Facile synthesis of CdS-Ag₂S hollow spheres with enhanced photocatalytic hydrogen evolution activity

Photocatalytic water splitting for hydrogen production is a promising strategy to alleviate the global energy crisis and environmental pollution. However, conventional CdS photocatalysts suffer from severe photogenerated charge carrier recombination and serious photocorrosion, which greatly limit their practical application. In this work, hollow CdS/Ag₂S composite photocatalysts were rationally fabricated via a template-assisted method combined with cation exchange. The loading amount of Ag₂S was systematically modulated to optimize the photocatalytic hydrogen evolution performance. The results demonstrate that the optimal CdS/Ag₂S-15% composite exhibits a remarkable hydrogen production activity, which is approximately 10.8-fold higher than that of pristine CdS hollow nanospheres, along with excellent cycling stability. Systematic characterizations, including X-ray photoelectron spectroscopy (XPS), transient photocurrent response, and electrochemical impedance spectroscopy (EIS), reveal that the enhanced performance originates from the formation of an intimate CdS/Ag₂S heterojunction. Moreover, XPS results of post-reaction catalysts verify the generation of metallic Ag species. Upon photoexcitation, photogenerated electrons partially reduce Ag₂S to dynamically construct an Ag/Ag₂S/CdS ternary heterostructure. Comparative tests between hollow and solid samples demonstrate that hollow cavities enhance light harvesting and charge migration, delivering ∼19.8-fold higher cumulative hydrogen yield within 4 h. The well-matched band alignment accelerates interfacial charge separation, restraining carrier recombination and CdS photocorrosion. This work reveals the synergistic effect of hollow architecture and in situ generated ternary heterojunctions, and provides a facile strategy to design high-performance, anti-photocorrosion sulfide photocatalysts.