Synthesis and photoluminescence properties of aqueous CdWO4 quantum dots with WO66− luminescence center

Aqueous CdWO4 QDs were synthesized by the reaction of CdCl2 and Na2WO4 in the presence of mercaptoacetic acid (TGA) as capping reagent. The crystal morphology, particle size and its distribution of as-prepared products were characterized by transmission electron microscopy (TEM, SAED) atomic force microscopy (AFM), high-resolution transmission electron microscopy (HRTEM), and photon correlation spectroscopy (PCS), respectively. Qualitative assays for functional groups on the QDs’ surface were measured by fourier transform infrared spectroscopy (FTIR). Photoluminescence properties of QDs were studied by photoluminescence spectroscopy (PL). The results showed that the single QD with diameter of about 8±2nm was single-crystal. The particle size distribution of QDs was normal. Infrared absorption bands of carboxylic group on the surface of CdWO4 QDs were observed around 1610–1550cm−1 (nonsymmetrical vibration of –COO−) and 1400cm−1 (symmetric vibration of C–O). With reaction-time going, PL peak position shifted from 498 to 549nm and intensity of PL increased first and then decreased. PL peak position of QDs was blue-shift compared with 570nm WO66− luminescence center of bulk CdWO4.