Optimal Excitation Wavelength Research Articles

A New approach for simultaneous detection and photocatalytic degradation of imidacloprid and dinotefuran in water using terbium-based fluorometry and mixed-phase TiO2

This study explores a novel method for detecting neonicotinoid insecticides, imidacloprid (IMD) and dinotefuran (DNT), in water using terbium (Tb3+) ions photo probe. The optimal excitation and emission wavelengths for Tb3+ luminescence were identified at 310 nm and 545 nm, respectively. The influence of pH and solvent on Tb-complex fluorescence was investigated. Results indicate a significant enhancement of luminescence intensity at pH 6 for IMD in DMF and pH 7.0 for DNT in DMSO. The fluorescence intensity exhibited a linear relationship with IMD and DNT concentrations ranging from 0.1 to 20 µg/mL (R2 > 0.99). Limits of quantitation (LOQ) were determined as 0.1 µg/mL for IMD and 0.05 µg/mL for DNT. This newly developed photo probe demonstrates the potential for monitoring photolysis and photocatalytic degradation of these neonicotinoids using TiO2 as a catalyst under controlled photoreactor conditions. The method offers a promising alternative for rapidly and sensitively detecting these prevalent insecticides in water samples.

Exploration and Design of Carbon Dot-Based Long Afterglow Materials Using Active Machine Learning and Quantum Chemical Simulations.

Long afterglow materials based on carbon dots (CDs) have attracted extensive attention in the field of optics due to their low cost and nontoxic properties. However, the targeted synthesis of specific properties of complex and unknown structures such as CDs remains a daunting challenge. In this study, the powerful nonlinear fitting ability of machine learning was used to explore the afterglow properties of CDs. The XGBoost algorithm demonstrates high prediction accuracy in determining the optimal excitation wavelength, optimal emission wavelength, and afterglow lifetime. Using Bayesian optimization, we screened and synthesized the CDs-based long afterglow materials with the longest lifetime reported so far by a one-step microwave method. By combining quantum chemical calculations with experimental data, we revealed the structure-function relationship between CDs and their precursors through electron-hole analysis. These results show that machine learning can establish nonlinear correlations between precursors and materials with unknown structures, clarify their intrinsic relationships, simplify the material design process, and thus accelerate the development of advanced materials.

Synthesis and application of optically stable red fluorescent carbon dots for sensitive and selective detection of ceftazidime

This study reports the successful synthesis of optically stable red-emitting carbon dots (R-CDs) through a solvothermal method, using glycine as the carbon source and o-phenylenediamine as the nitrogen-doping agent. The R-CDs exhibit long-wavelength emission characteristics with optimal excitation and emission wavelengths of 533 nm and 600 nm, respectively, and a quantum yield of 26.7 %. The results demonstrate that R-CDs possess excellent salt resistance and photostability. The R-CDs display bright fluorescence emission and show a sensitive response to ceftazidime (CF). Leveraging these properties, a fluorescent probe based on R-CDs was developed for the sensitive determination of CF. The fluorescence quenching intensity of this system exhibits a good linear relationship with CF concentration in the range of 0–0.7 mmol/L. The linear equation is (F0-F)/ F0 = 0.9564CCF (mmol/L) + 0.0089, with a linear correlation coefficient (R2) of 0.9945. The detection limit is 4.9 μmol/L, with recovery rates ranging from 94.2 % to 100.5 % and relative standard deviations between 2.2 % and 3.2 %. This work provides a theoretical basis for the detection of CF using red-emitting carbon dots and demonstrates promising potential for practical applications.

Molybdenum disulfide quantum dots for rapid fluorescence detection of glutathione and ascorbic acid

A method for the specific detection of glutathione (GSH) and ascorbic acid (AA) using 3-aminophenylboronic acid functionalized molybdenum disulfide quantum dots (APBA-MoS2 QDs) was reported. The APBA-MoS2 QDs synthesized using the hydrothermal method showed the strongest fluorescence intensity at an emission wavelength of 375 nm with the optimum excitation wavelength of 320 nm. The detection method was constructed by the combination of the dynamic and static quenching and the inner filter effect (IFE) of APBA-MoS2 QDs by permanganate (MnO4−) and the rapid redox reaction (1 min) of MnO4− by GSH or AA. The concentrations of GSH and AA showed good linear ranges of 10–500 μM and 10–100 μM, respectively, with limits of detection (LOD) of 0.476 μM and 0.185 μM, respectively. The spiked recovery tests in human serum and fresh fruit samples showed that APBA-MoS2 QDs had significant potential in the construction of fluorescent biological detection methods.

Nitrogen-doped carbon quantum dots (NCQDs) detected to mercury ions in food monitoring

Using 2,3-diaminopyridine and citric acid as precursors, blue fluorescent nitrogen-doped carbon quantum dots (NCQDs) with a narrow size distribution (∼7.2 nm) were prepared and applied in the following assay for mercury ion detection at a weight ratio of 2,3-diaminopyridine:citric acid = 1:1 (0.2 g: 0.2 g, 20 mL for H2O), 220 °C, and 10 h. NCQDs was characterized by TEM, FT-IR, XPS, UV–Vis and EDS, and the prepared NCQDs display excitation-independent behavior due to less surface defects and uniform size. The optimal excitation and emission wavelengths of the NCQDs were 380 nm and 430 nm, respectively. Interestingly, the fluorescence of the NCQDs could be rapidly and selectively quenched by Hg2+ within 9 min at room temperature without further modification. Under optimal conditions, the limit of detection (LOD) was measured to be at the nanomolar level (42.4 nmol/L) with a linear range of 0–5.0 μmol/L, and fluorescence analysis of NCQDs was successfully used for the qualitative and quantitative analysis of mercury ions in food samples. Furthermore, our results revealed that fluorescence quenching occurred under the common fluences of the inner filter effect, and the static quenching effect was authenticated in the process in which Hg2+ coordinates with the NCQDs to form nonfluorescent complexes.

Incorporating Sb (III) and Bi (III) ions into Cs2AgNaInCl6 perovskite toward efficient white-light emission with high color rendering index

Single phosphor with efficient and high quality white-light emission is necessary for lighting applications. In this work, we report a double perovskite, Cs2AgNaInCl6 with Bi3+ and Sb3+ incorporation, which demonstrates excellent white-light properties including tunable emission component and correlated colour temperature (CCT). Using the broad-band emission of self-trapped excitons (STEs) associated with Bi3+ and Sb3+ in the Cs2AgNaInCl6 host, the blue and orange dual-band STEs emission located at 460 and 565 nm covers the entire visible range to achieve high-quality white light emission. The relative intensity of the dual emission components can be adjusted flexibly by modulating the doping ratio of Bi3+ and Sb3+. The dual STEs emission shares the same optimal excitation wavelength at 340 nm. The optimal sample of Bi3+ (1 %) and Sb3+ (10 %) codoped Cs2Ag0.1Na0.9InCl6 exhibits high color rendering index (CRI) of up to 93, and high photo-luminescence quantum yield (PLQY) of 76 %. This codoping in double perovskite approach represents a promising method for achieving high-quality white lighting application within a single phosphor.

A Novel Synthesis Method of Dumbbell-like (Gd1-xTbx)2O(CO3)2·H2O Phosphor for Latent Fingerprint.

A novel method for synthesizing dumbbell-shaped (Gd1-xTbx)2O(CO3)2·H2O (GOC:xTb3+) phosphors using sodium carbonate was investigated. An amount of 1 mmol of stable fluorescent powder can be widely prepared using 3-11 mmol of Na2CO3 at a pH value of 8.5-10.5 in the reaction solution. The optimal reaction conditions for the phosphors were determined to be 7 mmol for the amount of sodium carbonate and a pH of 9.5 in the solution. Mapping analysis of the elements confirmed uniform distribution of Gd3+ and Tb3+ elements in GOC:xTb3+. The analysis of fluorescence intensity shows that an optimal excitation wavelength of 273 nm is observed when the concentration of Tb3+ is between 0.005 and 0.3. The highest emission intensity was observed for GOC:0.05Tb3+ with a 57.5% maximum quantum efficiency. The chromaticity coordinates show that the color of GOC:Tb3+ is stable and suitable for fluorescence recognition. Latent fingerprint visualization reveals distinctive features like whorls, hooks, and bifurcations. Therefore, the sodium carbonate method offers an effective alternative to traditional urea chemical reaction conditions for preparing GOC:Tb3+.

Self-assembled dipeptide confined in covalent organic polymers for fluorescence sensing of tryptamine in fermented meat products.

Diphenylalanine(FF)-Zn self-assembly (FS) confined in covalent organic polymers (FS@COPs) with efficient fluorescence was synthesizedfor fluorescence sensing of biogenic amines, which was one of the most important indicators for monitoring food freshness. FS@COPs combined excellent biodegradability of self-assembled dipeptide with chemical stability, porosity and targeted site recognition of COPs. With an optimal excitation wavelength of 360 nm and an optimal emission wavelength of 450 nm, FS@COPs could be used as fluorescence probes to rapidly visualize and highly sensitive determination of tryptamine (Try) within 15 min, and the linear range was from 40 to 900 μg L-1 with a detection limit of 63.08 μg kg-1. Importantly, the FS@COPs showed a high fluorescence quantum yield of 11.28%, and good stability, solubility, and selectivity, which could successfully achieve the rapid, accurate and highly sensitive identification of Try. Furthermore, we revealed the mechanism of FS@COPs for fluorescence sensing of targets. The FS@COPs system was applied to the fluorescence sensing of Try in real samples and showed satisfactory accuracy of 93.02%-105.25%.

A NIR fluorescent probe with large stokes shift for sensitive detection and imaging of G4s in live cells

G4s play a very important role not only in human biological systems but are associated with tumor formation, which is considered as a novel target for the exploitation of anti-tumor drugs. Therefore, it is essential to develop near-infrared (NIR) fluorescent probes to study G4s. In this article, we designed a large stokes shift probe (AOC) which can be activated NIR fluorescent by G4s in living cells and tumor tissue. In vitro experiments shown that AOC exhibited no fluorescence emission in aqueous solution, while significantly enhanced at 768 nm in the presence of the G4s. The optimal excitation wavelength of the probe is about 640 nm, indicating that the probe AOC has a large stokes shift (128 nm). Meanwhile, AOC is dynamically responsive to the concentrations of DNA G4s (22AG, Mito-160) and exhibits high selectivity toward DNA G4s with desirable stability in the physiological pH conditions. Imaging studies of different cell lines have shown that cancer cell lines fluoresced brightly than normal cell lines, implication that the expression of G4s may be higher in tumor cell lines. We further performed fluorescence imaging of tumor tissues using AOC, which showed that tumor tissues had the brightest fluorescence intensity relative to normal organ tissues. These experimental results further suggest that the NIR fluorescent probe may have tumor diagnostic properties with great potential for application.

Optimization of excitation and emission wavelengths for the UHPLC fluorescence detector for priority polycyclic aromatic hydrocarbons (PAHs)

AbstractPolycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants (POPs) that are widely distributed in the environment and cause significant environmental damage. Furthermore, they endanger human health by polluting food from the natural environment and food processing. Therefore, it is necessary to accurately detect PAHs in various sample matrices, which requires precise, practical, and rapid detection methods. The purpose of this research is to develop a high sensitivity analysis method by analyzing the optimum excitation and emission wavelengths of EPA's 15 priority polyaromatic hydrocarbons in the UHPLC fluorescence detector (Acenaphthene, Anthracene, Benzo[a]anthracene, Benzo[b]fluoranthene, Benzo[k]fluoranthene, Benzo[ghi]perylene, Benzo[a]pyrene, Chrysene, Dibenzo[a,h]anthracene, Fluoranthene, Fluorene, Indeno[1,2,3-cd]pyrene, Naphthalene, Phenanthrene, and Pyrene). An average of 17–25 analyses were performed for each polyaromatic hydrocarbon, and optimized excitation and emission wavelengths were obtained. LOD levels between 2 and 90 ppt were obtained with the method created in this direction. It is worth mentioning that the limits achieved for some PAH parameters are lower than those reported in the literature after pre-concentration steps.

Rapid Investigation of Oil Pollution in Water-Combined Induced Fluorescence and Random Sample Consensus Algorithm

The global issue of oil spreading in water poses a significant environmental challenge, emphasizing the critical need for the accurate determination and monitoring of oil content in aquatic environments to ensure sustainable development of the environment. However, the complexity arises from challenges such as oil dispersion, clustering, and non-uniform distribution, making it difficult to obtain real-time oil concentration data. This paper introduces a sophisticated system for acquiring induced fluorescence spectra specifically designed for the quantitative analysis of oil pollutants. The paper involved measuring the fluorescence spectra across 20 concentration gradients (ranging from 0 to 1000 mg/L) for four distinct oil samples: 92# Gasoline, Mobil Motor Oil 20w-40, Shell 10w-40 engine oil, and Soybean Oil. The research focused on establishing a relationship model between relative fluorescence intensity and concentration, determined at the optimal excitation wavelength, utilizing the segmented Random Sample Consensus (RANSAC) algorithm. Evaluation metrics, including standard addition recovery, average recovery, relative error, and average relative error, were employed to assess the accuracy of the proposed model. The experimental findings suggest that the average recovery rates for the four samples ranged between 99.61% and 101.15%, with the average relative errors falling within the range of 2.04% to 3.14%. These results underscore the accuracy and efficacy of the detection methodology presented in this paper. Importantly, this accuracy extends to scenarios involving heavier oil pollution. This paper exhibits exceptional sensitivity, enabling precise detection of diverse oil spills within the concentration range of 0~1000 mg/L in water bodies, offering valuable insights for water quality monitoring and sustainable development of the environment.

Identification of different plastic types and natural materials from terrestrial environments using fluorescence lifetime imaging microscopy

Environmental pollution by plastics is a global issue of increasing concern. However, microplastic analysis in complex environmental matrices, such as soil samples, remains an analytical challenge. Destructive mass-based methods for microplastic analysis do not determine plastics’ shape and size, which are essential parameters for reliable ecological risk assessment. By contrast, nondestructive particle-based methods produce such data but require elaborate, time-consuming sample preparation. Thus, time-efficient and reliable methods for microplastic analysis are needed. The present study explored the potential of frequency-domain fluorescence lifetime imaging microscopy (FD-FLIM) for rapidly and reliably identifying as well as differentiating plastics and natural materials from terrestrial environments. We investigated the fluorescence spectra of ten natural materials from terrestrial environments, tire wear particles, and eleven different transparent plastic granulates <5 mm to determine the optimal excitation wavelength for identification and differentiation via FD-FLIM under laboratory conditions. Our comparison of different excitation wavelengths showed that 445 nm excitation exhibited the highest fluorescence intensities. 445 nm excitation was also superior for identifying plastic types and distinguishing them from natural materials from terrestrial environments with a high probability using FD-FLIM. We could demonstrate that FD-FLIM analysis has the potential to contribute to a streamlined and time-efficient direct analysis of microplastic contamination. However, further investigations on size-, shape-, color-, and material-type detection limitations are necessary to evaluate if the direct identification of terrestrial environmental samples of relatively low complexity, such as a surface inspection soil, is possible.Graphical

Super Broadband Emission Across NIR‐I and NIR‐II Under Blue Light Excitation of Cr3+, Ni2+ Co‐Doped Sr2GaTaO6 Phosphor Achieved by Two‐Site Occupation and Effective Energy Transfer

AbstractThe performance of the near‐infrared phosphor‐converted light‐emitting diodes (NIR pc‐LEDs) mainly depends on the NIR emitting phosphors used. Cr3+ doped materials can be excited by blue light chips, but their emission is located in the NIR‐I region (650–1000 nm). Ni2+ doped materials are mainly located in the NIR‐II region (1000–1700 nm), but they cannot be effectively excited by blue light chips. Herein, Cr3+, Ni2+ mono‐doped, and co‐doped Sr2GaTaO6 NIR emitting phosphors are prepared and investigated. Cr3+ and Ni2+ ions occupy two octahedral sites of Ga3+ and Ta5+. The co‐doping of Cr3+ ions has achieved two breakthroughs. One is to shift the optimal excitation wavelength from violet light to blue light due to the energy transfer (efficiency up to 70%) from Cr3+ to Ni2+. The other is to achieve the broadband and continuous emission across NIR‐I and NIR‐II regions (650–1700 nm, with a full width at half maximum (FWHM) of 410 nm (173 nm + 237 nm)). The prepared Sr2GaTaO6: 0.02Cr3+, 0.01Ni2+ phosphor is combined with a commercial 460 nm blue chip to realize its application in organic compounds identification, night vision, and biological imaging. This work points out a direction for the future development of efficient super broadband NIR‐emitting phosphors.

Fluorescence spectroscopy detection of carbendazim residue in cucumber juice based on BC

Excessive residues of the carbendazim pesticide in food will cause food safety issues. Particularly, cucumber is one of the common vegetables with carbendazim residues. This study, using fluorescence spectroscopy technology, explored the residues of carbendazim in cucumbers. First, a fluorescence spectrophotometer was used to scan and obtain the three-dimensional fluorescence spectra of carbendazim standard and four carbendazim formulations. Analyzing and comparing their respective fluorescence characteristics, fluorescence peak 1: Ex/Em=245/300–320 nm and fluorescence peak 2: Ex/Em=280/300–320 nm have been identified as the fluorescence characteristic peaks of carbendazim, and the optimal excitation wavelengths Ex=245 nm and Ex=280 nm with carbendazim specificity was screened. Subsequently, two-dimensional fluorescence spectroscopy was performed on the carbendazim and cucumber-carbendazim mixed solutions using the optimal excitation wavelength. In order to obtain more effective two-dimensional spectral data, the original fluorescence spectrum of the cucumber-carbendazim mixed solution was subjected to Blank Correction (BC), significantly reducing the impact of cucumber's own fluorescent characteristics on the carbendazim fluorescent peak in the mixed solution. Polynomial models and linear prediction models were developed based on the concentration of carbendazim and the fluorescence peak intensity values obtained after BC. The detection limit value of carbendazim residues in the cucumber-carbendazim mixed system included the maximum pesticide residue limit specified by national food safety regulations. This research provides valuable data and technical support for efficient detection of pesticide residues in cucumbers.

Resonant Raman scattering on graphene: SERS and gap-mode TERS.

Nanoscale deformations and corrugations occur in graphene-like two-dimensional materials during their incorporation into hybrid structures and real devices, such as sensors based on surface-enhanced Raman scattering (SERS-based sensors). The structural features mentioned above are known to affect the electronic properties of graphene, thus highly sensitive and high-resolution techniques are required to reveal and characterize arising local defects, mechanical deformations, and phase transformations. In this study, we demonstrate that gap-mode tip-enhanced Raman Scattering (gm-TERS), which offers the benefits of structural and chemical analytical methods, allows variations in the structure and mechanical state of a two-dimensional material to be probed with nanoscale spatial resolution. In this work, we demonstrate locally enhanced gm-TERS on a monolayer graphene film placed on a plasmonic substrate with specific diameter gold nanodisks. SERS measurements are employed to determine the optimal disk diameter and excitation wavelength for further realization of gm-TERS. A significant local plasmonic enhancement of the main vibrational modes in graphene by a factor of 100 and a high spatial resolution of 10 nm are achieved in the gm-TERS experiment, making gm-TERS chemical mapping possible. By analyzing the gm-TERS spectra of the graphene film in the local area of a nanodisk, the local tensile mechanical strain in graphene was detected, resulting in a split of the G mode into two components, G+ and G-. Using the frequency split in the positions of G+ and G- modes in the TERS spectra, the stress was estimated to be up to 1.5%. The results demonstrate that gap-mode TERS mapping allows rapid and precise characterization of local structural defects in two-dimensional materials on the nanoscale.

SERS behaviors of multi-shape silver nanoparticles on Si substrate – An insight from both experimental and theoretical approaches

In this study, three types of silver nanostructures, including multi-shaped silver nanoparticles (MAgNPs), silver nanospheres (AgNSs), and triangular silver nanoparticles (TAgNPs), are developed, and their functions for surface-enhanced Raman scattering (SERS) application are investigated using both experimental and theoretical approaches. Particularly, the effects of Ag morphologies, excitation wavelength, and inter-particle gap on their SERS performance are focused. Simulation results show that MAgNPs possess a local-electric-field enhancement factor more than AgNSs (ca. 124 folds) and an electric field wider than TAgNPs. Materials characterization results show that the optimal excitation wavelengths of MAgNPs and AgNSs are in the range of 560–590 nm. Thus, employing the Raman laser source (532 nm) is highly suitable for exciting the SERS effects of Ag nanostructures in this study. For demonstrations, the MAgNPs-based SERS substrates are prepared by coating MAgNPs suspension on Si substrates. These substrates demonstrate high sensitivity to Rhodamine B (LOD of 10−13 M) with consistent reproducibility, robust durability, commendable selectivity, and impressive reusability. The results indicate that the experimental outcomes align with the theoretical simulations. These attributes collectively make the MAgNPs-based substrate a promising candidate for practical applications in Raman techniques.

Green fluorescent carbon dots for sensing of quercetin and pH and cell imaging

AbstractGreen fluorescent carbon dots (G‐CDs) were fabricated from Coptis chinensis directly via one‐step hydrothermal treatment for the determination of quercetin (QCT) and pH sensing. The obtained G‐CDs have low cytotoxicity, good photostability and excellent water solubility. The optimal excitation wavelength and emission wavelength were 480 and 530 nm. A remarkable emission reduction displayed when QCT was added to the G‐CDs and the linear detection range is 0–200 μM, the limit of detection is 4.41 nM. The proposed method was applied to the determination of QCT in Haerbin beer products with satisfactory successful recovery. Furthermore, the G‐CDs exhibited sensitive changes to pH and two fluorescent pH sensors in the linear ranges of 2.0–6.0 and 6.0–11.0 were constructed based on this. They also provide a feasible method to measure the pH value of real water samples. Importantly, the fluorescent sensor has been extended to detect QCT in yeast cell, demonstrating the G‐CDs present potential biosensing application prospect.

Multiple PAHs’ Detection under CDOM Interference Based on Excitation-Emission Matrix and Interval Selection

Fluorescence technology is an effective tool for detecting polycyclic aromatic hydrocarbons (PAHs) in water. However, the accuracy of fluorescence detection is reduced by the spectral overlap of different PAHs and coexisting colored dissolved organic matter (CDOM). In this study, a single-excitation interval selection method based on an excitation-emission matrix is proposed to quantify four PAHs: fluorene, pyrene, phenanthrene, and benzo(a)pyrene under CDOM interference. The optimal excitation wavelength for each PAH was obtained by stability analysis, based on which the optimal emission interval was obtained by chaotic particle swarm optimization. The partial least squares (PLS) prediction models of four PAHs under interference were established. On comparing with other modeling methods, the results show that the models with interval selection have better prediction accuracy (mean relative error &lt; 10%) under CDOM interference. The recovery rate and limit of detection of the method were also evaluated. This study provides a new and helpful strategy for fluorescence detection of interfering PAHs in water.

Synthesis and photoluminescence properties of single-phase Sr3B14O24:RE3+ (RE = Ce, Tb, Sm, Eu) phosphors and glass for WLEDs, UV and NIR shielding

Commercial white light-emitting diodes (WLEDs) usually face problems such as lack of red emission, color difference caused by different degradation rates of multiphase phosphors and the poor thermal stability of the organic encapsulants. The development of new single-phase phosphors and glass can solve these problems well. Sr3B14O24:RE3+ (RE = Ce, Tb, Sm, Eu) phosphors and glass were synthesized by solid-phase method. The obtained Sr3B14O24:RE3+ (RE = Ce, Tb, Sm, Eu) samples showed multicolor emission including blue, green, orange and red, respectively. The optimal excitation wavelength of these samples was located in the blue or ultraviolet (UV) light regions, which were well matched with the blue-violet light chips to manufacture WLEDs. More interestingly, UV absorption was found in Sr3B14O24:Ce3+/4+ glass samples. The doping of dual-valence cerium ions could enhance the shielding performance in the light of inferences drawn from the UV-Vis absorption and transmission spectra of glass samples. By co-doping different concentrations of Cs+ ions in Sr3B14O24:Ce3+/4+ glass samples, the function of near infrared (NIR) shielding was also realized. As a new optical multifunctional material, rare earth doped Sr3B14O24 have great potential for application in WLEDs, UV and NIR shielding.

A fluorescent probe based on carbon quantum dots with spectral selectivity for sensitive detection of Cr(VI) and Hg(II) in environmental waters

In this paper, fluorescent carbon dots were prepared by hydrothermal method using 3,5-dihydroxybenzoic acid and l-Arginine as precursors. The synthesized CDs have excitation-dependent emission with emission peaks at 354 nm and 460 nm, corresponding to the optimal excitation wavelengths of 295 nm and 330 nm, respectively. CDs have good dispersion and resistance to photobleaching in aqueous solution, and can maintain stable fluorescence in highly concentrated salt environment. Based on the inner filter effect, Cr(VI) with strong absorption can shield the excitation light of CDs at 295 nm and absorb the emission fluorescence at 354 nm simultaneously. Due to the intermolecular electrostatic interaction, Hg(II) can coordinate with CDs surface groups and cause static quenching, which significantly reduces the fluorescence intensity of CDs emitted at 460 nm. The linear ranges were 0.1–2 μM and 0.4–5 μM for Cr(VI) and Hg(II) detection, respectively, and limits of detection were 0.024 μM and 0.084 μM. Additionally, the probe was successfully applied to tap water and lake water samples. With high sensitivity and spectral selectivity, this sensing strategy realized the detection of two heavy metal ions by a single fluorescent probe, demonstrating its great potential in the field of environmental metal analysis.