Ti-decorated graphitic-C3N4 monolayer: A promising material for hydrogen storage

Abstract

Ti-decorated graphitic carbon nitride (g-C3N4) monolayer as a promising material system for high capacity hydrogen storage is proposed through density functional theory calculations. The stability and hydrogen adsorption of Ti-decorated g-C3N4 is analyzed by computing the adsorption energy, the charge population, and electronic density of states. The most stable decoration site of Ti atom is the triangular N hole in g-C3N4 with an adsorption energy of -7.58 eV. The large diffusion energy barrier of the adsorbed Ti atom of 6.00 eV prohibits the cluster formation of Ti atoms. The electric field induced by electron redistribution of Ti -adsorbed porous g-C3N4 significantly enhanced hydrogen adsorption up to five H-2 molecules at each Ti atom with an average adsorption energy of 0.30 eV/H-2. The corresponding hydrogen capacity reaches up to 9.70 wt% at 0 K. In addition, the hydrogen capacity is predicted to be 6.30 wt% at 233 K and all adsorbed H-2 are released at 393 K according to molecular dynamics simulation. Thus, the Ti -decorated g-C3N4 monolayer is suggested to be a promising material for hydrogen storage suggested by the DOE for commercial applications. (C) 2016 Elsevier B.V. All rights reserved.