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Nanoscale Res Lett. 2017 Dec;12(1):261. doi: 10.1186/s11671-017-2036-6. Epub 2017 Apr 7.

Photoelectrochemical Performance of Quantum dot-Sensitized TiO2 Nanotube Arrays: a Study of Surface Modification by Atomic Layer Deposition Coating.

Zhou Q1,2, Zhou J1,2, Zeng M1,2, Wang G2, Chen Y1,2, Lin S3,4.

Author information

1
State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, 570228, People's Republic of China.
2
College of Materials and Chemical Engineering, Hainan University, Haikou, 570228, People's Republic of China.
3
State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, 570228, People's Republic of China. linsw@hainu.edu.cn.
4
College of Materials and Chemical Engineering, Hainan University, Haikou, 570228, People's Republic of China. linsw@hainu.edu.cn.

Abstract

Although CdS and PbS quantum dot-sensitized TiO2 nanotube arrays (TNTAs/QDs) show photocatalytic activity in the visible-light region, the low internal quantum efficiency and the slow interfacial hole transfer rate limit their applications. This work modified the surface of the TNTAs/QDs photoelectrodes with metal-oxide overlayers by atomic layer deposition (ALD), such as coating Al2O3, TiO2, and ZnO. The ALD deposition of all these overlayers can apparently enhance the photoelectrochemical performance of the TNTAs/QDs. Under simulated solar illumination, the maximum photocurrent densities of the TNTAs/QDs with 10 cycles ZnO, 25 cycles TiO2, and 30 cycles Al2O3 overlayers are 5.0, 4.3, and 5.6 mA/cm2 at 1.0 V (vs. SCE), respectively. The photoelectrode with Al2O3 overlayer coating presents the superior performance, whose photocurrent density is 37 times and 1.6 times higher than those of the TNTAs and TNTAs/QDs, respectively. Systematic examination of the effects of various metal-oxide overlayers on the photoelectrochemical performance indicates that the enhancement by TiO2 and ZnO overcoatings can only ascribed to the decrease of the interfacial charge transfer impedance, besides which Al2O3 coating can passivate the surface states and facilitate the charge transfer kinetics. These results could be helpful to develop high-performance photoelectrodes in the photoelectrochemical applications.

KEYWORDS:

Atomic layer deposition; Photoelectrochemical performance; Quantum dots; Surface modification; TiO2 nanotube arrays

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