MnO₂ Nanosheets/N,S Co-Doped Carbon Nanoparticles Sensing Platform for Sensitive Detection of Hydroxylamine

Carbon nanoparticles (CNPs) integrated with nanomaterial-based quenchers have emerged as an innovative platform for developing advanced sensing systems. In this study, we developed a novel fluorescent sensing platform for the highly sensitive detection of hydroxylamine (HA). Through a one-step hydrothermal synthesis approach, nitrogen and sulfur co-doped carbon nanoparticles (N,S-CNPs) were successfully prepared using dimethylamine hydrochloride and dimethyl sulfoxide (DMSO) as precursors. The synthesized N,S-CNPs demonstrated exceptional fluorescence properties, achieving a remarkably high quantum yield of 50%, along with outstanding water solubility, photostability, and chemical stability. The fluorescence emission of N,S-CNPs could be effectively quenched by manganese dioxide (MnO₂) nanosheets through a combined mechanism of inner filter effect (IFE) and static quenching effect (SQE). Notably, HA induced the redox-mediated decomposition of MnO₂ nanosheets, converting MnO₂ to Mn²⁺ ions and consequently restoring the fluorescence of N,S-CNPs (turn-on response). Under optimized conditions, the proposed sensor exhibited a wide linear detection range (0.1-200 μM) with an ultra-low detection limit of 0.04 μM. The sensor demonstrated excellent analytical performance in real-world applications, successfully detecting HA in lake and river water samples with high accuracy and reliability. These findings highlight the great potential of this fluorescent sensing platform for environmental monitoring and water quality assessment.