LAUSR

Abstract This review presents recent progress in the understanding of electrochemical phase formation on low-energy substrates, which is essential for metal electrodeposition and the design of stable batteries. Advanced characterization techniques and ultrasensitive electrochemical instrumentation give access to experimental data that were not available a few years back. Besides, the continuous development of theoretical models gradually provides a more complete description of multiple nucleation. However, important contradictions between experimental findings and theoretical formulations are found: nonclassical growth pathways, single-atom critical clusters, and cluster densities that are orders of magnitude higher than the calculated number of active sites. New descriptions of the initial steps of nucleation are discussed. They are grounded on nucleation being a nonactivated process, in which the initial stages of phase formation could involve simply adsorbed atoms collapsing into larger clusters driven by minimization of the overall interfacial energy. Finally, some remaining challenges and possible research directions are outlined.