A metal dusting process for preparing nano-sized carbon materials and the effects of acid post-treatment on their hydrogen storage performance

The preparation of various nano-sized carbon materials (NCMs) using a metal dusting process, in which a stainless steel coupon and CO-CO₂ mixed gas are the only reactants needed, is demonstrated in this study. During the process, fresh Fe-Ni nano-particles, which catalyze the formation of the NCMs, are produced spontaneously and continuously from the steel. The possibility of using multi-wall carbon nanotubes (CNTs) prepared at 600 °C as a hydrogen storage material is studied. Our electrochemical testing results indicate that the obtained CNTs have a hydrogen discharge capacity of as high as 104 mAh/g after being etched in 15 M boiling nitric acid solution for 4 h. However, it was found that prolonging the etching time not only decreases crystallinity but also damages the tubular structure of the CNTs, degrading the hydrogen storage performance.