Ternary ZnxCd1_xTe QDs and Effect of Zn on Photoluminescence and CO2 Photoreduction

Abstract

Ternary ZnxCd1_xTe QDs have been synthesized VIa cost-effective colloidal method, using thioglycolic acid (TGA) as a capping ligand. Fourier-Transform Infrared (FT-IR) spectroscopy validated the functionalization of the synthesized QDs by the S-H group of TGA. The X-Ray Diffraction (XRD) analysis depicted the hexagonal wurtzite structure of the ZnCdTe QDs with a slight shift in peak positions for the samples doped with different concentrations of dopant. The UV -Visible absorption and photoluminescence (PL) analysis showed red shift with increasing concentration of Zn. Time-resolved photoluminescence (TRPL) is used to investigate the average lifetime of ZnCdTe QDs. The PL decay kinetics indicates that with an increase in dopant concentration, the PL lifetime of Zn doped CdTe QDs increases which results in slow decay of photoexcited charge carriers. The magnified photocatalytic activity of ZnCdTe QDs can be attributed to dopant Zn concentration. The photocatalytic efficiency was lowest for pure CdTe QDs and highest for the sample doped with largest concentration of Zn, which is consistent with the fact that lower the recombination rate of photo excited charge carriers, higher the photocatalytic activity. This research work provides a facile strategy to synthesize eco-friendly photocatalyst for the efficient reduction of CO2 to formaldehyde.