Ti decorated heterocyclic rings for hydrogen storage

This study uses first-principles calculations to investigate and compare the hydrogen storage properties of Ti doped benzene (C6H6Ti) and Ti doped borazine (B3N3H6Ti) complexes. C6H6Ti and B3N3H6Ti complex each can adsorb four H2 molecules, but the former has a 0.11 wt% higher H2 uptake capacity than the latter. Ti atoms bind to C6H6 more strongly than B3N3H6. The hydrogen adsorption energies with Gibbs free energy correction for C6H6Ti and B3N3H6Ti complexes are 0.17 and 0.45 eV, respectively, indicating reversible hydrogen adsorption. The hydrogen adsorption properties of C6H6Ti have also been studied after boron (B) and nitrogen (N) atom substitutions. Several B and N substituted structures between C6H6Ti and B3N3H6Ti with different boron and nitrogen concentration and at different positions were considered. Initially, one boron and one nitrogen atom is substituted for two carbon atoms of benzene at three different positions and three different structures are obtained. Seven structures are possible when four carbon atoms of benzene are replaced by two boron and two nitrogen atoms at different positions. The hydrogen storage capacity of the C6H6Ti complex increases as boron and nitrogen atom concentrations increases. The positions of substituted boron and nitrogen atoms have less impact on H2 uptake capacity for the same B and N concentration. The position and concentration of B and N affects the H2 adsorption energy as well as the temperature and pressure range for thermodynamically favorable H2 adsorption. The H2 desorption temperature for all the complexes is found to be higher than 250 K indicates the stronger binding of H2 molecules with these complexes. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study investigates and compares the hydrogen storage properties of Ti doped benzene (C6H6Ti) and Ti doped borazine (B3N3H6Ti) complexes using first-principles calculations. The results show that C6H6Ti has a higher H2 uptake capacity than B3N3H6Ti, and Ti atoms bind to C6H6 more strongly than B3N3H6. The positions and concentrations of boron and nitrogen atoms affect the H2 adsorption energy and the thermodynamically favorable range for H2 adsorption.