Design and application of a magnetic field gradient electrode

A platinum coated electrode, which creates a magnetic field of 25 mT and a field gradient of order 105 T m−1 within 100 nm of the electrode surface is produced by embedding an array of CoPt nanowires in an alumina membrane. There is an enhancement by up to a factor of three for a model oxygen reduction reaction in an alkaline medium when the nanowires in the electrode are in a magnetized state. We suggest that the enhancement of the oxygen reduction current is associated with an increase of concentration of HO2- on the surface of the electrode by the magnetic field gradient.