The Effect of Acid Washing and YAG:Nd Laser Irradiation on Increasing Hydrogen Storage Capacity in Carbon Nanotubes

This research used multi-walled carbon nanotubes with a 30 to 50  nm diameter and an approximate length of 6  µm to store hydrogen gas by the volumetric method. Carbon nanotubes' structure, shape, and physical properties were investigated by X-ray diffraction analysis, transmission electron microscopy, and infrared spectroscopic analysis. To investigate the hydrogen storage capacity in carbon nanotubes, the effect of two parameters, namely acid washing and YAG: Nd laser irradiation, were studied. The results showed that acid washing and laser irradiation increased the specific surface area of carbon nanotubes by 59%  and 100%, respectively. Studies also showed that purified carbon nanotubes stored 0.3 wt.% hydrogen, which revealed a 75% increase compared to the original nanotubes. Also, laser irradiation with different times changed the storage capacity of nanotubes. The optimal value of laser irradiation was obtained to be 90  minutes, which increased the storage capacity of hydrogen gas in nanotubes to 1.1 wt.%.