Demand of highly efficient earth-abundant transition metal-based electrocatalysts to replace noble metal materials for boosting oxygen evolution reaction (OER) is rapidly growing.Herein,an electrochemically exfoliated graphite (EG) foil supported bimetallic selenide encased in N-doped carbon (EG/(Co,Ni)Se2-NC) hybrid is developed and synthesized by a vapor-phase hydrothermal strategy and subsequent selenization process.The as-prepared EG/(Co,Ni)Se2-NC hybrid exhibits a core-shell structure where the particle diameter of (Co,Ni)Se2 core is about 70 nm and the thickness of N-doped carbon shell is approximately 5 nm.Benefitting from the synergistic effects between the combination of highly active Co species and improved electron transfer from Ni species,and N-doped carbon,the EG/(Co,Ni)Se2-NC hybrid shows remarkable electrocatalytic activity toward OER with a comparatively low overpotential of 258 mV at an current density of 10 mA cm-2 and a small Tafel slope of 73.3 mV dec-1.The excellent OER catalysis performance of EG/(Co,Ni)Se2-NC hybrid is much better than that of commercial Ir/C (343 mV at 10 mA cm-2 and 98.1 mV dec-1),and even almost the best among all previously reported binary CoNi selenide-based OER electrocatalysts.Furthermore,in situ electrochemical Raman spectroscopy combined with ex situ X-ray photoelectron spectroscopy analysis indicates that the superb OER catalysis activity can be attributed to the highly active Co-OOH species and modified electron transfer process from Ni element.