CdS/ZnS/ZnO ternary heterostructure nanofibers fabricated by electrospinning for excellent photocatalytic hydrogen evolution without co-catalyst

In recent years, ternary heterostructures (HSs) composed of three semiconductors have attracted significant attention because of the effective separation and transfer of photogenerated electrons and holes in these materials. In this work, new ternary CdS/ZnS/ZnO (CZZ) HSs with one-dimensional (1D) nanofiber morphology have been successfully fabricated for the first time by a series of processes: electrospinning ZnO nanofibers, sulfurizing ZnO in situ to form ZnS/ZnO binary HSs, and depositing CdS quantum dots in situ on the ZnS/ZnO HSs. Benefiting from the efficient separation and transfer of photoinduced charge carriers, the optimized CZZ ternary HSs exhibit a hydrogen evolution rate of 51.45 mmol h⁻¹ g⁻¹ (quantum efficiency: 26.88% at 420 nm) without any co-catalyst, which is 93.54 and 2.28 times higher than those exhibited by pristine ZnO and ZnS/ZnO binary HSs, respectively, under the same conditions. Furthermore, the rate of hydrogen evolution over the 1D CZZ nanofibers is significantly higher than that over 2D CZZ nanosheets (27.25 mmol h⁻¹ g⁻¹, in the presence of a Pt co-catalyst) prepared by the same sulfurization and deposition procedures. This can be ascribed to the significantly smaller geometric sizes of 1D nanofibers compared to those of 2D nanosheets, resulting in effectively suppressed recombination of photogenerated charge carriers and promotion of photocatalytic H₂ evolution performance.