Highly luminescent near-infrared-emitting gold nanoclusters with further natural etching: photoluminescence and Hg(2+) detection

Highly luminescent near-infrared (NIR)-emitting gold nanoclusters (Au NCs) protected by glutathione with ultra-small size were prepared at high temperature following with a further natural etching at room temperature. The optical and surface properties of Au NCs were monitored by ultraviolet–visible and photoluminescence (PL) spectra, high-resolution transmission electron microscopy, and electrospray ionization mass spectrometry. The diameter of the etched Au NCs was reduced to approximately 1.35 nm with 30 % PL quantum yield. Interestingly, the PL of Au NCs was decreased obviously by the addition of Hg(2+) and increased by the addition of Pb(2+) at certain concentration. Our preliminary results illustrated that the highly luminescent NIR-emitting Au NCs would be an alternative probe for the detection of heavy metal ions in water and environmental monitoring.