Efficient Near-Infrared Electrochemiluminescence from Au18 Nanoclusters.

Bright, near-infrared electrochemiluminescence (NIR-ECL) of Au18 nanoclusters is reported herein. Spooling ECL and photoluminescence spectroscopy were used to track and link NIR emissions at 832 and 848 nm to three emissive species, Au18 0 *, Au18 1+ * and Au18 2+ *, with a considerably high ECL efficiency of 5.5 relative to that of the gold standard Ru(bpy)3 2+ /TPrA (with 5-6 % reported ECL efficiency). The unprecedentedly high efficiency is due to the overlapped oxidation potentials of Au18 0 and tri-n-propylamine as co-reactant, the exposed facets of Au18 0 gold core, and electrocatalytic loops. These discoveries will add a new member to the efficient NIR-ECL gold nanoclusters family and bring more potential applications.