The conventional method of producing hydrogen does not promote sustainable development and gravely damages the environment. Nevertheless, this paper studies investigate the connection between the magic numbers (4, 10, 17) and the reactions of Ben (n = 14–17) clusters splitting H2O to produce H2 as well as the reaction mechanism, solving the environmental pollution problem. This experiment reveals the mechanism of hydrogen generation from H2O splitting of Ben (n = 14–17) clusters using the PBE0 functional and the def2-TZVP basis, which is based on density functional theory. We have plotted the energy gap diagrams, interaction region indicator diagrams, and density of state diagrams of Ben (n = 14–17) clusters in order to explore the intermolecular interactions and energy changes that occur during the adsorption and desorption of water molecule and clusters. The findings demonstrate that the reactions of Ben (n = 14–17) clusters splitting H2O to produce H2 is releasing energy. The Ben (n = 14–17) clusters have the best hydrogen evolution efficiency when the number of atoms is near the magic number.