Multiphase heterostructured Mo-doped NiSe catalyst with improved activity and stability for the hydrogen evolution reaction in alkaline electrolyte

Abstract

Electrochemical water splitting is an efficient and ecofriendly method for hydrogen production. Although Ptbased catalysts are the most widely used for the hydrogen evolution reaction (HER), their scarcity and high cost limit their applications. Therefore, the development of highly active catalysts based on nonprecious metals is required. In this study, a Mo-doped NiSe catalyst was synthesized on Ni foam (NF) as the Ni source via hydrothermal. The catalyst exhibited a two-dimensional nanoflower structure, and the presence of crystalline NiSe and Ni3Se2 was confirmed. Mo-doped NiSe achieved a current density of -10 mA cm- 2 at an overpotential of -148 mV in 1 M KOH, showing superior HER activity to that of NiSe (-194 mV), p-MoSe2 (-314 mV), and NF (-249 mV). Mo doping enhanced the activity by increasing the electrochemically active surface area and tuning the d-band of Ni. Long term stability tests over 6000 potential cycles reveal that the catalyst undergoes surface reconstruction while preserving its crystalline framework during this process. Mo is partially leached and readsorbed as high valent Mo6+, whereas Ni and Se remain largely unchanged. These results demonstrated that Mo-doped NiSe is a promising alkaline HER catalyst with excellent stability.