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, Au₁₈⁰*, Au₁₈¹⁺* and Au₁₈²⁺*, with a considerably high ECL efficiency of 5.5 relative to that of the gold standard Ru(bpy)₃²⁺/TPrA (with 5–6 % reported ECL efficiency). The unprecedentedly high efficiency is due to the overlapped oxidation potentials of Au₁₈⁰ and tri-n-propylamine as co-reactant, the exposed facets of Au₁₈⁰ 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.