Excitonic Chemiluminescence in Si and CdSe Nanocrystals Induced by their Interaction with Ozone

Abstract

The results of a systematic study of spectral and kinetic patterns of ozone-adsorption-induced luminescence (AL) in nanostructured Si and, for the first time, in colloidal CdSe/ZnS quantum dots (QDs) are reported and compared with photoluminescence (PL) of the same structures. The common excitonic nature of light emission under ozone chemisorption and photoexcitation is confirmed by excellent coincidence of AL and PL emission bands. This coincidence is maintained during correlated quenching of AL and PL emission caused by nonradiative defects generated under ozone adsorption. A possible mechanism for energy conversion is proposed in the framework of an exothermic oxidation reaction of core materials caused by ozone. The significant role of the quantum confinement effect differentiates the observed phenomenon from well-known chemiluminescence in molecular systems. This research establishes a physicochemical basis for the development of a gas sensor with high selectivity to ozone. Also, our findings may be useful for testing core-shell colloidal QDs with ozone.

The Adsorption of Ozone on the Solid Catalyst Surface and the Catalytic Reaction Mechanism for Organic Components

“…For porous silicon, the adsorption of ozone had two stages: [13c,d] In the first stage, ozone adsorbed on the surface and formed O 3 −Si−H, whose IR peak was at 2250 cm −1 , and then the adsorbed ozone decomposed to oxygen (2190 cm −1 ) and an oxygen atom in the excited state. In the second stage, the oxygen atom in the excited state reacted with a nearby Si−Si bond and formed the siloxane bridge Si−O−Si [13c,d] …”

Advances in chemiluminescence and electrogenerated chemiluminescence based on silicon nanomaterials

“…In the pSi solid–gas system, ozone (O 3 )‐induced CL in nanostructured pSi was reported; initial oxidation took place mostly at the Si–H bond on the pSi surface. [ 83 ] Monotonous decay of CL intensity with O 3 exposure time was found and could be used to detect ozone. Furthermore, pSi‐based platforms containing other ECL reagents have also been developed in which pSi was used as a support due to its large surface area, not as a CL emitter.…”

Development of Technologies for Sensing Ozone in Ambient Air

“…As contrasted with those QD-based sensor studies, only a small number of reports have appeared regarding PL-based gas sensing in the atmosphere by using QDs (oxygen, 74,77 ozone 57,88 and gaseous alkylamines 89,90 ). When specific gas molecules adsorb onto the inorganic surface of QDs through the thin layer of surfactant molecules, the gas molecule will react with the electrons located at the inorganic surface of the QDs, and the number of electrons for radiative recombination to emit PL will change.…”

“…These surface reactions are expected to bring about a change in the PL intensity and/or wavelength. Since there have been a small number of reports 74,77,88,89 on the gas-sensitive change in PL of QDs before our study, we started our research by designing an experimental setup for measuring the PL-based ozone gas sensing, based on the property of QDs. Figure 1 shows the gas flow system in our experimental setup.…”

“…Before our study, a Russian research group reported an ozonesensitive change in the PL intensity of CdSe-based QDs deposited on a cellulose acetate membrane filter. 88 The atmosphere was periodically changed between vacuum and air containing 1 ppm ozone. In their experimental results, the PL intensity decreased with exposure to ozone.…”