Dual Enhancement of Gold Nanocluster Electrochemiluminescence: Electrocatalytic Excitation and Aggregation-Induced Emission

Ligand-protected gold nanoclusters (AuNCs) have emerged as a new class of electrochemiluminescence (ECL) luminophores for their interesting catalytic and emission properties, although their quantum yield (phi(ECL)) in aqueous medium is low with a poor mechanistic understanding of the ECL process. Now it is shown that drying AuNCs on electrodes enabled both enhanced electrochemical excitation by an electrocatalytic effect, and enhanced emission by aggregation-induced ECL (AIECL) for 6-aza-2-thiothymine (ATT) protected AuNCs with triethylamine (TEA) as a coreactant. The dried ATT-AuNCs/TEA system resulted in highly stable visual ECL with a phi(ECL) of 78 %, and a similar enhancement was also achieved with methionine-capped AuNCs. The drying enabled dual-enhancement mechanism has solved a challenging mechanistic problem for AuNC ECL probes, and can guide further rational design of ECL emitters.