Successful synthesis of 3D CoSe2 hollow microspheres with high surface roughness and its excellent performance in catalytic hydrogen evolution reaction

Abstract To improve both the activity and stability of electrocatalyst in hydrogen evolution reaction (HER) remains a challenge. In this work, a facile and friendly way to synthesis of CoSe 2 hollow microspheres was reported by using organic selenium source. The growth mechanism of CoSe 2 hollow microspheres attributed to the Kirkendall effect with the hydrothermal reaction time is studied. This CoSe 2 hollow structure with high surface roughness makes this material to expose more active sites, bringing good HER activity with a small tafel slope of 55 mV·dec −1 . Besides, the HER activity of CoSe 2 was greatly improved via the introduction of graphene (CoSe 2 @G) without changing its hollow structure. The superior HER activity of CoSe 2 @G with a lower tafel slope of 42 mV·dec −1 was attributed to the crucial structural-functional coupling effects. Moreover, both CoSe 2 and CoSe 2 @G nanocomposites exhibit high durability and stability, which may provide promising applications in the fields of catalysis, optics, electronics and sensors due to its unique structure.