Influence of Co-Dopant on Structural, Optical and Electrochemical Properties of Zinc Sulphide Quantum Dots

In the present work, solution based simple chemical precipitation method has been employed to prepare undoped, cobalt (Co)-doped and cobalt, nickel (Co, Ni) co-doped ZnS quantum dots (QDs). The XRD pattern revealed that all samples displayed cubic zinc blende structure. The average crystallite size of as prepared ZnS QDs were found to be in 1.0 to 1.4 nm range. Surface morphological of synthesized samples were recorded and some distinction in morphological features between undoped, doped and co-doped ZnS QDs were noticed. EDX analysis confirms the presence of all corresponding elements in the samples. The blue-shift in the absorption spectra was observed. The optical band gap energy (Eg) for all the hybrid ZnS QDs samples were evaluated by using UV-Visible optical absorption spectral data. In PL analysis, emission band at 660 nm was found to be quenched as ZnS QDs interact with dopant and co-dopant. Electrochemical analysis was carried out by transition of photogenerated electrons in undoped, cobalt (Co)-doped and cobalt, nickel (Co, Ni) co-doped ZnS QDs modified glassy carbon electrodes. To authenticate the results of PL and electrochemical studies, photocatalytic behaviour of QDs were studied and positive impact of doping and co-doping process on photo degradation were noticed and discussed.