Fe-doped CoSe2 nanosheets as effective electrocatalysts for the oxygen evolution reaction in water splitting

Affordable and highly effective electrocatalysts are essential for achieving industrial-scale hydrogenation of water applications. The successful fabrication of Fe-doped CoSe₂ nanosheets supported on nickel foam (Fe_x-CoSe₂/NF) via a two-step electrochemical deposition method is presented in this study, showing their effectiveness as an electrocatalyst for the oxygen evolution reaction (OER) in water splitting. The performance of Fe_x-CoSe₂/NF initially improves with increasing x, reaching an optimal value before subsequently declining. The ideal catalyst, Fe_0.75-CoSe₂/NF, requires a low overpotential of 256 mV at 10 mA cm⁻², and even at 100 mA cm⁻², the overpotential remains as low as 291 mV. The catalyst also displays a low Tafel slope of 34.37 mV dec⁻¹, highlighting the fast OER kinetics. Furthermore, Fe_0.75-CoSe₂/NF demonstrates exceptional electrochemical stability. The enhanced OER catalytic performance of Fe-doped CoSe_2, compared to intrinsic CoSe_2, is attributed to the thinner nanosheets structure and optimized electronic structures, which provide a higher density of active sites and facilitate a new reaction coordination with a lower energy barrier during the OER process. These findings not only offer new mechanistic insights into Fe-doped CoSe₂ systems but also provide a scalable and cost-effective pathway for designing next-generation, non-precious-metal-based electrocatalysts.