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Updated: Sep 1, 2025
Compact Quantum Dots for Single-molecule Imaging
Published on: October 9, 2012
Investigating the effect of N-doping on carbon quantum dots structure, optical properties and metal ion screening
Kiem Giap Nguyen1, Ioan-Alexandru Baragau1,2, Radka Gromicova3
1London Centre for Energy Engineering (LCEE), School of Engineering, London South Bank University, 103 Borough Road, London, SE1 0AA, UK.
Abstract:
Carbon quantum dots (CQDs) derived from biomass, a suggested green approach for nanomaterial synthesis, often possess poor optical properties and have low photoluminescence quantum yield (PLQY). This study employed an environmentally friendly, cost-effective, continuous hydrothermal flow synthesis (CHFS) process to synthesise efficient nitrogen-doped carbon quantum dots (N-CQDs) from biomass precursors (glucose in the presence of ammonia). The concentrations of ammonia, as nitrogen dopant precursor, were varied to optimise the optical properties of CQDs. Optimised N-CQDs showed significant enhancement in fluorescence emission properties with a PLQY of 9.6% compared to pure glucose derived-CQDs (g-CQDs) without nitrogen doping which have PLQY of less than 1%. With stability over a pH range of pH 2 to pH 11, the N-CQDs showed excellent sensitivity as a nano-sensor for the highly toxic highly-pollutant chromium (VI), where efficient photoluminescence (PL) quenching was observed. The optimised nitrogen-doping process demonstrated effective and efficient tuning of the overall electronic structure of the N-CQDs resulting in enhanced optical properties and performance as a nano-sensor.
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