Cubic phase indium doped cadmium sulfide dispersed on zinc oxide: Enhanced photocatalytic activity for hydrogen generation from water

• Cubic phase In doped CdS-ZnO composite exhibits enhanced photocatalytic activity.
• The photoactive phase is identified as zinc cadmium sulfide solid solution.
• Photocatalytic activity of CdInS-ZnO is more than double with Pd co-catalyst.
• Lifetime for the charge carriers is higher for the composite samples.

In this study, we report the photocatalytic activity of cubic phase indium doped cadmium sulfide dispersed on zinc oxide having wurtzite structure (CdInS-ZnO). Enhanced photocatalytic activity for hydrogen generation is observed for CdInS-ZnO compared to CdS dispersed on ZnO. Photocatalytic activity of CdInS-ZnO is more than double when Pd was used as co-catalyst. Detailed characterization of the composite catalysts revealed that the dispersed phases of CdS/CdInS contain zinc dissolved in it. The particle size of CdS and indium doped CdS decreases significantly when dispersed on ZnO. Improved optical absorption is observed as a result of indium doping in CdS. Fluorescence lifetime studies indicated an increased lifetime for the charge carriers in the composites as compared to pure CdS. Surface analysis of Pd-CdInS-ZnO sample by XPS before and after photocatalysis work indicates a partial conversion of sulfide to sulfate species on the surface during photocatalytic process whereas no considerable change in the bulk occurs after the experiment as seen from the XRD pattern. The enhanced photocatalytic activity of CdInS-ZnO composite is attributed to a synergistic effect of improved visible light absorption and increased lifetime of the charge carriers.

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