Lattice Contracted Cobalt disulfide as an Outstanding Oxygen Reduction Reaction via Efficient Self‐assembly Arrangement

Identifying high-performance non-precious metal-based catalysts at the cathode is a major challenge for future practical applications. Herein, a soft-template route through a self-assembly arrangement of sulfur sources was successfully developed, facilitating the anion exchange. In addition, compared with pristine cobalt disulfide synthesized without templates, the cobalt disulfide prepared using the new method presented a lattice shrinking phenomenon due to the hindrance of cobalt hydroxide crystal cell. Based on X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculation, increased occupancy of eg orbitals was verified for the cobalt disulfide after shrinkage, which was the main factor for enhancing the intrinsic activity of the catalyst. Besides the microscopic morphologic structure, elementary composition, and the valence state of the elements, the possible growth process of the cobalt disulfide was also discussed in detail. As catalyst for the oxygen reduction reaction, CoS2 showed a similar half-wave potential (0.81 vs. 0.84 V for Pt/C) and higher diffusion-limiting current density (reaching 5.33 vs. 5.19 mA cm-2 for Pt/C) than a commercial Pt/C catalyst. Hence, our results provide a rational design direction for this type of catalysts.