Hydrogen storage analysis of fullerene and defective fullerenes: The first experimental study

Abstract

In this first experimental study, defective fullerenes were produced from fullerenes using a high-rate tungsten carbide mortar ball mill at different rates and times, characterized with different techniques, and their hydrogen storage capacities and kinetic properties were investigated. Structural characterizations showed that the structure, particle size and atomic mass composition of fullerene changed with increasing grinding rate and time, transforming into an amorphous carbonaceous structure. Fullerene decomposed in a single step, while defective fullerenes decomposed in two steps. Significant changes were observed in the morphology and topography of the samples with the formation of defective structures. No regular change was observed in the BET surface areas of the samples, and the sample with the highest BET and pore volume was determined as D-C60-1 h-500 rpm. Parallel to the BET surface area and pore volumes, the D-C60-1 h-500 rpm sample (2.17 wt% at 97 bar) has the highest hydrogen storage capacity. The hydrogen storage capacity of the samples increased with increasing pressure and decreasing temperature. The experimental data were consistent with Henry’s law at room temperature, while at cryogenic temperature, they exhibited a multilayer adsorption isotherm. Adsorptiondesorption isotherms exhibited hysteresis and were in good agreement with the Type IV isotherm. The experimental results showed that hydrogen was also stored in the inner parts of the defective fullerene, and the storage capacity of the defective fullerene was lower than the computational results. Moreover, the experimental data were analyzed by pseudo-first order, pseudo-second order and Elvoich equations, and were in good agreement with the second-order kinetic equation.