Prussian blue-derived hollow carbon-wrapped Fe-doped CoS2 nanocages as durable electrocatalyst for efficient hydrogen evolution

Cobalt disulfide (CoS2) is regarded as a low cost and abundant non-noble electrocatalyst, but some drawbacks limit its application due to its sluggish intrinsic electrocatalytic kinetics and high hydrogen evolution over -potential. In this work, carbon-wrapped Fe-doped CoS2 nanocages (C/Fe-CoS2) were synthesized via gradual sulfurization of cobalt hexacyanoferrate and evaluated as electrocatalysts for hydrogen evolution reaction (HER). The nanocage architecture exposes more electrochemically active site, and carbon wrapping reduces the agglomeration of C/Fe-CoS2 and optimizes the electronic structure, while the Fe doping decreases the hydrogen adsorption free energy of CoS2. Therefore, C/Fe-CoS2 demonstrates a superior HER performance, showing a benchmark current density of 10 mA cm-2 at the low overpotential of 151 mV in acidic electrolyte and a remarkable stability (cyclic voltammetry cycling for 3000 cycles and continuous electrolysis at the overpotential of 180 mV for 25,000 s). The as-designed C/Fe-CoS2 should be one of the most promising catalysts for HER application. This strategy highlights the construction of high performance electrocatalysts via structure designing and heteroatom doping for efficient and stable hydrogen generation.