Enhanced hydrogen evolution reaction in FePt film with remanence due to decrease in domain walls

As an effective strategy to improve the properties of electrocatalysts, magnetic field-assisted electrocatalytic water splitting has attracted increasing attention recently. However, the corresponding enhancements mostly depend on the exertion of an external magnetic field during electrochemical reactions, which results in a high cost of industrial production, and makes the magnetic field manipulation of electrocatalysis become a challenging task. In this work, instead of the external magnetic field, a bias magnetic field is self-supplied by the remanence state of a ferromagnetic electrocatalyst of FePt. Owing to the assistance of this bias magnetic field, the FePt film in the remanence state shows the overpotential of 229 mV during hydrogen evolution reaction, which is much lower than that in its demagnetization state (283 mV). Our findings demonstrate that the remanence in ferromagnetic electrocatalysts can improve the catalytic performance, which is attributed to the decrease in domain walls. Graphical abstract