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Sulfur and Nitrogen Co-Doped Graphene Quantum Dots as a Fluorescent Quenching Probe for Highly Sensitive Detection toward Mercury Ions
摘要： Sulfur and nitrogen co-doped graphene quantum dots (SN-GQDs) were synthesized through an efficient infrared (IR)-assisted pyrolysis of glucose, urea, and ammonia sulfate at 260°C. These served as a highly selective probe for the sensing of Hg2+ ions in an aqueous solution. The IR technique can also prepare N-doped graphene quantum dots (N-GQDs), which have been compared with SN-GQDs for their fluorescence (FL) quenching sensitivities by Hg2+ ions. The FL intensities of both GQDs show decreasing functions of concentration of Hg2+ ions within the entire concentration ranges of 10 ppb?10 ppm. The sensitivity of SN-GQD is 4.23 times higher than that of N-GQD, based on the calculation of the Stern-Volmer equation. One inter-band gap structure of SN-GQDs for the detection of mercury ions is proposed. The S doping can coordinate with phenolic groups on the edge of SN-GQDs (i.e., the formation of (CxO)2Hg2+) and induce the cutting off or alleviation of photon injection paths, thereby leading to significant FL quenching. This work proves that SN-GQD offers sufficient sensitivity for probing the quality of drinking water to ensure that it contains less than 10 ppb of Hg2+ ions, as per the World Health Organization standard.
关键词： Fluorescence quenching,Nitrogen doping,Infrared-assisted heating,Graphene quantum dots,Sulfur doping,Mercury detection
更新于2025-11-19 16:56:42
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Nitrogen-Sulfur-Doped Graphene Quantum Dots with Metal Ion-Resistance for Bioimaging
摘要： The development of ultra-stable and highly fluorescent heteroatoms-doped graphene quantum dots (GQDs) for bioimaging remains a challenge due to the fluorescence quenching caused by binding between the heteroatoms-based functional groups of the GQDs and common metal ions in biological systems. Here, we developed a facile hydrothermal method to prepare nitrogen-sulfur doped GQDs (NS-GQDs). The fluorescence signals of the NS-GQDs are highly stable in the existence of different metal ions. Two natural products, aspartic acid and cysteine, were utilized as the carbon precursors and heteroatomic (nitrogen and sulfur) sources. The produced NS-GQDs showed a quantum yield up to 19.3 ± 1.7 % with a maximum emission of 480 nm under the excitation of 400 nm. The elemental analysis, including X-ray photoelectron spectroscopy (XPS) and energy dispersive spectroscopy (EDS), and Fourier-transform infrared spectroscopy (FTIR), were performed to characterize the composition and surface groups of NS-GQDs. Additionally, the NS-GQDs not only showed notable photostability, but also thermostability and chemical stability. Moreover, the NS-GQDs demonstrated very low cellular cytotoxicity in vitro. Finally, the NS-GQDs were applied for fluorescence imaging of cells, which also exhibited excellent fluorescent stability even with treatment of copper ions. The results indicated that the developed novel NS-GQDs have a promising potential to be used as ultra-stable fluorescent agent in the field of bioimaging and biosensing.
关键词： bioimaging,nitrogen doping,sulfur doping,fluorescence,Graphene quantum dots
更新于2025-09-23 15:19:57
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Enhanced photovoltaic performance of dye-sensitized solar cells based on electrodeposited sulfur-doped MSex (M=Co, Ni) films
摘要： Rational design of ternary transition metal sulfoselenide films by an electrodeposition technique remains a critical challenge to further improve their catalytic activity. This study reports a fabrication approach of sulfur-doped MSex (M ? Co, Ni) films, which are directly employed as efficient counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The morphology and electronic structure of sulfur-doped MSex films are controlled by adjusting the molar ratio of S/Se in their electrodeposition solutions. It is found that sulfur-doped MSex films exhibit favorable electrocatalytic activity for the reduction of I3, owing to their more exposed activity sites and strong charge-transfer capability. Furthermore, the DSSC fabricated with the optimized sulfur-doped CoSex (sulfur-doped NiSex) CE has achieved the highest power conversion efficiency (PCE) of 7.44% (7.54%) than that of the DSSC fabricated with platinum (Pt) CE (6.38%). The results demonstrate that sulfur-doped MSex films have been applied as the attractive low-cost CEs with outstanding electrocatalytic activity for DSSCs.
关键词： Counter electrodes,Activity sites,CoSex,Electrodeposition technique,Sulfur doping,NiSex
更新于2025-09-11 14:15:04
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Sulfur doping of M/In <sub/>2</sub> O <sub/>3</sub> (M=Al,W) nanowires with room temperature near infra red emission
摘要： We have investigated the growth of Al doped In2O3 nanowires via the vapor-liquid-solid mechanism at 800?C using Au as a catalyst. We find that the Al is not incorporated into the cubic bixbyite crystal structure of In2O3 but nevertheless was detected in the form of Al2O3. The nanowires had metallic like conductivities and exhibited photoluminescence at 2.3 eV which shifted to 1.5 eV after exposure to H2S above 500?C due to the formation of β-In2S3 and deep donor to acceptor transitions with a lifetime of ≈ 1 μs. The near infra red emission was also observed in W/In2O3 but not in W/SnO2 core-shell nanowires after processing under H2S at 600?C, confirming it is related to β-In2S3. The nanowires remain one dimensional up to 900?C due to the shell which is interesting for the fabrication of high temperature nanowire sensors.
关键词： β-In2S3,M/In2O3 nanowires,Al doped In2O3,room temperature near infra red emission,Sulfur doping
更新于2025-09-09 09:28:46