Photocatalytic degradation of cationic and anionic dyes in water using hydrogen-terminated silicon nanowires as catalyst N. Brahiti a,b , T. Hadjersi a,* , S. Amirouche b , H. Menari a , O. ElKechai b a Centre de Recherche en Technologie des Semi-conducteurs pour L'Energ etique (CRTSE), Division TESE, 2 Bd. Frantz Fanon, B.P. 140 Alger-7 Merveilles, Alger, Algeria b Universit e Mouloud MAMMERI de TiziOuzou, Facult e des Sciences, Algeria article info Article history: Received 30 October 2017 Received in revised form 4 February 2018 Accepted 20 February 2018 Available online xxx Keywords: Nanostructures Silicon nanowires Chemical etching Electron microscopy Surface properties Photocatalysis abstract The photocatalytic degradation of cationic (methylene blue (MB)) and anionic (methyl or- ange (MO)) dyes was investigated using hydrogen-terminated silicon nanowires (H-SiNWs) as photocatalysts. Several silicon nanowires samples with different morphologies were elaborated and the morphology was changed by acting on the silicon nanowires formation parameters such as substrate type, doping level, crystallographic orientation, silver deposition time and etching time. It was shown that the photocatalytic activity strongly depends on the morphology of SiNWs arrays. Indeed, it was found that n-type H-SiNWs elaborated on highly doped Si (100) substrates exhibit the highest photocatalytic activity for the degradation of MB. In addition, it was demonstrated that H-SiNWs are more efficient for the photodegradation of MO than MB in the solutions with pH values higher than the pH of zero charge point of silica (pH pzc ). © 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Introduction The textile industry is a large consumer of water, much of which is used in the dyeing process. Thusa large quantity of dye ef- fluents is discharged in the environment [1]. The treatment of these waters remains a major challenge especially for devel- oping countries that did not have all the opportunities to inte- grate sustainable development concepts. Conventional treatments (activated carbon adsorption, membrane processes, coagulation-flocculation, chemical oxidation, etc.) have the disadvantage of transferring pollution from an aqueous phase to a new phase, and lead mostly to the formation of concen- trated sludge. This creates a problem of secondary waste which needs very expensive treatment processes [1,2]. Advanced Oxidation Processes (AOPs) are promising alternative tech- niques of destruction of dyes and many other organics in wastewater and effluents [3]. Indeed, they have the advantage to be less expensive and allow to a complete mineralization of organic pollutants. * Corresponding author. E-mail addresses: dihiabrahiti@yahoo.fr (N. Brahiti), hadjersi@yahoo.com (T. Hadjersi). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy xxx (2018) 1 e11 https://doi.org/10.1016/j.ijhydene.2018.02.141 0360-3199/© 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved. Please cite this article in press as: Brahiti N, et al., Photocatalytic degradation of cationic and anionic dyes in water using hydrogen- terminated silicon nanowires as catalyst, International Journal of Hydrogen Energy (2018), https://doi.org/10.1016/ j.ijhydene.2018.02.141