Magnetoelectric Effect in Hydrogen Harvesting: Magnetic Field as a Trigger of Catalytic Reactions

Magnetic fields have been regarded as an additional stimulus for electro‐ and photocatalytic reactions, but not as a direct trigger for catalytic processes. Multiferroic/magnetoelectric materials, whose electrical polarization and surface charges can be magnetically altered, are especially suitable for triggering and control of catalytic reactions solely with magnetic fields. Here, it is demonstrated that magnetic fields can be employed as an independent input energy source for hydrogen harvesting by means of the magnetoelectric effect. Composite multiferroic CoFe2O4–BiFeO3 core–shell nanoparticles act as catalysts for the hydrogen evolution reaction (HER), which is triggered when an alternating magnetic field is applied to an aqueous dispersion of the magnetoelectric nanocatalysts. Based on density functional calculations, it is proposed that the hydrogen evolution is driven by changes in the ferroelectric polarization direction of BiFeO3 caused by the magnetoelectric coupling. It is believed that the findings will open new avenues toward magnetically induced renewable energy harvesting. The hydrogen evolution reaction (HER) is initiated by exploiting the magnetoelectric nature of CoFe2O4–BiFeO3 core–shell nanoparticles purely with alternating magnetic fields. As a direct trigger for the HER, magnetic fields can open cooperative pathways for maximizing hydrogen production by synergetic combinations with other energy sources such as electric fields and light.