(Electrodeposition Division Research Award) Impact of Electrodeposition on the Design and Synthesis of Nanoporous Functional Materials
Authors: Dimitrov Nikolay 
Published: November 2022

The sustainable growth of efficient and durable functional nanomaterials applicable in a variety of practical fields is founded on the creative design, rational synthesis, extensive characterization, and realistic testing of products developed by countless hard-working research teams. Many of these nanomaterials must include high-cost and scarcely distributed elements and compounds that need to be either eliminated or minimally used as much as it is possible. Most commonly, such minimization has been approached by synthesizing the materials of interest in the form of nanoparticles. Nanoparticles are undoubtedly superior to other type of materials in a variety of fields and applications because of their large surface area to volume ratio and unique chemical and physical properties. Their implementation in practice also addresses well the objective for minimization of the use of expensive elements and compounds. At the same time, as class of nanomaterilas, the nanopartiles suffer some drawbacks like loss of material during synthesis, surface contamination/blockage by chemicals used in their synthesis, mechanical disconnection from carrier electrodes, and / or aggregation during exploitation. Such unwelcome developments often make it difficult to keep the cost low and/or lead to a reduction of the active surface area and thus, to loss of functionality, performance, and stability.

A way of addressing some of the mentioned shortcomings is to employ electrochemical approaches for synthesizing alternative nanostructured materials directly on the carrier electrode. Such approach not only provides for better adhesion and contamination free surface, but also enables an efficient control of the amount of the deposited material along with flexibility in the structuring during the material synthesis, thus most-certainly reducing its overall cost of the final product. The electrochemical means inevitably include controlled electrodeposition of a binary / ternary alloy layer with a desired thickness and pre-selected elemental composition. A naturally following step in the material's synthesis is the selective oxidative dissolution of the less / least noble metal (a.k.a. de-alloying) to create a continuous nanoporous film with tunable pore and ligament size comprising a length-scale in the single-digit nanometer range. Finally, as-synthesized nanostructured films may either be employed directly for the purposes of the intended applications or be subjected to an additional surface functionalization by a further electrodeposition or electroless of a thin layer with specific properties that is aimed at boosting the material's functionality, performance and stability.

This talk will introduce the use of electrochemical means in the design and synthesis of continuous nanoporous Au- and Cu-based functional alloy nanomaterials with applications in electrocatalysis, environmental protection, and electronic packaging. The discussed synthetic approaches will include bulk alloy electrodeposition, electrochemical de-alloying, and electrochemical atomic layer deposition for surface functionalization by films with a thickness in the range from a sub-monolayer to a few monolayers. The presentation of each class of nanostructured materials of interest to this talk will include a conceptual description of their synthetic routines, followed by an electrochemical and ultra-high vacuum-based characterization results, and concluded with a glimpse into the outcome of standard performance tests of the functionality, performance, and stability of said materials in intended applications. Finally, aspects of the materials performance associated with hypothesized mechanistic views will be critically discussed in comparison with other nanoparticulate and/or nanostructured counterpart materials in the literature.