Hydrogen evolution under visible light illumination on the solid solution CdxZn1-xS prepared by ultrasound-assisted route

Abstract

The complete solid solution CdxZn1-xS (0 ≤ x ≤ 1) prepared by ultrasound-assisted route is used for the H2 formation upon visible light illumination. The correlation of chemical and physical characterizations permits to assess the feasibility of the system for the photocatalytic hydrogen evolution. The compounds crystallize in a cubic structure (x < 0.5) and convert to hexagonal variety above 0.5 with a crystallite size (8–17 nm). All materials exhibit n-type conduction with an activation energy (0.22–0.05 eV). The optical transitions are directly allowed (3.10–2.30 eV) and appropriately matched to the sun spectrum while the conduction band, deriving from (Zn, Cd) ns orbital (∼-1 VSCE), is positioned above the H2O/H2 potential (∼-0.68 VSCE), allowing H2-liberation under visible illumination. The photocatalyst dose, pH and SO32− concentration are optimized. Under the favorable conditions, the H2 liberation rate reaches 12 × 10−4 mL mg−1 min−1 with a quantum yield η(H2) of 1.40%.