Highly active Zn_xCd_1-xS photocatalysts containing earth abundant elements only for H₂ production from water under visible light

A series of Zn_xCd_1-xS photocatalysts were synthesized via a solvothermal method using ethylenediamine (EDA) as the solvent. The structural, optical and morphological properties have been investigated extensively by various analytical techniques. It has been found that Zn _xCd_1-xS (x ≤ 0.5 in the precursor) nanorods and nanoparticles can be formed as good homogeneous solid solutions. During the synthesis process, EDA played an important dual role as the solvent and the coordinating agent, which contributed to the formation of nanosized Zn _xCd_1-xS solid solutions. Efficient hydrogen production from the aqueous solution containing S^2- and SO₃ ^2- sacrificial reagents was observed over these photocatalysts under visible light irradiation (λ ≥ 420 nm) in the absence of any expensive metal components and co-catalysts. The highest photocatalytic activity for hydrogen production was obtained over Zn_0.5Cd_0.5S with a rate of 1097 μmol h^-1 and the corresponding quantum efficiency of 30.4% at 420 nm. These values are much higher than those previously reported for Zn-Cd binary sulfide photocatalysts. The excellent photocatalytic performance can be attributed to the efficient visible light absorption and the suitable band structure due to the formation of solid solutions.