Serendipity in solution–GQDs zeolitic imidazole frameworks nanocomposites for highly sensitive detection of sulfide ions

다국어 초록 (Multilingual Abstract)

<P><B>Abstract</B></P> <P>An innovative and facile sensing approach for common inorganic anions present in aqueous media has been developed using nanocomposites of europium doped graphene quantum dots (GQDs:Eu) with zeolitic imidazole frameworks (ZIF-8). GQDs:Eu, prepared initially by solvothermal approach (at <10nm in diameter), exhibited a strong and intense blue emission at 430nm when dispersed in ethanol. ZIF-8 nanocubes, synthesized on a parallel basis, were in a fairly uniform size distribution (e.g., 185nm in diameter). The formation of nanocomposites by surface adsorption (between GQDs:Eu and ZIF-8) led to significant increase in fluorescence intensity as observed through photo-luminescence spectroscopy. Their interactions with anions (e.g., in terms of variations in the fluorescence intensity) were initially checked against sulfide and other anionic species (e.g., Br<SUP>−</SUP>, Cl<SUP>−</SUP>, F<SUP>−</SUP>, and NO<SUB>3</SUB> <SUP>−</SUP>). Among the tested ions, GQDs:Eu-ZIF-8 were found to effectively and sensitively detect sulfide (S<SUP>2−</SUP>) with significantly high turn on fluorescence. The feasibility of this nanosensing system was explored further toward the detection of S<SUP>2−</SUP> ions. These nanocomposites were thus demonstrated to be feasible for solution-based sensing of S<SUP>2−</SUP> ions with high reproducibility and sensitivity at limit of detection (LOD) of 0.12ppm.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An innovative approach for detection of pollutant sulfide ions is proposed. </LI> <LI> The method is built based upon turn on fluorescence intensity of GQDs:Eu in the matrix structure of Zeolitic Imidazole Framework Nanoparticles. </LI> <LI> Among the tested ions (e.g. S<SUP>2−</SUP>, Br<SUP>−</SUP>, Cl<SUP>−</SUP>, F<SUP>−</SUP>, and NO<SUB>3</SUB> <SUP>−</SUP>), the nanocomposites sensitively detect sulfide (S<SUP>2−</SUP>) with significantly high turn on fluorescence. </LI> <LI> This nanocomposite-based sensing method exhibit high reproducibility and sensitivity at limit of detection (LOD) of 0.12ppm. </LI> <LI> This approach can be extended further to the detection of sulfide ions from environmental samples. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>An innovative and facile sensing approach for solution-based sensing of sulfide (S<SUP>2−</SUP>) anions using nanocomposites of europium doped Graphene Quantum Dots (GQDs:Eu) with Zeolitic Imidazole Frameworks (ZIF-8) has been reported. These nanocomposites are thus demonstrated as an efficient platform for solution-based sensing of S<SUP>2−</SUP> ions with high reproducibility and selectivity.</P> <P>[DISPLAY OMISSION]</P>