Applied Catalysis B: Environmental 162 (2015) 27–33 Contents lists available at ScienceDirect Applied Catalysis B: Environmental j ourna l h om epage: www.elsevier.com/locate/apcatb Solvothermal synthesis and photocatalytic performance of Mn 4+ -doped anatase nanoplates with exposed {0 0 1} facets Maria-Veronica Sofianou a , Maria Tassi a , Vassilis Psycharis a , Nikos Boukos a , Stavros Thanos a , Tiverios Vaimakis b , Jiaguo Yu c , Christos Trapalis a,∗ a Institute of Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, National Center for Scientific Research “Demokritos”, 153 10 Attiki, Greece b Department of Chemistry, University of Ioannina, 451 10, Ioannina, Greece c State Key Laboratory for Advanced Technology Materials Synthesis & Processing, Wuhan University of Technology, Wuhan 430070, People’s Republic of China a r t i c l e i n f o Article history: Received 18 February 2014 Received in revised form 24 May 2014 Accepted 29 May 2014 Available online 5 June 2014 Keywords: Mn 4+ /TiO2 Anatase nanoplates {0 0 1} facets Photocatalysis NO oxidation Acetaldehyde decomposition a b s t r a c t The photocatalytic activity of TiO 2 and manganese doped TiO 2 nanoplates with various manganese atomic percentages, in the range of 2–7%, was studied. The undoped and doped nanoplates with exposed {0 0 1} facets were produced by a solvothermal method. The crystal structure as well as the shape of the TiO 2 and Mn 4+ /TiO 2 anatase nanoparticles was determined with X-ray powder diffraction (XRD) and trans- mission electron microscopy (TEM). Both techniques revealed that the nanocrystals are in the form of plates. Moreover, the anisotropic peak broadening of the X-ray diffraction patterns was studied using the Rietveld refining method. Chemical analysis of the photocatalyst that was carried out with X-ray photoelectron spectroscopy (XPS) showed the presence of manganese ions in the TiO 2 anatase matrix. The Density Functional Theory (DFT) calculations exhibited a decrease in the energy gap and an increase in the density of the electronic stated inside the gap for the doped TiO 2. These observations were in agreement with the results of the UV–visible diffuse reflectance spectroscopy (DRS) that demonstrated an adsorption shift towards the visible region for the same samples. The photocatalytic activity of the synthesized catalysts was investigated by the photocatalytic oxidation of the gaseous nitric oxide (NO) and decomposition of the gaseous acetaldehyde (CH 3 CHO) under visible light irradiation. The optimal concentration of dopant that improves the photocatalytic activity of the nanoplates was determined. © 2014 Elsevier B.V. All rights reserved. 1. Introduction Titanium dioxide (TiO 2 ), also known as titania, is an exten- sively studied oxide semiconductor photocatalysts. The anatase phase of titania has been proven to be among other various oxide semiconductors the most suitable photocatalyst for environmen- tal applications due to its nontoxicity, low cost, strong oxidizing power and long term stability against photocorrosion and chemical corrosion [1–4]. However, its relatively large wide band gap (∼3.2 eV) and the high recombination rate of the photogenerated electron and hole pairs hinders its applications [5]. Therefore, considerably efforts ∗ Corresponding author at: Institute of Advanced Materials, Physicochemical Processes, Nanotechnology and Microsystems, NCSR “Demokritos”, 153 10 Ag. Paraskevi, Attikis, Greece. Tel.: +30 210 650 3343; fax: +30 210 651 9430. E-mail address: trapalis@ims.demokritos.gr (C. Trapalis). have been made in order to narrow the anatase band gap towards the visible region of the light spectrum. Some of these several band gap modifications have been suggested such as fabricating com- posites with other oxide semiconductors, sensitizing with low bad semiconductors, adding nonmetals or metal ions [6–9]. One of the most efficient way to make the TiO 2 anatase active under visible light is doping or surface modification with transition metal cations or their oxides [10–15]. It has also been proven that the transition metal dopants also inhibit the photogenerated charge recombi- nation as the meta sites are considered to act as trapping site by accepting the photogenerated electrons from the TiO 2 valance band [16,17]. Moreover, several theoretical and experimental stud- ies have shown that the (0 0 1) surface of the anatase crystal is more reactive than the (1 0 1) surface [18,19]. This implies that TiO 2 anatase structures with exposed {0 0 1} crystal facets doped with transition metal ions will achieve high photocatalytic activity. This study reports the synthetic procedure of manganese ion doped TiO 2 anatase crystalline structures in the form of nanoplates http://dx.doi.org/10.1016/j.apcatb.2014.05.049 0926-3373/© 2014 Elsevier B.V. All rights reserved.