Please cite this article in press as: G.F. Samu, et al., Photocatalytic, photoelectrochemical, and antibacterial activity of benign-by-design mechanochemically synthesized metal oxide nanomaterials, Catal. Today (2016), http://dx.doi.org/10.1016/j.cattod.2016.07.010 ARTICLE IN PRESS G Model CATTOD-10319; No. of Pages 8 Catalysis Today xxx (2016) xxx–xxx Contents lists available at ScienceDirect Catalysis Today journal homepage: www.elsevier.com/locate/cattod Photocatalytic, photoelectrochemical, and antibacterial activity of benign-by-design mechanochemically synthesized metal oxide nanomaterials Gergely F. Samu a,b , Ágnes Veres a,b,c , Szabolcs P. Tallósy a , László Janovák a , Imre Dékány a,c , Alfonso Yepez d , Rafael Luque d,∗∗ , Csaba Janáky a,b,∗ a Department of Physical Chemistry and Materials Science University of Szeged, Aradi sq. 1, 6720 Szeged Hungary b MTA-SZTE “Lendület” Photoelectrochemistry Research Group Szeged, Rerrich sq. 1, 6720 Hungary c MTA-SZTE Supramolecular and Nanostructured Materials Research Group, Universiy of Szeged, Dóm Sq. 8., 6720, Szeged Hungary d Departamento de Quimica Organica, Universidad de Cordoba, Campus de Rabanales, Edificio Marie Curie (C-3), Ctra Nnal IV-A, Km 396, E14014, Cordoba Spain a r t i c l e i n f o Article history: Received 21 May 2016 Received in revised form 6 July 2016 Accepted 14 July 2016 Available online xxx Keywords: Green synthesis Photocatalysis Environmental remediation Mechanochemistry Nanostructures a b s t r a c t In the search for highly active and stable photocatalysts, significant efforts are devoted to find both new materials and innovative synthetic methods. In this study, an environmentally friendly and sus- tainable approach, dry reactive milling, was employed to synthesize two different semiconducting oxide nanomaterials, namely TiO 2 and ZnO using polysaccharides as sacrificial templates. The as synthesized nanomaterials were characterized by powder X-ray diffraction, transmission electron microscopy, scan- ning electron microscopy, diffuse reflection UV-vis and Raman spectroscopy, and N 2 adsorption tests. Their photocatalytic activity was tested in ethanol degradation, followed by gas chromatographic anal- ysis. Photoelectrochemical measurements were performed to assess the optoelectronic properties and the antimicrobial activity of these photocatalysts was also tested under visible light irradiation. Overall, we found that the performance of the synthesized nanomaterials was comparable to the benchmark P25 EVONIK titania, with ZnO exhibiting a remarkably superior antibacterial activity against E. coli. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Sunlight is undoubtedly the most valuable resource in the quest for a sustainable chemical and energy industry [1]. Photo- catalytic (for thermodynamically downhill) and photo-driven (for thermodynamically uphill) processes [2] can both contribute to the efficient and selective transformation of raw materials to either useful fuels or chemicals. In this regard, nanoparticles of oxide semiconductors are attractive candidates to be employed in envi- ronmental remediation [3,4] (e.g., water purification), solar energy conversion (i.e., water splitting [5,6] or CO 2 reduction [7,8]), and biomass valorization [9,10] to obtain value-added products from earth abundant resources. ∗ Corresponding author at: Rerrich Sq. 1, Szeged, H6720, Hungary. ∗∗ Corresponding author at: Ctra Nnal IV-A, Km 396, E14014, Cordoba, Spain. E-mail addresses: q62alsor@uco.es (R. Luque), janaky@chem.u-szeged.hu (C. Janáky). While there is an extensive and exponentially growing lit- erature covering various fundamental and application oriented aspects of semiconductor photocatalysis (ranging from enhanced light absorption, through size effects, to crystallinity related phe- nomena) [2], much less attention has been devoted to synthetic procedures targeting a benign-by-design approach for nanoma- terials preparation. TiO 2 nanomaterials have been extensively synthesized by means of different strategies [11], mostly related to sol–gel or hydrothermal methods. Despite these efforts, there is a continuously growing need for new methods, which result in crystalline samples with high specific surface areas and excelling physicochemical properties. In addition, time and energy-efficient methods came to the fore- front of interest recently, because they offer shorter energy payback time, which is of prime importance in all solar energy application schemes. For example, solution combustion synthesis [12,13] can be an attractive approach where the exothermicity of the reac- tion together with the release of different gases results in the formation of crystalline nanoparticles. Mechanochemical protocols ensure a rapid, mild, simple, and highly reproducible alternative to http://dx.doi.org/10.1016/j.cattod.2016.07.010 0920-5861/© 2016 Elsevier B.V. All rights reserved.