An amorphous FeOOH-modified spongy steamed-twisted-roll SnS2/Ni3S2 hierarchical electrocatalyst for efficient oxygen evolution reaction

Abstract

The preparation of high-efficiency, durable and earth-abundant water oxidation electrocatalysts is increasingly appealing; however, it remains a significant challenge for generating renewable H₂ as an energy source, due to the sluggish kinetics of the key oxygen evolution reaction (OER). Herein, four different morphologies of amorphous FeOOH-modified heterostructured SnS₂/Ni₃S₂, including rose, cauliflower, spherical and spongy steamed-twisted-roll nano-arrays, are directly grown on self-supporting nickel foam (NF) by the hydrothermal and wet chemical immersion methods. Compared with the rose, cauliflower and spherical heterostructures, the spongy steamed-twisted-roll FeOOH/SnS₂/Ni₃S₂/NF heterostructure exhibits the best electrocatalytic OER activity with an ultra-low overpotential of 198 mV at 10 mA cm⁻² and a small Tafel slope of 31.9 mV dec⁻¹ in alkaline media, and also exhibits excellent stability with no evident decay of the current density after 200 hours of OER. The reason for the exceptional performance of the spongy steamed-twisted-roll FeOOH/SnS₂/Ni₃S₂/NF may be ascribed to its improved charge transfer, larger surface area and more electroactive sites. Theoretical study further discloses that the integration of amorphous FeOOH with SnS₂/Ni₃S₂ is beneficial for charge redistribution, adsorption energy regulation of the OER intermediates, and the reduction of the reaction energy barrier. Owing to its remarkably improved OER performance, the spongy steamed-twisted-roll FeOOH/SnS₂/Ni₃S₂/NF is utilized to fabricate an electrolytic Pt–C/NF∥FeOOH/SnS₂/Ni₃S₂/NF cell, whose cell voltage is only 1.42 V at 10 mA cm⁻², significantly exceeding that (1.63 V) of the standard electrolytic Pt/C/NF∥RuO₂/NF cell.