Core‐shell architecture of <scp> NiSe ₂ </scp> nanoparticles@nitrogen‐doped carbon for hydrogen evolution reaction in acidic and alkaline media

Electrochemical water splitting is known to be one of the most potential pathways for hydrogen generation. However, this process is limited by the sluggish cathodic hydrogen evolution reaction (HER) kinetics. Nitrogen-doped materials have been exploited for the development of efficient electrocatalysts because of their tunable electronic properties. Herein, we illustrate a facile route to construct the core-shell architecture in NiSe2@nitrogen-doped carbon (NiSe2@NC) as efficient catalysts for the HER. NiSe2@NC samples were prepared through a two-step process involving pyrolysis and selenization at various temperatures from a nitrogen-rich Ni-based metal-organic framework (MOF) precursor. NiSe2@NC-500°C was considered as the optimal sample because it showed outstanding catalytic properties for the HER with low overvoltages of 161 and 220 mV to deliver a current density of 10 mA/cm2 in acidic and alkaline solutions, respectively. In addition, NiSe2@NC-500°C exhibited excellent stability after 2000 cycles and 12 h of operation. The high catalytic performance was attributed to the synergistic effect of the core-shell structure and the carbon layers doped with high pyridinic-N content, which play a vital role in providing a large number of active centers, imparting high conductivity, and enhancing the durability of the electrocatalyst. This account may open an approach to the design and fabrication of low-cost electrode materials for HER.