One-pot synthesis of self-assembled coral-like hierarchical architecture constructed by polymorphic CoSe2 nanocrystals as superior electrocatalyst for hydrogen evolution reaction

It is imperative to exploit highly efficient and stable non-precious electrocatalyst, particularly consisting of low-cost and earth-abundant elements, to produce clean hydrogen energy via hydrogen evolution reaction. To realize this target, herein, for the first time, self-assembled coral-like hierarchical network being formed from polymorphic CoSe2 nanocrystals is synthesized by a one-pot dimethylformamidesolvothermal reaction. This non-precious transition-metal dichalcogenide exhibits superior hydrogenevolution performance: it has an ultra-small Tafel slope of 31.6 mV dec(-1), which is comparable to that of commercial Pt/C catalyst; moreover, it delivers a quite low onset overpotential of similar to 126 mV and very large cathode current density of -60 mAcm(-2) at -250 mV overpotential; most importantly, it demonstrates favorable stability even after 1500 cycles. The outstanding electrocatalytic performance is attributed to its unique coral-like porous hierarchical structure established by conductive CoSe2 nanocrystals, which can not only offer abundant electrocatalytic active sites, but also boost the ability of charge transportation. We expect that the precious metal-free electrocatalysts with high efficiency and low production cost for hydrogen evolution reaction could be prepared through our proposed rational design strategy in this work. (C) 2018 Elsevier Ltd. All rights reserved.