstructured copper electrode is composed of CuO as a thin outer layer and a significant amount of inner Cu₂O. Furthermore, the oxide film thickness (between 1 and 70 µm), the surface morphology, and the chemical composition can be tuned by controlling the plasma parameters. Remarkably, the fabricated microstructures can be transformed to nanospheres assembled in coral‐like microstructures by a simple electrochemical treatment.

Significant water oxidation reactivity enhancement in BiVO ₄ photoanodes is achieved by simultaneous bulk doping with molybdenum and surface-modification with a polyoxometalate water oxidation co-catalyst.

This work provides deep insights into the structural changes likely to occur at cathodes under highly reducing conditions, such as HER, CO₂, and N₂ reduction, as well as cathodic electro-conversion in various (organic) electrosynthesis reactions.

Cathodic corrosion of Au wires in highly concentrated NaOH (5–20 M) is systemically investigated to monitor the structural transformation as a function of applied electrode potential, polarization time, and electrolyte concentration. Current–potential curves for the restructured Au electrodes in 0.1 M H ₂ SO ₄ demonstrate preferential (111)-orientation of nanofacets and an increase in electrochemically active surface area as a function of the applied parameters. SEM shows that polarizing the Au surfaces at sufficiently negative potentials leads to the growth of nanosized octahedral and triangular crystallites that can be tailored by varying NaOH concentrations. The nanocrystal growth occurs through dissolution and metal redeposition. The formation of etching pits indicates that Au dissolution is dominating during the initial stages of cathodic corrosion. The number of nanocrystals increases at more negative potentials due to the greater nucleation density induced by the higher concentration of dissolved Au species. Polarization times above 5.0 min result in fractal growth indicated by the appearance of multi-armed nanostructures. This work not only advances our understanding of the initial stages of nanocrystal formation but also offers a powerful means for controlling the shape and size of metal nanocrystals simply by the rational design of the cathodic corrosion.

Applying a voltage to metal electrodes in contact with aqueous electrolytes results in the electrolysis of water at voltages above the decomposition voltage and plasma formation in the electrolyte at much higher voltages referred to as contact glow discharge electrolysis (CGDE). While several studies explore parameters that lead to changes in theI–Ucharacteristics in this voltage range, little is known about the evolution of the structural properties of the electrodes. Here we study this aspect on materials essential to electrocatalysis, namely Pt, Au, and Cu. The stationaryI–Ucharacteristics are almost identical for all electrodes. Detailed structural characterization by optical microscopy, scanning electron microscopy, and electrochemical approaches reveal that Pt is stable during electrolysis and CGDE, while Au and Cu exhibit a voltage‐dependent oxide formation. More importantly, oxides are reduced when the Au and Cu electrodes are kept in the electrolysis solution after electrolysis. We suspect that H₂O₂(formed during electrolysis) is responsible for the oxide reduction. The reduced oxides (which are also accessibleviaelectrochemical reduction) form a porous film, representing a possible new class of materials in energy storage and conversion studies.