In this study, Nitrogen and Sulfur co-doped Graphene Quantum Dots (N, S-GQDs) were synthesized via a pyrolysis approach, utilizing citric acid as the carbon source and L-cysteine as the nitrogen and sulfur sources. These N, S-GQDs were used to develop a novel paper-based electrochemiluminescence (ECL) sensor for the detection of catechol (CC) and tryptophol, two potentially hazardous substances in the environment. Screen printing technology was utilized to construct the ECL sensor on filter paper, incorporating a hydrophobic layer, working and counter electrodes, and a reference electrode. The presence of CC and tryptophol was found to result in a decrease in the ECL intensity of the quantum dots (QDs), this quenching phenomenon is attributed to the oxidation of these substances within the electrochemical system and the subsequent electron transfer from the excited state of the QDs to the oxidation products. The sensor demonstrated a linear detection range for CC and tryptophol from 0.01 to 1000 mu M, with detection limits of 0.0082 mu M and 0.0066 mu M, respectively, and exhibited excellent selectivity, stability, and repeatability. This cost-effective and efficient monitoring technique holds significant promise for environmental and health safety by facilitating the detection of CC and tryptophol, thereby mitigating their potential adverse impacts.

In this study, a portable electrochemiluminescence (ECL) imaging system based on Raspberry Pi was developed for the instant detection of melamine. The system employed a lithium battery as the excitation source and Ru (bpy)32+/TPA as the reaction system. A homemade 3D-printed black box served as a reaction chamber for the ECL reaction. ECL images were captured by a camera and subsequently classified by the MobileNet model. Over 500 images obtained from the experiment were used as a self-built dataset to train the neural network model. As the core processor, Raspberry Pi was not only used to control the camera, but also to perform Image enhancement and color analysis. The experimental results were further validated using image processing algorithms. The system demonstrated highly sensitive detection of melamine under optimal conditions, with a linear fit curve in the range of 10-8-10- 3 M and a detection limit of 3.54 nM. In conclusion, this system holds great potential for the instant detection of melamine.

Nitrogen-doped graphene quantum dots (N-GQDs) were prepared using pyrolysis, with citric acid and urea as the carbon and nitrogen sources, respectively, to be used for Cu2+ ion detection in a paper-based ECL sensor. Existing methods for Cu2+ detection require expensive equipment, specialized experimental chambers, or complex sample pretreatment procedures, which limit their functionality. Using first principles, the electronic and optical properties of graphene quantum dots (GQDs) and N-GQDs were calculated and analyzed. The N-GQDs showed clearer green fluorescence under long-wave ultraviolet light and a better, more stable electrochemiluminescence (ECL) performance. Using first principles, the electronic and optical properties of the GQDs and N-GQDs were calculated and analyzed, and A theoretical mechanism for the observed ECL enhancement in the N-GQDs was proposed. A paper-based ECL sensor with N-GQDs was then developed, using a screen-printing technique, to detect Cu2+ ions. The results showed that the ECL intensity of the sensor increased as the Cu2+ ion concentration increased, and the sensor demonstrated a linear detection range of 0.01-1000 mu M. Overall, the sensor exhibited excellent ECL stability, reproducibility, and selectivity. This simple, inexpensive, and effective monitoring technique can be used to detect Cu2+ to prevent negative effects on human health and the environment.

In this study, nitrogen-doped carbon quantum dots and ZnO (N-CQDs/ZnO) composites were prepared to improve the electrochemiluminescence (ECL) performance of carbon quantum dots (CQDs) for detecting copper ions. Nitrogen-doped carbon quantum dots (N-CQDs) were prepared by a pyrolysis method using glucosamine as a carbon source and urea as a nitrogen source. In addition, N-CQDs/ZnO composites were prepared using zinc acetate in the same way, and they were characterized by the ECL method. The ECL performance of composite ZnO materials with paper-based modified electrodes improved, and the principle of signal enhancement of the N- CQDs/ZnO composite material was demonstrated. The paper electrode was modified with the composite material to detect copper ions via the quenching reaction. The results show that the sensitivity and detection limit (6.13 x 10-9 M) of the paper ECL sensor improved across a wide linear detection range (1.0 x 10-8-1.0 x 10-3 M). Therefore, N-CQDs/ZnO composites prepared by this method have potential applications in ECL signal amplification.