Anodization of large area Ti: a versatile material for caffeine photodegradation and hydrogen production

Abstract

Facile, single-step, and scalable fabrication of large-area (i.e., ~20 cm2) TiO2 nanostructures (TNS) with excellent photocatalytic activity under UVA-light were prepared via electrochemical anodization. Anodization in glycerol-based electrolyte containing fluoride...

Porous vs. Nanotubular Anodic TiO2: Does the Morphology Really Matters for the Photodegradation of Caffeine?

“…Titanium foil (Sigma-Aldrich, Darmstadt, Germany, 99.7% purity, 0.127 mm thickness, 20 cm 2 area) was used as a starting substrate for the formation of TNS. According to our previous work [9], a circle of 5 cm in diameter was drawn on the square titanium foil and cut out into three corners to make a drop-like shape which was used as a working electrode (titanium foil of 5 × 2 cm 2 was used as a counter electrode). One corner of the electrode was utilized as a handle to fasten the electrode.…”

“…To avoid overheating of the electrolyte, cooling with an ice bath was conducted to possess a constant temperature of 8 • C during anodization. Three different types of electrolytes based on either glycerol or ethylene glycol were used for the synthesis of TNS according to our previous works [9,23]. We also used three optimized electrolyte compositions, which our group often uses [24][25][26][27][28][29][30].…”

“…In particular, anodic TiO 2 nanotube layers [7] with unique properties of a 1D material are promising for photocatalysis [8], hydrogen production [9], DSSCs [10], or biomedical applications [11]. This is due to [7]: (i) high specific surface area and enhanced light absorption due to the materials' 1D structure, (ii) a vertical transport of the photogenerated charge carriers (electron/holes), and (iii) tunable dimensions of the nanotubes, in particular, their length and diameter.…”

“…The flowing high current leads to an increase in the electrolyte temperature and subsequently a dielectric breakdown will occur [13]. To this day, only a few reports deal with the preparation of TiO 2 nanotube layers on areas >10 cm 2 [9,[13][14][15][16][17][18][19][20]. A fieldassisted dissolution of titanium supported by fluoride ions is responsible for the formation of a nanotubular structure [7].…”

“…However, this formed porous TiO 2 possesses a high specific surface area and a sufficient number of active sites necessary for, e.g., photocatalysis similarly to nanotubular TiO 2 . In our recent work [9], we reported that both nanotubular and porous anodic TiO 2 nanostructures (TNS) possess efficient properties in the photocatalytic degradation of caffeine and hydrogen production. Therefore, we aim this work as a followup to our recent paper.…”