K+ Ion-Doped Mixed Carbon Nitride: A Daylight-Driven Photocatalyst and Luminophore for Enhanced Chemiluminescence

Amino-rich silicon quantum dots as efficient activator with intrinsic chemiluminescence for the detection of peroxydisulfate

The specific detection of peroxydisulfate (S2O82-, PDS) is significant and challenging due to the rapid development of PDS-related technologies and their widespread application in multiple fields. However, traditional analytical methods are mainly based on their strong oxidizing properties, making it difficult to simultaneously achieve specific identification and high sensitivity for PDS detection in complex water environments. Here, we purposely prepared amino-rich SiQDs (N-SiQDs) as an effective catalyst and introduced H2O2 acts as a co-reactant for PDS activation and determination with strong intrinsic chemiluminescence (CL) emission. High yield of reactive active oxygen (mainly O2˙- and ˙OH) were generated during CL process, which trigger electron-hole annihilation between the N-SiQDs˙+ and N-SiQDs˙- accounted for extraordinary CL emission. On this basis, a new CL assay for PDS detection was fabricated with broad linear range of 5 × 10-7M-5 × 10-5 M and low detection limit (3.2 × 10-7 M). Due to the absence of SO4˙- involvement during CL emission, the sensing platform is sensitive enough, satisfactory selectivity and does not respond to transition-metal ions and inorganic anions that have interferences in the PDS CL sensors reported before. This work not only deepens insight into the mechanisms of nanomaterials assisted PDS activation but also provides a new perspective on the modified metal-free QDs CL probe for chemical species detection.

Cobalt-Modified Black Phosphorus Nanosheets-Enabled Ferrate (VI) Activation for Efficient Chemiluminescence Detection of Thiabendazole

The development of chemiluminescence-based innovation sensing systems and the construction of a sensing mechanism to improve the analytical performance of compounds remain a great challenge. Herein, we fabricated an advanced oxidation processes pretreated chemiluminescence (AOP-CL) sensing system via the introduction of cobalt-modified black phosphorus nanosheets (Co@BPNs) to achieve higher efficient thiabendazole (TBZ) detection. Co@BPNs, enriched with lattice oxygen, exhibited a superior catalytic performance for accelerating the decomposition of ferrate (VI). This Co@BPNs-based ferrate (VI) AOP system demonstrated a unique ability to selectively decompose TBZ, resulting in a strong CL emission. On this basis, a highly selective and sensitive CL sensing platform for TBZ was established, which exhibited strong resistance to common ions and pesticides interference. This was successfully applied to detecting TBZ in environmental samples such as tea and kiwi fruits. Besides, the TBZ detection mechanism was explored, Co@BPNs-based ferrate (VI) AOP system produced a high yield of ROS (mainly 1O2), which oxidized the thiazole-based structure of TBZ, generating chemical energy that was transferred to Co@BPNs via a chemical electron exchange luminescence (CIEEL) mechanism, leading to intense CL emission. Notably, this study not only proposed an innovative approach to enhance the chemical activity and CL properties of nanomaterials but also offered a new pathway for designing efficient CL probes for pollutant monitoring in complex samples.

Quantification strategy of absolute chemiluminescence efficiency for systems of luminol with hydrogen peroxide

An important feature to be determined in mechanistic studies on chemiluminescence (CL) is its quantum efficiency, which can give significant chemical reaction information on the influence of the reactant structures and reaction conditions. However, most of the previous quantitative measurements of luminescence and quantum efficiencies are complex and incomplete. To overcome the inconvenience and underestimated quantum efficiency in each measurement, we report a simple and highly effective strategy to determine the absolute CL quantum efficiencies for three systems of luminol with hydrogen peroxide by means of a spectrometer along with an integrating sphere. The integrating sphere facilitated collection of all the emitted light and then transferred it to the spectrometer via an optical fiber proportionally. The CL quantum efficiency was determined by taking the ratio of total photons generated in the reaction system to the number of the limiting reactant molecules consumed. Absolute CL efficiencies of three luminol-H2O2 reaction systems with varied reactant concentrations or coreactants were found to be 37 %, 7.0 % and 6.6 % in a time course, which are much higher than those previously reported values of 1.0-1.3 %. Due to our complete photon collection design, a higher absolute CL efficiency can be realized. Furthermore, spooling CL spectra also provided a powerful visualization tool to observe the real-time CL evolution and devolution, allowing the study on kinetics of CL reaction systems. The above investigations are anticipated to promote further development of CL methodologies and their applications.

K-N Bridge-Mediated charge separation in hollow g-C3N4 Frameworks: A bifunctional photocatalysts towards efficient H2 and H2O2 production

The development of bifunctional photocatalysts for enhancing hydrogen (H2) and hydrogen peroxide (H2O2) production from water is essential in addressing environmental and energy issues. However, the practical implementation of photocatalytic technology is still constrained by the inadequate separation of photo-generated charge carriers. Herein, potassium (K) atoms are introduced into the interlayers of graphitic carbon nitride (g-C3N4) with a hollow hexagonal structure (K-TCN) and are coordinated with N atoms in adjacent layers. The presence of K-N coordination serves as a layer bridge, facilitating the separation of charge carriers. The hollow hexagonal structure reduces the distance over which photogenerated electrons migrate to the surface, thereby enhancing the reaction kinetics. Consequently, the optimized K-TCN exhibits a dramatically improved photocatalytic H2 (941.6 μmol g-1h-1 with platinum (Pt) as the cocatalyst) and H2O2 (347.6 μmol g-1h-1) generation as compared to hollow g-C3N4 (TCN) and bulk g-C3N4 nanosheet (CN) without K-N bridge under visible light irradiation. The unique design holds promising potential for developing highly efficient bifunctional photocatalysts towards producing renewable fuels and value-added chemicals.

Controllable Synthesis of Defective UiO-66 for Efficient Degradation and Detection of Ozone

Metal-organic framework (MOF) structures have gained significant attention for their exceptional catalytic performance in ozone degradation, even under high humidity conditions, which is attributed to the presence of unsaturated metal sites (MOF defects). However, the correlation between MOF defects and catalytic ozone remains ambiguous, and a general approach for the controllable synthesis of high-performance MOF structures is currently lacking. Herein, different defective UiO-66 materials with cluster or ligand defects were obtained by precisely controlling small molecular acid modulators. Their catalytic performance can be analyzed in real time through the specific cataluminescence (CTL) signal of ozone at the interface. The presence of ligand defects was found to be crucial for both catalytic degradation and luminescence of ozone, and the CTL signal exhibited a positive correlation with the endogenous hydroxyl group content in the material (R2 = 0.982), while external humidity further supplemented internal water molecules within the material. Furthermore, theoretical calculations were conducted to compare the adsorption behaviors of ozone on the defective UiO-66 under dry/wet conditions, leading to the proposal of two potential reaction pathways. Subsequently, UiO-66-DA with superior catalytic performance was employed to develop a highly efficient CTL sensor capable of accurately detecting ozone (LOD = 23.3 ppb). This study held significant value in elucidating the reaction site of ozone on MOFs and achieving optimal catalytic effects through the careful selection of modulators and humidity levels.

Europium-Functionalized Graphitic Carbon Nitride for Efficient Chemiluminescence Detection of Singlet Oxygen

Enhancing the sensitivity and selectivity of chemiluminescence (CL) sensors for detecting chemical species in complex samples poses a significant challenge in nanoparticle surface engineering. Graphitic carbon nitride (CN) shows promise but suffers from weak CL intensity and unknown luminescence mechanisms. In this study, we propose a nitrogen defect strategy to enhance the CL efficiency of europium-functionalized graphitic carbon nitride (Eu-CNNPs). By controlling the dosage of the europium modification, we can adjust the nitrogen defect content to reduce the energy gap and improve the CL performance. Remarkably, Eu-CNNPs with rich nitrogen defects exhibit strong chemiluminescence emission specifically for singlet oxygen (1O2) without responding to other reactive oxygen species (ROS). Building upon this finding, we developed a direct, selective, and sensitive CL sensing platform for 1O2 in PM2.5 and monitored 1O2 production in photosensitizers without interference from metal ions. Through extensive experiments, we attribute the 1O2-driven CL response to the presence of abundant nitrogen defects in the CN material, accelerating electron transfer and yielding a high generation of 1O2. Furthermore, chemiluminescence resonance energy transfer (CRET) between (1O2)2* (1O2 dimeric aggregate) and Eu-CNNPs contributes to strong CL emission. This work provides insights into enhancing the CL performance of CN and offers new possibilities for advancing the practical analysis of nanomaterials using the intriguing mechanism of nitrogen defects.

Potassium Molten Salt-Mediated In Situ Structural Reconstruction of a Carbon Nitride Photocatalyst

Metal-free polymeric carbon nitride (PCN) materials are at the forefront of photocatalytic applications. Nevertheless, the overall functionality and performance of bulk PCN are limited by rapid charge recombination, high chemical inertness, and inadequate surface-active sites. To address these, here, we employed potassium molten salts (K⁺X^-, where X^- is Cl^-, Br^-, and I^-) as a template for the in situ generation of surface reactive sites in thermal pyrolyzed PCN. Theoretical calculations imply that addition of KX salts to PCN-forming monomers causes halogen ions to be doped into C or N sites of PCN with a relative trend of halogen ion doping being Cl < Br < I. The experimental results show that reconstructing C and N sites in PCN develops newer reactive sites that are beneficial for surface catalysis. Interestingly, the photocatalytic H₂O₂ generation rate of KBr-modified PCN was 199.0 μmol h^-1, about three times that of bulk PCN. Owing to the simple and straightforward approach, we expect molten salt-assisted synthesis to have wide exploration in modifying PCN photocatalytic activity.