Phosphorous doped carbon quantum dots as an efficient solid state electrochemiluminescence platform for highly sensitive turn-on detection of Cu2+ ions

Developing a unique luminophores especially nanomaterial based quantum dots to enhance the quantum yield of ECL as well as selective sensing of heavy metal ions or biomarkers are really challenging research area in analytical chemistry. Herein, we demonstrate for the time that newly synthesized phosphorous doped carbon quantum dots (P-CQDs) utilized as a solid-state sensing platform for the detection of Cu2+ ion by ECL signal-on strategy using H2O2 as co-reactant. The average size of P-CQDs is 6.4 nm with spherical shape determined by HR-TEM. The FT-IR and XPS results confirm the presence of phosphorous doping in the CQDs. The electrochemical studies clearly revealed that the formation of OH radicals during the electro reduction of H2O2 which react with electrochemically generated P-CQDs anion radicals to produce excited state of P-CQDs and emit the light through reductive oxidation mechanism. The doping of phosphorus in CQDs alters the electronic state levels and produces more emissive sites in CQDs which generates more intense ECL signals than un-doped or pristine CQDs. Interestingly, ECL intensity of P-CQDs-H2O2 system is further enhanced linearly with each addition of Cu2+ ion and the detection limits of Cu2+ ion found to be 0.27 nM. The developed P-CQDs could be a promising luminophore for the fabrication of solid state ECL platform and more sensitive to determine Cu2+ ions. (c) 2019 Elsevier Ltd. All rights reserved.