Crystallization Regulation Engineering in the Carbon Nitride Nanoflower for Strong and Stable Electrochemiluminescence

Cathode electrochemiluminescence (ECL) of C3N4 material has suffered from weak and unstable ECL emission for a long time, which greatly limits its practical application. Herein, a novel approach was developed to improve the ECL performance by regulating the crystallinity of the C3N4 nanoflower for the first time. The high-crystalline C3N4 nanoflower achieved a pretty strong ECL signal as well as excellent long-term stability compared to low-crystalline C3N4 when K2S2O8 was used as a co-reactant. Through the investigation, it is found that the enhanced ECL signal is attributed to the simultaneous inhibition of K2S2O8 catalytic reduction and enhancement of C3N4 reduction in the high-crystalline C3N4 nanoflower, which can provide more opportunities for SO4• - to react with electro-reduced C3N4• -, and a new "activity passivation ECL mechanism" was proposed, while the improvement of the stability is mainly ascribed to the long-range ordered atomic arrangements caused by structure stability in the high-crystalline C3N4 nanoflower. As a benefit from the excellent ECL emission and stability of high-crystalline C3N4, the C3N4 nanoflower/K2S2O8 system was employed as a Cu2+ detection sensing platform, which exhibited high sensitivity, excellent stability, and good selectivity with a wide linear range from 6 nM to 10 μM and a low detection limit of 1.8 nM.