Encapsulating Gold Nanoclusters into Melamine–Formaldehyde Polymer Nanoparticles for Confinement Induced Enhanced Emission toward Ratiometric Sensing and Light-Emitting Diode Fabrication

Low photoluminescence quantum yield (PLQY) has long been one of the key issues that impedes the versatile applications of gold nanoclusters (AuNCs). In this work, melamine–formaldehyde polymer nanoparticles were employed as carriers to encapsulate AuNCs (AuNCs-MF PNPs), which can trigger the confinement induced enhanced emission (CIEE) effect, remarkably enhancing the PLQY more than 25 times from 1.46% (AuNCs) to 36.90% (AuNCs-MF PNPs) and improving the stability toward pH. By simultaneously incorporating AuNCs-MF PNPs and CDs as sensing probes, ratiometric fluorescence detection of H2S with improved sensitivity was achieved. To realize the on-site detection of H2S, a portable sensing platform based on a smartphone was constructed. Considering the high PLQY of AuNCs-MF PNPs, a light-emitting device (LED) was fabricated based on AuNCs-MF PNPs with favorable characteristics. This work not only provides a novel strategy for preparing AuNCs with high PLQY but also highlights their potential in fluorescence sensing and the field of intelligent luminescence.