Syntheses, characterizations and testings of carbon nanofiber for hydrogen adsorption studies

Abstract

Renewable energy (RE) has been declared as the fifth fuel of Malaysia in addition to oil, gas, coal and hydropower. One of RE which is hydrogen and has became an alternative fuel for transportation instead of petroleum. For sufficient hydrogen storage, the system requires an inexpensive, safe, low weight tank, comparable in to a gasoline tank with capability of quick loading and unloading hydrogen fuel. Carbon nanomaterials have been nominated as one of the best medium to store hydrogen due to its light weight, low cost production depending upon types of synthesis methods, non-toxic and can be generated with improvement in its storage capacity. The research work focuses on the development of graphitic nanofibers by using chemical vapor deposition method. The development of catalyst which was iron (III) oxide and nickel (II) oxide for the synthesis of graphitic nanofibers has also been investigated. The capacity of the developed materials in hydrogen adsorption is tested at 298K and the pressure up to 100 bar using gravimetric measurement technique. Sample imaging observations using field emission electron microscopy (FESEM) and transmission electron microscopy (TEM) indicate that the synthesized graphitic nanofibers (GNFs) have both platelet and herringbone structure with little carbon nanotubes (CNTs). Iron-based catalyst GNF (FG) samples have diameter size of 170 nm while nickel-based catalyst GNF (NG) has diameter size of 200 nm. Specific BET surface area of FG and NG are 92.34 m2/g and 45.96 m2/g, respectively. Both analysis which are energy-dispersive X-ray (EDX) and thermogravimetric proved that purity of FG is between 88% to 95% while purity of NG is ranges from 95% to 97%. For iron-based catalyst GNF, the highest uptake is 0.46wt % at 70 bar and for nickel-based catalyst GNF, the highest uptake is 1.7611wt % at 70 bar.