Electron-rich silicon quantum dots-based charge transfer probe for highly selective chemiluminescence detection of Fe2+ in PM2.5

• A general route was proposed to construct chemiluminescence nanoprobe by extensively exploiting the charge transfer of electron-rich SiQDs. • A highly sensitive and selective chemiluminescence sensing platform with real time monitoring for ferrous in PM 2.5 was established. • The sensing mechanism was explained by the electron hole annihilation between chemically injected exogenous holes and pre-existing endogenous CB electrons in SiQDs/ferrous CL system. Quantum dots (QDs) assist chemiluminescence (CL) sensor, especially metal-free QDs, are currently attracting considerable attention in the establishment of new CL systems to expand their analytical applications with good biocompatibility, controllable properties, and easy functionalization, while the fundamental CL process from QDs are still far from clear by now. Herein, A strategy of constructing CL probe is developed by carefully studying the charge transfer process in the electron-rich QDs. We purposefully synthesized silicon QDs (SiQDs) with electron-rich property, which can react with hole injector (oxidants) forming extraordinary CL emission. According to the characterization of reactive intermediates and emitting species, a possible CL mechanism was proposed, where radiative recombination of the exogenous holes-injected and existing electrons SiQDs resulted in the surprising SiQDs CL behavior. Interestingly, when Fe 2+ were added, more exogenous holes and active sites were formed on the surface of SiQDs during Fe 2+ /Fe 3+ conversion, which can significantly amplify CL signal. On this basis, a new CL system for the detection of ferrous in airborne fine particulate matter (PM 2.5 ) was constructed. This work provides a charge transfer-based path for designing a simple and highly sensitive CL probe.