Issue 1, 2015

N-doped TiO2 nanotubes coated with a thin TaOxNy layer for photoelectrochemical water splitting: dual bulk and surface modification of photoanodes

Abstract

TaON is a good photoanode material with a suitable band structure for water splitting as well as coupling with TiO2 for efficient charge separation. However, the synthesis of TaON that requires high temperature nitridation (850 °C) limits the combination with other materials. In this work, we deposited a thin amorphous TaOxNy layer on N-doped TiO2 nanotubes (N-TNTs) through low temperature nitridation (500 °C) and demonstrated its successful performance as an efficient photoanode for water-splitting. Since the preparation temperature is low, TaOxNy on N-TNTs has a unique amorphous structure with a smooth thin layer (5 nm). It is proposed that the thin amorphous TaOxNy layer plays dual roles: (i) surface sensitization and/or charge rectification at the heterojunction between the TaOxNy layer and N-TNTs, and (ii) passivation of N-TNT surface trap states to retard the charge recombination. TaOxNy layer-decorated N-TNTs as dual modified TNTs (N-doping in the bulk and TaOxNy overlayer deposition on the surface) have significantly improved both visible (ca. 3.6 times) and UV (ca. 1.8 times) activities for PEC water-splitting as well as the faradaic efficiency (ca. 1.4 times, η = 98%) for H2 production. Making the amorphous TaOxNy layer crystalline at higher temperatures reduced the PEC activity of the hybrid photoanode, in contrast, which indicates that the amorphous TaOxNy layer deposition on N-TNTs through low temperature nitridation (500 °C) is optimized for the PEC activity. A range of spectroscopic and electrochemical techniques were systematically employed to investigate the properties of the PEC process.

Graphical abstract: N-doped TiO2 nanotubes coated with a thin TaOxNy layer for photoelectrochemical water splitting: dual bulk and surface modification of photoanodes

Supplementary files

Article information

Article type
Paper
Submitted
12 Jul 2014
Accepted
12 Sep 2014
First published
02 Okt 2014

Energy Environ. Sci., 2015,8, 247-257

N-doped TiO2 nanotubes coated with a thin TaOxNy layer for photoelectrochemical water splitting: dual bulk and surface modification of photoanodes

H. Kim, D. Monllor-Satoca, W. Kim and W. Choi, Energy Environ. Sci., 2015, 8, 247 DOI: 10.1039/C4EE02169J

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements