Fe-Doped Cose2 Nanosheets as Effective Electrocatalysts for the Oxygen Evolution Reaction in Water Splitting

Abstract

Affordable and highly effective electrocatalysts are essential for achieving industrial-scale hydrogenation of water applications. This study innovatively proposes a two-step electrochemical deposition strategy with tunable Fe doping levels to fabricate ultrathin Fe-doped CoSe2 nanosheets anchored on nickel foam (Fex-CoSe2/NF). The as-prepared catalyst demonstrates exceptional efficiency for the oxygen evolution reaction (OER) in water splitting. The performance of Fex-CoSe2/NF initially improves with increasing x, reaching an optimal value before subsequently declining. The ideal catalyst, Fe0.75-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, Fe0.75-CoSe2/NF demonstrates exceptional electrochemical stability. Notably, density functional theory (DFT) calculations reveal that Fe doping fundamentally alters the OER reaction pathway of CoSe2, significantly lowering the reaction energy barriers and thus enhancing the catalytic efficiency. The superior OER performance is attributed to the synergy between the ultrathin nanosheet architecture, enhanced electron conductivity from the nickel foam substrate, and electronic structure modulation induced by Fe incorporation. This work not only establishes an effective and scalable fabrication method but also provides critical mechanistic insights into the rational design of high-performance, non-precious metal-based electrocatalysts for sustainable energy applications.

Keywords: OER performance, Fe-doped, CoSe2 nanosheets, Electrochemical Deposition, DFT calculations