Fabrication of NiFe-LDH/FeSe₂ heterojunction: Se species and vacancy induced rapid surface reconstruction for...

Layered double hydroxide (LDH) is a common electrocatalyst for oxygen evolution reaction (OER). However, LDH materials usually undergo a relatively slower reconstruction process, which hinders the efficiency of electrochemical water splitting. Herein we modify pristine NiFe-LDH with Se species-containing FeSe₂ to fabricate NiFe-LDH/FeSe₂ heterojunction catalyst. At the same time, heterojunction constructing also triggers vacancy formation, which is further proved by electron paramagnetic resonance (EPR) and X-ray absorption spectroscopy (XAS) measurements. In situ Raman spectra and a series of electrochemical experiments have proved the synergistic effect of Se species introduction and vacancy to accelerate the surface reconstruction process of the catalyst, thus greatly enhance OER performance, with a low overpotential of 256 mV under the current density of 10 mA cm^-2. This work shed light on ways to design catalysts wither rapid surface reconstruction process and develop catalysts with high efficiency toward electrochemical water splitting.