Hierarchical Ta-Doped TiO₂ Nanorod Arrays with Improved Charge Separation for Photoelectrochemical Water Oxidation under FTO Side Illumination.

Shiman He,Jingling Yang,Yangfei Cao,Mingmei Wu,Yuying Meng,Senchuan Huang,Shengfu Tong

doi:10.3390/nano8120983

Shiman He, Jingling Yang + Show 5 more

Open Access

https://doi.org/10.3390/nano8120983

Copy DOI

Journal: Nanomaterials	Publication Date: Nov 28, 2018
Citations: 12	License type: CC BY 4.0

Affiliation: Sun Yat-sen University

Abstract

TiO2 is one of the most attractive semiconductors for use as a photoanode for photoelectrochemical (PEC) water oxidation. However, the large-scale application of TiO2 photoanodes is restricted due to a short hole diffusion length and low electron mobility, which can be addressed by metal doping and surface decorating. In this paper we report the successful synthesis of hierarchical Ta doped TiO2 nanorod arrays, with nanoparticles on the top (Ta:TiO2), on F-doped tin oxide (FTO) glass by a hydrothermal method, and its application as photoanodes for photoelectrochemical water oxidation. It has been found that the incorporation of Ta5+ in the TiO2 lattice can decrease the diameter of surface TiO2 nanoparticles. Ta:TiO2-140, obtained with a moderate Ta concentration, yields a photocurrent of ∼1.36 mA cm−2 at 1.23 V vs. a reversible hydrogen electrode (RHE) under FTO side illumination. The large photocurrent is attributed to the large interface area of the surface TiO2 nanoparticles and the good electron conductivity due to Ta doping. Besides, the electron trap-free model illustrates that Ta:TiO2 affords higher transport speed and lower electron resistance when under FTO side illumination.

Highlights

With the growing demand for energy and the concern of environmental problems worldwide, solar energy has long been regarded as one of the cleanest and renewable energy sources to address these challenges [1]
We demonstrate that the efficiency of the TiO2 nanorod arrays can be improved by surface nanoparticles and Ta doping
As shown in the cross image of Ta:TiO2-140 inserted in Figure 1b, there was no obvious difference in the nanorods’ diameter and length in comparison with Ta:TiO2-0, while viewed from the surface image, the diameter of the particles on the top of the nanorods was only 40 nm

Summary

Introduction

With the growing demand for energy and the concern of environmental problems worldwide, solar energy has long been regarded as one of the cleanest and renewable energy sources to address these challenges [1]. From an unlimited solar energy perspective, it is highly desirable to convert sunlight into an energy storage medium to provide continuous and stable power. Photoelectrochemical (PEC) water splitting is an attractive, clean, and environmentally-friendly approach to producing oxygen and hydrogen using sunlight and bias voltage [2]. A key target in PEC research continues to be the development of novel and efficient semiconductor photoelectrocatalysts. TiO2 has been one of the most promising candidates among various semiconductors since the pioneering work demonstrated by Fujishima and Honda in 1972, because of its chemical stability, cost effectiveness, and nontoxicity [3]. Many efforts have been devoted to addressing these issues [4]

Methods

Results

Conclusion