CoS₂/FeS₂ hollow microspheres: Bimetallic synergistic acceleration of surface reconstruction for efficient and stable...

Seawater electrolysis presents a promising strategy for large-scale hydrogen production, with the primary challenge being the development of efficient and stable anodic catalysts capable of withstanding the oxygen evolution reactions in the presence of chloride-induced corrosion. During the electrooxidation process, the surfaces of transition metal electrocatalysts often undergo reconstruction to form electrocatalytic active sites. However, the effective promotion of this reconstruction process remains a critical issue. In this study, we developed a CoS₂/FeS₂ hollow microsphere (HMS) catalyst. The unique hollow microsphere structure, combined with the synergistic interactions between bimetallic components, significantly accelerates the surface reconfiguration process, facilitating the rapid formation of the CoFeOOH active phase. Moreover, an in-situ formed SO₄^2- protective layer effectively repels corrosive chloride ions, thereby alleviating concerns related to catalyst activity and stability. Experimental results demonstrate the superior efficiency and stability of the CoS₂/FeS₂-HMS electrocatalyst for seawater oxidation under alkaline conditions. Specifically, the catalyst achieves low overpotentials of 212, 263, and 310 mV to attain current densities of 10, 100, and 400 mA cm^-2, respectively. At a current density of 100 mA cm^-2, the catalyst maintains stable performance for up to 500 hours without evidence of chloride corrosion. Furthermore, in the CoS₂/FeS₂-HMS (+)║Pt/C (-) seawater electrolytic cell configuration, the system exhibits a low cell voltage of 1.68 V at a current density of 100 mA cm^-2, while demonstrating stable operation for over 100 hours. This finding provides new strategies and insights for the design of efficient, corrosion-resistant catalysts for industrial seawater electrolysis.