Hydrogen production via alkaline seawater electrolysis using iron-doped nickel diselenide as an efficient bifunctional electrocatalyst

Green hydrogen production via seawater electrolysis is a promising pathway towards sustainable energy future. However, seawater splitting is hindered by the low stability and selectivity of electrocatalysts towards hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and faces severe electrode corrosion. Herein, we report the synthesis of highly active and durable Fe-doped nickel diselenide (Fe–NiSe2) nanoparticles supported on nickel foam as bifunctional electrocatalysts for efficient alkaline seawater electrolysis via an electrodeposition method followed by low-temperature annealing. The electrocatalytic properties of as-prepared Fe–NiSe2 toward HER and OER are investigated in different electrolytes. The optimized electrocatalyst (20-Fe-NiSe2) shows very low overpotential of 92 and 96 mV in alkaline (1.0 M KOH) and simulated seawater (1.0 M KOH + 0.5 M NaCl) electrolytes, respectively, to reach the current density of 10 mA cm−2 for HER. For the OER, 20-Fe-NiSe2 exhibits an overpotential of 333 and 311 mV in alkaline and simulated seawater electrolytes, respectively, to attain a current density of 100 mA cm−2. Further, full-cell studies are carried out with 20-Fe-NiSe2 as bifunctional electrocatalysts, which requires cell potential of 1.83 V and 1.81 V to deliver a current density of 100 mA cm−2 in alkaline and simulated seawater electrolytes, respectively. Additionally, the electrode shows tremendous potential for use in alkaline seawater electrolysis with stability over 100 h, at a current density of 100 mA cm−2, which is achieved at a low cell voltage of 1.87 V. The present work offers a simple, efficient, and cost-effective method for the development of heterogeneous Fe-doped nickel diselenide electrocatalysts for seawater electrocatalysis.