Plasmon-Assisted Enhancement of the Ultraweak Chemiluminescence Using Cu/Ni Metal Nanoparticles

Cu/Ni nanoparticles (NPs) with stable fluorescence and excellent water dispersion were synthesized through a facile aqueous solution method with a similar Kirkendall effect. Ultraweak chemiluminescence (CL) from the oxidation reaction between sodium hydrogen carbonate (NaHCO3) and hydrogen peroxide (H2O2) in neutral medium was significantly enhanced by 60 +/- 5 nm Cu/Ni NP with a copper and nickel molar ratio of 1:2. The enhancement of the time-dependent CL was dependent on the composition of the NP and the order of reagent addition. On the basis of studies of CL emission spectra, electron spin resonance spectra, UV-vis absorption, and fluorescence spectra, a mechanism of plasmon-assisted metal catalytic effect for this metal NP (MNP)-enhanced CL was proposed. The surface plasmons of MNP can obtain energy from chemical reaction, forming the activated MNP (MNP*), which was coupled to center dot OH radical to produce the new adduct center dot OH-MNP*. The center dot OH-MNP* can accelerate the reaction rate of HCO3- for the generation of emitter intermediate (CO2)(2)*, which can lead the enhanced CL for the overall reaction.