Uncovering the Promotion of CeO₂/CoS_1.97 Heterostructure with Specific Spatial Architectures on Oxygen Evolution Reaction

Abstract

Structural engineering and compositional controlling are extensively applied in rationally designing and fabricating advanced freestanding electrocatalysts. The key relationship between the spatial distribution of components and enhanced electrocatalysis performance still needs further elaborate elucidation. Here, CeO₂ substrate supported CoS_1.97 (CeO₂ -CoS_1.97 ) and CoS_1.97 with CeO₂ surface decorated (CoS_1.97 -CeO₂ ) materials are constructed to comprehensively investigate the origin of spatial architectures for the oxygen evolution reaction (OER). CeO₂ -CoS_1.97 exhibits a low overpotential of 264 mV at 10 mA cm^-2 due to the stable heterostructure and faster mass transfer. Meanwhile, CoS_1.97 -CeO₂ has a smaller Tafel slope of 49 mV dec^-1 through enhanced adsorption of OH^- , fast electron transfer, and in situ formation of Co(IV)O₂ species under the OER condition. Furthermore, operando spectroscopic characterizations combined with theoretical calculations demonstrate that spatial architectures play a distinguished role in modulating the electronic structure and promoting the reconstruction from sulfide to oxyhydroxide toward higher chemical valence. The findings highlight spatial architectures and surface reconstruction in designing advanced electrocatalytic materials.