  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, we demonstrate 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) that is triggered when an
alternating magnetic field is applied to an aqueous dispersion of the
magnetoelectric nanocatalysts. Based on density functional calculations, we
propose that the hydrogen evolution is driven by changes in the ferroelectric
polarization direction of BiFeO3 caused by the magnetoelectric coupling. We
believe our findings will open new avenues towards magnetically induced
renewable energy harvesting.
