Enhanced Photoluminescence of Electrodeposited Europium Complex on Bare and Terpyridine-Functionalized Porous Si Surfaces

Abstract

The trivalent Eu(III) ion exhibits unique red luminescence and plays an significant role in the display industry. Herein, the amperometry electrodeposition method was employed to electrodeposit Eu(III) materials on porous Si and terpyridine-functionalized Si surfaces. The electrodeposited materials were fully characterized by scanning electron microscopy, X-ray diffraction crystallography, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Photoluminescence (PL) spectroscopy revealed that PL signals were substantially increased upon deposition on porous Si surfaces. PL signals were mainly due to direct excitation and charge-transfer-indirect excitations before and after thermal annealing, respectively. The as-electrodeposited materials were of a Eu(III) complex consisting of OH, H2O, NO3−, and CO32− groups. The complex was transformed to Eu2O3 upon thermal annealing at 700 °C. The electrodeposition on porous surfaces provide invaluable information on the fabrication of thin films for displays, as well as photoelectrodes for catalyst applications.

Electrochemistry, Electrodeposition, and Photoluminescence of Eu (III)/Lanthanides (III) on Terpyridine-Functionalized Ti Nanospikes

“…Other CV profiles (Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, Tm, and Yb mixed Eu ions) showed the curvature between −1.4 V and −1.2 V. The peak position (±0.01 V) was determined by the intersection point of the two crossing lines as depicted in the corresponding CV profile in Figure 1. Joo et al also observed similar CV profiles for Ln (III) ions on carbon, Ni, and porous Si electrodes [21][22][23]. There was a weak inclination that the CV peak became slightly shifted to a positive direction, as shown in Figure 1n.…”

“…57) to Yb (No. 70) [21][22][23]. For Eu (III) ions, the CV peak position was observed to be around −0.9 V, about −0.3 V lower than other Ln (III) ions.…”

“…S1 and Figure S2, respectively. In a blank 0.1 M NaClO 4 electrolyte, the CV profile (dotted gray line) between +0.5 V and −1.8 V (vs. Ag/AgCl) showed no meaningful redox peaks, except a sharp current increase (starting from −0.8 V during the negative-going scan) due to the hydrogen evolution reaction [21][22][23]. Upon addition of Ln (III) ions, the CV profile became meaningfully changed and a new curvature appeared between −0.9 V and −1.5 V. In 5 mM Eu (III) + 5 mM La (III)/0.1 M NaClO 4 electrolyte (Figure 1a), a curvature (or a CV peak) appeared around −1.25 V (vs. Ag/AgCl).…”

“…The Ln elements have very unique and similar physicochemical properties because of electronic configurations in 4f-block in the periodic table. To achieve better roles of Ln elements, the studies on Ln elements include Ln coordination chemistry, electrochemical Ln redox reactions, luminescent materials, and selective recovery (for recycling of precious elements) by electrodeposition [11][12][13][14][15][16][17][18][19][20][21][22][23]. Bejan et al synthesized three-dimensional Ln-organic frameworks of [LnL (H 2 O) 2 ] n •DMF•yH 2 O with a surface area of about 400 m 2 /g by the solvothermal method and demonstrated as a catalyst in acylation reaction of 2-naphthol with acetic anhydride [11].…”

“…They also applied the spheres to in vitro cell imaging. Joo et al have demonstrated electrodeposition of Ln elements on diverse electrodes such as carbon, Ni, and porous Si, and showed that Ln elements were successfully recovered on the electrodes [21][22][23].…”