Doped and undoped anatase-based plates obtained from paper templates for photocatalytic oxidation of NO X Siara Silvestri a,n , Bruno Szpoganicz a , Juliana Schultz b , Antonio S. Mangrich b,c , Dachamir Hotza d , Daniel E. García d , João A. Labrincha e a Departamento de Química (QMC), Universidade Federal de Santa Catarina (UFSC), 88040-900 Florianópolis, SC, Brazil b Departamento de Química, Universidade Federal do Paraná (UFPR), 81531-980 Curitiba, PR, Brazil c Instituto Nacional de Ciência e Tecnologia de Energia e Ambiente (INCT E&A), Universidade Federal da Bahia (UFBA), 40170-115 Salvador, BA, Brazil d Departamento de Engenharia Química (EQA), Universidade Federal de Santa Catarina (UFSC), 88040-900 Florianópolis, SC, Brazil e Departamento de Engenharia de Materiais e Cerâmica, Universidade de Aveiro, 3810-193 Aveiro, Portugal article info Article history: Received 2 February 2016 Received in revised form 23 April 2016 Accepted 23 April 2016 Keywords: Titanium dioxide NO x Photocatalysis Biotemplate abstract Titanium dioxide is frequently used for the photocatalytic degradation of organic and inorganic pollu- tants present in the air, such as NOx. In this work, biomorphic anatase-based plates were manufactured using paper as an innovative template for fixation of TiO 2 . Ceramics with microstructure similar to paper were produced by infiltration of titanium isopropoxide (TTiP) and dopants, followed by hydrolysis in NH 4 OH, air drying, and calcination at temperatures up to 1000 °C. After heat treatment, the samples were characterized by XRD, TG/DTA, BET, EPR, and SEM. Anatase was obtained as the major phase at 800 °C and remained present up to 1000 °C. In tests of photocatalytic efficiency of produced plates for de- gradation of NO x gases, the best performance was obtained with a biomorphic anatase-based plate prepared using TTiP doped with 5% Zr 4 þ , corresponding to 100% degradation of NO x in 35 min. & 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved. 1. Introduction Due to the increased emissions of greenhouse gases (GHG) by motor vehicles and agricultural activities, there is a need to re- move pollutants including nitrogen oxides (NO x ) from the atmo- sphere. In addition to their effects as GHG, these gases are also harmful to health [1]. In atmospheric chemistry, NO x refers to the sum of nitric oxide (NO) and nitrogen dioxide (NO 2 ). NO x , CO, and volatile organic compounds (VOCs) are O 3 precursors, so an indirect way to reduce tropospheric ozone levels is to remove these local pollutants by photocatalytic processes [2]. NO x pollution is also often associated with particulate matter, which can exacerbate the effects on hu- man health [2]. Inorganic photocatalysts, such as titanium dioxide, have been employed for the relatively inexpensive and effective removal of toxic organic compounds and pollutant gases from both air and aqueous environments [1,3]. Organic compounds can be oxidized to CO 2 by free radicals generated on TiO 2 surfaces when activated by UV light [4], including radical species such as O 2   [5–7] and O 3   [8,9], Consequently, there have been many studies of TiO 2 photocatalysis using titania thin films, powders, paving, and paints for the removal of pollutants from the environment [1,3,4,10–12]. In NO x degradation tests using TiO 2 powder, Chin et al. [10] reported NO x degradation efficiency that was 10% higher than achieved with commercial P25 powder. Using immobilized pow- der paint, Maggos et al. [12] obtained a photocatalytic efficiency of 20% in 600 min, while addition of the powder to cement mortars resulted in photocatalytic efficiencies of 90% in 40 min [11] and 100% in 90 min [1]. Biomodeling or biotemplating techniques have been developed using natural structures such as wood, fibers, and pulp as models in conversion techniques employing ceramic materials and com- posites [13,14]. Natural structures are low-cost materials and are available at the commercial scale. Different processing techniques can be employed to manufacture ceramics and composites from natural preformed structures, depending on the desired properties of the final materials, considering parameters such as mechanical strength, specific surface area, porosity, and pore size distribution [14–16]. Photocatalysts activated by UV light have a wide range of po- tential new applications, including the improvement of air quality in external environments. Paper has been used as a biotemplate to produce biomorphic TiO 2 plates, as an innovative green technique for the fixation of TiO 2 , without any need to remove the particles at the end of the process [17]. Structures of this type are important Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/ceramint Ceramics International http://dx.doi.org/10.1016/j.ceramint.2016.04.137 0272-8842/& 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved. n Corresponding author. E-mail address: siarasilvestri@gmail.com (S. Silvestri). Please cite this article as: S. Silvestri, et al., Doped and undoped anatase-based plates obtained from paper templates for photocatalytic oxidation of NO X , Ceramics International (2016), http://dx.doi.org/10.1016/j.ceramint.2016.04.137i Ceramics International ∎ (∎∎∎∎) ∎∎∎–∎∎∎