N-doped carbon-enveloped CoSe2/NiSe2@Cu2Se core-shell nanospheres as non-Pt electrocatalysts for enhanced wide-pH hydrogen evolution reactions

An available approach to ameliorate the property of electrocatalysts for transition metal selenides (TMSs) is to transform their structure, morphology, and elemental composition, especially for hydrogen evolution reactions (HER), which can be a long-term task. In this work, Ni-Co nanospheres were synthesized by a hydrothermal method, and then in the synchronous processes of selenization and carbonization, it reacted with the peripherally coated melamine-copper complex, which was the reactant between melamine and copper ions. Ultimately, CoSe2/NiSe2@Cu2Se-NC nanospheres with a core-shell structure were synthesized after annealing process. This special structure provided more active attachment sites, enabling CoSe2/NiSe2@Cu2Se-NC to exhibit excellent HER properties under wide-pH range. Especially, in acidic conditions, it had a low initial potential of 41.0 mV, a small Tafel slope value of 48.7 mV dec–1, and a long service life. The proposed scheme indicates that a new approach will be added to the synthesis of electrocatalysts based on TMSs.