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

Abstract

CdSe nanorods (NRs) with an average length of ≈120 nm were prepared by a solvothermal process and associated to TiO2 nanoparticles (Aeroxide® P25) by annealing at 300 °C for 1 h. The content of CdSe NRs in CdSe/TiO2 composites was varied from 0.5 to 5 wt %. The CdSe/TiO2 heterostructured materials were characterized by XRD, TEM, SEM, XPS, UV–visible spectroscopy and Raman spectroscopy. TEM images and XRD patterns show that CdSe NRs with wurtzite structure are associated to TiO2 particles. The UV–visible spectra demonstrate that the narrow bandgap of CdSe NRs serves to increase the photoresponse of CdSe/TiO2 composites until ≈725 nm. The CdSe (2 wt %)/TiO2 composite exhibits the highest photocatalytic activity for the degradation of rhodamine B in aqueous solution under simulated sunlight or visible light irradiation. The enhancement in photocatalytic activity likely originates from CdSe sensitization of TiO2 and the heterojunction between these materials which facilitates electron transfer from CdSe to TiO2. Due to its high stability (up to ten reuses without any significant loss in activity), the CdSe/TiO2 heterostructured catalysts show high potential for real water decontamination.

Shape Effect of Zinc-Tin Oxide Nanostructures on Photodegradation of Methylene Blue and Rhodamine B under UV and Visible Light

“…A slight hypsochromic shift of RhB absorption bands can be observed after 4 h of irradiation for all experiments due to the photo-oxidative N-deethylation of RhB. 70 Unlike what was observed for MB, RhB does not show a significant degradation on its own, even after 12 h of exposure, and is in fact similar to the control experiment performed in the dark. In the presence of ZTO nanostructures, the amount of RhB decreased by approximately 40, 50, and 24% after 12 h of exposure, corresponding to degradation rates of 0.0488 ± 0.0042 h −1 (=8.1 × 10 −4 ± 0.7 × 10 −5 min −1 ), 0.0608 ± 0.0018 h −1 (=10.1 × 10 −4 ± 0.3 × 10 −5 min −1 ), and 0.0283 ± 0.0018 h −1 (=4.7 × 10 −4 ± 0.3 × 10 −5 min −1 ) when using ZnSnO 3 nanowires and Zn 2 SnO 4 nanoparticles and Zn 2 SnO 4 polyhedrons, respectively.…”

“…The photocatalytic degradation of RhB under visible light was measured for 12 h (Figure ). A slight hypsochromic shift of RhB absorption bands can be observed after 4 h of irradiation for all experiments due to the photo-oxidative N-de-ethylation of RhB …”

Ligand exchange on CdSe nanoplatelets for the solar light sensitization of TiO2 and ZnO nanorod arrays

“…[3] QD sensitizers show several advantages such as a tunable absorption spectra [4] and the possibility of breaking the Shockley-Queisser efficiency limit of p-n junction photovoltaic solar cells [5] via multiple exciton generation (MEG) and hot carrier collection. [6] CdSe nanoparticles of different shapes, including QDs, have been widely used to efficiently sensitize ZnO and TiO2 nanostructures for photovoltaic [7] and catalytic applications [8]. In a recent work, we have demonstrated the successful incorporation of quasi-two dimensional (2D) CdSe nanoplatelets (NPLs) into solar cells.…”

FABRICATION OF TiO2 BASED COMPOSITE MATERIALS BY HYDROTHERMAL METHOD

“…Eg values were calculated as 3.18 eV for pure TiO2 sample, 3.26 eV for CdO: TiO2 (10:90) sample and finally 2.87 eV for CdO: TiO2 (20:80) sample(A. Aadim et al 2016;Laatar et al 2017;Kamil et al 2018). The optical band spacing of the composite materials produced varies depending on the composite ratio of the material.…”