InP quantum dots (QDs) with low toxicity
are an ideal alternative
to Cd-based QDs. However, the optical properties and stability of
blue-emitting InP QDs are far inferior to those of red and green QDs.
In this work, we report the synthesis of highly fluorescent InP/GaP/ZnS
core/shell/shell QDs with an emission wavelength of 484 nm and photoluminescence
quantum yield of 71%, along with a full width at half-maximum as narrow
as 45 nm. In addition, we encapsulated the QDs with siloxane via specific
ligand exchange and condensation reactions to improve their stability.
The corresponding siloxane capping QD light-emitting device (QLED)
shows a maximum luminance of 690 Cd m–2, an external
quantum efficiency of 0.09%, and a much longer lifetime than pristine
QDs. As a result, these enable the siloxane capping QDs to achieve
a much stronger storage stability and a longer QLED lifetime than
pristine QDs.
Mastery over the structure of nanocrystals is a powerful tool for the control of their fluorescence properties and to broaden the range of their applications. In this work, the crystalline structure of CdSe can be tuned by the precursor concentration and the dosage of tributyl phosphine, which is verified by XRD, photoluminescence and UV-vis spectra, TEM observations, and time-correlated single photon counting (TCSPC) technology. Using a TBP-assisted thermal-cycling technique coupled with the single precursor method, core–shell QDs with different shell thicknesses were then prepared. The addition of TBP improves the isotropic growth of the shell, resulting in a high QY value, up to 91.4%, and a single-channel decay characteristic of CdSe/ZnS quantum dots. This work not only provides a facile synthesis route to precisely control the core–shell structures and fluorescence properties of CdSe nanocrystals but also builds a link between ligand chemistry and crystal growth theory.
The transformations of physicochemical properties on manganese oxides during peroxymonosulfate (PMS) activation are vital factors to be concerned. In this work, Mn3O4 nanospheres homogeneously loaded on nickel foam are prepared, and the catalytic performance for PMS activation is evaluated by degrading a target pollutant, Acid Orange 7, in aqueous solution. The factors including catalyst loading, nickel foam substrate, and degradation conditions have been investigated. Additionally, the transformations of crystal structure, surface chemistry, and morphology on the catalyst have been explored. The results show that sufficient catalyst loading and the support of nickel foam play significant roles in the catalytic reactivity. A phase transition from spinel Mn3O4 to layered birnessite, accompanied by a morphological change from nanospheres to laminae, is clarified during the PMS activation. The electrochemical analysis reveals that more favorable electronic transfer and ionic diffusion occur after the phase transition so as to enhance catalytic performance. The generated SO4•− and •OH radicals through redox reactions of Mn are demonstrated to account for the pollutant degradation. This work will provide new understandings of PMS activation by manganese oxides with high catalytic activity and reusability.
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