Synthesis of Zn_xCd_1-xS solid solution by stratified method

In this study, we focused our attention on photocatalytic decomposition of hydrogen sulfide as the resource of hydrogen using solar energy and prepared Zn_xCd_1-xS solid solution as photocatalyst. Samples were prepared by "stratified" method using Zn and Cd hydroxides as precursors and "coprecipitation" method under various Zn/ Cd ratios to study the influence of Cd concentration on the properties such as crystal structure, light absorption and reactivity. The continuous change in the crystal lattice constant and UV-VIS reflection spectra from ZnS to CdS was observed in the Zn_xCd_1-xS samples prepared by both "coprecipitation" and "stratified" methods with increasing concentration of Cd. In the case of coprecipitation method, the reactivity was improved with the increase of Cd. But, in the case of stratified method, the particles prepared at Zn:Cd=2:1 showed higher reactivity than the samples prepared at higher ratios of Cd and the samples prepared by coprecipitation method with similar Zn/Cd ratios. The samples prepared by stratified method at higher ratio of Zn/Cd turned black from yellow in color when exposed to light irradiation. This was believed due to the metal deposited by photocatalytic reduction of precursors. This metal deposition influences the photoreactivity of Zn_xCd_1-xS particles and is optimum for Zn _0.67Cd_0.33S.