Dipole Coupling Accelerated H₂ O Dissociation by Magnesium-Based Intermetallic Catalysts

The water (H₂ O) dissociation is critical for various H₂ O-associated reactions, including water gas shift, hydrogen evolution reaction and hydrolysis corrosion. While the d-band center concept offers a catalyst design guideline for H₂ O activation, it cannot be applied to intermetallic or main group elements-based systems because Coulomb interaction was not considered. Herein, using hydrolysis corrosion of Mg as an example, we illustrate the critical role of the dipole of the intermetallic catalysts for H₂ O dissociation. The H₂ O dissociation kinetics can be enhanced using Mg_x Me_y (Me=Co, Ni, Cu, Si and Al) as catalysts, and the hydrogen generation rate of Mg₂ Ni-loaded Mg reached 80 times as high as Ni-loaded Mg. The adsorbed H₂ O molecules strongly couple with the Mg-Me dipole of Mg_x Me_y , lowering the H₂ O dissociation barrier. The dipole-based H₂ O dissociation mechanism is applicable to non-transition metal-based systems, such as Mg₂ Si and Mg₁₇ Al₁₂ , offering a flexible catalyst design strategy for controllable H₂ O dissociation.