Triggering Anodic Luminol Electrochemiluminescence through Electrostatic Interactions: An Innovative Approach Utilizing Conductive Metal–Organic Framework Co-HHTP

Classical anodic luminol electrochemiluminescence (ECL) often relies on the addition of hydrogen peroxide (H2O2) to generate significant ECL emission, as water is not readily oxidized to produce reactive oxygen species (ROS). This study introduces an effective method for triggering ECL by combining cathodic reduction of dissolved oxygen and anodic oxidation of luminol at an electrode modified with a conductive metal–organic framework, specifically Co-HHTP (HHTP = 2,3,6,7,10,11-hexahydroxytriphenylene). Within the potential range of −0.5 to 1.0 V, Co-HHTP exhibits an ECL intensity 30 times higher than that observed within the range of 0 to 1.0 V. Moreover, ECL with improved electrical conductivity was developed based on the superior electrical conductivity of Co-HHTP. Compared to Ni-HHTP and HHTP, the ECL intensity of Co-HHTP increases significantly by approximately 1.5 times and 8 times, respectively, due to enhanced electrical conductivity. Co-HHTP, characterized by a negatively charged large-channel skeleton, effectively encapsulates charge and size-matched luminol into the aperture through electrostatic action, facilitating charge transport. This innovative approach not only generates strong ECL signals but also broadens the application scope of conductive metal–organic framework materials.