Synergistic Coupling of CoS₂/MoS₂ with Polypyrrole as a Highly Efficient and Robust Bifunctional Electrocatalyst for Water Splitting

Abstract

The construction of multicomponent coupled interfaces is crucial to designing highly effective and robust bifunctional electrocatalysts for water splitting. Transition metal sulfides are widely applied as efficient catalysts, but building strong coupling interfaces to enhance electrocatalytic properties remains a tremendous challenge. Here, we reported a distinctive heterostructure electrocatalyst consisting of conductive polypyrrole (PPy)-decorated cobalt−molybdenum sulfide (CoS 2 /MoS 2 ) nanosheets supported on nickel foam (CoS 2 /MoS 2 @PPy/NF) using a simple two-step hydrothermal and subsequent electrodeposition approach. Experimental results reveal that the interfacial coupling and synergistic effect between the conductive PPy and CoS 2 /MoS 2 with tunable electronic configuration are favorable for the charge transport and the electronic structure optimization of the coupled interface, where this integrated PPy can improve the conductivity and offer a guarantee for the durability of CoS 2 /MoS 2 @PPy/NF. Density functional theory (DFT) calculations verify that electronic interaction and charge redistribution in heterogeneous CoS 2 /MoS 2 can flexibly adjust the interfacial electronic configuration and lower the d-band center. Thanks to the advantages mentioned above, the obtained CoS 2 /MoS 2 @PPy/NF exhibits outstanding catalytic properties with the overpotentials of 46 mV for the hydrogen evolution reaction (HER) and 231 mV for the oxygen evolution reaction (OER) at 10 mA cm −2 . Remarkably, assembled CoS 2 /MoS 2 @PPy/NF || CoS 2 /MoS 2 @PPy/NF only acquires 1.52 V at 10 mA cm −2 in 1.0 M KOH with a durability of 50 h. This study affords a significant reference for designing bimetallic sulfide/polymer catalysts toward high-efficiency overall water splitting.