Heterostructure CdS/ZnS nanoparticles as a visible light-driven photocatalyst for hydrogen generation from water

ABSTRACT

(CdS)_x/(ZnS)_1–x nanoparticles were synthesized as a visible light-driven photocatalyst using the stepped microemulsion technique with a series of the ratio factors (x). The photocatalytic test results showed that (CdS)_x/(ZnS)_1-x with x = 0.8 had the highest photo-reactivity for H₂ production from water under visible light. The composite (CdS)_0.8/(ZnS)_0.2 catalyst had a heterogeneous structure that exhibited a much greater photocatalytic hydrogen production activity than either pure CdS or the homogeneous Cd_0.8Zn_0.2S solid solution. ZnS deposition also was shown to largely improve the stability of CdS in the heterostructured CdS/ZnS catalyst. Thermal treatment of the catalyst, i.e., annealing (CdS)_0.8/(ZnS)_0.2 at 723 K, improved the crystallinity of the catalyst and increased its photocatalytic H₂ production rate by more than 36 times. Deposition of Ru on the surface of the catalyst particles by in situ photo-deposition further increased the photo-H₂ generation rate by 3 times. The photocatalyst of 0.5%Ru/CdS/ZnS achieved the highest H₂ production activity, at a rate of 12650 μmol/g-h and with a light to hydrogen energy conversion efficiency of 6.5%.

KEYWORDS:

• CdS-ZnS
• heterostructure
• hydrogen generation
• photocatalyst
• Ru coating
• solar energy

Acknowledgments

The technical assistance of Mr. Keith C.H. Wong is highly appreciated.

Funding

This research was supported by grant HKU714112E from the Research Grants Council (RGC) of the Government of Hong Kong SAR and project 51308230 from the National Natural Science Foundation of China (NSFC).

Supplementary data

Supplemental data for this article can be accessed on the publisher’s website.

Additional information

Funding

This research was supported by grant HKU714112E from the Research Grants Council (RGC) of the Government of Hong Kong SAR and project 51308230 from the National Natural Science Foundation of China (NSFC).