Prussian blue analog derived carbon-rich FeS2@CoS2 nano composites as bifunctional electrocatalyst for water splitting

Abstract

Developing highly efficient and durable bifunctional electrocatalysts for water splitting largely depends on creating multicomponent coupled interfaces. Transition metal sulfides are commonly used as efficient catalysts; however, creating strong coupling interfaces to improve their electrocatalytic performance presents a considerable challenge. Herein, we present prussian blue analogue derived carbon-rich cobalt-iron disulfide (C@CoS₂@FeS₂) nanocomposites employing different post-sulfurization temperatures as bifunctional catalysts for water splitting. Experimental results demonstrated that the synergistic interaction between C and CoS₂@FeS₂, high degree of defects and optimized electronic structure of heterogeneous interfaces, enhances conductivity, catalytic activity and ensures long-term durability. Consequently, the C@CoS₂@FeS₂ nanocomposites sulfurized at 500 °C exhibited outstanding catalytic properties with overpotentials of 303 mV at 50 mA cm⁻² for oxygen evolution reaction (OER) and 138 mV at 20 mA cm⁻² for hydrogen evolution reaction (HER). Notably, the assembled C@CoS₂@FeS₂ ||C@CoS₂@FeS₂ electrolyzer system only requires 1.829 V at 50 mA cm⁻² in 1 M KOH and maintaining stability for 10 h. These findings indicate that the C@CoS₂@FeS₂-500 catalyst could be an efficient and cost-effective option for water-splitting technologies.