2D Porous TiO2 Single-Crystalline Nanostructure Demonstrating High Photo-Electrochemical Water Splitting Performance

Teera Butburee; Yang Bai; Huanjun Wang; Hongjun Chen; Zhiliang Wang; Gang Liu; Jin Zou; Pongtanawat Khemthong; Gao Qing Max Lu; Lianzhou Wang

doi:10.1002/adma.201705666

2D Porous TiO₂ Single-Crystalline Nanostructure Demonstrating High Photo-Electrochemical Water Splitting Performance

Adv Mater. 2018 May;30(21):e1705666. doi: 10.1002/adma.201705666. Epub 2018 Apr 16.

Authors

Teera Butburee^{1

2}, Yang Bai¹, Huanjun Wang¹, Hongjun Chen¹, Zhiliang Wang¹, Gang Liu^{3

4}, Jin Zou⁵, Pongtanawat Khemthong², Gao Qing Max Lu⁶, Lianzhou Wang¹

Affiliations

¹ Nanomaterials Centre, Australian Institute for Bioengineering and Nanotechnology and School of Chemical Engineering, The University of Queensland, St Lucia, QLD, 4072, Australia.
² National Nanotechnology Center (NANOTEC), National Science and Technology Development Agency (NSTDA), Klong Luang, Pathumthani, 12120, Thailand.
³ Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang, 110016, China.
⁴ School of Materials Science and Engineering, University of Science and Technology of China, 72 Wenhua Road, Shenyang, 110016, China.
⁵ Materials Engineering and Centre for Microscopy and Microanalysis, The University of Queensland, St. Lucia, QLD, 4072, Australia.
⁶ The University of Surrey, Guildford, Surrey, GU2 7XH, UK.

PMID: 29659100
DOI: 10.1002/adma.201705666

Abstract

Porous single crystals are promising candidates for solar fuel production owing to their long range charge diffusion length, structural coherence, and sufficient reactive sites. Here, a simple template-free method of growing a selectively branched, 2D anatase TiO₂ porous single crystalline nanostructure (PSN) on fluorine-doped tin oxide substrate is demonstrated. An innovative ion exchange-induced pore-forming process is designed to successfully create high porosity in the single-crystalline nanostructure with retention of excellent charge mobility and no detriment to crystal structure. PSN TiO₂ film delivers a photocurrent of 1.02 mA cm^-2 at a very low potential of 0.4 V versus reversible hydrogen electrode (RHE) for photo-electrochemical water splitting, closing to the theoretical value of TiO₂ (1.12 mA cm^-2 ). Moreover, the current-potential curve featuring a small potential window from 0.1 to 0.4 V versus RHE under one-sun illumination has a near-ideal shape predicted by the Gartner Model, revealing that the charge separation and surface reaction on the PSN TiO₂ photoanode are very efficient. The photo-electrochemical water splitting performance of the films indicates that the ion exchange-assisted synthesis strategy is effective in creating large surface area and single-crystalline porous photoelectrodes for efficient solar energy conversion.

Keywords: 2D; ion-exchange; pore-forming; porous single-crystalline TiO2 films; water splitting.