Hydrogen evolution from water molecule reactions with Ge7 and Ge6Al clusters

• Published in: International journal of hydrogen energy 2021-04, Vol.46 (24), p.12693-12700
• Main Authors: Lei, Jia-Le, Shi, Shun-Ping, Guo, Wei, Wan, Ming-Jie, Yan, Min, Liu, Yi-Liang, Li, Xia
• Format: Article
• Language: English
• Subjects: Germanium clusters; H2O; Hydrogen generation; NBO analysis; Reaction pathways
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2021.01.092

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 Ge7 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 Ge7 and Ge6Al clusters can completely release H2 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 Ge7 cluster and water. The NPA charge of Ge7O and Ge6AlO means both of them can react with another H2O molecule. •Structures of Ge7 and Ge6Al are similar.•Reaction pathways of Ge6Al and Ge7 with a single H2O molecule are predicted.•Both of Ge7 and Ge6Al clusters can completely release H2 from water after a three steps reaction.•Dopant Al atom will improve the reactivity between Ge7 cluster and water.•Both of Ge6AlO and Ge7O can react with another water molecule.