Cu doped CdTe QDs and Effect of Doping on Photoluminescence Kinetics and CO2 Photoreduction

Abstract

To deal with the challenging problem, namely global warming, C02 capture and utilization (CCU) strategy was applied to reduce CO2 into useful chemical formaldehyde. For this purpose photocatlysts (quantum dots) were synthesized and applied. CdTe was used as a base material for its high high electron mobility. In order to adjust band gap of CdTe QDs and increase average decay time for reduction of CO2 to facilitate, copper (Cu) was used as a dopant. Colloidal method was used for the synthesis of CdTe and Cu doped CdTe QDs. In Cu doped CdTe QDs, CuxCd1_xTe amount of x was varied from 0.01 to 0.05 to see the effect of various concentrations of Cu on the photoluminescence (PL) kinetics of CdTe QDs. Different characterization techniques namely UV -Vis spectroscopy, X-ray Diffraction, Fourier Transform Infrared spectroscopy, steady-state PL analysis and time resolved PL were used for the confirmation of the synthesis of QDs and to see the effect of Cu dopant on CdTe QDs optical properties. Cu doping caused quenching of PL and the average PL decay time to increase. Cu doped CdTe QDs were then used as a photo catalysts for CO2 reduction into HCHO. Distilled water was used as a solvent in the synthesis and application of QDs. The basic pH was provided to facilitate the solubility of CO2 gas into water in order to adsorb on the surface of QDs which are capped with mercaptoacetic acid to facilitate the reduction of CO2 towards HCHO. Then the efficiencies of Cu doped CdTe QDs were compared to conclude that 1 % Cu doped CdTe QDs gave higher efficiency for its low band gap and large average PL lifetime.