Fabrication of Porous Mesh-Like FeCo2S4 Nanosheet Arrays on Ni Foam for High Performance all Solid-State Supercapacitors and Water Splitting

Porous mesh-like FeCo2S4 nanosheet arrays on Ni foam (NF) have been prepared by a two-step hydrothermal approach and employed as electrodes for supercapacitors and efficient bifunctional electrocatalysts for water splitting. FeCo2S4/NF exhibits ultrahigh areal capacitance of 7.37 F cm(-2) at current density of 5 mA cm(-2) and achieves good cycling stability retaining 92% capacitance after 3000 cycles at 10 mA cm(-2). Symmetric solid-state device of FeCo2S4/NF as positive and negative electrodes delivers a remarkable energy density of 19.12 W h kg(-1) (434.61 W kg(-1)). Furthermore, FeCo2S4/NF electrode delivers a low overpotential of 155 mV at a hydrogen evolution reaction (HER) current density of 10 mA cm(-2) and shows no obvious attenuation after stability test for 100,000 s in 1 M KOH solution. While a low overpotential of 234 mV at 50 mA cm(-2) for oxygen evolution reaction (OER) can be demonstrated in alkaline environment as an anode electrocatalyst. FeCo2S4/NF shows excellent activity toward overall water splitting with 10 mA cm(-2) by applying just 1.405 V across the two electrodes. Hence, the porous mesh-like FeCo2S4 nanosheet arrays on Ni foam are promising electrode materials for supercapacitor application and water splitting.