Chalcogenide nanoparticles like CdxZn(1-x)SySe(1-y) applied to photocatalytic hydrogen production from natural seawater under visible light irradiation

Selenides and sulfoselenides containing cadmium and zinc were prepared by the coprecipitation method in aqueous solution at room temperature and applied to photocatalytic production of hydrogen from natural seawater assisted by visible light. The materials were characterized by XRD, EDX, DRS, SEM, TEM, and N-2 adsorption. The analyses indicated the formation of nanocrystals with cubic structure and wide size distribution of CdSe, ZnSe, and solid solutions like CdxZn(1-x)SySe(1-y). All samples were photoactive for hydrogen production in natural seawater and lactic acid as a sacrificial reactant. Among them, sulfoselenides were the most active photocatalysts and the use of natural seawater increased hydrogen production by 16% compared to deionized water. The insertion of zinc and sulfur in the CdSe sphalerite matrix as well as the presence of zinc segregated phases contributed to improve the photocatalytic activity and the stability of the photocatalysts in aqueous media. Solid solution Cd0.5Zn0.5S0.1Se0.9 (sample named CdZnSSe1) and CdSe associated with Zn-5(OH)(8)Cl-2 center dot H2O and Zn(OH)(2) (sample named CdZnSSe8) were the most active photocatalysts, with H-2 production rates 350 mu mol g(cat)(-1) h(-1) and 395 mu mol g(cat)(-1) h(-1), respectively.