Aqueous solutions of mixed CdS/ZnS semiconductor (SC) nanoparticle suspensions in phosphate buffers containing 10 mM [Fe(CN)<sub>6</sub><sup>]4–</sup> were used for photochemical production of hydrogen via hydrated electron intermediates. CdS was doped with varying percentages of ZnS to expand the absorption range of the composite to the UV region. Results show that maximum generation of hydrated electrons by [Fe(CN)<sub>6</sub><sup>]4–</sup> occurs at pH 6. Furthermore, native CdS amorphous nanoparticles give the greatest photocurrent. Studies also show that, in phosphate buffer, the steady state photocurrent was directly proportional to the CdS content in the mixture of CdS/ZnS. The aqueous nano-systems sustained their stability as indicated by the reproducibility of their photocatalytic activities. Solar radiated assemblies of CdS/ZnS/ [Fe(CN)<sub>6</sub><sup>]4–</sup> sustained cyclic systems for continuous hydrogen production.
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