Structural transformations of metal alloys under electrocatalytic conditions

Nanostructured alloys are efficient catalysts for mediating renewable energy storage and recovery reactions. The morphology and composition of an alloy can change during catalysis; particularly for potentials more oxidizing than the reversible hydrogen electrode. The formation of noble-metal shells covering an alloy core, or bi-continuous nanoporosity, is a common way an alloy can evolve by a corrosion mediated process. Recently, it was found that alloys can reconstruct within the bulk and form an ordered intermetallic material with different crystal structures and compositions than the starting material during corrosion. This review will discuss the different pathways alloys can be altered by electrochemistry. We will discuss the mechanisms which cover known structural changes and the more recently discovered process involving electrochemically driven incongruent phase transformations. Insights into the transformation of alloy materials are important for understanding how to prepare catalysts with improved electrochemical stability, and for synthesizing materials.