A study on electron acceptor of carbonaceous materials for highly efficient hydrogen uptakes

Abstract

Significant efforts have been directed toward the identification of carbonaceous materials that can be utilized for hydrogen uptake in order to develop on-board automotive systems with a gravimetric capacity of 5.5 wt.%, thus meeting the U.S. Department of Energy technical targets. However, the capacity of hydrogen storage is limited by the weak interaction between hydrogen molecules and the carbon surface. Cigarette butts, which are the most abundant form of primary plastic waste, remain an intractable environmental pollution problem. To transform this source of waste into a valuable adsorbent for hydrogen uptake, we prepared several forms of oxygen-rich cigarette butt-derived porous carbon (CGB-AC, with the activation temperature range of 600 and 900 °C). Our experimental investigation revealed that the specific surface area increased from 600 to 700 °C and then decreased as the temperature rose to 900 °C. In contrast, the oxygen contents gradually decreased with increasing activation temperature. CGB-AC700 had the highest H2 excess uptake of 8.54 wt.% at 77 K and 20 bar, which was much higher than that of porous carbon reported in the previous studies. We found that the dynamic interaction between the porosity and the oxygen content determined the hydrogen storage capacity. The underlying mechanisms pro-posed in the present study would be useful in the design of efficient hydrogen storage because they explain the interaction between positive carbonaceous materials and negative hydrogen molecules in quadrupole orbitals.