Pre-Adsorbed H-Mediated Electrochemiluminescence
Mengzhen Xi, Yu Wu, Jingshuai Li, Hengjia Wang, Ying Qin, Canglong Wang, Liuyong Hu, Wenling Gu, Chengzhou Zhu
Abstract
In conventional electrochemiluminescence (ECL) systems, the presence of the competitive cathodic hydrogen evolution reaction (HER) in aqueous electrolytes is typically considered to be a side reaction, leading to a reduced ECL efficiency and stability due to H 2 generation and aggregation at the electrode surface. However, the significant role of adsorbed hydrogen (H*) as a key intermediate, formed during the Volmer reaction in the HER process, has been largely overlooked. In this study, employing the luminol-H 2 O 2 system as a model, we for the first time demonstrate a novel H*-mediated coreactant activation mechanism, which remarkably enhances the ECL intensity. H* facilitates cleavage of the O–O bond in H 2 O 2, selectively generating highly reactive hydroxyl radicals for efficient ECL reactions. Experimental investigations and theoretical calculations demonstrate that this H*-mediated mechanism achieves superior coreactant activation compared to the conventional direct electron transfer pathway, which unveils a new pathway for coreactant activation in the ECL systems.