Generating H2 from a H2O molecule by catalysis using a small Al6Cu cluster

•More efficient method to generate H2 from H2O molecule is investigated.•Extract H2 molecule from H2O molecule with cluster Al6Cu.•Intrinsic reaction coordinate is calculated to validate the reaction process.•Total energy to trigger the whole reaction and to release a free H2 molecule is 1.3321 eV.

Only one H atom is extracted from a single H2O molecule in a usual reaction for hydrogen generation. In this study, a three-step reaction has been identified for completely extracting H2 from H2O molecule with the catalysis of a small Al6Cu cluster, based on the first principles calculations. All the reactants, products, and transition states are determined by optimization calculation and confirmed by frequency analysis. The intrinsic reaction coordinate is also calculated to validate the reaction process. Results show that the whole reaction is an endothermic reaction. The charge distribution is used to understand the novel reaction. It is found that Al6Cu cluster can strongly capture H2O molecule and extract the H2 molecule completely, which may present a more efficient way to generate H2 from a single H2O molecule.