Review Applications of TiO 2 nanotube arrays in environmental and energy fields: A review Qingxiang Zhou ⇑ , Zhi Fang, Jing Li, Mengyun Wang Beijing Key Laboratory of Oil and Gas Pollution Control, College of Geosciences, China University of Petroleum Beijing, Beijing 102249, China article info Article history: Received 31 December 2013 Received in revised form 1 September 2014 Accepted 15 September 2014 Available online 29 September 2014 Keywords: TiO 2 nanotube arrays Photocatalysis Environmental analytical chemistry Hydrogen production Solar cells abstract TiO 2 nanotube arrays, novel TiO 2 -based nanomaterials with unique chemical and physical properties, have been demonstrated to serve as multifunctional materials which show great promise in addressing many challenges in both environmental and energy technology fields. They have exhibited extraordinary catalytic abilities in several cases: in the degradation of environmental inorganic and organic pollutants to less toxic compounds, water splitting, and in the reduction of atmospheric CO 2 levels by incorporation of CO 2 into hydrocarbons, among others. Moreover, the wide absorption spectrum characteristics and dis- tinct electrochemical properties of modified TiO 2 nanotube arrays make them excellent candidates for use in solar cells and sensitive sensors for trace compounds, etc. This review focuses on the recent applications of TiO 2 nanotube arrays in removal of pollutants, environmental analytical chemistry, water splitting, solar cells and CO 2 conversion. Ó 2014 Elsevier Inc. All rights reserved. Contents 1. Introduction .......................................................................................................... 23 2. Photocatalytic degradation of pollutants ................................................................................... 23 2.1. TiO 2 nanotube arrays as photocatalysts ............................................................................... 23 2.2. Modified TiO 2 nanotube arrays as photocatalysts ....................................................................... 25 2.2.1. Doping TiO 2 nanotube arrays................................................................................ 25 2.2.2. Loading on the TiO 2 nanotube arrays ......................................................................... 25 2.2.3. TiO 2 nanotube array heterojunctions ......................................................................... 28 3. Environmental analytical chemistry ....................................................................................... 28 3.1. Sensors ......................................................................................................... 28 3.1.1. Gas monitoring ........................................................................................... 28 3.1.2. Detection of heavy metal ions ............................................................................... 28 3.1.3. Detection of organic pollutants .............................................................................. 29 3.2. Measurement of COD ............................................................................................. 29 3.3. Sample pretreatment ............................................................................................. 29 4. Applications in sensitized solar cells (SSCs) ................................................................................. 30 5. Hydrogen production ................................................................................................... 32 6. Photocatalytic conversion of CO 2 ......................................................................................... 33 7. Conclusions ........................................................................................................... 34 Acknowledgements .................................................................................................... 34 References ........................................................................................................... 34 http://dx.doi.org/10.1016/j.micromeso.2014.09.040 1387-1811/Ó 2014 Elsevier Inc. All rights reserved. ⇑ Corresponding author. Tel./fax: +86 10 89732300. E-mail address: zhouqx@cup.edu.cn (Q. Zhou). Microporous and Mesoporous Materials 202 (2015) 22–35 Contents lists available at ScienceDirect Microporous and Mesoporous Materials journal homepage: www.elsevier.com/locate/micromeso