The scaling of the photocatalytic decay rate with the length of aligned TiO2 nanorod arrays

The photodecay rate κ of methylene blue catalyzed by well-aligned TiO2 nanorod arrays is found to follow a quasi-scaling relationship with the nanorod length h, κ ∝ Mh ξ + N , where M and N are constants, and ξ = 1.0 ± 0.5. A theoretical model based on first-order surface photoreaction predicts that this scaling behavior is directly related to the morphological scaling, ξ = 1 + p + γ, where p = 0.6 ± 0.3 and γ = −0.3 ± 0.3 are the scaling exponents for the nanorod circumference and density versus length. This prediction is consistent with the experimental results.