Formation of ferromagnetic Fe5Se8 via phase transition and enhanced hydrogen evolution reaction with alternating magnetic fields

Abstract

Leveraging alternating magnetic fields (AMFs) to induce localized heating in catalysts has emerged as a powerful approach to boost electrocatalytic reactions. However, the rational design and synthesis of ferromagnetic catalysts that can be stably coupled with an AMF to improve the hydrogen evolution reaction (HER) performance are still urgent and challenging. Herein, the ferromagnetic triclinic Fe5Se8 has been realized through the phase transition from nonmagnetic orthorhombic FeSe2 synergistically triggered by the selenium vacancies and the strain engineering, making it a good candidate for AMFs-assisted HER. Experimental results and theoretical calculation demonstrate that the phase transition-prepared ferromagnetic Fe5Se8 exhibits much better HER performance than nonmagnetic FeSe2. More importantly, under high-frequency AMF stimulation, the HER performance of ferromagnetic Fe5Se8 is greatly enhanced (the overpotential decreased by 63 mV), which is mainly attributed to the localized magnetic heating effect. This study realizes the controlled phase transition synthesis of ferromagnetic catalysts, indicating that AMF is an effective approach to manipulate the performance of ferromagnetic catalysts.