Fabrication of metallic surfaces with controlled roughness by electrochemical methods

The surface roughness has long been considered as a critical characteristic of a material as it could greatly influence and determine the material's functionality. Due to this reason, the development of electrochemical protocols that enable the fabrication of metallic surfaces with tunable roughness and controlled structure is the primary focus of this dissertation. Taking advantage of de-alloying (selectively dissolving the less noble element from an alloy), galvanic displacement, and electrodeposition, this work demonstrates considerable progress in the generation of surfaces displaying morphologies in the length scale of a few nano-meters to several hundred nano-meters and structures ranging from interconnected-porous to dendrite-crystalline. In addition to the synthetic work, a Pb UPD-assisted method was developed and employed for quantitative characterization of surface roughness.;For nano-rough surfaces, an approach that extends the fabrication of nanoporous metal to nanoporous alloy upon the de-alloying of a single-phase binary alloy is established. This method could be utilized in the synthesis of high-performance catalysts. Another direction of this work is associated with a systematic study of de-alloying in amorphous alloys that as an alternative route for the preparation of nanoporous metals from precursors featuring thermodynamically immiscible metals. Furthermore, a galvanic displacement carefully tuned by the application of external voltage is explored for further expansion of the application of electrochemical techniques in nanoporous metal synthesis. Besides nano-rough surfaces, the synthesis of micro-rough surfaces with dendrite-crystalline structure by both electrodeposition and direct galvanic displacement methods is explored in a more applied twist of this dissertation. The ultimate goal of this approach is generation of surface roughness that after modification with a hydrophobic layer rendering the surface superhydrophobic.;Overall, issues regarding the implementation of the above electrochemical approaches have been deliberately addressed; advantages and limitations of those methods have been elucidated and systematically documented; factors that influence the roughness and the structure evolution have been identified; potential applications of the metallic surfaces with different roughness levels are demonstrated and proposed for future work. This dissertation, thus, provides a powerful outlook on the design of controlled-roughness metallic surfaces using the electrochemical methods.