Characteristic assessment of stabilized polyacrylonitrile nanowebs for the production of activated carbon nano-sorbents

Fixing PAN Nanofiber Mats during Stabilization for Carbonization and Creating Novel Metal/Carbon Composites

Polyacrylonitrile (PAN) is one of the materials most often used for carbonization. PAN nanofiber mats, created by electrospinning, are an especially interesting source to gain carbon nanofibers. A well-known problem in this process is fixing the PAN nanofiber mats during the stabilization process which is necessary to avoid contraction of the fibers, correlated with an undesired increase in the diameter and undesired bending. Fixing this issue typically results in breaks in the nanofiber mats if the tension is too high, or it is not strong enough to keep the fibers as straight as in the original state. This article suggests a novel method to overcome this problem by electrospinning on an aluminum substrate on which the nanofiber mat adheres rigidly, stabilizing the composite and carbonizing afterwards either with or without the aluminum substrate to gain either a pure carbon nanofiber mat or a metal/carbon composite.

Cotton Wool Derived Carbon Fiber Aerogel Supported Few-Layered MoSe2 Nanosheets As Efficient Electrocatalysts for Hydrogen Evolution

Recent studies have proven that newly emerging two-dimensional molybdenum diselenide (MoSe2) is a promising noble-metal-free electrocatalyst for hydrogen evolution reaction (HER). Increasing the exposures of the active edges of MoSe2 nanostructures is a key issue to fully realize the excellent electrochemical properties of MoSe2. In this work, a few-layered MoSe2/carbon fiber aerogel (CFA) hybrids have been facilely obtained through the combination of high-temperature carbonization and one-pot solvothermal reaction. CFA derived from cotton wool is used as a three-dimensional conductive network for construction of hierarchical MoSe2/CFA hybrids, where few-layered MoSe2 nanosheets are uniformly and perpendicularly decorated on the surfaces of CFA. In the designed and prepared hybrids, CFA effectively increases the exposures of the active edges of MoSe2 nanosheets as well as provides reduced lengths for both electron transportation and ion diffusion. Therefore, the obtained optimal MoSe2/CFA hybrid exhibits excellent electrochemical activity as HER electrocatalyst with a small onset potential of -0.104 V vs reversible hydrogen electrode and a small Tafel slope of 62 mV per decade, showing its great potential as a next-generation Pt-free electrocatalyst for HER.