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Dealloying is widely utilized but is a dangerous corrosion process as well. Here we report an atomistic picture of the initial stages of electrochemical dealloying of the model system Cu(3)Au (111). We illuminate the structural and chemical changes during the early stages of dissolution up to the critical potential, using a unique combination of advanced surface-analytical tools. Scanning tunneling microscopy images indicate an interlayer exchange of topmost surface atoms during initial dealloying, while scanning Auger-electron microscopy data clearly reveal that the surface is fully covered by a continuous Au-rich layer at an early stage. Initiating below this first layer a transformation from stacking-reversed toward substrate-oriented Au surface structures is observed close to the critical potential. We further use the observed structural transitions as a reference process to evaluate the mechanistic changes induced by a thiol-based model-inhibition layer applied to suppress surface diffusion. The initial ultrathin Au layer is stabilized with the intermediate island morphology completely suppressed, along an anodic shift of the breakdown potential. Thiol-modification induces a peculiar surface microstructure in the form of microcracks exhibiting a nanoporous core. On the basis of the presented atomic-scale observations, an interlayer exchange mechanism next to pure surface diffusion becomes obvious which may be controlling the layer thickness and its later change in orientation.

We report the onset of electrochemical doping and subsequent visible light emission at 5V and 360K from a planar light-emitting electrochemical cell with a 1mm interelectrode gap containing poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1, 4-phenylenevinylene] (MEH-PPV), poly(ethylene oxide) (PEO), and XCF3SO3 (X=K,Li) as the active material. We rationalize the unprecedented low turn-on voltage of such wide-gap light-emitting electrochemical cells by demonstrating that the active material contains a mixture of crystalline PEO+XCF3SO3 domains and amorphous MEH-PPV domains at room temperature, but that the crystalline domains have melted at 360K resulting in a significant increase in the ionic conductivity.

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