Colloidal Cd Zn S nanocrystals as efficient photocatalysts for H production under visible-light irradiation.

Cd Zn S nanocrystals with sizes ranging from 3-11 nm were synthesized by a simple organic solution method. The nanocrystals possess a cubic zinc-blende structure and the bandgap blue-shifts from 2.1 eV to 3.4 eV by increasing the composition of Zn ions in the solid solutions. After a facile ligand exchange process, the photocatalytic activity for H production of the Cd Zn S nanocrystals was investigated under visible-light irradiation ( ≥ 420 nm) with NaSO/NaS as the electron donor. It was found that the CdZnS had the highest photoactivity with H evolution rate of 6.32 mmol g h. By adding Pt precursors into the reaction solution, inhomogenous Pt-Cd Zn S nanoheterostructures were formed, which accounted for a 30% enhancement for the H evolution rate comparing with that of pure CdZnS nanocrystals. This work highlights the use of facile organic synthesis in combination with suitable surface modification to enhance the activity of the photocatalysts.