Hydrogen evolution from water molecule reactions with Ge7 and Ge6Al clusters

The most stable structures of Ge6M (M = Ge, Al) clusters and reactions of Ge6M clusters with a single water molecule are investigated theoretically by density functional theory (DFT) calculation and reaction pathway search method at the same level. The calculated binding energies of Ge-7 and Ge6Al clusters show that the stabilities of two clusters are close. The most stable geometric structures and electronic structures of Ge6M@H2O complex and reaction pathways of Ge6M with a single H2O molecule are predicted. All geometric structures of reactants, intermediate products, final products and transition states are confirmed by frequency analysis. Our results show that both of Ge-7 and Ge6Al clusters can completely release H-2 from water after a three steps reaction and both reactions are endothermic. The calculated adsorption energies and energy barriers indicate that the dopant Al atom will improve the reactivity between Ge-7 cluster and water. The NPA charge (C) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.