Zn-rich ZnCdS nanoparticles (NPs) are successfully synthesized by a facile chemical co-precipitation technique at room temperature. The crystal structure homogeneity of the as-synthesized ternary alloy is examined by the x-ray diffraction pattern and the micro-Raman spectroscopy. The average crystalline domain size is about 4 nm
indicating the spatial particle confinement of ternary ZnCdS NPs. The optical bandgap (Eg) of the as-synthesized
ZnCdS NPs is 3.95 eV that is higher than the corresponding ternary bulk alloy due to the improvement in the
quantum size effect. The effect of UV irradiation on the optical band gap of ZnCdS NPs is investigated at different
exposure times. A strong decrease in Eg is observed with increasing exposure time up to 60 min followed by Eg
saturation at higher UV exposure times. The as-synthesized ZnCdS nanopowder exhibits a wide emission spectrum extending from UV to visible spectral region, which originating from various intrinsic structural defects.
The aging of the as-synthesized ZnCdS nanopowder results in emission intensity quenching without changing
peak positions. The emission intensity is recovered by the direct exposure to UV irradiation. This indicates the
ability of UV irradiation to cure the emission characteristics of small NPs. This would provide more durability
about the emission characteristics of the ZnCdS NPs-based fluorescence sensor.