Nitrogen Functionalization of CVD Grown Three-Dimensional Graphene Foam for Hydrogen Evolution Reactions in Alkaline Media.

Three-dimensional graphene foam (3D-GrFoam) is a highly porous structure and sustained lattice formed by graphene layers with sp2 and sp3 hybridized carbon. In this work, chemical vapor deposition (CVD)-grown 3D-GrFoam was nitrogen-doped and platinum functionalized using hydrothermal treatment with different reducing agents (i.e., urea, hydrazine, ammonia, and dihydrogen hexachloroplatinate (IV) hydrate, respectively). X-ray photoelectron spectroscopy (XPS) survey showed that the most electrochemically active nitrogen-doped sample (GrFoam3N) contained 1.8 at % of N, and it exhibited a 172 mV dec-1 Tafel plot associated with the Volmer-Heyrovsky hydrogen evolution (HER) mechanism in 0.1 M KOH. By the hydrothermal process, 0.2 at % of platinum was anchored to the graphene foam surface, and the resultant sample of GrFoamPt yielded a value of 80 mV dec-1 Tafel associated with the Volmer-Tafel HER mechanism. Furthermore, Raman and infrared spectroscopy analysis, as well as scanning electron microscopy (SEM) were carried out to understand the structure of the samples.

Electrospinning Fabrication and Cytocompatibility Investigation of Nanodiamond Particles-Gelatin Fibrous Tubular Scaffolds for Nerve Regeneration.

This paper reports the electrospinning fabrication of flexible nanostructured tubular scaffolds, based on fish gelatin (FG) and nanodiamond nanoparticles (NDs), and their cytocompatibility with murine neural stem cells. The effects of both nanofiller and protein concentration on the scaffold morphology, aqueous affinity, size modification at rehydration, and degradation are assessed. Our findings indicate that nanostructuring with low amounts of NDs may modify the fiber properties, including a certain regional parallel orientation of fiber segments. NE-4C cells form dense clusters that strongly adhere to the surface of FG50-based scaffolds, while also increasing FG concentration and adding NDs favor cellular infiltration into the flexible fibrous FG70_NDs nanocomposite. This research illustrates the potential of nanostructured NDs-FG fibers as scaffolds for nerve repair and regeneration. We also emphasize the importance of further understanding the effect of the nanofiller-protein interphase on the microstructure and properties of electrospun fibers and on cell-interactivity.