Unlocking Bright and Switchable Dimeric Singlet Oxygen Electrochemiluminescence by Surface Engineering.

Visible electrochemiluminescence (ECL) of singlet oxygen (O) from the dimeric Δ state is a versatile and cost-efficient tool for sensing and imaging in various application fields such as biochemistry, pharmaceuticals, and material science. However, its implementation is hindered by weak emission and complex generation mechanisms. In this work, we enable a bright and switchable dimeric O ECL through facile yet effective surface engineering strategies on a screen-printed carbon electrode in aqueous media. Specifically, we complement a stepwise potential procedure with a pre-cathodic process to switch on the anodic O ECL and unravel how the electrochemical pretreatments remarkably amplify the ECL intensity by modifying the surface oxygenates and promoting the O-generating reactions. Additionally, oxygen plasma treatment on the electrode surface, which switches off the O ECL, further demonstrates the surface specificity of the O ECL from another perspective. Leveraging these surface strategies, we establish a sensing capability of the O ECL system with high sensitivity and selectivity toward tertiary amines. This work paves the way for translating a laboratory-scale O-ECL system to portable and patternable sensing, imaging, and display applications.