Hydrothermally synthesized NiSe2 nanospheres for efficient bifunctional electrocatalysis in alkaline seawater electrolysis: High performance and stability in HER and OER

• we synthesized a series of NiSe 2 nanosphere with meticulously engineered morphology and architecture. • NiSe 2 nanosphere showed low overpotentials of 154.5 mV in alkaline seawater and 149.7 mV in 1.0 M KOH for HER . • NiSe 2 nanosphere showed low overpotentials of 182.5 mV in alkaline seawater and 198 mV in 1.0 M KOH for OER . Finding active and stable electrocatalysts composed of inexpensive elements, with simple synthesis methods, high catalytic performance, and excellent cycling stability is crucial for hydrogen production through water electrolysis. In this study, NiSe 2 nanospheres were grown on nickel-cobalt precursor foam nickel using a hydrothermal method. At a current density of 10 mA cm -2, the overpotential for the hydrogen evolution reaction (HER) was 149.7 mV, while the overpotential for the oxygen evolution reaction (OER) was 198 mV. The electrocatalyst maintained its morphology almost intact even after 12 h of stability testing, and its performance remained stable after cyclic testing. Furthermore, in an alkaline seawater electrolysis environment at a current density of 10 mA cm -2 , the overpotential for HER was 154.5 mV, and the overpotential for OER was 182.5 mV. In this work, NiSe 2 nanosphere were synthesized through a two-step hydrothermal. The NiSe 2 demonstrated excellent OER performance at a current density of 10 mA cm -2 to achieve a low overpotential of 198 mV in 1 M KOH, which to 182.5 mV in 1 M seawater KOH. For HER, the overpotential decreased from 149.7 mV in 1 M KOH to 154.5 mV in seawater.