Encapsulation of Zinc Oxide Nanorods and Nanoparticles

Abstract

A simple method for encapsulating zinc oxide nanoparticles within an organic matrix is described that consists of dispersing them in an ethanolic solution, adding an organothiol, and stirring while heating. Electron microscopy, photoemission, Raman spectroscopy, and thermal gravimetric analyses demonstrate that partial dissolution of the oxide occurs, accompanied by encapsulation within a matrix consisting of a 1:2 zinc/thiol complex. Using this methodology, it is possible to surround ZnO within diverse matrices, including fluorescent ones. The process is demonstrated for 1-dodecanethiol (DDT) and fluorescent 2-naphthalenethiol (NPT). For DDT, ZnO nanorods become surrounded by a layer of the zinc-thiol complex that is greater than 100 A thick. In the case of NPT, significantly greater dissolution of the ZnO occurs, with the encapsulated rods taking on a spherical geometry, as evidenced by electron microscopy.

Ethanedithiol Treatment of Solution‐Processed ZnO Thin Films: Controlling the Intragap States of Electron Transporting Interlayers for Efficient and Stable Inverted Organic Photovoltaics

“…The S 2p peak located at 163.2 eV with a shoulder at 164.3 eV (Figure S2) indicates that EDT molecules were covalently bonded onto the surfaces of ZnO nanocrystals, forming zinc thiolates. [30][31][32] Figure 1c shows the O 1s core level spectra, which can be deconvoluted into two peaks. The lower-binding-energy peak is associated with the oxygen atoms in a ZnO matrix, i.e.…”

“…The more negative oxidation state of the zinc ions is consistent with the formation of Zn-S bonds, which replaces the original Zn-O bonds of the hydroxyl groups or carboxylate groups. [31] A quantitative depth-profile study on the E-ZnO films was carried out (Figure 1e). With the prolonged sputter time, the atomic ratio of sulfur to zinc is kept in the range of 0.25 to 0.29, indicating that EDT treatment effectively modified all the ZnO nanocrystals in the bulk films which are ~85 nm in thickness.…”

Surface Modification of Zinc Oxide Nanorods with Zn-Porphyrin via Metal-Ligand Coordination for Photovoltaic Applications

“…As shown in the S 2p spectrum of the Figure 2(a), a strong peak appeared at 163.1 eV agrees to the Zn-S covalent bond signal in literatures. [16][17][18][19] The existence of PTT on the nanorod surface was also verified with the UV-absorption spectrum (the thick solid line in Figure 2(b)). The strong absorption at 244 nm originates from PTT while the strong absorption peak at 362 nm is characteristic for ZnO nanorods.…”

“…We think that such a slightly roughened surface morphology originates from the dissolution of the Zn-thiol complex during the thiol grafting reaction. The mechanism of this dissolution was recently suggested by Singh et al 16 In brief, hydroxyl groups can be bonded to zinc atoms on the zinc oxide lattice (ZnO-OH) and thiol molecules (RSH) react at the hydroxylated sites, forming a zinc-thiol complex (ZnO-SR) and liberating a water molecule. This complex can readily be dissolved out into solution (Zn-SR+) and the freshly exposed ZnO surface further react with thiol molecules, which should be accelerated upon heating.…”

Chemisorption of a thiol-functionalized ruthenium dye on zinc oxide nanoparticles: Implications for dye-sensitized solar cells

“…Various experiments, including ones in our laboratories, have demonstrated that underivatized alkanethiols chemisorb onto zinc oxide [13][14][15][16][17][18][19][20][21], and quantum mechanical modeling confirms chemisorption [22]. In contrast, however, FTIR measurements on ZnO nanotips indicate an absence of hexanethiol adsorption [23].…”