Theoretical Kinetic Analysis of Heterogeneous Photocatalysis by TiO2 Nanotube Arrays: the Effects of Nanotube Geometry on Photocatalytic Activity

• Published in: Journal of physical chemistry. C Vol. 116; no. 13; pp. 7471 - 7479
• Main Authors: Liu, Baoshun, Nakata, Kazuya, Liu, Shanhu, Sakai, Munetoshi, Ochiai, Tsuyoshi, Murakami, Taketoshi, Takagi, Katsuhiko, Fujishima, Akira
• Format: Journal Article
• Language: English
• Published: Columbus, OH American Chemical Society 05-04-2012
• Subjects: Catalysis; Catalysts: preparations and properties; Chemistry; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; General and physical chemistry; Materials science; Nanoscale materials and structures: fabrication and characterization; Nanotubes; Physics; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; Thickness; Kinetic model; Experimental result; Photocatalysis; Size effect; Nanotubes; Theoretical study; Light absorption; Kinetics; Surface area; Arrays; Catalyst activity
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp300481a

TiO2 nanotube arrays are important functional materials in photocatalysis. Compared with other TiO2 materials, the geometrical parameters of the nanotubes in an array significantly affect photocatalytic activity, but how they do this remains unclear. In the present work, a simple theoretical kinetic model to study the effects of nanotube diameter, wall thickness, and length on the photocatalytic activity of TiO2 nanotube arrays is developed, in which reactant (O2) transport is considered. The photocatalytic activity first increases and then decreases as the diameter and wall thickness of the nanotubes increase because of changes in light absorption, surface area, and reactant transport. The photocatalytic activity increases, and then reaches saturation as the nanotube length increases, which is mainly influenced by the change of light absorption along the nanotube. The present kinetic model agrees well with experimental results and clearly explains the photocatalytic activity of TiO2 nanotubes, helping us to understand nanotube photocatalysis.