Aqueous synthesis of Ag⁺doped CdS quantum dots and its application in H₂O₂sensing

Abstract

A novel detection system based on the fluorescence quenching of CdS-Ag 2 S quantum dots (QDs) was designed for the direct measurement of hydrogen peroxide (H 2 O 2 ). Experimental results showed that an excellent response to the concentrations of H 2 O 2 was found within the range from 1.0 Â 10 À6 to 1.0 Â 10 À2 M with a detection limit of 3.0 Â 10 À7 M. The CdS-Ag 2 S QDs have been synthesized at room temperature in an aqueous solution using thioglycollic acid as stabilizing agents, which were spectratunable and water-soluble. Different influencing factors including pH, variable ratio of [Cd 2+ ]/[S 2À ], dopant concentration, precursor concentration, and aging time of CdS-Ag 2 S QDs were studied. It was found that the emission colors of the prepared CdS-Ag 2 S QDs could be readily tuned from green to red by varying pH. Furthermore, the CdS-Ag 2 S QDs were characterized by fluorescence and time-resolved emission spectroscopy, TEM, EDX, XRD, XPS, ESR. The long decay times, large surface area, and good chemical stability of the CdS-Ag 2 S QDs have made this material suitable as a fluorescence probe.

Recent advances in electrochemiluminescence

“…In addition to changing the ligand structure, 38, 39 the emission colors of ECL systems can also be tuned by changing coreactant molecule, 40 pH of the solution, 41 and frequency of applied current, 42 or energy transfer processes. 43 ), while simultaneous ECL from the two complexes was observed at high potentials (1.30 V vs. Fc 0/+ ), allowing the overall emission color to be tuned from red to yellow-green.…”

“…In addition to changing the ligand structure, 38,39 the emission colors of ECL systems can also be tuned by changing the coreactant molecule, 40 pH of the solution, 41 and frequency of the applied current, 42 or energy transfer processes. 43 Recently, a new strategy for color tunable ECL was developed by adjusting potential to tune the color of the ECL emission from a binary mixture of a red light-emitting luminophore [Ru(bpy) 2 (L)] 2+ and a green light-emitting luminophore [Ir(df-ppy) 2 (BPS)] À .…”

A single source-precursor route for the one-pot synthesis of highly luminescent CdS quantum dots as ultra-sensitive and selective photoluminescence sensor for Co2+and Ni2+ions

“…30 Nowadays, functionalized QDs have generated incredible interest in the sensing applications owing to their high photoluminescence (PL) quantum yield, broad absorbance spectra, and narrow size-tunable emission from visible to infrared wavelengths and high photochemical stability. 32 CdS QD-based sensing of several ions [33][34][35][36] and biomolecules [37][38][39] has been reported to date. Among these ions, selective detection of cobalt (Co 2+ ) and nickel (Ni 2+ ) ions is important, as these heavy metals rapidly diffuse in both the environment and living systems.…”

Oriented attachment of nanoparticles to form micrometer-sized nanosheets/nanobelts by topotactic reaction on rigid/flexible substrates with improved electronic properties

“…As shown in Figures 5d and e, the observed binding energy values of Cd 3d and S 2p are in agreement with the reported data on CdS Qds. [34][35][36] Furthermore, their invariant features and positions during the sputtering process confirm that the Cd and S elements maintain an unchanged chemical state from the surface into the film. In particular, as shown in Figure 5f, during depth profiling, the Ag residue is uniform throughout the film with a ratio of~1.5%.…”

“…The fitting results of the Ag 3d5/2 and Ag 3d3/2 peaks also confirm that the Ag residue exists as a Ag + dopant instead of Ag 0 . 36 From the EDS elemental mapping and line scan analysis of one single CdS nanosheet (Figures 5g and h), the Ag residue distributes uniformly across the nanosheet with a ratio of 2%. In other words, through this topotactic reaction process, the Ag residue acts as an efficient dopant throughout the as-prepared CdX nanosheets.…”