Li–fluorine codoped electrospun carbon nanofibers for enhanced hydrogen storage

Xiaohong Chen,Wei Lv Wei Lv,Hong Zeng,Ying Wu,Zhongyu Li,Zhiyong Xue,Kai Niu,Bao Zhang,Yongming Zhang,Yu Ren,Xundao Liu

doi:10.1039/d0ra06500e

Abstract

Carbon materials have attracted increasing attention for hydrogen storage due to their great specific surface areas, low weights, and excellent mechanical properties. However, the performance of carbon materials for hydrogen absorption is hindered by weak physisorption. To improve the hydrogen absorption performance of carbon materials, nanoporous structures, doped heteroatoms, and decorated metal nanoparticles, among other strategies, are adopted to increase the specific surface area, number of hydrogen storage sites, and metal catalytic activity. Herein, Li–fluorine codoped porous carbon nanofibers (Li–F–PCNFs) were synthesized to enhance hydrogen storage performance. Especially, perfluorinated sulfonic acid (PFSA) polymers not only served as a fluorine precursor, but also inhibited the agglomeration of lithium nanoparticles during the carbonization process. Li–F–PCNFs showed an excellent hydrogen storage capacity, up to 2.4 wt% at 0 °C and 10 MPa, which is almost 24 times higher than that of the pure porous carbon nanofibers. It is noted that the high electronegativity gap between fluorine and lithium facilitates the electrons of the hydrogen molecules being attracted to the PCNFs, which enhanced the hydrogen adsorption capacity. In addition, Li–F–PCNFs may have huge potential for application in fuel cells.

Highlights

PAN/PVP/perfluorinated sulfonic acid (PFSA) nano bers were rst obtained via electrospinning of the mixture of PAN, PVP and PFSA in DMF solution
The emerging peak at 1063 cmÀ1 associated with –SO3–Li is observed, indicating SO3–H successfully converted into the SO3–Li of PFSA.[54,55]
With uorine doping and lithium incorporation, the broad diffraction peak at 24.0 became redshi ed to a sharp diffraction peak at 25.6, indicating the graphitization degree enhancement of the 0.1Li–F–PCNFs composites, which is caused by the formation of Li nanoparticles (Li NPs) and uorine doping on the surface of PCNFs (Fig. 3b and c)

Summary

Introduction

Hydrogen has attracted increasing attention as an environmentally safe energy source, and with great potential for application in powered vehicles.[1,2] In recent decades, signi cant efforts to nd new hydrogen storage materials have been made, such as metal alloys, complex hydrides, metal–organic frameworks, carbon materials, etc.[3,4,5,6,7,8,9,10,11,12,13,14,15] Interestingly, carbon-based materials, with their low cost and weight, have long been considered as suitable adsorption substrates for the reversible storage of hydrogen. We explore an easy and facile strategy to obtain Li– uorine codoped porous carbon nano bers (Li–F–PCNFs) for a higher hydrogen adsorption, prepared through electrospun, hydrothermal and calcination methods.

Results

Conclusion