Colloidal Cu2−x(SySe1−y) alloy nanocrystals with controllable crystal phase: synthesis, plasmonic properties, cation exchange and electrochemical lithiation

Abstract

Cubic and hexagonal phase Cu 2-x (S y Se 1-y ) alloy nanocrystals, with a well-defi ned near-infrared valence band plasmon resonance, were transformed in the corresponding Cd-based alloy nanocrystals, with the comparable S y Se 1-y stoichiometry, by cation exchange preserving the original crystal structure. Cubic Cu 2-x (S 0.5 Se 0.5 ) nanocrystals were then evaluated as anode material in Li-ion batteries. As featured in:See E. Dilena et al., J. Mater. Chem., 2012, 22 We report synthetic routes to both cubic and hexagonal phase Cu 2Àx (S y Se 1Ày ) alloy nanocrystals exhibiting a well-defined near-infrared valence band plasmon resonance, the spectral position of which is dependent mainly on x, i.e. on Cu stoichiometry, and to a lesser extent on the crystal phase of the NCs. For cubic Cu 2Àx (S y Se 1Ày ) nanocrystals y could be varied in the 0.4-0.6 range, while for hexagonal nanocrystals y could be varied in the 0.3-0.7 range. Furthermore, the Cu 2Àx (S y Se 1Ày ) nanocrystals could be transformed into the corresponding Cd-based alloy nanocrystals with comparable S y Se 1Ày stoichiometry, by cation exchange. The crystal phase of the resulting Cd(S y Se 1Ày ) nanocrystals was either cubic or hexagonal, depending on the phase of the starting nanocrystals. One sample of cubic Cu 2Àx (S y Se 1Ày ) nanocrystals, with S 0.5 Se 0.5 chalcogenide stoichiometry, was then evaluated as the anode material in Li-ion batteries. The nanocrystals were capable of undergoing lithiation/delithiation via a displacement/conversion reaction (Cu to Li and vice versa) in a partially reversible manner.

Dispersible Plasmonic Doped Metal Oxide Nanocrystal Sensors that Optically Track Redox Reactions in Aqueous Media with Single‐Electron Sensitivity

“…To that end, our results are complementary to recent work by Gamelin and Mayer to advance the understanding of lightdriven redox chemistry of ZnO nanocrystals in organic media as it relates to their infrared plasmonic properties, [20][21][22][23][24][25][26] as well as work by Manna and Tassone, [27][28][29][30][31][32] Talapin and Feldmann, [ 33 ] and Jain and Alivisatos [ 34 ] investigating chemically induced NIR plasmon shifts in substrate-bound Cu 2− x E nanostructures, where E = S, Se, or Te. Our use here of plasmonic-doped metal oxides is expected to overcome the experimental challenges in using noble metal NCs to detect optically one or a few redox events per nanocrystal, owing to the signifi cantly higher carrier concentrations typifi ed by Au and Ag nanostructures.…”

Morphology‐Dependent Electrochemical Properties of CuS Hierarchical Superstructures

“…Also, the relative extent of the formation of soluble discharged products (such as polysulfides) with both morphologies can affect their electrochemical activities in terms of voltage plateaus. We then performed electrochemical impedance spectroscopy (EIS) measurements to probe the CuS electrode/electrolyte interface; this can reveal information concerning charge‐transfer resistance for Li ions and various electrochemical processes contributing to the total impedance of electrodes . Figure reports the EIS data (in the range of 100 kHz–10 mHz with an AC amplitude of 10 mV s −1 ) recorded on cells after the first twenty charge/discharge cycles.…”

Analytical modeling of localized surface plasmon resonance in heterostructure copper sulfide nanocrystals

“…The use of cation exchange to modify the optical properties of metal chalcogenides nanocrystals remains a novel field of inquiry. Dilena et al 29 investigated the plasmonic properties of Cu 2−x (S y Se 1−y ) nanocrystals converted to Cd(S y Se 1−y ) upon reacting with Cd ions; however, heterostructure formation was not reported. Huang et al 30 studied the plasmonic absorbance spectra of Cu 1.94 S-ZnS "sandwich-like" heterostructure nanocrystals.…”