Capability of coupled CdSe/TiO2 heterogeneous structure for photocatalytic degradation and photoconductivity.

Miao Zhang,Gang He,Xishun Jiang,Zhaoqi Sun,Lei Yang,Xueping Song,Yanyan Xu,Jianguo Lv

doi:10.1186/1556-276x-9-636

Abstract

Highly ordered TiO2 nanotube arrays (TiO2-NTAs), with a uniform tube size on titanium substrate, were obtained by means of reoxidation and annealing. A composite structure, CdSe quantum dots@TiO2 nanotube arrays (CdSe QDs@TiO2-NTAs), was fabricated by assembling CdSe quantum dots into TiO2-NTAs via cyclic voltammetry electrochemical deposition. The X-ray diffractometer (XRD), field-emission scanning electron microscope (SEM), and transmission electron microscope (TEM) were carried out for the determination of the composition and structure of the tubular layers. Optical properties were investigated by ultraviolet-visible spectrophotometer (UV-Vis). Photocurrent response under visible light illumination and photocatalytic activity of samples by degradation of methyl orange were measured. The results demonstrated that the photo absorption of the composite film shifted to the visible region, and the photocurrent intensity was greatly enhanced due to the assembly of CdSe QDs. Especially, photocurrent achieved a maximum of 1.853 μA/cm2 after five voltammetry cycles of all samples. After irradiation under ultra violet-visible light for 2 h, the degradation rate of composition to methyl orange (MO) reached 88.20%, demonstrating that the CdSe QDs@TiO2-NTAs exhibited higher photocatalytic activity.

Highlights

Very recently, highly ordered TiO2 nanotube arrays (TiO2-NTAs), which were synthesized by anodic oxidation on titanium substrate, had attracted great attention in recent years for solar cells [1], photocatalysis [2], water photoelectrolysis [3], and so on
Quantum dot-sensitized solar cells (QDSSCs) are renowned energy devices known in the past decade for their distinct qualities, including absorb light in the visible region, simplicity in fabrication, tunable band gaps [6], and low cost
The phase of TiO2NTAs transforms to anatase phase under 350°C; it is shown that the CdSe covered both inner and outer wall of TiO2-NTAs efficiently through five cycles voltammetry electrochemical deposition

Summary

Introduction

Highly ordered TiO2 nanotube arrays (TiO2-NTAs), which were synthesized by anodic oxidation on titanium substrate, had attracted great attention in recent years for solar cells [1], photocatalysis [2], water photoelectrolysis [3], and so on. Much effort has been dedicated to expanding the photocatalytic function of the TiO2-NTAs to the visible light region [5]. Quantum dot-sensitized solar cells (QDSSCs) are renowned energy devices known in the past decade for their distinct qualities, including absorb light in the visible region, simplicity in fabrication, tunable band gaps [6], and low cost. Te [10]) QDs, which have small and size-dependent band gaps and provide new opportunities for harvesting light energy in the visible and infrared regions of solar light [11,12,13]. The microstructure, composition, optical activity, and photocatalytic effect of CdSe QDs@TiO2NTAs were investigated systematically

Methods

Results

Conclusion