Heterostructured iron-cobalt sulfides nanoclusters entrenched in 3D-nanosheets as high-efficient electrocatalysts for oxygen evolution reaction

Abstract

Three dimensional (3D) binary Earth-abundant transition metal derived layered nanomaterials are presently considered as the emergent catalysts for the oxygen evolution reaction (OER). In the present study, we demonstrate morphology-controlled bimetallic iron-cobalt (FeCo) nanoclusters (∼3.2 nm) embedded in 3D nanosheets (3D-FeCoS NS) on nickel foam (NF) electrode using of single-step electrochemical fabrication approach. The as-developed binder-free 3D-FeCoS NS employ as the potential electrocatalysts for improved OER in 1.0 M KOH. Results display that the 3D-FeCoS NS-B (“B” represents the molar ratio of Fe and Co (1:1)) exhibited an exceptional catalytic OER activity, including a low overpotential (η) (∼223 mV @ 10 mA cm−2), small Tafel slope (∼66 mV dec−1), high mass activity (∼208 Ag−1), high turnover frequency (TOF) (∼1.2 s−1), and long-term stability (over 100 h). More significantly, the 3D-FeCoS NS-B‖PtC couple attained the current density of ∼10 mA cm−2 only at the potential of ∼1.53 V, comparing positively with the state-of-the-art RuO2‖PtC couple. The abundant active sites of nanoclusters and edges of the sheets, synergy between the heterostructures, and accompanied by the presence of surface sulfides/oxides yield improved the OER activity. This study signifies a novel strategy to establish 3D Earth-abundant transition metal sulfides nanosheets for various electrochemical applications, including energy conversion and storage systems.