A Unique, Porous C3N4 Nanotube for Electrochemiluminescence with High Emission Intensity and Long-Term Stability: The Role of Calcination Atmosphere.

Developing excellent strategies to optimize the electrochemiluminescence (ECL) performance of C3N4 materials remains a challenge due to the electrode passivation, causing weak and unstable light emission. A strategy of controlling the calcination atmosphere was proposed to improve the ECL performance of C3N4 nanotubes. Interestingly, we found that calcination atmosphere played a key role in specific surface area, pore-size and crystallinity of C3N4 nanotubes. The C3N4 nanotubes prepared in the Air atmosphere (C3N4 NT-Air) possess a larger specific surface area, smaller pore-size and better crystallinity, which is crucial to improve ECL properties. Therefore, more C3N4•- excitons could be produced on C3N4 NT-Air, reacting with the SO4•- during the electrochemical reaction, which can greatly increase the ECL signal. Furthermore, when C3N4 nanotube/K2S2O8 system is proposed as a sensing platform, it offers a high sensitivity, and good selectivity for the detection of Cu2+, with a wide linear range of 0.25 nM~1000 nM and a low detection limit of 0.08 nM.

A scaffold of thermally activated delayed fluorescent polymer dots towards aqueous electrochemiluminescence and biosensing applications.

To achieve the most efficient, all-exciton-harvesting organic electrochemiluminescence (ECL) for biosensing, aqueous thermally activated delayed fluorescence (TADF)-ECL (aqueous TADF-ECL) was successfully launched to provide a breakthrough for the theoretical ECL efficiency limitation of aqueous fluorescence ECL (aqueous FL-ECL). However, achieving efficient TADF emitters suitable for aqueous TADF-ECL remains challenging. A previous strategy relied on TADF small molecular nanoparticles (NPs). However, the aggregation caused quenching of such TADF molecules within NPs is intense, which renders such NPs inefficient for ECL emission. Herein, we propose developing conjugated polymer dots (Pdots) based aqueous TADF-ECL. Compared to the intrinsic TADF polymer, the Pdots achieve a comparable TADF photophysical properties in water, i.e., the comparable PL spectra, similar PL quantum efficiency (ΦPL) and intense delayed fluorescent contributions via a fast reverse intersystem crossing rate (kRISC) of 1.5 × 106 s-1. The resultant relative ECL efficiency (ΦECL) of the oxidative-reduction ECL system (C2O42- as the co-reactant) is as high as 11.73% (vs. the Ru(bpy)32+ counterpart). Additionally, satisfactory dopamine biosensing was accomplished for such TADF-Pdots/C2O42- couple. All those results are combined to highlight the promising potential of such an aqueous TADF-ECL strategy.

Aggregation-induced delayed fluorescence luminogens: the innovation of purely organic emitters for aqueous electrochemiluminescence.

Due to overcoming the limitation of aggregation caused quenching (ACQ) of solid-state emitters, aggregation-induced emission (AIE) organic luminogens have become a promising candidate in aqueous electrochemiluminescence (ECL). However, restricted by the physical nature of fluorescence, current organic AIE luminogen-based ECL (AIECL) faces the bottleneck of low ECL efficiency. Here, we propose to construct de novo aqueous ECL based on aggregation-induced delayed fluorescence (AIDF) luminogens, called AIDF-ECL. Compared with the previous organic AIE luminogens, purely organic AIDF luminogens integrate the superiorities of both AIE and the utilization of dark triplets via thermal-activated spin up-conversion properties, thereby possessing the capability of close-to-unity exciton utilization for ECL. The results show that the ECL characteristics using AIDF luminogens are directly related to their AIDF properties. Compared with an AIECL control sample based on a tetraphenylethylene AIE moiety, the ECL efficiency of our AIDF-ECL model system is improved by 5.4 times, confirming the excellent effectiveness of this innovative strategy.

Graphite-like Carbon Nitride Nanotube for Electrochemiluminescence Featuring High Efficiency, High Stability, and Ultrasensitive Ion Detection Capability.

Herein, for the first time, we introduced a novel electrochemiluminescence (ECL) luminophore based on a one-dimensional g-C3N4 nanotube using K2S2O8 as the coreactant. The g-C3N4 nanotube/K2S2O8 couple displayed very satisfactory ECL performance, i.e., an ECL efficiency (ΦECL) of 437% (vs 100% for the Ru(bpy)32+/K2S2O8 reference) and excellent ECL stability (the relative standard deviation (RSD) = 0.78%). By contrast, ΦECL and RSD of the control g-C3N4 nanosheet/K2S2O8 couple were merely 196% and 45.34%, respectively. The mechanism study revealed that the g-C3N4 nanotube features a large surface area and much lower interfacial impedance in the porous microstructure, which are beneficial for accelerating the charge transfer rate and stabilizing charge/excitons for ECL. Moreover, using the g-C3N4 nanotube/K2S2O8 system as a sensing platform, excellent Cu2+ detection capability was also achieved. Our work thus triggers a promising g-C3N4 nanomaterial system toward ECL application.

Nanoencapsulation strategy: enabling electrochemiluminescence of thermally activated delayed fluorescence (TADF) emitters in aqueous media.

A nanoencapsulation strategy is introduced to a state-of-the-art thermally activated delayed fluorescence (TADF) molecule, i.e. 4CzIPN, which ensures the achievement of air-stable, water-soluble TADF nanoparticles featuring efficient TADF property without an unsatisfactory oxygen quenching effect. Accordingly, we report here for the first time the electrochemiluminescence of TADF emitters in aqueous media.