Highly fluorescent metal doped carbon quantum dots prepared from hen feather demonstrating pH-dependent dual sensing of 4-nitrophenol and Hg2+ ion
Sohel Das, Uma Sankar Mondal, Subhankar Paul
Abstract
Mg/Zn modified carbon quantum dots (CQD) were synthesized from hen feather for the fluorescence-based pH dependent optical sensing of mercury (Hg 2+ ) and p-Nitrophenol (4-NP). TEM imaging confirmed the size of QDs as ∼ 3.4 nm for Mg doped CQDs (MgCQD) and ∼ 4.09 nm for Zn doped CQDs (ZnCQD). ZnCQD showed the lowest band gap, and highest fluorescence quantum yield (QY) compared to native CQD and MgCQD. MgCQD and ZnCQD demonstrated 70% and 52% fluorescence quenching, respectively, in the presence of 20 ppm of Hg 2+ at pH 7. For 0–20 ppm Hg 2+ concentration range, two linear detection regions were observed by both the QDs. Further, the prepared QDs also showed high selectivity towards 4-NP at pH 2. The detection of 4-NP was highly linear for both MgCQD and ZnCQD. The fluorescence of MgCQD and ZnCQD was found quenched more than 90% in the presence of 20 ppm 4-NP in acidic pH. Therefore, our synthesized metal-doped QDs prepared from hen feather waste demonstrated efficient pH-responsive dual sensing of Hg 2+ and 4-NP and are also very cheap, rapid, and can be used for multifunctional pollutant detection in the aquatic environment.