Catalytic approaches towards highly durable proton exchange membrane fuel cells with minimized Pt use.

Proton exchange membrane fuel cells (PEMFCs) produce electricity from H2 without carbon emission, and they are considered as environmentally benign energy conversion devices. Although PEMFCs are mature enough to find themselves in a few commercial automobiles such as Hyundai Nexo and Toyota Mirai, their durability should be enhanced, especially under transient conditions, and Pt use should be reduced significantly to expand their market. Herein, we introduce examples of how catalysts can contribute to enhancing the durability of PEMFCs while minimizing Pt use. Numerous electrocatalysts have been reported claiming superior activity in a half-cell setup, but they often fail to show the same enhancement in a single cell setup due to various transfer problems, impurity poisoning, etc. This perspective focuses on catalysts tested in a membrane-electrode-assembly (MEA) setup. As examples to obtain durability under transient conditions, catalysts used in reversal-tolerant anodes (RTAs) and selective anodes are explained. RTAs can endure sudden H2 starvation, and selective anodes can operate properly when O2 is unexpectedly mixed with H2 in the anode. As examples with high durability in long-term operation, Pt-based nanoparticle catalysts encapsulated with carbon shells are explained. Interestingly, PtCo nanoparticles supported on Co-N-C or PtFe nanoparticles encapsulated with a carbon shell presented a superior cell performance in spite of <1/10 Pt use in an MEA setup. Non-Pt group metal (PGM) catalysts used in an MEA setup are also briefly explained. With these highly durable catalysts which can respond properly under transient conditions with minimum Pt use, PEMFC technology can bring about a more sustainable society.

High-throughput production of silk fibroin-based electrospun fibers as biomaterial for skin tissue engineering applications.

In this work, a nozzle-free electrospinning device was built to obtain high-throughput production of silk fibroin-based biocompatible composite fibers with tunable wettability. Synthetic biomaterials tend to present suboptimal cell growth and proliferation, with many studies linking this phenomenon to the hydrophobicity of such surfaces. In this study, electrospun mats consisting of Poly(caprolactone) blended with variant forms of Poly(glycerol sebacate) (PGS) and regenerated silk fibroin were fabricated. The main aim of this work was the development of fiber mats with tunable hydrophobicity/hydrophilicity properties depending on the esterification degree and concentration of PGS. A variation of the conventional protocol used for the extraction of silk fibroin from Bombyx mori cocoons was employed, achieving significantly increased yields of the protein, in a third of the time required via the conventional extraction protocol. By altering the surface properties of the electrospun membranes, the trinary composite biomaterial presented good in vitro fibroblast attachment behavior and optimal growth, indicating the potential of such constructs towards the development of an artificial skin-like platform that can aid wound healing and skin regeneration.

2D and 3D electrospinning technologies for the fabrication of nanofibrous scaffolds for skin tissue engineering: A review.

This review provides insights into the current advancements in the field of electrospinning, focusing on its applications for skin tissue engineering. Furthermore, it reports the evolvement and present challenges of advanced skin substitute product development and explores the recent contributions in 2D and 3D scaffolding, focusing on natural, synthetic, and composite nanomaterials. In the past decades, nanotechnology has arisen as a fascinating discipline that has influenced every aspect of science, engineering, and medicine. Electrospinning is a versatile fabrication method that allows researchers to elicit and explore many of the current challenges faced by tissue engineering and regenerative medicine. In skin tissue engineering, electrospun nanofibers are particularly attractive due to their refined morphology, processing flexibility-that allows for the formation of unique materials and structures, and its extracellular matrix-like biomimetic architecture. These allow for electrospun nanofibers to promote improved re-epithelization and neo-tissue formation of wounds. Advancements in the use of portable electrospinning equipment and the employment of electrospinning for transdermal drug delivery and melanoma treatment are additionally explored. Present trends and issues are critically discussed based on recently published patents, clinical trials, and in vivo studies. This article is categorized under: Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Therapeutic Approaches and Drug Discovery > Emerging Technologies Implantable Materials and Surgical Technologies > Nanomaterials and Implants.