Two dimetallocenes with vanadium and chromium: Electronic structures and their promising application in hydrogen storage

Abstract The hydrogen storage capacities of the two sandwich-type Cp 2 TM 2 [Cp = cyclopentadienyl (C 5 H 5 ); TM = V or Cr)] dimetallocenes were studied using first-principles calculations. According to the B3PW91 method in density functional theory (DFT), Cp 2 V 2 and Cp 2 Cr 2 could adsorb up to seven and six hydrogen molecules, respectively. The predicted hydrogen storage densities of Cp 2 V 2 and Cp 2 Cr 2 were 5.73 and 4.91 wt%, respectively. Additionally, because hydrogen binding energies bound by Kubas model were 0.39 and 0.43 eV/H 2 , respectively, both the Cp 2 V 2 and Cp 2 Cr 2 dimetallocenes were proven to be favourable for reversible adsorption and desorption of hydrogen molecules under ambient conditions.