(594e) Directed Self-Assembly of Block Copolymers for Well-Defined Nanostructured Electrocatalysts

Periodic nanostructures with long-range order and low-level structure defects are hallmark achievements of Directed Self-Assembly (DSA) of block copolymers for lithographic patterning. This bottom-up, macromolecular nanomanufacturing platform has been adopted by numerous industrial companies and consortiums for developing the next-generation microelectronics with smaller feature sizes that enable greater data processing speeds and storage. However, the DSA platform has largely been confined to the patterning of semiconductor materials and little attention has been given to the potential it offers for electrochemical applications. In particular, the DSA platform for fabricating well-defined electrocatalysts with high fidelity is intriguing as model nanoscale electrocatalyst studies often do not feature uniform spacing and a single morphology when processed as thin electrodes for electrocatalytic activity studies (e.g., in a rotating disk electrode setup). The lack of well-defined electrocatalyst structures hinder structure-property relationships that definitively reveal how nanoscale attributes govern electrocatalytic activity.

This talk will present two different DSA nanomanufacturing platforms to access platinum, palladium, and gold nanowires and dots (and alloys of these metals) from perpendicular lamellae and cylinder block copolymer templates on electron conducting glassy carbon substrates and interdigitated electrode substrates. The two nanomanufacturing methods consisted of: i.) incipient wetness impregnation of self-assembled poly(styrene-block-2-vinyl-methyl pyridinium iodide/pyridine) with metal salts followed by reduction and ii.) self-assembled block copolymers were one polymer block is etched out, physical vapor deposition of electrocatalyst metals occurs followed by liftoff of the porous polymer mask. X-ray photoelectron spectroscopy and electron microscopy were used to characterize the morphology and chemical composition of the extended surface electrocatalysts. Catalytic activity for model reactions (e.g., oxygen reduction and water oxidation) were substantiated with the well-defined nanostructure materials. Connections between morphology to electrocatalytic activity will be disseminated.