title: Self-Organized TiO₂-MnO₂ Nanotube Arrays for Efficient Photocatalytic Degradation of Toluene.
abstract: Vertically oriented, self-organized TiO₂-MnO₂ nanotube arrays were successfully obtained by one-step anodic oxidation of Ti-Mn alloys in an ethylene glycol-based electrolyte. The as-prepared samples were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), UV-Vis absorption, photoluminescence spectroscopy, X-ray diffraction (XRD), and micro-Raman spectroscopy. The effect of the applied potential (30-50 V), manganese content in the alloy (5-15 wt. %) and water content in the electrolyte (2-10 vol. %) on the morphology and photocatalytic properties was investigated for the first time. The photoactivity was assessed in the toluene removal reaction under visible light, using low-powered LEDs as an irradiation source (λmax= 465 nm). Morphology analysis showed that samples consisted of auto-aligned nanotubes over the surface of the alloy, their dimensions were: diameter = 76-118 nm, length = 1.0-3.4 μm and wall thickness = 8-11 nm. It was found that the increase in the applied potential led to increase the dimensions while the increase in the content of manganese in the alloy brought to shorter nanotubes. Notably, all samples were photoactive under the influence of visible light and the highest degradation achieved after 60 min of irradiation was 43%. The excitation mechanism of TiO₂-MnO₂ NTs under visible light was presented, pointing out the importance of MnO₂ species for the generation of e-and h⁺.
authors.affiliation: Facultad de Ingeniería Química y Agroindustria, Escuela Politécnica Nacional, Ladrón de Guevara E11-253, P.O. Box 17-01-2759, Quito 170525, Ecuador. ma.cristina.nevarez@gmail.com.|Centro de Investigación y Control Ambiental "CICAM", Departamento de Ingeniería Civil y Ambiental, Facultad de Ingeniería Civil y Ambiental, Escuela Politécnica Nacional, Ladrón de Guevara E11-253, P.O. Box 17-01-2759, Quito 170525, Ecuador. ma.cristina.nevarez@gmail.com.
authors.forename: María C
authors.initials: MC
authors.lastname: Nevárez-Martínez
authors.affiliation: Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, 80-308 Gdansk, Poland. marek.kobylanski@phdstud.ug.edu.pl.
authors.forename: Marek P
authors.initials: MP
authors.lastname: Kobylański
authors.affiliation: Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, 80-308 Gdansk, Poland. pawel.mazierski@phdstud.ug.edu.pl.
authors.forename: Paweł
authors.initials: P
authors.lastname: Mazierski
authors.affiliation: Faculty of Chemistry, Nicolaus Copernicus University, 87-100 Torun, Poland. jolanta.wolkiewicz@umk.pl.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Wółkiewicz
authors.affiliation: Faculty of Chemistry, Nicolaus Copernicus University, 87-100 Torun, Poland. tryki@umk.pl.
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Trykowski
authors.affiliation: Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, 80-308 Gdansk, Poland. anna.malankowska@ug.edu.pl.
authors.forename: Anna
authors.initials: A
authors.lastname: Malankowska
authors.affiliation: Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, 80-308 Gdansk, Poland. magda.kozak@ug.edu.pl.
authors.forename: Magda
authors.initials: M
authors.lastname: Kozak
authors.affiliation: Centro de Investigación y Control Ambiental "CICAM", Departamento de Ingeniería Civil y Ambiental, Facultad de Ingeniería Civil y Ambiental, Escuela Politécnica Nacional, Ladrón de Guevara E11-253, P.O. Box 17-01-2759, Quito 170525, Ecuador. patricio.espinoza@epn.edu.ec.
authors.forename: Patricio J
authors.initials: PJ
authors.lastname: Espinoza-Montero
authors.affiliation: Department of Environmental Technology, Faculty of Chemistry, University of Gdansk, 80-308 Gdansk, Poland. adriana.zaleska@ug.edu.pl.
authors.forename: Adriana
authors.initials: A
authors.lastname: Zaleska-Medynska
mesh_terms: D002384:Catalysis / Q000528:radiation effects; D007700:Kinetics; D017895:Manganese Compounds / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure; D010087:Oxides / Q000737:chemistry*; D055668:Photochemical Processes / Q000528:radiation effects*; D013056:Spectrophotometry, Ultraviolet; D013059:Spectrum Analysis, Raman; D014025:Titanium / Q000737:chemistry*; D014050:Toluene / Q000737:chemistry* / Q000528:radiation effects*; D014961:X-Ray Diffraction
chemical_list: D017895:Manganese Compounds; D010087:Oxides; C009495:titanium dioxide; D014050:Toluene; C027424:manganese oxide; D014025:Titanium
keywords: TiO2–MnO2 nanotubes; alloys; anodization; toluene degradation; visible light induced photocatalysis