Abundant heterointerfaces in CoS2/MoS2 nanosheet array electrocatalysts for the enhanced oxygen evolution reaction

Abstract

Two-dimensional transition metal sulfides possess high intrinsic catalytic activity for the oxygen evolution reaction (OER) during water splitting but are restricted by their low conductivity and unattractive stability in alkaline electrolytes. Herein, newly designed CoS₂/MoS₂ nanosheets with enriched heterointerfaces synthesized by the combination of hydrothermal and vulcanization methods showed great promise as a highly efficient OER electrocatalyst. Owing to the fast vulcanization process, some heterometallic sulfide nanoparticles get distributed on the nanosheets, thus forming a nanoparticle-nanosheet bridging structure. The rich heterogeneous interface between CoS₂ and MoS₂ regulates the electronic structure and provides sufficient electrochemical active sites, thus forming a fast channel conducive to electron transport and ensuring high OER activity. Besides, the rough heterostructured surface enhances hydrophilicity, which promotes the decomposition of H₂O and decreases the energy barrier of intermediate reactions, leading to fast electrochemical kinetics. Benefiting from the structural merits, the optimized CoS₂/MoS₂-1 : 1 nanosheets exhibit a low overpotential of 283 mV at 10 mA cm⁻², a small Tafel slope of 105.32 mV dec⁻¹ and long-term durability for the OER.