Enhanced charge separation in a CoOx@CdS core–shell heterostructure by photodeposited amorphous CoOx for highly efficient hydrogen production†

The efficient spatial separation of charges is crucial for augmenting the photocatalytic efficiency of H₂ evolution. Herein, a CoO_x@CdS core–shell heterostructure was fabricated via the photodeposition of amorphous CoO_x on the surface of 3D CdS for highly efficient photocatalytic hydrogen evolution (PHE). Amorphous CoO_x extends the optical absorption range, suppresses photocorrosion and enhances the specific surface area of CoO_x@CdS. Consequently, optimized 2%CoO_x@CdS exhibits superior PHE activity (16.30 mmol h⁻¹ g⁻¹) and outstanding photostability beyond 70 h, which is 2.9 times greater than that of pure CdS. The markedly enhanced photoactivity of optimized 2%CoO_x@CdS is primarily due to the establishment of the core–shell architecture, wherein CoO_x serves as a medium for the extraction of photogenerated holes. This structure efficiently accelerates charge separation and electron transfer at the CoO_x@CdS interface. Specifically, CoO_x acts as a hole collector, promoting more efficient photogenerated charge separation. Thus, this work presents a straightforward approach for the construction of the CoO_x@CdS core–shell heterostructure as a robust photocatalyst for the transformation of solar energy.