Biomass-derived carbon quantum dot: “On–off-on” fluorescent sensor for rapid detection of multi-metal ions and green photocatalytic CO2 reduction in water

Raja Sebastian (Lead Author), Gelson T. S. T. da Silva, Anbu Sellamuthu Kooduthurai, Caue Ribeiro, Luiz H. C. Mattoso

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We have developed carbon quantum dots (CQDs) with excellent photoluminescence (PL) properties from macaúba (Acrocomia aculeate) fibers; a widely available cellulosic biomass species of palm trees in South America. As-prepared CQDs showed quasi-spherical morphology with high aqueous solubility and strong excitation-dependent fluorescence behaviour. Interestingly, the CQDs display fluorescence 'turn-off' response with excellent sensitivity toward multi-metal ions including Fe3+, Cu2+ and Hg2+ with very low detection limits of 0.69 μM, 0.99 μM, 0.25 μM, respectively. Notably, ascorbic acid (AA) induced a change in the (turn-off) fluorescence of Fe3+-CQDs, which caused an almost 70% revival of fluorescence (turn-on) by displacing Fe3+ ions. We have also harnessed CQDs as the visible-light-induced photocatalyst to reduce CO2 in water. Especially, the CQDs efficiently promote the photocatalytic reduction of CO2 into methane (CH4) with an evolution rate of 99.8 nmol/g at 436 nm in aqueous conditions. This indicates that the CQDs provide abundant active sites for CO2 adsorption and thus enhance the separation and migration of photo-induced charge carriers that efficiently reduce CO2 into CH4 without any cocatalyst in 100% water.
Original languageEnglish
JournalBiomass Conversion and Biorefinery
Early online date2 May 2023
Publication statusE-pub ahead of print - 2 May 2023


  • Carbon quantum dots
  • Macaúba
  • Metal ion detection
  • On–off-on
  • Photocatalytic CO reduction
  • Visible-light

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