Pore Confinement-Enhanced Electrochemiluminescence on SnO₂ Nanocrystal Xerogel with NO₃^- As Co-Reactant and Its...

Herein, 10-fold electrochemiluminescence (ECL) enhancement from a porous SnO₂ nanocrystal (SnO₂ NC) xerogel (vs discrete SnO₂ NCs) was first observed with NO₃^- as a novel coreactant. This new booster phenomenon caused by pore characteristic was defined as "pore confinement-induced ECL enhancement", which originated from two possible reasons: First, the SnO₂ NC xerogel with hierarchically porous structure could not only localize massive luminophore near the electrode surface, more importantly, but could accelerate the electrochemical and chemiluminescence reaction efficiency because the pore channels of xerogel could promote the mass transport and electron transfer in the confined spaces. Second, the NO₃^- could be in situ reduced easily to the active nitrogen species by means of the pore confinement effect, which could be served as a new coreactant for nanocrystal-based ECL amplification with the excellent stability and good biocompatibility. As a proof of concept, a facile and sensitive sensing platform for SO₃^2- detection has been successfully constructed upon effectively quenching of SO₃^2- toward the SnO₂ NC xerogel/NO₃^- ECL system. The key feature about this work presented a grand avenue to achieve the strong ECL signal, especially from weak emitters, which gave a fresh impetus to the construction of new-generation of surface-confined ECL platform with potential applications in ECL imaging and sensing.