Is chitin a promising hydrogen storage material? A thorough quantum mechanical study

Abstract

Due to their biodegradability and low toxicity, biopolymers have drawn much research interest in the field of material science. The stability of the biopolymers due to existence of strong intermolecular hydrogen bonding makes these materials more promising as suitable adsorbents. In the current study, chitin has been explored as potential hydrogen storage material using density functional theory calculations. The presence of several heteroatoms on the surface of adsorbent makes it suitable for hydrogen adsorption. Thirty hydrogen molecules are adsorbed at six available sites on monomeric chitin, making it a promising naturally available hydrogen storage material. Natural bond orbital analysis and surface analysis reveal that hydrogen is adsorbed on the substrate by charge transfer from heteroatom on the adsorbent to the adsorbed hydrogen molecule. Independent gradient model analysis and atoms-in-molecules analysis have revealed the weak dispersion forces between the adsorbate and the adsorbent. The adsorbent also exhibits high gravimetric density (∼27%) and the adsorption process is thermodynamically favorable.