Engineering Nanocage-Like Fe-Doped CoS₂Interwoven with Carbon Nanotubes as a Bifunctional Electrocatalyst with Efficient Water Splitting Capacity

The electrochemical water splitting process is fundamentally constrained by sluggish intrinsic reaction kinetics and low energy conversion efficiency. Developing highly efficient bifunctional electrocatalysts is crucial for enhancing electrocatalytic reaction kinetics and improving electron transfer efficiency. Herein, we fabricated the nanocage-like Fe-doped CoS₂interwoven with carbon nanotubes (FCS/CNT) as a bifunctional electrocatalyst. The nanocage architecture imparts a high surface area, thereby augmenting the number of electrochemically active sites. The incorporation of carbon nanotubes (CNTs) mitigates CoS₂agglomeration and enhances the electrical conductivity, thereby amplifying the charge transfer efficiency. Doping with Fe lowers the adsorption energy of intermediates, thereby enhancing electrocatalytic performance. Crucially, the CoS₂phase undergoes in situ reconstruction into CoOOH during the high redox potential, which acts as highly active electrocatalytic material facilitating oxygen evolution. Through optimizing CNT concentration, this FCS/CNT configuration exhibits remarkable HER activity (η₁₀= 143 mV) and an excellent OER performance (η₁₀= 265 mV). Furthermore, the electrocatalysts demonstrate exceptional stability, retaining 90.9% of the current density for HER and 89.0% for OER after 36,000 s of continuous operation. This approach underscores the design of high-performance electrocatalysts through strategic structural engineering, heteroatom doping, and carbon incorporation, resulting in outstanding hydrogen and oxygen evolution activity.