Dipole Coupling Accelerated H₂O Dissociation by Magnesium-Based Intermetallic Catalysts

The water (H2O) dissociation is critical for various H2O-associated reactions, including water gas shift, hydrogen evolution reaction and hydrolysis corrosion. While the d-band center concept offers a catalyst design guideline for H2O 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 H2O dissociation. The H2O dissociation kinetics can be enhanced using MgxMey (Me=Co, Ni, Cu, Si and Al) as catalysts, and the hydrogen generation rate of Mg2Ni-loaded Mg reached 80 times as high as Ni-loaded Mg. The adsorbed H2O molecules strongly couple with the Mg-Me dipole of MgxMey, lowering the H2O dissociation barrier. The dipole-based H2O dissociation mechanism is applicable to non-transition metal-based systems, such as Mg2Si and Mg17Al12, offering a flexible catalyst design strategy for controllable H2O dissociation.