Electrochemical route to the preparation of highly dispersed composites of ZnO/carbon nanotubes with significantly enhanced electrochemiluminescence from ZnO

Abstract

ZnO nanostructures were electrochemically deposited on the surfaces of carbon nanotubes (CNTs) supported on a Zn foil cathode, leading to the facile formation of ZnO/CNT composites with uniform mixing, high dispersion and high-quality interfaces. The electrochemical deposition method circumvents the need for bridging molecules to bring together the two phases and has the key advantage of controllability. By increasing the deposition time, the individual CNTs were first fully covered with ZnO and then the morphology of the deposited ZnO nanostructures was gradually changed from spherical nanoparticles to lily-like nanoflowers. The lily-like structures of ZnO/CNT nanocomposites showed enhanced electrochemiluminescence (ECL). Significantly, the ECL intensity of the lily-like structure of ZnO/CNT nanocomposites was almost an order of magnitude larger than that of pure ZnO nanoflowers, and the ECL starting voltage shifts positively from À1.06 to À0.41 V. These have been attributed to the presence of CNTs which decrease the barriers of ZnO reduction during the ECL process and the special structure of ZnO on the surface of CNTs as well. This work has demonstrated a new strategy to directly coat CNTs with oxides, probably many other inorganic materials, with tunable coverage and nanostructure. Furthermore, the significantly enhanced ECL of ZnO by interfacing with the CNTs highlights the importance and potential utility of such nanostructuring in the development of optoelectronic and biomedical devices.

Highly efficient luminescence from hybrid structures of ZnO/multi-walled carbon nanotubes for high performance display applications

“…Figure 4(a) shows the broad green emission peaking at 510 nm (with colour coordinate, x = 0.2225, y = 0.4004) and the inset of figure 4(b) shows the excitation spectra of ZnO/MWCNTs at 376 nm which is slightly shifted from the band edge of ZnO 380 nm (3.26 eV). The mechanism of the defect related electron-hole recombination process in ZnO has been intensively investigated, yet it remains a controversial subject [5]. Among the different mechanisms proposed to explain the visible luminescence, oxygen vacancies have been widely considered as the most probable candidate [8][9][10][11].…”

“…At nanoscale, hybridization of ZnO with other materials alters the properties of both components which may give rise to functional materials with desirable properties. Few studies have been carried out in this direction in order to achieve the desired optical and electronic properties [5]. The co-operative structural and electronic interaction between ZnO and multi- 3 Author to whom any correspondence should be addressed.…”

Quantum Dots in Bioanalysis: A Review of Applications across Various Platforms for Fluorescence Spectroscopy and Imaging

“…The incorporation with other nanomaterials (e.g., carbon nanotubes, nanoflowers, graphene oxide, gold nanoparticles) is often observed to enhance ECL intensi- ties. [158][159][160][161] The origin of ECL from QDs is strongly sensitive to surface chemistry and surface states. For example, in initial reports, ECL from CdSe QDs was observed from band gap states, 162 whereas ECL from CdSe/ZnS QDs corresponded to band-edge emission.…”

High Electron Transfer Efficiency of Titania Dioxide Nanotube for Low Potential Electrochemiluminescent Biosensing

“…However, the overwhelming used QDs ECL emitters were focused on II-VI QDs, which were of great biotoxicity and suffered instability during storage even at 4 8C. Recently, many nanostructures with low biotoxicity such as Au 25 [5] and Ag [6] nanoclusters, C-dots [7], and ZnO [8] and TiO 2 nanoparticles (NPs) [9] have shown excellent ECL emission and been used as ECL emitters. However, most of these nano-ECL emitters show relatively high emission potential and need strong oxidant S 2 O 8 2À as coreactant to produce ECL signal, which greatly increase the occurrence of undesired reaction and are adverse for both bioanalysis and fabrication of energy devices.…”