Abstract: The present invention relates to processes for fabricating polymeric hollow fibers. Specifically, a removable solid core fiber is provided for coating one or more layers of a polymeric membrane-forming material thereon. After treating the polymeric membrane-forming material layer to form a solidified polymeric membrane having a permanent tubular shape, the solid core fiber is selectively removed, leaving an elongated lumen inside the solidified polymeric membrane, which forms a high quality polymeric hollow fiber that is substantially free of deformation defects. The solid core fiber can be made of a removable substrate material, such as water-soluble polymers polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), or polyethylene glycol (PEG), which are subsequently and selectively removable by water. Alternatively, the solid core fiber can be coated with a removable substrate material, which imparts removability to such solid core fiber.

Abstract: This invention relates to a microfibrous fuel cell having at least one high quality electrocatalyst layer of a dual-layer structure, i.e., a catalyst layer comprising a catalytic material, and an interfacial composition layer comprising a mixture of catalytic material and electrolyte medium. Said high quality electrocatalyst layer can be formed by various catalyzation methods, including diffusion catalyzation, ion-exchange catalyzation, electrodeposition catalyzation, impregnation catalyzation, chemical deposition catalyzation, and alternating catalyst/electrolyte addition catalyzation. The present invention also relates to a fuel cell assembly comprising multiple such microfibrous fuel cells bundled together, and methods for in situ catalyzation of such fuel cell assembly to form high quality electrocatalyst layers of such dual-layer structure.