γ-Radiation Induced Deposition of Au Nanoparticles on Defect-Rich CdS for Enhanced CO₂ Photoreduction Under Visible Light

Photoreduction of CO₂ into high-value chemicals is one of the promising strategies to mitigate CO₂ emission and alleviate energy challenges, while the design and development of high-performance photocatalysts are recognized as the pivotal part. Herein, CdS-xAu catalysts with abundant S vacancies and Au nanoparticles were successfully synthesized via one-step γ-ray radiation method. The characterization results showed that the CdS-γ had smaller spherical particles compared to the CdS-H catalyst prepared by hydrothermal method, which was favorable for exposing more active sites. Besides, the Au was reduced by solvated electrons and anchored on the in situ generated S vacancies within CdS. By acting as the photogenerated electrons extractors, the generated Au nanoparticles synergized with S vacancies to promote the charge separation and inhibit the recombination of photogenerated carriers, thus enhancing the photocatalytic activities. Consequently, the CdS-2.5Au photocatalyst with appropriate loading amount presented the optimal performance for achieving the CO yield of 12.48 μmol g⁻¹ h⁻¹, which was superior to CdS-γ and even 2.8 times that of the hydrothermal synthesized CdS-H. This study provided new insights into the applications of γ-ray radiation in the preparation of high-performance photocatalytic materials.