Black Si-doped TiO2 nanotube photoanode for high-efficiency photoelectrochemical water splitting.

Zhenbiao Dong,Congqin Ning,Ting Li,Dongyan Ding

doi:10.1039/c8ra00021b

Abstract

Black Si-doped TiO2 (Ti–Si–O) nanotubes were fabricated through Zn metal reduction of the Ti–Si–O nanotubes on Ti–Si alloy in an argon atmosphere. The nanotubes were used as a photoanode for photoelectrochemical (PEC) water splitting. Both Si element and Ti3+/oxygen vacancies were introduced into the black Ti–Si–O nanotubes, which improved optical absorption and facilitated the separation of the photogenerated electron–hole pairs. The photoconversion efficiency could reach 1.22%, which was 7.18 times the efficiency of undoped TiO2. It demonstrated that a Si element and Ti3+/oxygen vacancy co-doping strategy could offer an effective method for fabricating a high-performance TiO2-based nanostructure photoanode for improving PEC water splitting.

Highlights

PEC solar-driven water splitting hydrogen production based on semiconductor photocatalysts has been regarded as a promising method to decrease fossil fuel consumption and solve environmental problems.[1]
The black Ti–Si–O nanotubes photoanode co-doped with Si element and Ti3+ exhibited remarkable PEC water splitting properties in comparison with undoped TiO2
Electronic structure calculation was carried out using the Cambridge Serial Total Energy Package (CASTEP) module based on the density functional theory (DFT) rst-principles.[18]

Summary

Introduction

PEC solar-driven water splitting hydrogen production based on semiconductor photocatalysts has been regarded as a promising method to decrease fossil fuel consumption and solve environmental problems.[1]. One is the short diffusion paths of the charge carriers, and another is its large band gap. This leads to rapid recombination of photoinduced electrons–holes and little absorption in the visible light region.[6,7] great efforts have been made to improve the photoelectrical properties through ion doping,[8,9] narrow band gap semiconductor coupling,[10,11] noble metal deposition,[12,13] quantum dot sensitization, etc.[14,15]. The black Ti–Si–O nanotubes photoanode co-doped with Si element and Ti3+ exhibited remarkable PEC water splitting properties in comparison with undoped TiO2

Preparation of the black Ti–Si–O nanotubes

Electronic structure calculation

Material characterization

PEC measurement

Results and discussion

Conclusions