Effect of Anodization Time and Temperature on the Morphology of TiO2Nanotube Arrays for Photocatalytic Hydrogen Production from Glycerol Solution

Abstract

Effect of anodization time and temperature on the morphology of TiO2 nanotube arrays (TNTAs) photocatalyst and its application for H2 production from glycerol-water solution has been investigated.The TNTAs were synthesized by anodic oxidation of titanium metal in glycerol electrolyte solution containing NH4F, at 30 V with magnetically stirring. Annealing of the formatted TNTAs were performed at 500 oC for 3 hours under H2in an argon atmosphere, to produce crystalline phase photocatalyst. FESEM analysis showed that up to around 1.57 µm, self-organized and well ordered TNTAs have range of inner diameters and wall thicknesses approximately 67-205 nm and 10-30 nm respectively. Increasing the tube length (as a result of longer anodization time up to 6 hours), produced TNTAs with morphology disintegration. TNTAs synthesized at 50 oC for 1-6 hours anodization time produced TNTAs with length of the tube around 0.8–1 µm. It was found that the inner diameter value of the TNTAs increasing as anodization time increase across the range of 1-6 hours and the temperature increase from 28 to 50 oC. Photocatalytic H2 production indicated that accumulative H2 generation was found to depend on the tube dimension and the morphology of TNTAs as those factors would influence photon absorption. For the TNTAs synthesized at 28 oC for 2 hours, FTIR analysis indicated that C and N were incorporated into the TNTAs lattice. As a result, this TNTAs has the band gap of 2.7 eV, with anatase phase. Photocatalytic H2 production test indicated that this photocatalyst showed higher H