Growth of Robust Carbon Nitride Films by Double Crystallization with Exceptionally Boosted Electrochemiluminescence for Visual DNA Detection

Abstract Electrochemically generated chemiluminescence (ECL) has attracted significant interest over the past decades, ranging from fundamental studies on highly efficient electron‐to‐photon interconversion to practical bioassays. Nonetheless, the ECL efficiency (Φ ECL ) of most emitters is low, which significantly hampers further development. Herein, this work reports a highly robust carbon nitride film with unusually enhanced ECL efficiency (2256 times higher than that of the reference Ru(bpy) 3 Cl 2 /K 2 S 2 O 8 ). Double crystallization, which provides the primary interaction of carbon nitride with the substrate and subsequent growth, plays a crucial role in the preparation. The improved ECL efficiency is ascribed to little pinholes suppressing futile co‐reagent reduction, maintenance of more orbit‐delocalized heptazine subunits improving ECL kinetics, and high transparency avoiding self‐absorption. As a potential application, an ultrasensitive visual DNA biosensor by the naked eye is further successfully developed with a linear detection range of 100 p m to 1 µ m and limit of detection of 27 p m ( S / N = 3).