title: Polymorphic CoSe2 with mixed orthorhombic and cubic phases for highly efficient hydrogen evolution reaction.
abstract: We report polymorphic CoSe2 (p-CoSe2) with mixed orthorhombic and cubic phases as a highly active electrocatalyst toward hydrogen evolution reaction (HER). The p-CoSe2 is obtained by calcining CoSex via electrodeposition at 300 °C. The results of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) demonstrated the crystal structure of p-CoSe2. The p-CoSe2 exhibits excellent electrocatalytic activity for HER with a low onset overpotential of -70 mV and a small Tafel slope of ∼30 mV/decade, which are basically state-of-the-art performance of earth-abundant electrocatalysts. The HER performance of p-CoSe2 was much higher than that of amorphous CoSex, cubic CoSe2, and CoSe. This study offers a competitive electrocatalyst for HER and opens up a new strategy to the synthesis of catalysts for energy conversion.
authors.affiliation: Key Laboratory of Biomass Chemical Engineering of Ministry of Education, College of Chemical and Biological Engineering, Zhejiang University , Hangzhou, Zhejiang Province 310027, China.
authors.forename: Hongxiu
authors.initials: H
authors.lastname: Zhang
authors.forename: Bin
authors.initials: B
authors.lastname: Yang
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Wu
authors.forename: Zhongjian
authors.initials: Z
authors.lastname: Li
authors.forename: Lecheng
authors.initials: L
authors.lastname: Lei
authors.forename: Xingwang
authors.initials: X
authors.lastname: Zhang
keywords: earth-abundant elements; electrocatalysis; electrodeposition; hydrogen evolution reaction; polymorphic CoSe2