Effect of Fe doping on Co-S/carbon cloth as bifunctional electrocatalyst for enhanced water splitting

Abstract

• Fe-Co-S nanoflakes were successfully grown on the carbon cloth. • Fe doping can tuning the electronic structure of the Fe-Co-S/CC. • The Fe-Co-S/CC-75 shows superior alkaline HER and OER catalytic kinetics. • The Fe-Co-S/CC-75 as bifunctional electrocatalyst exhibits excellent electrocatalytic capability for overall water splitting. Considering the sluggish kinetics of oxygen evolution reaction (OER), rational design of HER and OER electrocatalysts with high catalytic activity in alkaline conditions remains a challenge for achieving large-scale commercial application of water splitting. In this paper, the Fe-Co-S nanoflakes grown on the carbon cloth (Fe-Co-S/CC) were fabricated by hydrothermal method and subsequent annealing treatment to enhance the crystallinity. Fe doping could regulate the d orbital electron density to improve the electrocatalytic kinetics for HER and OER. The hierarchical Fe-Co-S/CC as a binder-free electrode with more active sites and enhanced electronic conductivity exhibits low overpotentials of 258 mV and 320 mV for the oxygen evolution reaction (OER) and hydrogen evolution overpotential (HER) in an alkaline solution at the current densities of 10 mA cm −2 , respectively. Meanwhile, the Tafel slope is 61.20 mV dec -1 and 82.60 mV dec -1 , along with long-term stability for over 48 h.