This journal is c The Royal Society of Chemistry 2012 Chem. Commun., 2012, 48, 5733–5735 5733 Cite this: Chem. Commun., 2012, 48, 5733–5735 Hydrogenated titania: synergy of surface modification and morphology improvement for enhanced photocatalytic activityw Zhaoke Zheng, a Baibiao Huang,* a Jibao Lu, b Zeyan Wang, a Xiaoyan Qin, a Xiaoyang Zhang, a Ying Dai b and Myung-Hwan Whangbo c Received 27th March 2012, Accepted 14th April 2012 DOI: 10.1039/c2cc32220j Surface-hydrogenated anatase TiO 2 (TiO 2 –H) nanowire- microspheres were prepared by converting protonated titanate nanotube to TiO 2 –H under a hydrogen atmosphere. We show that TiO 2 –H nanowire-microspheres have Ti–H and O–H bonds on their surface and exhibit improved visible-light absorption and highly enhanced photocatalytic activity. Titanium dioxide (TiO 2 ) can use the UV part of solar energy to produce hydrogen from water and oxidize water pollutants, and hence has been the most widely used oxide semiconductor photocatalyst. 1 However, the efficiency of TiO 2 is substantially limited by its large band gap energy and usually fast electron– hole recombination. For the latter constraint, it can be improved by nanostructuring the morphology (e.g., nanowire). 2 To our knowledge, single-crystalline anatase nanowire with diameter less than 10 nm has not been reported for photo- catalysis. On the other hand, it is equally essential to funda- mentally improve the visible-light absorption of TiO 2 . Recently, Mao et al. 3 presented a radically different method to enable the visible-light absorption in TiO 2 , namely, hydro- genation of the surface of anatase TiO 2 to introduce surface disorder. Further, Li et al. 4 showed that the performance of TiO 2 for photo-electrochemical water splitting is strongly improved upon hydrogen treatment. So far, it has been unclear how hydrogenation modifies the TiO 2 surface and why such a modified surface enhances the photocatalytic activities of TiO 2 . There has been no systematic study con- cerning the nature of the surface change brought about by hydrogenation. Moreover, most surface modification methods require good crystalline TiO 2 samples as precursors, 3–6 and are difficult to implement for practical use because they usually require high pressure and high energy. It is desirable to find an economical way of generating surface modified and morphology- improved TiO 2 . Protonated titanate nanotubes (H–TiNTs), with general formula [H 2 Ti n O 2nm+1 (OH) 2m xH 2 O], possess a large number of protons on their walls and a high capacity for molecular hydrogen storage. 7,8 Herein, we report a facile method to synthesize surface-hydrogenated anatase TiO 2 (TiO 2 –H) nanowire-microspheres by converting H–TiNT to TiO 2 –H under a hydrogen atmosphere. We show that TiO 2 –H nanowire- microspheres, consisting of anatase nanowires with a tiny diameter of 8 nm, have Ti–H and O–H bonds on their surface, and exhibit improved visible-light absorption and highly enhanced photocatalytic activity. For comparison, the sample obtained from H–TiNT microspheres by annealing them in air will be denoted as TiO 2 –air microspheres. Diffuse reflectance measurements reveal that TiO 2 –H nanowire-microspheres exhibit highly enhanced visible-light absorption (Fig. 1a). In good agreement with these measurements, Fig. 1 (a) UV-vis absorption spectra, (b) XRD pattern of TiO 2 –H and TiO 2 –air microspheres. (c,d) SEM and (e,f) HRTEM images of TiO 2 –H nanowire-microspheres. a State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, China. E-mail: bbhuang@sdu.edu.cn; Tel: +86-531-8836-6324 b School of Physics, Shandong University, Jinan 250100, China c Department of Chemistry, North Carolina State University, Raleigh, USA w Electronic supplementary information (ESI) available: Experimental details, HRTEM, FTIR spectra and TGA curve. See DOI: 10.1039/ c2cc32220j ChemComm Dynamic Article Links www.rsc.org/chemcomm COMMUNICATION Downloaded by SHANDONG UNIVERSITY on 09/04/2013 10:29:30. Published on 16 April 2012 on http://pubs.rsc.org | doi:10.1039/C2CC32220J View Article Online / Journal Homepage / Table of Contents for this issue