Dai Pan-Pan, Yu Tao, Shi Hai-Wei, Xu Jing-Juan, Chen Hong-Yuan
State Key Laboratory of Analytical Chemistry for Life Science and Collaborative Innovation Center of Chemistry for Life Sciences, School of Chemistry and Chemical Engineering, Nanjing University , Nanjing 210023, China.
Anal Chem. 2015 Dec 15;87(24):12372-9. doi: 10.1021/acs.analchem.5b03890. Epub 2015 Nov 24.
Semiconductor nanocrystals usually suffer from weak electrogenerated chemiluminescence (ECL) emissions compared with conventional organic emitters. In this work, we propose, for the first time, a very convenient but effective way to greatly enhance ECL emission of semiconductor TiO2 nanotubes (NTs) by H2O2 and K2S2O8 as dual coreactants, generating ECL emission ca. 6.3 and 107 times stronger than that of K2S2O8 or H2O2 as an individual coreactant, respectively. Scanning electron microscopy, X-ray diffraction, and electron paramagnetic resonance spectral studies were carried out to investigate the ECL enhancement mechanism. The ECL enhancement of TiO2 NTs by the K2S2O8-H2O2 system was supposed to originate from the coordination of H2O2 to the TiO2 surface and the synergy effect between H2O2 and K2S2O8 in the ECL process. The coordination of H2O2 to the surface of TiO2 could stabilize the electrogenerated coreactant-related radical OH(•) (hydroxyl radical), which could obviously promote the amount of sulfate radical anion (SO4(•-)) near the electrode surface by inducing decomposition of K2S2O8 into SO4(•-) or inhibiting the consumption of SO4(•-) by its reaction with H2O. The holes (h(+)) released from SO4(•-) were injected into the valence band of TiO2, resulting in more TiO2(+), which combined with the electrons coming from the conduction band with an enhanced light emission. Moreover, this enhancement effect was also applicable to ECL of a CdS nanocrystal film on a glass carbon electrode, with ca. 2.74- and 148.3-fold enhanced ECL intensity correspondingly, indicating wide applications in the development of semiconductor nanocrystal-based ECL biosensors.
与传统有机发光体相比，半导体纳米晶体通常存在电化学发光（ECL）发射较弱的问题。在本工作中，我们首次提出了一种非常简便但有效的方法，通过使用H2O2和K2S2O8作为双共反应剂来大幅增强半导体TiO2纳米管（NTs）的ECL发射，产生的ECL发射分别比单独使用K2S2O8或H2O2作为共反应剂时强约6.3倍和107倍。进行了扫描电子显微镜、X射线衍射和电子顺磁共振光谱研究以探究ECL增强机制。K2S2O8 - H2O2体系对TiO2 NTs的ECL增强作用被认为源于H2O2与TiO2表面的配位以及H2O2和K2S2O8在ECL过程中的协同效应。H2O2与TiO2表面的配位可以稳定与电生共反应剂相关的羟基自由基OH(•)，这可以通过诱导K2S2O8分解为SO4(•-)或抑制SO4(•-)与H2O反应导致的消耗，从而显著促进电极表面附近硫酸根阴离子（SO4(•-)）的量。从SO4(•-)释放的空穴（h(+)）被注入到TiO2的价带中，产生更多的TiO2(+)，其与来自导带的电子结合并增强发光。此外，这种增强效应也适用于玻碳电极上CdS纳米晶体薄膜的ECL，相应地ECL强度增强了约2.74倍和148.3倍，表明在基于半导体纳米晶体的ECL生物传感器开发中具有广泛应用。
