{"doi":"10.1039/d5ra08448b","title":"DMF-mediated synthesis of N,S-co-doped carbon quantum dots and their fluorescence quenching mechanism toward Hg\n                    <sup>2+</sup>\n                    <i>via</i>\n                    surface complexation","abstract":"Nitrogen and sulfur co-doped carbon quantum dots (N,S-CQDs) were synthesized <i>via</i> a green, one-step hydrothermal method using waste lemon peel as the carbon source and glutathione (GSH) as the N,S dopant in a dimethylformamide (DMF) medium. The reaction was conducted at 180 °C for 10 hours to achieve efficient synthesis. The resulting N,S-CQDs showed excellent water dispersibility, strong photostability, and bright fluorescence, with optimal excitation and emission wavelengths of 340 nm and 420 nm, respectively. High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) confirmed their uniform morphology and successful incorporation of nitrogen and sulfur heteroatoms. Notably, the fluorescence of the N,S-CQDs could be rapidly and selectively quenched by Hg<sup>2+</sup> within 10 minutes at room temperature, without requiring any additional surface modification of the CQDs or auxiliary reagents in the sensing procedure. Under optimized conditions, the sensor exhibited a linear fluorescence quenching response to Hg<sup>2+</sup> over the concentration range of 17.6 nM to 20 µM (<i>R</i> <sup>2</sup> = 0.9899), with a low detection limit of 17.6 nM. Mechanistic studies suggested that the quenching primarily resulted from the formation of nonfluorescent complexes between Hg<sup>2+</sup> and functional groups on the CQD surface. The developed sensor was successfully applied to detect trace levels of Hg<sup>2+</sup> in real lake water samples collected near textile manufacturing sites, demonstrating its potential as a sustainable, rapid, and cost-effective tool for practical environmental mercury monitoring.","journal":"RSC Advances","year":2026,"id":7688,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.0432,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2026-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":69311,"name":"Shancai Guo","orcid":null,"position":1,"is_corresponding":false},{"id":39636,"name":"Teng Wang","orcid":"0000-0002-2850-6711","position":2,"is_corresponding":false},{"id":69312,"name":"Jianyuan Lin","orcid":null,"position":3,"is_corresponding":false},{"id":69313,"name":"Zhijian Jia","orcid":null,"position":4,"is_corresponding":false},{"id":69314,"name":"Fuhang Xu","orcid":null,"position":5,"is_corresponding":false},{"id":69315,"name":"Renyue Huang","orcid":null,"position":6,"is_corresponding":false},{"id":69316,"name":"Haili Wang","orcid":null,"position":7,"is_corresponding":false},{"id":69317,"name":"Chunjie Bai","orcid":null,"position":8,"is_corresponding":false},{"id":2876,"name":"Jianghua Chen","orcid":"0000-0002-3282-3998","position":9,"is_corresponding":false},{"id":30887,"name":"Alexandra P. Lewis","orcid":"0000-0002-6195-4786","position":10,"is_corresponding":false},{"id":69310,"name":"Yongjian Pan","orcid":"0009-0006-4373-7362","position":0,"is_corresponding":true}],"reference_count":46,"raw_metadata":null,"created_at":"2026-03-01T18:20:47.508186Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}