ZnO nanoparticles sensitized by CuInZn_xS_2+x quantum dots as highly efficient solar light driven photocatalysts

Abstract

Alloyed CuInZnxS2+ x (ZCIS) quantum dots (QDs) were successfully associated to ZnO nanoparticles by a thermal treatment at 400 °C for 15 min. The ZnO/ZCIS composite was characterized by TEM, SEM, XRD, XPS and UV–vis absorption spectroscopy. ZCIS QDs, with an average diameter of ≈4.5 nm, were found to be homogeneously distributed at the surface of ZnO nanoparticles. ZCIS-sensitized ZnO nanoparticles exhibit a high photocatalytic activity under simulated solar light irradiation for the degradation of Orange II dye (>95% degradation after 180 min of irradiation at an intensity of 5 mW/cm2). The heterojunction built between the ZnO nanoparticle and ZCIS QDs not only extends the light adsorption range by the photocatalyst but also acts to decrease electron/hole recombination. Interestingly, the ZnO/ZCIS composite was found to produce increased amounts of H2O2 and singlet oxygen 1O2 compared to ZnO, suggesting that these reactive oxygen species play a key role in the photodegradation mechanism. The activity of the ZnO/ZCIS composite is retained at over 90% of its original value after ten successive photocatalytic runs, indicating its high stability and its potential for practical photocatalytic applications.

Enhanced Photocatalytic Activity toward Organic Pollutants Degradation and Mechanism Insight of Novel CQDs/Bi2O2CO3 Composite

“…Meanwhile, CQDs function as an excellent electron mediator and acceptor in CQDs/Bi 2 O 2 CO 3 to effectively separate e − -h + pairs, and improve degradation efficiency. The function mechanism was similar to that of previous studies [51,52,53]. Figure 5b shows the UV-vis absorption spectra temporal changes for MB solutions in the presence of 50-CQDs/Bi 2 O 2 CO 3 .…”

Growth of ZnO Nanorods on Graphitic Carbon Nitride gCN Sheets for the Preparation of Photocatalysts with High Visible‐Light Activity

“…At pH 5, the adsorption is the highest (C/C 0 =0.74) likely due to the strong association of Orange II with the photocatalyst via H‐bonding. Contrary to most of ZnO photocatalysts which exhibit the highest activity of basic pH, the photocatalytic activity of the ZnO/gCN (10 %) composite is the highest at pH 5 (k=0.038 min −1 ) and the complete bleaching of Orange II under visible light irradiation could be achieved in 300 min. Noteworthy is that no significant dissolution of the photocatalyst is observed at pH 5 as indicated by Inductively Coupled Plasma‐Optical Emission Spectrometry (ICP‐OES) analyses of the aqueous solution.…”

“…3.2 eV and a large exciton binding energy (60 meV at room temperature). ZnO exhibits good photosensitivity, high carrier mobility and is therefore used in numerous photocatalytic applications but also in photodetectors and in solar cells ,. However, the use of ZnO as photocatalyst for practical applications is generally restricted because (1) it can only be activated by UV‐light due to its wide bandgap, (2) photogenerated electron/hole pairs exhibit a short lifetime and (3) its photocorrosion.…”

“…Doping of ZnO with metal,, or non‐metal elements, coupling with metal nanoparticles or with graphene derivatives,, or constructing heterostructures with low bandgap semiconductors, have been demonstrated to be effective strategies to enhance both the charge separation and the visible light photoresponse of ZnO‐based photocatalysts.…”

CdSe nanorod/TiO2 nanoparticle heterojunctions with enhanced solar- and visible-light photocatalytic activity

“…The interfacial electron transfer between two semiconductors has gained significant interest because the heterojunction improves both the optical absorption in the visible range and the charge separation yield and thus the charge carrier lifetime [3–8]. The photocatalytic activity is enhanced because oxidation of water by holes and reduction of oxygen by electrons are retained at two different sites.…”