Ti-decorated graphitic-C ₃ N ₄ monolayer: A promising material for hydrogen storage

Ti-decorated graphitic carbon nitride (g-C ₃ N ₄ ) 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-C ₃ N ₄ 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-C ₃ N ₄ 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-C ₃ N ₄ 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-C ₃ N ₄ monolayer is suggested to be a promising material for hydrogen storage suggested by the DOE for commercial applications.