Microwave-assisted preparation and characterization of Zn1-xCdxS nanoparticles in presence of an ionic liquid and their photocatalytic activities

Nanoparticles of Zn1-xCdxS (x = 0-1) were prepared in aqueous solution of 1-ethyl-3-methylimidazolium ethyl sulfate, [EMIM][EtSO4], a halide-free and low-cost room-temperature ionic liquid (RTIL) by 4 min microwave irradiations. Powder X-ray diffraction (XRD) patterns of the nanoparticles demonstrate that the diffraction peaks gradually shift to lower angles with increasing Cd content. UV-Vis diffuse reflectance spectra (DRS) indicate that the absorption edges for Zn1-xCdxS nanoparticles are red-shifted as the value of x increases. Scanning electron microscopy (SEM) images demonstrate that the nanoparticles are nearly spherical with different sizes. Photocatalytic activities of the nanoparticles towards photodegradation of methylene blue (MB) were evaluated under UV and visible irradiations. The results indicate that Zn0.2Cd0.8S nanoparticles exhibit highest photocatalytic activity among the as-prepared samples. Also, observed first-order rate constant of the reaction for Zn0.2Cd0.8S nanoparticles prepared in aqueous solution of the RTIL is about three and two times greater than the prepared sample in water under UV and visible irradiations, respectively.